METHODS AND OUTCOMES

CARDIOVERSION AND ABLATION

JASSIN M. JOURIA

Dr. Jassin M. Jouria is a practicing Emergency Medicine physician, professor of academic medicine, and medical author. He graduated from Ross University School of Medicine and has completed his clinical clerkship training in various teaching hospitals throughout New York, including King’s County Hospital Center and Brookdale Medical Center, among others. Dr. Jouria has passed all USMLE medical board exams, and has served as a test prep tutor and instructor for Kaplan. He has developed several medical courses and curricula for a variety of educational institutions. Dr. Jouria has also served on multiple levels in the academic field including faculty member and Department Chair. Dr. Jouria continues to serve as a Subject Matter Expert for several continuing education organizations covering multiple basic medical sciences. He has also developed several continuing medical education courses covering various topics in clinical medicine. Recently, Dr. Jouria has been contracted by the University of Miami/Jackson Memorial Hospital’s Department of Surgery to develop an e-module training series for trauma patient management. Dr. Jouria is currently authoring an academic textbook on Human Anatomy & Physiology.

ABSTRACT

Atrial are serious disorders that can cause an irregular and/or rapid heartbeat, which can lead to serious clinical sequelae. Atrial is an example of an atrial that can lead to blood clots, stroke, or failure. Electrical cardioversion and ablation are two procedures that can minimize these risks and treat atrial arrhythmia. Each of these treatments have risks and neither offers a complete success rate, but they can be very effective in providing greater quality of life, and extending the life expectancy of patients.

1 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Policy Statement

This activity has been planned and implemented in accordance with the policies of NurseCe4Less.com and the continuing nursing education requirements of the American Nurses Credentialing Center's Commission on Accreditation for registered nurses. It is the policy of NurseCe4Less.com to ensure objectivity, transparency, and best practice in clinical education for all continuing nursing education (CNE) activities.

Continuing Education Credit Designation

This educational activity is credited for 2.5 hours. Nurses may only claim credit commensurate with the credit awarded for completion of this course activity. Pharmacology content is 0.5 hours (30 minutes).

Statement of Learning Need

Cardioversion and cardiac ablation for the treatment of resistant atrial arrhythmia has been analyzed in the medical literature, including benefits and risks. Clinicians need to understand the indications and efficacy of both procedures to treat atrial arrhythmia and to reduce cardiac system burden. Clinical research is growing with evolving recommendations for clinicians managing refractory atrial arrhythmia and to plan cardioversion or ablation.

Course Purpose

To provide clinicians with knowledge of cardiac atrial arrhythmias and of the treatments of cardioversion and cardiac to reverse symptoms of atrial arrhythmia and potentially adverse outcomes.

2 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Target Audience

Advanced Practice Registered Nurses and Registered Nurses (Interdisciplinary Health Team Members, including Vocational Nurses and Medical Assistants may obtain a Certificate of Completion)

Course Author & Planning Team Conflict of Interest Disclosures

Jassin M. Jouria, MD, William S. Cook, PhD, Douglas Lawrence, MA, Susan DePasquale, MSN, FPMHNP-BC – all have no disclosures

Acknowledgement of Commercial Support

There is no commercial support for this course.

Please take time to complete a self-assessment of knowledge, on page 4, sample questions before reading the article. Opportunity to complete a self-assessment of knowledge learned will be provided at the end of the course.

3 nursece4less.com nursece4less.com nursece4less.com nursece4less.com 1. The external electrical cardioversion procedure is used to treat arrhythmias

a. only if cardiac catheter ablation fails. b. as the first-line therapy. c. to reorganize the heart’s electrical rhythm. d. by delivering a “shock” directly to a mechanical pacemaker.

2. The electrical cardioversion procedure is contraindicated for patients with

a. digitalis toxicity. b. mechanical pacemakers. c. very low blood pressure. d. breathing difficulties.

3. Planned cardioversion is usually performed

a. in an outpatient setting. b. in an emergency setting because of the risks. c. with an analgesic, not a . d. in a hospital setting.

4. Synchronized cardioversion uses ______delivered at a timed point in the to reset an arrhythmia back to normal .

a. a high-energy shock b. a charged chemical c. a low-energy shock d. a random-level shock

5. Synchronized cardioversion means the electrical impulse is delivered

a. during the T wave. b. during the QRS complex, at the peak of the R wave. c. to the SA node. d. to the atria.

4 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Introduction

When an arrhythmia develops, the heart may beat at a rate that is irregular and that is faster or slower than normal. If the is significantly abnormal, the affected person may experience distressing symptoms because not enough blood is being pumped to the tissues. Electrical cardioversion has been developed specifically to manage arrhythmias that are causing these symptoms and that are decreasing a patient’s quality of life. This procedure is designed to change how the heart contracts so that it resumes a normal rate and rhythm and resolves the arrhythmia. Electrical cardioversion is indicated for the treatment of various tachyarrhythmias. Electrical cardioversion may be performed in an emergency setting or as an elective, planned procedure.

Electrical Cardioversion

Electrical cardioversion is sometimes referred to as direct current (DC) cardioversion. The cardioversion machine emits an electrical current that is delivered through the chest to the heart. This is also referred to as “shocking” the heart. The electrical impulse delivered through cardioversion reaches all parts of the heart, including the heart muscle tissue, the various conduction nodes, and the internodal pathways, all at the same time. The delivery of a shock through the patient’s chest wall works to convert the heart’s rhythm from an arrhythmia into normal rate and rhythm once again. It is often administered after a stable patient has tried taking antiarrhythmic medications without success.

When cardioversion becomes a necessary part of treatment, the method and circumstances surrounding the shock delivery depend on the patient’s condition and level of stability, as well as the equipment and instruments

5 nursece4less.com nursece4less.com nursece4less.com nursece4less.com available. Emergency cardioversion may be performed when a patient is hemodynamically unstable and the heart’s rhythm must be reset immediately. If a patient is experiencing symptoms of distress, altered mental status, chest pain or breathing difficulties, or has very low blood pressure, it is understood that the patient is not medically stable and needs emergent treatment, which may consist of cardioversion.8,26

Emergency cardioversion is often performed in the emergency department or intensive care unit. It is performed after a rapid assessment by a health clinician who determines that the patient needs prompt assistance, and the cardioversion machine and medications to administer for the procedure are gathered and used quickly. Alternatively, elective cardioversion is a planned procedure that is done after a health clinician has assessed the patient’s condition in a non-emergency setting. The clinician must assess whether there are underlying conditions contributing to the arrhythmia that should be treated before cardioversion is done.26,45 In this assessment, the clinician will also consider potential alternative treatments. Once this assessment is completed, a determination is made that cardioversion is appropriate or necessary.

With planned cardioversion, the patient typically has an arrhythmia that needs treatment but is most likely in a stable enough condition that the arrhythmia is not an emergency. With elective cardioversion, there is time to plan and set up for the procedure, discuss the benefits of the process with the patient and the patient’s family, and deliver the appropriate medications that will be needed. Planned cardioversion is typically delivered under controlled conditions. The procedure may be performed on an outpatient basis but a patient is usually admitted to a hospital for the procedure. A patient who is already hospitalized may have cardioversion during an

6 nursece4less.com nursece4less.com nursece4less.com nursece4less.com inpatient stay. The process is set up so that the patient is closely monitored throughout the cardioversion, and this may take place in a procedure room or specialty suite that has the equipment needed for hemodynamic monitoring.

To maintain controlled conditions, the patient’s blood pressure and oxygen saturations are monitored throughout the procedure. The patient’s heart is also monitored to evaluate the heart rate and the rhythm. The patient’s arrhythmia may exhibit a regular or irregular rate, and continuous monitoring throughout cardioversion will allow the medical clinician to observe whether a change has occurred with both the heart rate and rhythm regularity. With elective cardioversion, the patient is also sedated so that the event is not remembered.45

The types of cardioversion are also further categorized based on how the arrhythmia needs to be treated. Two types of cardioversion, synchronized or unsynchronized, describe how the shock is delivered.

Synchronized Cardioversion

Synchronized cardioversion is a low-energy shock delivered at a timed point in the cardiac cycle to reset an arrhythmia back to normal sinus rhythm. As mentioned above, the electrical impulse delivered through cardioversion reaches all parts of the heart all at the same time but with synchronized cardioversion the impulse is timed to be delivered at the moment of the QRS complex, at the peak of the R wave. The patient is connected to the cardioversion machine, which evaluates the patient’s heart rhythm and determines the correct point of delivering the shock, such as, during the QRS complex.45,65

7 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Synchronized cardioversion may be performed for a hemodynamically stable patient who has a tachyarrhythmia. When the shock is delivered at the exact point, the pattern of arrhythmia that developed is interrupted due to the instant depolarization that the charge causes. This depolarization allows the conduction system to reset and restart with a normal pattern. It is essential that synchronization occurs to allow the cardioversion machine to deliver the impulse at precisely the right time, rather than slightly later in the cardiac cycle on the T wave. If the shock is delivered on the T wave, the patient’s rhythm can be converted into , which can be life- threatening.45,65

Unsynchronized Cardioversion

Unsynchronized cardioversion is also referred to as . Sometimes, defibrillation is required if the cardioverter attempts to sync with a patient’s cardiac rhythm but is unable to do so. When the cardioverter is unsuccessful with synchronization and the patient is hemodynamically unstable, defibrillation through unsynchronized cardioversion should be performed.

With unsynchronized cardioversion, the patient is quickly prepped and electrodes or paddles are put into place on the patient’s chest. The clinician presses a button and the machine delivers the shock immediately without waiting to sync. Unsynchronized cardioversion involves an electrical current or impulse that is not delivered at a specific time during the cardiac cycle; the shock is delivered randomly at the point when the delivery button is pushed. When unsynchronized cardioversion is necessary, the patient is typically exhibiting an arrhythmia that does not manifest any sort of pattern or cycle on the electrocardiogram (ECG). Consequently, the machine cannot sync to any one point; instead, the shock is delivered quickly and indiscriminately during the cardiac conduction cycle.45,65

8 nursece4less.com nursece4less.com nursece4less.com nursece4less.com An example of how unsynchronized cardioversion would be administered is for treatment of an arrhythmia such as ventricular fibrillation, in which there is no regular pattern of cardiac contractions; the ventricles are only quivering. If ventricular fibrillation occurs, the patient needs the shock to restore normal heart rhythm, and synchronization with the cardiac cycle is not possible or necessary.

Unsynchronized cardioversion is typically used for defibrillation in an emergency setting. This is because the arrhythmias treated by defibrillation are life-threatening. Another example includes pulseless ventricular . The amount of energy delivered with the shock during pulseless and ventricular fibrillation is much higher than what is administered during synchronized cardioversion.45,65

Chemical Cardioversion

Chemical cardioversion describes the use of antiarrhythmic medication to reset the heart’s pace and rhythm back to normal in a manner similar to electrical cardioversion. While chemical cardioversion is an option in some cases, electrical cardioversion is more appropriate for patients who are experiencing prolonged cardiac arrhythmias.81

There are several differences between electrical and chemical cardioversion and the decision of which type to use is based on the patient’s circumstances and the underlying arrhythmia. Electrical cardioversion may be preferred over chemical cardioversion because there are more controls and monitoring.81 The clinician can set the amount of voltage on the cardioversion machine, and monitor the patient closely throughout the process. The patient is also less likely to experience side effects from drugs that are sometimes used in chemical cardioversion.

9 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Anticoagulation

When a patient is undergoing cardioversion, anticoagulant medications are typically prescribed both before and after the procedure. The process of cardioversion for the treatment of or other cardiac arrhythmias places the patient at higher risk of thrombosis, which could cause various complications, including a pulmonary embolism or stroke. Studies have shown that patients who undergo cardioversion have a 5 to 7 percent risk of thromboembolism when no anticoagulant medications are provided.8 Further, a study published in Arrhythmia Review pointed out that 15 percent of all strokes are due to atrial fibrillation (AF) among persons over 80 years of age, and that strokes that develop because of AF have greater morbidity and mortality overall when compared to strokes that develop from other factors.61 Anticoagulant medications play an important role in the treatment process of arrhythmias such as atrial fibrillation, including with preparation for cardioversion.

Anticoagulants may be administered prior to the start of cardioversion to prevent thrombosis or emboli from the procedure. When the cardioversion is planned, anticoagulant medications may be prescribed up to several weeks in advance as part of preparation. Although anticoagulants are almost always prescribed prior to cardioversion, there are some cases where an individual who has had atrial fibrillation for less than 48 hours may not receive these medications when the risk of embolism is lower.28 Additionally, when a patient requires emergency cardioversion or defibrillation, anticoagulant drug therapy may not have been previously prescribed.

Research has shown that patients who have anticoagulant therapy for a period prior to cardioversion tend to have better overall outcomes following the procedure when compared to those who do not undergo anticoagulant

10 nursece4less.com nursece4less.com nursece4less.com nursece4less.com therapy. The type of drug and the amount prescribed depend on the arrhythmia present and the patient’s overall condition. According to the American College of (2014), patients who are undergoing elective cardioversion and who have had atrial fibrillation for more than 48 hours (or an undetermined amount of time) should have anticoagulant therapy for three weeks prior to the procedure and then for another four weeks after cardioversion and restoration to normal sinus rhythm.27

Warfarin is often considered to be the gold standard for anticoagulation because it allows close laboratory trending of blood clotting and close medical follow up, but heparin is another drug that may also be prescribed prior to cardioversion. Warfarin may be titrated to keep INR levels, determining blood clotting tendencies, within a range of 2 and 3. Warfarin is more likely to be prescribed for patients with an arrhythmia combined with some other form of heart disease.3,27

Warfarin is beneficial because it is an oral medication prescribed for patients to take at home. The disadvantage is ongoing blood draws and monitoring of the INR, as well as bleeding and bruising. Many patients with longstanding atrial fibrillation may already be taking warfarin to prevent stroke. A patient who is medically stable but who cannot take warfarin may be able to still take aspirin 325 mg combined with clopidogrel each day for suitable anticoagulation.3,27

Clopidogrel, like warfarin, is also an oral medication and is considered an antiplatelet drug.27 Typically, patients who take clopidogrel do not need routine laboratory monitoring to check clotting activity, but the drug can increase the risk of bleeding while being used and for several days after it has been discontinued.

11 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Heparin may be prescribed as low molecular weight heparin prior to a cardioversion procedure. Low molecular weight heparin can be administered at home by the patient or family, given as a subcutaneous injection once or twice daily, depending on the prescription. The patient taking heparin at home may still need laboratory testing to determine whether the dose is at a therapeutic level, but heparin dosing often does not require as much laboratory testing as warfarin.63 Any time a patient routinely takes anticoagulant medications for a period of time, he/she must also monitor activity levels to avoid injury from strenuous activity. In addition to preventing blood clots, anticoagulant medication also increases the risk of bleeding when injury occurs. Because patients may need to take these medications for several weeks both before and after cardioversion, they should be educated about the purpose as well as the risks associated with anticoagulant medication.

When a patient is hemodynamically unstable and cardioversion is emergent, it is often not possible to provide anticoagulant therapy prior to the procedure. However, if the person has reached a stable state and is in normal sinus rhythm because of the cardioversion, anticoagulant therapy should be provided for up to four weeks afterward while being monitored.

In some cases, a transesophageal echocardiogram (TEE) may be performed prior to cardioversion to determine whether a thrombus is present. The TEE is suitable in cases where an individual has not had time to undergo several weeks of anticoagulant therapy before cardioversion.32 The TEE is planned as a procedure immediately prior to cardioversion and typically takes place in the same room where the cardioversion will be completed afterward. With a TEE, the patient is given a mild sedative and a topical anesthetic spray is administered to the back of the throat to prevent gagging. A probe is then

12 nursece4less.com nursece4less.com nursece4less.com nursece4less.com passed into the mouth and down the esophagus to the level of the heart. The tip of the probe has an ultrasound monitor that can perform the echocardiogram when it reaches the correct location. The echocardiogram allows the clinician to clearly visualize the structures of the heart and the surrounding blood vessels.

If a thrombus is present, the ultrasound will identify its location and the clinician can view the site on the monitor. Because the esophagus is in such close proximity to the heart, the TEE can identify the presence of a clot much more effectively when compared to a standard echocardiogram through the chest wall.32 Typically, if a clot is identified near the heart during a TEE, the cardioversion procedure is delayed so that the patient can start anticoagulation therapy for several weeks first. If there is no clot present, the cardioversion procedure can carry on as planned.

There has been some evidence that TEE prior to cardioversion can be inconclusive, often due to poor image quality, which can still place a patient at higher risk of damage from blood clots. This may be of even greater importance among patients who already suffer from atrial fibrillation and who are already at higher risk of blood clots. One study published in the journal Cardiovascular Ultrasound investigated the use of contrast to enhance the TEE results in detecting the presence of blood clots prior to cardioversion. The study showed that among the groups analyzed that underwent TEE, there were more difficulties with imaging of clots with native TEE (transesophageal echocardiogram) performed without contrast in comparison to TEE performed with contrast. Overall, the use of contrast with the TEE increased the ability to identify blood clots in the heart and surrounding prior to planned cardioversion, potentially preventing many complications.32

13 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Undoubtedly, the risk of thrombus is important enough to delay cardioversion if a blood clot is detected with TEE prior to the procedure. Because a patient with an arrhythmia who needs cardioversion is already at risk of thrombus formation and the subsequent complications that could occur, anticoagulant therapy is a very important part of preparation for the procedure.

Sedation And Intravenous Procedure

The administration of intravenous (IV) fluids is a typical part of the process of electrical cardioversion. Most patients will benefit from some supplemental IV fluid with electrolytes, particularly when they have fasted for a period before the procedure. With planned cardioversion, a patient most likely has been kept fasting; administration of intravenous fluids during and after the procedure can manage electrolyte levels and prevent any electrolyte disturbances. Regular maintenance fluid provided before and after the procedure will also help preserve the patient’s fluid volumes and inhibit dehydration.3,8,51,64

Medications provided for pain or sedation can be administered in the IV tubing along with routine fluids. Most anesthetics and administered during the procedure are available as IV doses because of their rapid onset of action. The IV line is also important for administering other types of medication as well, including anticoagulants. Unfractionated heparin may be administered intravenously after cardioversion to start the process of post- operative anticoagulation.

If the procedure is elective and is being done on an outpatient basis, an IV line is typically placed when the patient arrives for the procedure. At times, an individual may already be an inpatient and if cardioversion is planned as

14 nursece4less.com nursece4less.com nursece4less.com nursece4less.com part of hospitalization, an IV site may already be available. If a person’s medical condition is unstable and the patient needs emergent cardioversion, an IV line is quickly inserted if one is not already in place. A peripheral catheter can be inserted and will usually provide enough access for regular amounts of fluids and medication during the procedure. A patient does not necessarily need a central line. If possible, a larger gauge catheter (18 G or more) will be large enough to accommodate rapid fluid replacement or blood if an emergency occurs. A 20 G catheter can also handle routine administration of fluids during the procedure and administration of IV medications for sedation.8,51,64

A patient who was medically stable prior to the procedure may become unstable at any time throughout the procedure. This may occur as an effect of the sedatives used as well as the effects of the cardioversion. The procedure typically causes a decrease in the heart rate, and this change, combined with the effects of sedatives or analgesic medications, may result in decreased perfusion and a drop in blood pressure. With a drop in heart rate or blood pressure in the time surrounding the procedure, IV access is important for administration of resuscitative emergency medications and fluids if needed. For example, a patient may quickly develop hypotension just after cardioversion. Access to an IV line would allow the clinician to quickly administer a fluid bolus to try to rectify the low blood pressure.

Because the shock delivered through cardioversion can be painful, IV access will allow for the administration of pain medication. The patient will already have sedation during the procedure, but additional pain medication may also be necessary, given either prophylactically just before the cardioversion or afterward during recovery. A study by Ozkan, et al., (2016) in the European Review for Medical and Pharmacological Sciences compared the pain control

15 nursece4less.com nursece4less.com nursece4less.com nursece4less.com effects of three different analgesic medications - alfentanil, fentanyl, and remifentanil - administered with propofol and midazolam during electrical cardioversion.64 The study elected to evaluate drugs that could be administered intravenously, that were short-acting and that had a rapid rate of onset, and that had a decreased risk of deleterious effects on the cardiovascular system. The study showed that of the three drugs administered, alfentanil combined with propofol and midazolam offered a rapid onset of action, less respiratory depression, and shorter periods of recovery.64 While all of the drugs in the study had positive effects of sedation and analgesia, and all could be given through an IV, the alfentanil had more positive effects in comparison.

Following the cardioversion, the patient may have the IV cannula in place throughout the recovery phase. Once it is evident that the patient’s condition is stable, the IV may be removed prior to discharge if the cardioversion was performed as an outpatient procedure. Other patients who have cardioversion as part of their hospitalization may continue to have the line in place for further administration of medication and fluids, as needed.

Preparation and Sedation Types

The cardioversion process can be painful and frightening for the patient. Sedation is administered intravenously prior to the procedure to produce a state of calm for the patient or to induce sleep. The electrical current delivered through the chest wall provides a shock that is uncomfortable against the skin and muscles of the chest. With sedation, the patient will not remember the event. Anesthetics given for sedation are delivered prior to the actual cardioversion, after all of the equipment has been set up and while the patient is being monitored. An clinician remains at the

16 nursece4less.com nursece4less.com nursece4less.com nursece4less.com bedside throughout the procedure to administer the sedative drugs, and to monitor the patient and the patient’s level of consciousness.

Before the elective cardioversion, the patient’s history should be carefully assessed to determine if the patient had an adverse reaction to anesthesia in a prior procedure. If a patient has had a difficult reaction to sedative agents or there are other potential problems, such as the possibility for difficult intubation (should the need arise), a backup plan with alternative measures should be implemented to ensure that the patient stays safe throughout cardioversion while receiving sedation.

The medications delivered typically provide conscious sedation (also called moderate sedation), which describes a condition of being sleepy during the procedure but the patient is still able to be aroused in comparison to deep sedation. During deep sedation the person may need greater stimuli to respond and may need respiratory support throughout the procedure. With conscious sedation, medications administered are usually short acting, as the entire process of cardioversion is relatively brief. Ideally, the medications should have a rapid onset after administration but then should subside quickly during recovery. Additionally, the best sedative medications are those that do not cause complications with the cardiovascular or respiratory systems.

The most appropriate medications used for sedation may vary between cases. Some sedative agents are used more commonly with cardioversion, but often the anesthesia clinician makes the decision of what drugs are most appropriate according to institutional policies. A review by Lewis, et al., (2014) published in the Cochrane Database of Systematic Reviews aimed to examine some of the differences between sedative agents used during

17 nursece4less.com nursece4less.com nursece4less.com nursece4less.com electrical cardioversion, including the overall safety and effectiveness of some of the more commonly used agents.45 The drugs utilized in the various studies that were reviewed included such agents as propofol, etomidate, midazolam, and diazepam. Overall, the review determined that all of the different agents that were compared were adequate for their sedative effects during cardioversion and there was not one particular drug that was better or more effective than the others.45

The goal of the sedation is to place the patient into a state of unawareness of the procedure, such that the patient will not remember what happens or feel distress. With deeper levels of sedation, the patient may experience negative effects in some organ systems that could cause complications. For instance, too much sedation could have an effect on the respiratory system and could slow the patient’s breathing rate, requiring further intervention. Because of the possible negative effects of sedation, the patient is hemodynamically monitored throughout the procedure and recovery phase.45,61

Endotracheal intubation may be necessary for some patients, although this is typically not needed in most situations. If the patient becomes unstable because of the arrhythmia to the point that breathing becomes affected, intubation will be needed to assist with respiratory efforts. Additionally, some patients who are already in the intensive care unit and who have ventilator support may undergo cardioversion and will remain intubated throughout the procedure. Because the patient is anesthetized, emergency equipment, including a crash cart and intubation supplies must remain at the bedside in case resuscitation becomes necessary.

18 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Typically, the goal of sedation with cardioversion is not a complete state of unconsciousness. There are some anesthetic medications used during cardioversion that could induce this state. Examples of anesthetic agents include propofol, etomidate, or thiopentone.

A study by Desai, et al., and published in the Annals of Cardiac Anesthesia (2015) compared propofol and etomidate as agents used for sedation during cardioversion.51 In the majority of cases, the patients being studied remained hemodynamically stable. Propofol was noted to cause a greater drop in systolic blood pressure in the period just following cardioversion when compared to etomidate, although the measured outcomes were considered clinically insignificant. The subjects in the study were also given fentanyl for pain control and sedation, which could have further perpetuated a drop in blood pressure.51 Both propofol and etomidate are still used for their effects during cardioversion, and both fulfill the measures needed to provide anesthesia for the procedure.

Sedative agents are somewhat similar to anesthetics, but the patient is able to respond to stimulation. The patient may sleep during the procedure but can respond during attempts to be aroused, and may answer questions or follow directions when asked. Sedative agents still require that the patient is monitored when they are used, as they could cause hemodynamic changes. A patient who has been given a sedating agent is at greater risk of falls or injury and must be monitored for safety.

Overall, a sedative provides a sense of calm throughout the process so that it can be completed safely and successfully. Some types of sedatives used during cardioversion include benzodiazepine medications such as diazepam or midazolam.

19 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Many patients require some amount of supplemental oxygen in the period surrounding cardioversion. A person may already be using supplemental oxygen when arriving for the cardioversion procedure. Alternatively, some people are given extra oxygen along with the sedative medications to prevent hypoxia. If oxygen is in place prior to cardioversion, it should be removed for the actual procedure. The oxygen tubing can then be replaced after the shock is delivered.

Analgesia

Some patients also receive analgesia as part of sedation or after the cardioversion procedure. Analgesic agents must be delivered carefully, with continued monitoring of the patient, as they can affect level of consciousness as well as the respiratory and cardiovascular systems. Analgesia is important to consider, as the actual cardioversion shock can be painful and the patient should have some amount of pain medication available to keep comfortable. Sedative and anesthetic agents used to sedate the patient do not necessarily provide pain control and analgesic drugs are administered separately. Often, a combination of drugs is administered to provide the most effective sedation and analgesia.64

External Cardioversion

The process of delivering a shock to the heart administered through the chest wall is known as external cardioversion. It requires a cardioversion machine that will deliver the energy, as well as paddles or electrodes that are connected to the patient’s body.

If electrodes will be used, they are applied as patches to certain areas of the skin. The skin is cleaned beforehand and any excess hair will need to be

20 nursece4less.com nursece4less.com nursece4less.com nursece4less.com shaved to allow the electrodes to adhere. Excess hair can prevent adequate delivery of the electrical charge; if too much hair is present, the electrode will not have full contact with the skin.29

The electrodes are applied in certain areas based on the method that will be conducted. The electrodes that are placed on the patient’s chest and/or back range in size from 8 to 13 cm in diameter. The larger size of the patches may assist with greater distribution of the impulse over a slightly larger area. The anteroposterior placement of pads involves placing one patch on the patient’s front and one on the back. The anterior patch is placed on the chest on the upper right side, near the right and the location of the SA node. For female patients, the patch should not be placed directly over the breast tissue. The posterior patch is applied on the left side at the level of the chest, often just under the shoulder blade. Anterolateral patch placement uses the patient’s front and sides as sites for patch placement; one patch is placed at the midaxillary line on the left side at the level of the heart’s apex and the other patch is positioned on the right side next to the sternum and just below the clavicle.29

Paddles may also be used to administer the shock, rather than electrodes. When paddles are used, the patient still may require patches placed on the skin at the locations for the paddles; alternatively, gel may be added to the paddles to improve impulse conduction when the shock is delivered. When paddles are used, the clinician first prepares the machine; when it is time to deliver the shock, the paddles are placed in the locations on the chest and side and the shock is delivered. In the different scenarios, the energy travels from the machine to the electrodes or paddles and passes between their locations in the patient’s body to stimulate the heart.

21 nursece4less.com nursece4less.com nursece4less.com nursece4less.com The patient is placed supine for the procedure. Once the monitors have been placed, the clinician should ensure that there are no extraneous metal objects touching the patient, such as hair clips or jewelry, as these items could cause burns when the shock is administered. Other items could also injure the patient and should be removed if at all possible prior to cardioversion, including the person’s glasses, dentures, or hearing aids.

Typically, a 12-lead ECG is performed prior to the procedure to verify the actual arrhythmia present. This can be used as a baseline for comparison with the patient’s results after the procedure. Before the actual cardioversion, other monitoring equipment will also be applied, including pulse oximetry and a blood pressure monitor. The anesthesiologist will then administer a sedative or anesthetic agent to calm the patient and induce sedation.

Once everything is ready, the cardioversion machine must read the patient’s cardiac rhythm for a few moments prior to shock delivery. With synchronized cardioversion, the system must determine the correct moment to deliver the impulse. It must be synced to the patient’s heart rhythm, and there is a SYNC button that is pressed prior to shock delivery to determine the correct timing of the impulse. The machine reads the patient’s ECG over the course of several beats to prepare to coordinate with the QRS complex but the clinician should also visually review the ECG tracing to ensure the cardioverter is correctly sensing the heart rhythm. A mark will appear above the rhythm, which demonstrates that the machine is sensing the QRS complex.

The clinician sets the amount of energy to deliver during cardioversion, which is determined based on physician orders according to the patient’s

22 nursece4less.com nursece4less.com nursece4less.com nursece4less.com condition and the arrhythmia present. Clinicians administering cardioversion follow the parameters set forth through American Cardiac Life Support (ACLS) guidelines, and different amounts of energy are needed for various arrhythmias.59 The amount of voltage can range between approximately 50 and 200 joules (J) with synchronized cardioversion, since it is a low-energy shock. A patient with supraventricular tachycardia or may need up to 100 J of energy to restore normal sinus rhythm. For atrial fibrillation, the amount of energy required is greater, and 100 to 200 J may be delivered.29

The direction and efficiency of the shocks delivered during cardioversion is also sometimes based on the particular system in use. Cardioverters can be described as monophasic or biphasic systems, depending on how the energy is transferred to the patient. In a monophasic system, when the shock is delivered, the energy enters the patient and travels in one direction, from one electrode to the other, creating a monophasic waveform. This conduction momentarily stops the heart and it converts back to normal sinus during the pause. Cardioversion with a monophasic system may require higher amounts of energy to convert the heart back to a normal rhythm. In a biphasic system, the current travels back and forth several times between the electrodes or the paddles. A biphasic system may use lower levels of energy, but the amount is usually more efficient when compared to monophasic systems. Because of this, patients who receive cardioversion through biphasic systems may experience fewer side effects of the treatment.67

In general, the clinician should begin with shocking at the lowest voltage required for the particular rhythm and only increase the amount of energy during subsequent shocks if the initial impulse is ineffective in resolving the

23 nursece4less.com nursece4less.com nursece4less.com nursece4less.com arrhythmia. Often, healthcare centers have step-up energy protocols in place that guide clinicians about how to increase energy amounts with the next round. The patient is at greater risk of injury to the heart when larger voltages are applied. To minimize this risk, the clinician starts at a lower voltage dose and only increases as needed. Shocks can be delivered at increasing voltage with synchronized cardioversion; up to 360 J has been shown to be delivered safely for the patient.36

Because the cardioverter will record an ECG before, during, and after the event, the health clinician will be able to monitor the timing of the shock as well as the patient’s cardiac rhythm after the shock is delivered. When the actual impulse is delivered, all people assisting with the procedure must stand clear and should not come into contact with the patient’s body. This is to avoid the possibility of additional personnel also receiving a shock from the current as it passes into the patient’s body. Confirmation that everyone in the area is standing clear must be performed prior to shock delivery.

With emergency cardioversion or defibrillation, many aspects of the process are similar to elective cardioversion. Additionally, when defibrillation is performed, there is less of a delay between the setup of the machine and actual shock delivery, as the cardioverter does not need the extra time to sync to the patient’s heart rhythm.

The amount of energy applied during defibrillation is higher than that with synchronized cardioversion, and may start at 300 to 360 J. When defibrillation is necessary during an emergency, ACLS guidelines are implemented.59 Chest compressions and airway management through bag- mask ventilation are employed while preparing the defibrillator. Once the electrodes of the defibrillator have been attached, chest compressions are

24 nursece4less.com nursece4less.com nursece4less.com nursece4less.com halted momentarily to allow the machine to analyze the patient’s rhythm, and then the shock is quickly administered. All personnel must still refrain from touching the patient during shock delivery, even if the procedure is emergent or the patient is receiving defibrillation.

If the patient’s heart rhythm does not return to normal, cardiopulmonary resuscitation (CPR) is resumed while preparing the machine to defibrillate again. Because defibrillation is used in situations of pulseless ventricular tachycardia or ventricular fibrillation, the patient is in a life-threatening situation and needs continuous CPR until a normal heart rhythm resumes.66 The cardioverter/defibrillator may analyze the rhythm and determine that it is a non-shockable rhythm (asystole or pulseless electrical activity), in which case CPR continues but defibrillation is not an option. In these emergency situations, the clinician may administer medications and follows the principles set forth in the ACLS guidelines.59

When the impulse is delivered, the ECG will show whether the rhythm has been restored to normal sinus. It is possible that a patient may need more than one shock to resolve the arrhythmia. For instance, a patient may receive an initial shock of 120 J to convert atrial fibrillation with elective cardioversion, however if the first impulse is not successful, a second shock may be given at a higher voltage. Of note, when administering cardioversion and before delivering another shock, the clinician should always ensure that the machine is set to synchronized cardioversion again.

Many times, the cardioverter will reset to unsynchronized cardioversion after the shock is delivered and will be set to defibrillate if it is not changed. The patient is moved to recovery after the rhythm converts back to normal sinus.

25 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Internal Cardioversion

Internal cardioversion may be a treatment option as an alternative to external cardioversion for some patients. Internal cardioversion also may be attempted in cases where external cardioversion is unsuccessful. While external cardioversion involves the placement of patches or paddles on the skin and delivery of the shock through the chest wall, internal cardioversion delivers the shock through a catheter that has been placed inside the chest cavity. The procedure is usually performed in a surgical suite or the catheterization lab.

The process of internal cardioversion involves placement of several , which are able to conduct electricity to the specific site in the heart. They are inserted in a larger , including the subclavian or femoral , and threaded to the heart, with being used as a guide for identifying the correct locations. Two of the catheters are placed in the right atrium and the left pulmonary , while the third is threaded to the right to be able to synchronize with the R wave during the conduction cycle. The process still delivers a low-energy shock and voltage levels may range from as low as 1 J up to approximately 30 J, depending on the patient’s condition and response to the cardioversion.59,68

The amount of voltage administered is usually much lower than that administered with external cardioversion. Internal cardioversion is often successful in converting the patient to normal sinus rhythm, but as with external cardioversion, it sometimes requires more than one shock with an increase in voltage to correct the arrhythmia.68

During the internal cardioversion procedure, the patient will require moderate sedation and may be asleep for the duration but can still be

26 nursece4less.com nursece4less.com nursece4less.com nursece4less.com aroused. The injection site is also infused with a so that the patient does not feel the initial needle. Typically, patients do not remember the procedure, even though they may be able to be aroused or follow commands throughout the procedure.

Many of the procedures that are performed prior to external cardioversion, for example, a 12-lead ECG to use as a baseline and blood collection for laboratory analysis, are also completed prior to internal cardioversion. A patient who is planning for an elective procedure will also need to take anticoagulant medications for a month or more prior to prevent damage from blood clots that could be dislodged during the procedure. As with external cardioversion, the clinician may monitor the patient’s coagulation status through laboratory values by checking the INR. Often, the INR must be within a certain range to determine the rate of blood clotting before the patient can undergo cardioversion. The patient will remain on a monitor to assess his/her hemodynamic status throughout the procedure as well. An anesthesia clinician remains present at the bedside to provide sedation to help maintain the patient’s comfort.

Internal cardioversion is an option in some cases where the external process has not been successful, often because of physical factors related to the patient’s condition. Some morbidly obese patients cannot undergo external cardioversion and some patients with chronic obstructive pulmonary disease have developed air trapping around the lungs, making it otherwise difficult to transmit enough energy through the chest wall to reach the heart. With the development of biphasic cardioversion systems, though, there are fewer situations where internal cardioversion is needed due to unsuccessful external cardioversion.68

27 nursece4less.com nursece4less.com nursece4less.com nursece4less.com If a clinician believes that it may take several shocks to convert a patient back to normal sinus rhythm, internal cardioversion may be more appropriate, as there is less chance of skin damage due to electrode or paddle placement for external cardioversion. Alternatively, internal cardioversion is not used on patients who already have pacemakers in place. Internal cardioversion shares some of the same risks to the patient as the external version of the procedure. The patient is at risk of damage from blood clots and there is a chance that the arrhythmia could recur quickly after the procedure and could cause more harm than the initial arrhythmia. Additionally, because internal cardioversion involves catheter placement through a puncture site, the patient may be at risk of bleeding from the catheter insertion site, as well as swelling and hematoma formation. Some people are at higher risk of infection as well, particularly if they are already immunocompromised before the procedure.

After the process is complete, the catheter and sheath will be removed and direct pressure is placed over the puncture site to ensure that blood clots and no excess bleeding occur. A small amount of bruising at the insertion site is normal. The patient will go through a period of recovery before being discharged to home, as internal cardioversion may take place on an outpatient basis. For most people who have the elective form of internal cardioversion, they are monitored in the recovery room for a period of time until they demonstrate hemodynamic stability. If the heart rhythm remains normal and they are able to move and perform routine activities without complications, they can be discharged from the facility.

Many patients must continue to take anticoagulant medications for a period of time following internal cardioversion and antiarrhythmic medications are often warranted as well to ensure that the patient’s heart rate remains at a

28 nursece4less.com nursece4less.com nursece4less.com nursece4less.com normal pace and rhythm. The patient will usually need to follow-up within a few days or weeks afterward.

Another method of internal cardioversion that may be considered for some patients is the process of using an electrode on the end of a balloon that is placed in the esophagus. Just as transesophageal can identify the presence of a clot in the heart or surrounding blood vessels, a catheter inserted into the esophagus and placed at the level of the heart brings it close enough that cardioversion can be performed at this level as well. Esophageal electrical cardioversion is done by inserting a catheter with a probe tip into the patient’s esophagus in a manner similar to that performed with a TEE.32 The end of the probe has an electrode, which emits a shock when it is positioned at the level of the heart. Because the esophagus runs directly behind the heart, the probe can be placed very close to the right atrium. The placement of the electrode still achieves pacing and synchronization to the R wave in the QRS complex.

Esophageal cardioversion is beneficial in that it requires a smaller amount of total energy delivered when compared to external procedures. The close proximity of the esophagus to the atrium means that energy passes through fewer layers of tissue to reach the heart. In the Oxford Desk Reference: Cardiology book, it is estimated that when external cardioversion procedures are performed on obese patients or those with chronic lung disease, only 20 percent of the energy delivered actually reaches the heart, while the rest is absorbed by the surrounding tissues. Esophageal cardioversion minimizes this distribution of energy so that it is concentrated in the heart, thereby preventing less energy delivery overall.68

29 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Typically, esophageal cardioversion requires less sedation when compared to other forms of the procedure and there are fewer side effects. Most patients can tolerate the process on an outpatient basis. The patient who receives this particular type of cardioversion may undergo a period of lighter sedation with less need for analgesia. Overall, transesophageal cardioversion has been shown to be completed at a much faster pace than internal cardioversion with an atrial catheter and the patient may receive fewer shocks, allowing recovery earlier to happen.

Recovery Phase

The entire process of cardioversion occurs very quickly. In many cases, it is the setup of equipment and monitoring for the patient that takes longer than the actual shock delivery. Because the patient is sedated for the procedure, continued monitoring will be needed after cardioversion. When conscious sedation is used, the effects typically wear off after 20 to 30 minutes, although it can take up to 24 hours for some people to feel back to normal again.

During the immediate recovery period, the patient will need hemodynamic monitoring to assess for changes in heart rate and to ensure that the heart’s rhythm remains normal. Blood pressure and oxygen saturations are also monitored because of the possibility of changes due to sedation. Once a patient regains full consciousness after the procedure, he/she can continue to recover for about an hour. If the patient remains medically stable, he/she may stay in a treatment room for a while with less frequent monitoring, eventually being discharged to home.

The recovery process can vary between patients. Some people have smooth recovery periods where they regain full consciousness after sedation and are

30 nursece4less.com nursece4less.com nursece4less.com nursece4less.com stable enough to move on. Other patients experience adverse side effects associated with some part of the procedure and may need to stay in recovery for longer. The sedatives or anesthetic agents used during cardioversion can cause side effects. For example, use of propofol may cause panic or fear in some patients, and these factors may need to be addressed during recovery.64 Some sedative or anesthetic agents can cause nausea as a side effect and the patient may have abdominal pain or may vomit. Anti- nausea medications are often given during recovery to help the person to recuperate until the sedative agents wear off.

In the previously-mentioned study published by Desai, et al., in the Annals of Cardiac Anesthesia where researchers compared the effects of propofol and fentanyl versus etomidate and fentanyl during cardioversion, subjects seemed to recover more quickly after receiving etomidate when compared to propofol. The study also showed that with the addition of fentanyl, the patients required less etomidate overall and were therefore able to awaken more quickly during recovery. Neither drug caused a delay in the final discharge time of the patients.51

Capnography, sometimes referred to as end-tidal carbon dioxide monitoring, may also be needed during recovery to ensure that the patient does not become hypoxic. Generally, pulse oximetry is applied after sedation or anesthesia to ensure that the patient is maintaining adequate oxygen within the bloodstream. However, carbon dioxide can also build up in the body, particularly if the patient is hypoventilating or has periods of apnea.46 Capnography is performed through a device that measures exhaled carbon dioxide. A capnograph can be attached to the endotracheal tube if the patient is intubated so that with breathing, the device measures the amount of carbon dioxide with exhalation. Face mask capnography can also be used

31 nursece4less.com nursece4less.com nursece4less.com nursece4less.com when the patient is not intubated but has supplemental oxygen delivered through a mask. The device is attached to the mask to measure end-tidal carbon dioxide.

Once the patient has received a shock during the procedure, the clinician will assess the ECG to determine whether the heart’s rhythm converted to normal and the arrhythmia resolved. There may be times when an initial shock is ineffective in treating the arrhythmia and the patient will receive more than one impulse with increasing amounts of voltage applied. Once the rhythm has converted to normal, the patient can be monitored for procedural recovery. The health clinician continues to monitor the patient’s vital signs and oxygen status, providing supplemental oxygen as needed during recovery. If the patient was using supplemental oxygen prior to cardioversion, it is usually removed for the actual procedure and then replaced afterward.

In order to accurately assess how well the individual is recovering from the procedure, the patient may also need follow-up laboratory work, including arterial blood gases or a serum chemistry panel. Continued assessment for normal breathing rate and effort is also essential, as well as assessment of any other signs that signify that the patient is becoming unstable.

Some people have ongoing mild pain following cardioversion and will need analgesia. Typically, discomfort is minor and does not require large doses of pain medication to control. The IV site is maintained throughout the recovery phase as the patient wakes up from anesthesia to be able to provide analgesics for pain control. Skin burns are possible complications associated with cardioversion; these injuries may develop in areas where the electrode patches are placed. Of note, the extent of the burns could be

32 nursece4less.com nursece4less.com nursece4less.com nursece4less.com related in part to the type of cardioversion system that was used. Biphasic systems are associated with fewer skin burns when compared to monophasic systems.65 The clinician may need to provide cream or prescription ointment as treatment for these types of burns during recovery, if they are present. The patient will also need later instruction about skin care before being discharged, if burns have occurred during cardioversion.

Once the patient can be shown to be hemodynamically stable, with pain under control, and that the anesthetics or sedatives have worn off, he/she may be moved from the recovery area. If the cardioversion was performed on an outpatient procedure, the health clinician may then make plans to discharge the patient to home.

Risks Of Cardioversion

Cardioversion, while often very successful in treating certain tachyarrhythmias, is not without risks. One of the most common dangers of the procedure is thrombosis. People who undergo cardioversion are at greater risk of having a stroke when the procedure causes a previously formed clot to release and travel through the bloodstream to the brain. A person with atrial fibrillation is already at greater risk of blood clot formation when the atria are not able to pump as much blood through to the ventricles and blood has a greater chance of pooling and coagulating.

For some people, blood clots can form as a result of AF but the clots have never moved. Cardioversion may release a clot from its location, potentially causing a stroke. A patient who has had AF for a longer period is at greater risk of a blood clot when compared to someone who more recently developed the arrhythmia. The risk of blood clots and stroke because of

33 nursece4less.com nursece4less.com nursece4less.com nursece4less.com cardioversion is also decreased when anticoagulant medications are administered as part of the procedural process.

One study by Hansen, et al., in EP Europace reviewed the medical charts of over 16,000 patients who had received cardioversion for the treatment of AF. Of these, some of the patients received oral anticoagulation prior to cardioversion and some did not. Those who did not receive anticoagulation therapy had greater than 50 percent increased risk of thromboembolism development within a year following the procedure.28 The study also showed that in some cases, atrial stunning occurred with cardioversion, in which there is dysfunction in the atria and they are slow to return to their usual pace when the heart has been shocked back into normal sinus rhythm. Atrial stunning is associated with a greater risk of thrombosis. As part of assessing the likelihood of events among some of the patients pooled from studies in the review, 2 percent had thrombosis within 18 days following cardioversion. These results were thought to be related to atrial stunning that occurred with cardioversion.28

Some patients who have pacemakers or implantable defibrillators in place are at risk of complications associated with external cardioversion. The patches used for cardioversion must be placed at least 12 cm away from the site of the implanted device.26 If the shock is delivered too closely to the device, it could alter its settings or simply damage it overall so that it no longer functions.

A patient who takes digoxin could be at risk of complications if undergoing cardioversion and has concurrent high levels of digoxin in the bloodstream. Digitalis toxicity is considered to be a contraindication to cardioversion, as it can increase the risk of the patient developing a serious arrhythmia.29 When

34 nursece4less.com nursece4less.com nursece4less.com nursece4less.com a person is planning to undergo cardioversion, laboratory testing of serum digoxin levels is necessary prior to the procedure. The patient may also have lab testing of electrolytes at the same time to determine whether any electrolyte levels, i.e., potassium, are abnormal that could contribute to an arrhythmia with the cardioversion. Depending on the situation, the patient could then be treated for electrolyte imbalance or digitalis toxicity, as necessary.

Some arrhythmias are not appropriate for cardioversion and may actually increase a patient’s risk if they are present when cardioversion is performed. These include , due to increased activity or exercise, tachycardia caused by digitalis toxicity, or multifocal atrial tachycardia.29 Sinus tachycardia indicates an adult heart rate greater than 100 beats per minute, although the rhythm is regular. The impulse is generated from the SA node, but the rate is faster than normal.

In some cases, when examining an ECG, it can be difficult to differentiate sinus tachycardia from a type of supraventricular tachycardia (SVT) with a rate greater than 150 beats per minute, and it is difficult to visualize P waves. However, regular sinus tachycardia is caused by any number of conditions, from dehydration to exercise, and is not considered a rhythm that requires cardioversion. Regular sinus tachycardia can resolve when the underlying causative issue itself resolves; it is not descriptive of an arrhythmia that originates outside of the AV node. Consequently, cardioversion for this particular type of rhythm is not effective, because the location of impulse generation does not need to be reset.31

Multifocal atrial tachycardia (MAT) describes a condition of atrial tachycardia in which the rate is greater than 100 beats per minute but the impulse

35 nursece4less.com nursece4less.com nursece4less.com nursece4less.com generation occurs from multiple locations. The condition is said to occur from a wandering pacemaker, in which pacing may come from the SA node, but the cardiac impulse can also be generated from various areas within the atria. MAP is often associated with an underlying disease process, most commonly chronic obstructive pulmonary disease (COPD), particularly during times of symptom aggravation. However, when symptoms of COPD are under control, MAP may also disappear. Because MAP is typically a benign condition that is settled with resolution of the underlying disease, cardioversion is usually not necessary for its treatment.31 Further, treatment with cardioversion when it is not necessary puts the patient at undue risk of other complications and to unnecessary discomfort.

Hypoxia is a potential complication associated with cardioversion. Many patients arrive at the procedural suite with supplemental oxygen already in place, as some arrhythmias can lead to breathing difficulties. This oxygen is removed briefly for the cardioversion and then replaced as the patient recovers. Even if a person does not already have oxygen in place prior to cardioversion, 100 percent oxygen may be given for several minutes before receiving sedation. Because the patient receives sedation for the procedure, there is a risk of oxygen desaturation due to a decreased breathing rate as well as decreased concentration of oxygen in the bloodstream. In some cases, a patient may need bag-mask ventilation after sedation has been administered, and if significant hypoxia develops, endotracheal intubation is warranted.

Sedation is necessary for cardioversion. The patient should not undergo the procedure without it. Therefore, if oxygen desaturation is a risk because of sedation, measures should be taken to prepare for supplemental ventilation for the patient to decrease the risk of hypoxia and its damaging effects.

36 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Some people experience burns at the sites where electrodes or paddles are placed for cardioversion; in fact, burns are one of the more commonly known adverse effects associated with the procedure. As the current passes through the patch or the paddle during the procedure, the skin can be damaged. Some people experience skin redness and blisters at the sites of electrode placement. While most instances of skin irritation are relatively minor, there have been some cases where patients recovering from cardioversion have the effects of first- or second-degree burns.

The amount of energy and voltage used during a cardioversion procedure can have an impact on the risk of skin burns. If the patient requires several shocks to convert to a normal rhythm, he/she may be at higher risk of incurring burned skin. The risks may be lessened by using lower amounts of energy with each shock, as well as using a biphasic rather than monophasic system, but this may depend on how the patient’s heart rate and rhythm respond to the cardioversion.

A study by Yava, et al., in the Emergency Medicine Journal evaluated the effectiveness of cold therapy to burn sites among patients who received electrical cardioversion in one health center. Because there is a higher risk of burned skin during cardioversion, the authors sought to determine whether local cold application would reduce the severity and the incidence of burns. The cold application was applied just following the cardioversion procedure. Those who received cold therapy had lower pain scores and a significantly decreased burn incidence following electrical cardioversion when compared to those in the control group.33 The application of cold therapy for limited periods can decrease the skin damage incurred during cardioversion and can promote greater comfort for the patient after the procedure.

37 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Finally, some people take medication through transdermal patches that deliver the drug directly through the skin. These patches should be removed if they are on the chest or back in locations that are close to placement of the cardioverter electrodes or paddles. The use of the cardioversion paddles over a site with a transdermal patch can impact the effects of the medication. Additionally, attempting to cardiovert through transdermal patches can worsen skin damage and further contribute to burns.

Cardioversion Success Rate

The success of cardioversion is impacted not only by the ability to convert the arrhythmia back to normal sinus rhythm during the time of the cardioversion procedure, but also for the long-term effects of maintaining a normal heart rate and rhythm. When a patient undergoes cardioversion for management of arrhythmia, there is always potential for the abnormality to recur. When cardioversion is performed as treatment of atrial fibrillation, for example, several factors may be involved that affect how successful the procedure is, as well as whether the patient later experiences a recurrence of AF. The length of time the arrhythmia has been present, whether the patient has any underlying disease, and various personal factors such as age, can all play a role in the success of the cardioversion.

During the actual cardioversion procedure, success of the process is determined by whether the cardioverter is able to convert the patient’s heart rhythm back to normal sinus at the time. This may happen after one shock or it could take several tries, each with increasing amounts of voltage to find success. In many facilities, the health clinician follows a protocol as a guide to know how much to increase the voltage with each subsequent shock.

38 nursece4less.com nursece4less.com nursece4less.com nursece4less.com One study published in the journal BMC Cardiovascular Disorders examined almost 2000 electrical cardioversion procedures to determine the factors influencing the success of the process in converting patients from AF into normal sinus rhythm. The study showed that among the approximately 1300 patients who had the procedure, most only required one shock to convert to normal sinus, although the overall range was between 1-10 . Approximately 15 percent of the cardioversions failed entirely. Of these, the long-term presence of AF was associated with more instances of cardioversion failure. Further, various factors were shown to be associated with an increased risk of later recurrence of atrial fibrillation after the cardioversion (within 30 days). These factors included female gender, the presence of renal failure, the use of certain antiarrhythmic medications at discharge, and a higher ventricular rate. These factors seemed to be independent variables when it came to predicting whether AF would return. In all, almost half of the patients studied during the investigation developed a recurrence of AF within one month after undergoing cardioversion.35

Atrial flutter has been shown to be successfully treated through cardioversion in 90 to 100 percent of patients who undergo the procedure.26 However, as with atrial fibrillation, the actual length of success may vary and there is a higher likelihood that the affected patient may convert back to atrial flutter after undergoing cardioversion. Another study published in the Canadian Journal of Emergency Medicine showed that when patients presented to emergency departments with recent-onset atrial fibrillation or atrial flutter, they were less likely to convert back to their previous arrhythmias after treatment with cardioversion when they first received medications to control their ventricular rates.

39 nursece4less.com nursece4less.com nursece4less.com nursece4less.com In some instances, patients receive medications to slow the ventricular rate when atrial arrhythmias are present that significantly increase the heart rate, including treatment with beta blockers or calcium channel blockers. Anecdotal evidence has assumed that slowing the ventricular rate increases the chances that cardioversion will improve the chances of success, but the study showed that when patients received these types of drugs prior to cardioversion (and the patients had recent onset arrhythmias), they had decreased success rates.81 Of note, the study did examine the effects of both electrical and chemical cardioversion cases, although the results of electrical cardioversion were prominently impacted by prophylactic rate control. Additionally, the study discussed the use of cardioversion that was performed more frequently in emergent situations, rather than elective cases.

Once a patient has undergone cardioversion, the long-term impact of the process will be determined by whether he/she continues to exhibit a normal cardiac rhythm or eventually converts back to an arrhythmia. Often, patients are already taking antiarrhythmic medications such as when arrhythmias are present. In some cases, a patient may undergo cardioversion and then receive a prescription for an additional antiarrhythmic drug afterward, which can further decrease the risk of recurrence of the initial arrhythmia.

A review published in the journal Clinical Cardiology examined various studies that assessed the factors related to long-term maintenance of normal sinus rhythm among patients who had undergone cardioversion for treatment of atrial fibrillation. Overall, the review stated that over 90 percent of people who have cardioversion for the treatment of AF are able to be converted to normal sinus rhythm. However, of these people, fewer than

40 nursece4less.com nursece4less.com nursece4less.com nursece4less.com half of them still have normal sinus rhythm one year later. The review went on to cover various factors that carry predictive capacity for whether AF will be held back after cardioversion or will be more likely to recur.

Factors such as the length of time that AF is present (less than one month showed greater probability that cardioversion would be successful), as well as the presence of underlying heart disease had impacts on whether cardioversion would be a successful form of treatment for atrial fibrillation. Finally, there was evidence that showed various factors were associated with a lower rate of success with cardioversion (such as age over 80 years, the presence of AF for over three years, a previous history of cardioversion attempts, increased size of the left atrium, and significant mitral valve disease) as opposed to factors that indicated a high likelihood of success with cardioversion (the patient had no previous episodes of AF, age is less than 65 years, and there is no evidence of cardiac structural or valve disease present).34

Overall, electrical cardioversion has been shown to be effective for treatment of paroxysmal AF and the patient may return to and remain in normal sinus rhythm for an extended period of time following the procedure. When persistent or longstanding AF is present, or other types of tachyarrhythmias have developed, the long-term success rates can vary.

Some people can successfully treat AF through cardioversion once and maintain a normal rhythm with prescription antiarrhythmic medications. Alternatively, there are others who undergo cardioversion only to later need subsequent procedures or to progress to other routes, such as cardiac ablation, that can provide further treatment.

41 nursece4less.com nursece4less.com nursece4less.com nursece4less.com Summary

Chemical cardioversion, the use of antiarrhythmic medication to reset the heart’s pace and rhythm back to normal, is an option in some cases of tachyarrhythmia. Electrical cardioversion, however, is more appropriate for patients who are experiencing prolonged cardiac arrhythmias. Electrical cardioversion may be preferred over chemical cardioversion, as setting the amount of voltage on the cardioversion machine and the close monitoring of the patient that takes place throughout the process allow the health clinician to have more control over the entire situation.

Sedation during cardioversion may include some anesthetic agents, however the goal is not to induce unconscious but to make it so the patient does not remember. The patient’s vital signs and oxygen status need to be continuously monitored, and supplemental oxygen provided as needed.

Electrical cardioversion has been shown to have varied long-term success results for the different types of arrhythmias. To maintain a normal sinus rhythm, a person may need only one single cardioversion or may require multiple cardioversions, and possibly combined with antiarrhythmic medication. When cardioversion becomes necessary, the method of shock delivery and the patient’s condition will influence the benefit and risk of undergoing a cardioversion procedure.

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42 nursece4less.com nursece4less.com nursece4less.com nursece4less.com 1. The external electrical cardioversion procedure is used to treat arrhythmias

a. only if cardiac catheter ablation fails. b. as the first-line therapy. c. to reorganize the heart’s electrical rhythm. d. by delivering a “shock” directly to a mechanical pacemaker.

2. The electrical cardioversion procedure is contraindicated for patients with

a. digitalis toxicity. b. mechanical pacemakers. c. very low blood pressure. d. breathing difficulties.

3. Planned cardioversion is usually performed

a. in an outpatient setting. b. in an emergency setting because of the risks. c. with an analgesic, not a sedative. d. in a hospital setting.

4. Synchronized cardioversion uses ______delivered at a timed point in the cardiac cycle to reset an arrhythmia back to normal sinus rhythm.

a. a high-energy shock b. a charged chemical c. a low-energy shock d. a random-level shock

5. Synchronized cardioversion means the electrical impulse is delivered

a. during the T wave. b. during the QRS complex, at the peak of the R wave. c. to the SA node. d. to the atria.

43 nursece4less.com nursece4less.com nursece4less.com nursece4less.com 6. ______may be administered prior to the start of cardioversion to prevent thrombosis or emboli from the procedure.

a. Sedatives b. Anticoagulants c. Antiarrhythmics d. Analgesics

7. Patients who are undergoing elective cardioversion and who have had atrial fibrillation for more than 48 hours (or an undetermined amount of time) should have anticoagulant therapy

a. for two weeks after the procedure. b. during the procedure only. c. prior to the procedure only. d. for three weeks prior to, and four weeks after, the procedure.

8. A patient who routinely takes anticoagulant medications for a period of time must monitor activity levels

a. to avoid injury from strenuous activity. b. to avoid headaches from the medication. c. to avoid electrolyte imbalance. d. to determine if an embolus will form.

9. True or False: The administration of intravenous (IV) fluids is a typical part of the process of electrical cardioversion.

a. True b. False

10. A patient who is scheduled for an electrical cardioversion will typically be administered anesthesia to induce

a. mild sedation. b. deep sedation. c. conscious sedation. d. anxiolysis.

44 nursece4less.com nursece4less.com nursece4less.com nursece4less.com 11. A patient who is preparing for an electrical cardioversion procedure must not wear metal objects such as hair clips or jewelry because these items

a. may prevent the machine from emitting a charge. b. could cause burns when the shock is administered. c. will ground the electrical charge. d. will interfere with sedation.

12. The amount of voltage used in electrical cardioversion can range between approximately

a. 10 to 50 joules. b. 200 to 300 joules. c. 50 and 200 joules. d. 300 to 400 joules.

13. In a monophasic, cardioversion system, the shock is delivered

a. once during the entire procedure. b. using one electrode. c. and travels in one direction. d. below 50 joules.

14. Patients who receive cardioversion through biphasic systems may experience fewer side effects than monophasic systems because biphasic systems

a. use lower energy levels. b. are more efficient. c. send current back and forth several times between the electrodes or the paddles. d. All of the above

15. One of the most common dangers of electrical cardioversion is

a. hypoxia. b. atrial flutter. c. digitalis toxicity. d. thrombosis.

45 nursece4less.com nursece4less.com nursece4less.com nursece4less.com CORRECT ANSWERS:

1. The external electrical cardioversion procedure is used to treat arrhythmias

c. to reorganize the heart’s electrical rhythm.

“Electrical cardioversion ... is a type of reorganization of the heart’s electrical rhythm so that it works appropriately and functions normally.... The delivery of a shock through the patient’s chest wall works to convert the heart’s rhythm from an arrhythmia into normal rate and rhythm once again. It is often administered after a stable patient has tried taking antiarrhythmic medications without success.”

2. The electrical cardioversion procedure is contraindicated for patients with

a. digitalis toxicity.

“Digitalis toxicity is considered to be a contraindication to cardioversion, as it can increase the risk of the patient developing a serious arrhythmia.”

3. Planned cardioversion is usually performed

d. in a hospital setting.

“Planned cardioversion is typically delivered under controlled conditions. The procedure may be performed on an outpatient basis but a patient is usually admitted to a hospital for the procedure.”

4. Synchronized cardioversion uses ______delivered at a timed point in the cardiac cycle to reset an arrhythmia back to normal sinus rhythm.

c. a low-energy shock

“Synchronized cardioversion is a low-energy shock delivered at a timed point in the cardiac cycle to reset an arrhythmia back to normal sinus rhythm.”

46 nursece4less.com nursece4less.com nursece4less.com nursece4less.com 5. Synchronized cardioversion means the electrical impulse is delivered

b. during the QRS complex, at the peak of the R wave.

“… with synchronized cardioversion the impulse is timed to be delivered at the moment of the QRS complex, at the peak of the R wave. The patient is connected to the cardioversion machine, which evaluates the patient’s heart rhythm and determines the correct point of delivering the shock ...”

6. ______may be administered prior to the start of cardioversion to prevent thrombosis or emboli from the procedure.

b. Anticoagulants

“Anticoagulants may be administered prior to the start of cardioversion to prevent thrombosis or emboli from the procedure.”

7. Patients who are undergoing elective cardioversion and who have had atrial fibrillation for more than 48 hours (or an undetermined amount of time) should have anticoagulant therapy

d. for three weeks prior to, and four weeks after, the procedure.

“According to the American College of Cardiology (2014), patients who are undergoing elective cardioversion and who have had atrial fibrillation for more than 48 hours (or an undetermined amount of time) should have anticoagulant therapy for three weeks prior to the procedure and then for another four weeks after cardioversion and restoration to normal sinus rhythm.”

8. A patient who routinely takes anticoagulant medications for a period of time must monitor activity levels

a. to avoid injury from strenuous activity.

“Any time a patient routinely takes anticoagulant medications for a period of time, he/she must also monitor activity levels to avoid injury from strenuous activity. In addition to preventing blood clots, anticoagulant medication also increases the risk of bleeding when injury occurs.”

47 nursece4less.com nursece4less.com nursece4less.com nursece4less.com 9. True or False: The administration of intravenous (IV) fluids is a typical part of the process of electrical cardioversion.

a. True

“The administration of intravenous (IV) fluids is a typical part of the process of electrical cardioversion.”

10. A patient who is scheduled for an electrical cardioversion will typically be administered anesthesia to induce

c. conscious sedation.

“The medications delivered typically provide conscious sedation, which describes a condition of being sleepy during the procedure but the patient is still able to be aroused. The state may also be referred to as moderate sedation.”

11. A patient who is preparing for an electrical cardioversion procedure must not wear metal objects such as hair clips or jewelry because these items

b. could cause burns when the shock is administered.

“The patient is placed supine for the procedure. Once the monitors have been placed, the provider should ensure that there are no extraneous metal objects touching the patient, such as hair clips or jewelry, as these items could cause burns when the shock is administered.”

12. The amount of voltage used in electrical cardioversion can range between approximately

c. 50 and 200 joules.

“The amount of voltage can range between approximately 50 and 200 joules (J) with synchronized cardioversion, since it is a low- energy shock. A patient with supraventricular tachycardia or atrial flutter may need up to 100 J of energy to restore normal sinus rhythm. For atrial fibrillation, the amount of energy required is greater, and 100 to 200 J may be delivered.”

48 nursece4less.com nursece4less.com nursece4less.com nursece4less.com 13. In a monophasic, cardioversion system, the shock is delivered

c. and travels in one direction.

“In a monophasic system, when the shock is delivered, the energy enters the patient and travels in one direction, from one electrode to the other, creating a monophasic waveform.”

14. Patients who receive cardioversion through biphasic systems may experience fewer side effects than monophasic systems because biphasic systems

a. use lower energy levels. b. are more efficient. c. send current back and forth several times between the electrodes or the paddles. d. All of the above [correct answer]

“Cardioversion with a monophasic system may require higher amounts of energy to convert the heart back to a normal rhythm. In a biphasic system, the current travels back and forth several times between the electrodes or the paddles. A biphasic system may use lower levels of energy, but the amount is usually more efficient when compared to monophasic systems. Because of this, patients who receive cardioversion through biphasic systems may experience fewer side effects of the treatment.”

15. One of the most common dangers of electrical cardioversion is

d. thrombosis.

“One of the most common dangers of the procedure is thrombosis.

49 nursece4less.com nursece4less.com nursece4less.com nursece4less.com References

The reference section of in-text citations includes published works intended as helpful material for further reading. [References are for a multi-part series on CARDIOVERSION AND ABLATION].

1. Mitchell, L. (2017). Atrial fibrillation (AF). Retrieved from http://www.merckmanuals.com/professional/cardiovascular- disorders/arrhythmias-and-conduction-disorders/atrial-fibrillation-af 2. National Heart, Lung, and Blood Institute. (n.d.). How the heart works. Retrieved from https://www.nhlbi.nih.gov/health/health- topics/topics/hhw/electrical 3. Thompson, A. (2015). Atrial fibrillation. JAMA 313(10): 1070. Retrieved from https://jamanetwork.com/journals/jama/fullarticle/2190988 4. Emdin, C., et al. (2017). Usual blood pressure, atrial fibrillation and vascular risk: evidence from 4.3 million adults. International Journal of Epidemiology 46(1): 162-172. Retrieved from https://academic.oup.com/ije/article/46/1/162/2617172 5. Cantillon, D. (2014). Atrial fibrillation. Retrieved from http://www.clevelandclinicmeded.com/medicalpubs/diseasemanageme nt/cardiology/atrial-fibrillation/ 6. Howlett, P., et al. (2015). Diagnosing paroxysmal atrial fibrillation: are biomarkers the solution to this elusive arrhythmia? BioMed Research International, Article ID 910267. Retrieved from https://www.hindawi.com/journals/bmri/2015/910267/ 7. Nattel, S., Harada, M. (2014). Atrial remodeling and atrial fibrillation: recent advances and translational perspectives. Journal of the American College of Cardiology 63(22); 2335-2345. 8. Camm, J. (2015). NOACS in AF patients undergoing cardioversion. [PowerPoint]. St. George’s University of London. 9. Burns, E. (2017) Atrial flutter. LITFL ECG library. Retrieved from https://lifeinthefastlane.com/ecg-library/atrial-flutter/ 10. Fogors, R. (n.d.). Cardiac anatomy and physiology – the cardiac action potential. The EP Lab.com. Retrieved from http://www.theeplab.com/B-The-Members-Center/C-Cardiac- AnatomyPhysiology/F-Action-Potential/CF00-Action-Potential.php 11. Ikonnikov, G. and Yelle, D. (2009). Cardiac conducting system. Clin Anat. 22(1): 99-113. Retrieved from http://www.pathophys.org/physiology-of-cardiac-conduction-and- contractility/ 12. National Heart, Lung, and Blood Institute. (n.d.). Arrhythmia. Retrieved from https://www.nhlbi.nih.gov/health-topics/arrhythmia

50 nursece4less.com nursece4less.com nursece4less.com nursece4less.com 13. Atlantic Cardiology Group, LLP. (2018). Atrial arrhythmias. Retrieved from http://www.mccardio.com/handler.cfm?event=practice,template&cpid =3330 14. Conen, D., et al. (2012). Premature atrial contractions in the general population. Circulation 2012; 126: 2302-2308. Retrieved from http://circ.ahajournals.org/content/126/19/2302 15. Mitchell, B. (2017). Atrial flutter. Retrieved from http://www.merckmanuals.com/professional/cardiovascular- disorders/arrhythmias-and-conduction-disorders/atrial-flutter 16. Aksu, T., et al (2015). of typical atrial flutter via right jugular vein due to bilateral obstructed iliac veins in a patient with dilated cardiomyopathy. Case Reports in Cardiology, Article ID 401580, 3 pages. Retrieved from https://www.hindawi.com/journals/cric/2015/401580/ 17. Dewland, T., Glidden, D., Marcus, G. (2014). Healthcare utilization and clinical outcomes after catheter ablation of atrial flutter. PLOS One. Retrieved from http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0100 509 18. EKG.Academy.com. (2017). Junctional dysrhythmias – premature junctional complex (PJC) and junctional escape beats. Retrieved from https://ekg.academy/learn-ekg?courseid=314&seq=6 19. Nurses Learning Network. (2018). EKG interpretation. Retrieved from https://www.nurseslearning.com/courses/nrp/nrp1619/section%202/p 02.html 20. U.S. National Library of Medicine Genetics Home Reference. (2017). Wolff-Parkinson-White syndrome. Retrieved from https://ghr.nlm.nih.gov/condition/wolff-parkinson-white-syndrome 21. Mitchell, B. (2017). Atrial fibrillation and Wolff-Parkinson-White Syndrome (WPW). Retrieved from http://www.merckmanuals.com/professional/cardiovascular- disorders/arrhythmias-and-conduction-disorders/atrial-fibrillation-and- wolff-parkinson-white-syndrome-wpw 22. Mahida, S., et al. (2015). Science linking pulmonary veins and atrial fibrillation. Arrhythmia & Electrophysiology Review 4(1): 40-43. 23. Tidy, C. (2014). Sick sinus syndrome. Retrieved from https://patient.info/doctor/sick-sinus-syndrome 24. Semelka, M., Gera, J., Usman, S. (2013). Sick sinus syndrome: a review. Am Fam Physician 87(10): 691-696. Retrieved from https://www.aafp.org/afp/2013/0515/p691.html 25. Lumen Learning. (n.d.). and electrical activity. Retrieved from

51 nursece4less.com nursece4less.com nursece4less.com nursece4less.com https://courses.lumenlearning.com/ap2/chapter/cardiac-muscle-and- electrical-activity/ 26. Knight, B. (2017). Cardioversion (beyond the basics). Retrieved from https://www.uptodate.com/contents/cardioversion-beyond-the-basics 27. American College of Cardiology. (2018). Recommended doses of anticoagulant/antithrombotic therapies for patients with atrial fibrillation. Retrieved from http://www.acc.org/tools-and-practice- support/clinical-toolkits/atrial-fibrillation-afib/anticoagulant-dosing- table 28. Hansen, M., et al. (2015). Thromboembolic risk in 16274 atrial fibrillation patients undergoing direct current cardioversion with and without oral anticoagulant therapy. EP Europace 17(1): 18-23. Retrieved from https://academic.oup.com/europace/article/17/1/18/503751 29. Lippincott. (2016). Lippincott nursing procedures. (7th ed.). Philadelphia, PA: Lippincott Williams & Wilkins 30. Baumrind, D. (2013). The trouble with sinus tachycardia. Retrieved from http://www.ems12lead.com/2013/04/30/the-trouble-with-sinus- tachycardia/ 31. Custer, A., Lappin, S. (2017). Rhythm, tachycardia, multifocal atrial (MAT). Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK459152/ 32. Jung, P., et al. (2013). Contrast enhanced transesophageal echocardiography in patients with atrial fibrillation referred to electrical cardioversion improves atrial thrombus detection and may reduce associated thromboembolic events. Cardiovascular Ultrasound 11(1). Retrieved from https://cardiovascularultrasound.biomedcentral.com/articles/10.1186/ 1476-7120-11-1 33. Yava, A., et al (2012). Effectiveness of local cold application on skin burns and pain after transthoracic cardioversion. Emergency Medicine Journal 29(7): 544-549. 34. Jin, Q., et al (2017). Prediction and prognosis of ventricular tachycardia recurrence after catheter ablation with remote magnetic navigation for electrical storm in patients with ischemic cardiomyopathy. Clinical Cardiology 40(11): 1083-1089. 35. Hellman, T., et al. (2017). Prediction of ineffective elective cardioversion of atrial fibrillation: a retrospective multi-center patient cohort study. BMC Cardiovascular Disorders 17(33). Retrieved from https://bmccardiovascdisord.biomedcentral.com/articles/10.1186/s128 72-017-0470-0 36. Mann, D., et al (Eds.). (2015). Braunwald’s heart disease: a textbook of cardiovascular medicine. (10th ed.). Philadelphia, PA: Elsevier Saunders

52 nursece4less.com nursece4less.com nursece4less.com nursece4less.com 37. Babic, D., Benussi, S., Schwarz, U., Valli, P., Matter, C. (2016). Endocarditis, hemiparesis, and upper GI bleeding 4 weeks after radiofrequency ablation for atrial fibrillation. European Heart Journal – Cardiovascular Imaging 17(6): 703. 38. Hamaya, R., et al. (2017). Management of cardiac tamponade in catheter ablation of atrial fibrillation: single-centre 15 year experience on 5222 procedures. EP Europace. doi: 10.1093/europace/eux307. 39. Wynn, G., et al. (2016). Long-term outcomes after ablation of persistent atrial fibrillation: an observational study over 6 years. Open Heart. doi: 10.1136/openhrt-202015-000394 40. Canadian Heart Rhythm Society. (n.d.). (EPS) and catheter ablation. Retrieved from https://www.chrsonline.ca/index.php/heart-rhythm-health- resources/electrophysiology-study-eps-and-catheter-ablation 41. Peichl, P., et al (2014). Complications of catheter ablation and ventricular tachycardia: a single-center experience. Circulation: Arrhythmia and Electrophysiology, 7: 684-690. Retrieved from http://circep.ahajournals.org/content/7/4/684 42. Maruyama, M. (2014). Management of electrical storm: the mechanism matters. Journal of Arrhythmia 30(4): 242-249. 43. Medtronic. (2017). Micra transcatheter pacing system. Retrieved from http://www.medtronic.com/us-en/patients/treatments- therapies/pacemakers/our/micra.html 44. Ho, J., Prutkin, J. (2017). Simultaneous atrioventricular node ablation and leadless pacemaker implantation. Heart Rhythm Case Rep. 3(3): 186-188. 45. Lewis, S., et al (2015). Anaesthetic and sedative agents used for electrical cardioversion. Cochrane Database of Systematic Reviews. doi: 10.1002/14651858.CD010824.pub2 46. Srinivasa, V. and Kodali, B. (2017). Capnography during sedation. Capnography. Harvard Medical School. Boston, Mass. Retrieved from http://www.capnography.com/capnosedation/capnography-is-vital- during-sedation 47. Merit Medical. (2018). Safeguard® pressure assisted device. Retrieved from https://www.merit.com/cardiac- intervention/hemostasis/compression-devices/safeguard-pressure- assisted-device/ 48. Schreiber, D., et al. (2015). Five-year follow up after catheter ablation of persistent atrial fibrillation using the “stepwise approach” and prognostic factors for success. Circulation: Arrhythmia and Electrophysiology 8(2): 308-317. 49. Steinberg, J., et al. (2014). Very long-term outcome after initially successful catheter ablation of atrial fibrillation. Heart Rhythm 11(5): 771-776.

53 nursece4less.com nursece4less.com nursece4less.com nursece4less.com 50. Mathew, D. (2018). . Heart Rhythm Consultants. Sarasota, Florida. Retrieved from https://www.heartrhythmdoc.com/arrhythmia-treatment- options/cryoablation/ 51. Desai, P., Kane, D., Sarkar, M. (2015). Cardioversion: what to choose? Etomidate or propofol. Ann Card Anaesth. 18(3): 306-311. 52. Washington Heart Rhythm Associates. (2015). AV Nodal Reentrant Tachycardia (AVNRT). Retrieved from http://www.washingtonhra.com/arrhythmias/av-nodal-reentrant- tachycardia-avnrt.php 53. Shukla, A. and Curtis, A. (2014). Avoiding permanent atrial fibrillation: treatment approaches to prevent disease progression. Vasc Health Risk Manag. 10: 1-12. 54. Ogunsua, A., et al (2015). Atrial fibrillation and hypertension: mechanistic, epidemiologic, and treatment parallels. Methodist Debakey Cardiovasc J. 11(4): 228-234. 55. Mody, B., et al. (2017). Ablation of long-standing persistent atrial fibrillation. Ann Transl Med. 5(15): 305. 56. Di Biase, L., Santangeli, P., Natale, A. (2013). How to ablate long- standing persistent atrial fibrillation? Current Opinion in Cardiology 28(1): 26-35. Retrieved from http://journals.lww.com/co- cardiology/fulltext/2013/01000/How_to_ablate_long_standing_persist ent_atrial.6.aspx 57. Senoo, G., et al (2015). Residual risk of stroke and death in anticoagulated patients according to the type of atrial fibrillation. Stroke 46(9). Retrieved from http://stroke.ahajournals.org/content/46/9/2523.full 58. Mayo Clinic. (2017). Supraventricular tachycardia. Retrieved from https://www.mayoclinic.org/diseases-conditions/supraventricular- tachycardia/symptoms-causes/syc-20355243 59. ACLS Certification Institute. (2018). Vagal maneuvers. Retrieved from https://acls.com/free-resources/knowledge-base/tachycardia/vagal- maneuvers 60. Yoo, B. (2018). Atrioventricular reentrant tachycardia (AVRT) & AV nodal reentrant tachycardia (AVNRT). Retrieved from https://www.khanacademy.org/science/health-and- medicine/circulatory-system-diseases/dysrhythmias-and- /v/avrt-avnrt 61. Washington Heart Rhythm Associates. (2015). Wolff-Parkinson White Syndrome (WPW) and atrioventricular reciprocating tachycardia (AVRT). Retrieved from http://www.washingtonhra.com/arrhythmias/wolff-parkinson-white- syndrome-wpw-and-atrioventricular-reciprocating-tachycardia- avrt.php

54 nursece4less.com nursece4less.com nursece4less.com nursece4less.com 62. Bushoven, P., et al (2015). Optimal anticoagulation strategy for cardioversion in atrial fibrillation. Arrhythm Electrophysiol Rev. 4(1): 44-46. 63. American Heart Association. (n.d.). Anticoagulation. Retrieved from http://www.heart.org/idc/groups/heart- public/@wcm/@hcm/documents/downloadable/ucm_317635.pdf 64. Ozkan, G., et al. (2016). Sedoanalgesia for cardioversion: comparison of alfentianil, remifentanil and fentanyl combined with propofol and midazolam: a prospective, randomized, double-blind study. European Review for Medical and Pharmacological Sciences, 20: 1140-1148. 65. Rull, G. (2017). Defibrillation and cardioversion. Retrieved from https://patient.info/doctor/defibrillation-and-cardioversion 66. Pozner, C. (2018). Advanced cardiac life support (ACLS) in adults. Retrieved from https://www.uptodate.com/contents/advanced- cardiac-life-support-acls-in-adults 67. METsis Medikal. (2015). PLUS defibrillator. Retrieved from http://www.metsismedikal.com/en/defibrillator/ 68. Tse, H., Lip, G., Coats, A. (Eds.). (2011). Oxford desk reference cardiology. Oxford, UK: Oxford University Press 69. Stanford Health Care. (2017). How epicardial ablation works. Retrieved from https://stanfordhealthcare.org/medical-treatments/e/epicardial- ablation/procedures.html 70. Deng, Y., et al (2016). Anesthetic management in radiofrequency catheter ablation of ventricular tachycardia. Tex Heart Inst J. 43(6): 496-502. 71. Passman, R. (2017). Catheter ablation to prevent recurrent atrial fibrillation: Clinical applications. UpToDate. Retrieved online at https://www.uptodate.com/contents/catheter-ablation-to-prevent- recurrent-atrial-fibrillation-clinical- applications?search=Pulmonary%20vein%20radiofrequency%20cathet er%20ablation%20therapy%20for%20atrial%20fibrillation.&source=se arch_result&selectedTitle=1~150&usage_type=default&display_rank= 1 72. Bunch, J. and Cutler, M. (2015). Is pulmonary vein isolation still the cornerstone in atrial fibrillation ablation? J Thoracic Dis. 7(2): 132- 141. 73. Gasparini, M., et al. (2013). Cardiac resynchronization therapy in patients with atrial fibrillation. JACC: Heart Failure. Retrieved from http://heartfailure.onlinejacc.org/content/1/6/500 74. MedMovie.com. (2018). 3D electrical mapping of the heart. Retrieved from http://medmovie.com/library_id/7556/topic/cvml_0307a/ 75. Nedios, S., et al (2016). Advanced mapping systems to guide atrial fibrillation ablation: electrical information that matters. J Atr Fibrillation 8(6): 1337.

55 nursece4less.com nursece4less.com nursece4less.com nursece4less.com 76. Kern, M. (2013). Back to basics: femoral artery access and hemostasis. Digest 21(10). Retrieved from https://www.cathlabdigest.com/articles/Back-Basics-Femoral-Artery- Access-Hemostasis 77. Yasgur, B. (2016). Cryoablation vs. radiofrequency ablation in atrial fibrillation. Cardiology Advisor. Retrieved from http://www.thecardiologyadvisor.com/arrhythmia/atrial-fibrillation- ablation-techniques/article/503405/ 78. Angiodynamics. (n.d.). How does RFA work? Retrieved from http://www.angiodynamics.com/uploads/pdf/Understanding%20Radiof requency%20Ablation.pdf 79. Radiology Info.org. (2018). Cryotherapy. Retrieved from https://www.radiologyinfo.org/en/info.cfm?pg=cryo 80. Lee, R.L. (2018). Surgical ablation to prevent recurrent atrial fibrillation. UpToDate. Retrieved online at https://www.uptodate.com/contents/surgical-ablation-to-prevent- recurrent-atrial- fibrillation?search=surgical%20ablation%20a%20fib&source=search_r esult&selectedTitle=1~150&usage_type=default&display_rank=1. 81. Blecher, G. et al. (2012). Use of rate control medication before cardioversion of recent-onset atrial fibrillation or flutter in the emergency department is associated with reduced success rates. Canadian Journal of Emergency Medicine 14(3), 169-177.

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