NWT Clinical Practice Guidelines for Primary Community Care Nursing - Cardiovascular System

Dysrhythmias Definition Atrial Fibrillation (A.Fib) Abnormal heart rhythm. The most common types This is the commonest arrhythmia. There are three are as follows: classifications of A.Fib. 1. Paroxysmal - which is self-terminating Sinus arrhythmia 2. Persistent - which can be converted to sinus A cyclic increase in heart rate associated with rhythm inspiration and decrease in heart rate with 3. Chronic expiration. No clinical significance and is common in the elderly and children. (Current Atrial Fib. is the only common arrhythmia in Medical Diagnosis and Treatment, 38th edition, which the ventricular rate is rapid and the rhythm 1999, p389) is highly irregular. The atrial rate can be > 350 bpm, most are not conducted through the AV Sinus Bradycardia node. The ventricular rate can be normal or > 150 Heart rate < 60 bpm; impulse originates in SA bpm and there is usually a difference between the node, but is slowed through the AV node. Usually radial rate and the apical rate (Rosenthal, R., 2002. bradycardia is an accidental finding and can be Atrial Fibrillation, eMedecine Journal, 3:1) normal for the young or for athletes. Severe bradycardia can be an indication of sinus node Atrial Flutter pathology, such as sick sinus syndrome or heart This is less common than A.Fib and is most often block, wherein the SA node does not generate or associated with COPD. Atrial rates can be as high transmit a signal to the atria as 250-300 bpm with transmission of every second (Livingston, M., 2001, eMedecine Journal, 2:7) impulse through the AV node, which gives a ventricular rate of about 150 bpm. Ventricular Sinus rate is usually regular and the P waves have a Heart rate >100-160 bpm; is caused by rapid distinct saw-tooth appearance, especially in leads impulse formation from the SA node (Current II, III and AVF. (Ganz, L., Ahluwalia, M., 2002, Medical Diagnosis and Treatment, 38th edition, eMedecine Journal, 3:1) 1999, p389) Wide QRS Complex : Narrow QRS Complex Tachycardias: Premature Ventricular Contractions Paroxysmal Supraventricular These beats have a wide QRS complex, are not Tachycardia (PSVT) usually preceded by a P wave, usually there is a The most commonly occurring paroxysmal pause before the next normal beat. Bigeminy and tachycardia. Episodes may last from seconds to trigeminy are rhythms in which every second or hours. Rate is usually 160-220 bpm and are third beat is a PVC. Usually benign in patients regular even with exercise and position changes. without heart disease.

Supraventricular Tachycardia (SVT) Ventricular Tachycardia (VT) Accessory pathways between atria and ventricles Three or more consecutive ventricular premature allow an avoidance of the delay at the AV node, beats. The rate is > 100 bpm (usually 150-200) thus predisposing the heart to re-entry tachycardia. and is moderately regular. The complexes are The QRS is usually narrow and the P wave occurs wide and there is AV dissociation. There are also after the QRS (the PR interval is greater than the fusion beats. It is either sustained - lasting > 30 RP interval) (1999, The Merck Manual, Sec. 16, seconds, or unsustained - lasting < 30 seconds. p205) VT may be asymptomatic or can be associated with syncope, dizziness, diaphoresis or nausea. VT can quickly deteriorate into ventricular fibrillation. (Ernoehazy, W. Jnr., 2001, eMedecine Journal, 2:12)

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Torsades de Pointes waveform that resembles a squiggle that fades to a This is a variant of VT. The complexes are wide flat line. (Kazzi, A., 2001 eMedecine Journal, 2:8) and bizarre and look like the axis is changing (QRS from positive to negative and back). Pulseless Electrical Activity (PEA) Usually associated with drugs or conditions that A clinical condition "characterized by loss of increase the QT interval. (Ernoehazy, W. Jnr., palpable pulse (or ventricular contraction) in the 2001, eMedecine Journal, 2:12) presence of recordable cardiac electrical activity." ECG recording may show myocardial infarction, Ventricular fibrillation (VF) signs of hyperkalemia, prolonged QT interval VF is a pulseless arrhythmia that is irregular and related to tricyclic drug overdose. PEA is caused chaotic. The heart can no longer pump blood by an inability to generate a strong contraction in around the body. VF is the primary cause of spite of adequate electrical impulse. "PEA is sudden cardiac death. VF is most commonly seen always caused by a profound global cardiac following an MI. VF can be coarse or fine. The insult." (Verma, S., Marks, D., 2001, Pulseless heart rate is irregular, usually > 300 bpm, and a Electrical Activity, eMedicine Journal 2:9

Predisposing Factors Bradycardia PSVT Ventricular Fibrillation • Increased vagal tone • Gender (more common in females) • Severe coronary artery disease • Decreased sympathetic drive • Rheumatic heart disease • Acute myocardial infarction with • Ischemia to sinoatrial node • shock • Drug use: digoxin, beta blockers • Myocardial infarction • Myocardial reperfusion after thrombolysis • Athletic activity (normal variant in • Mitral valve prolapse athletes) • Preexcitation syndrome Premature Ventricular Contractions • Injury or other insult • Stress Atrial Fibrillation • Acute myocardial infarction • Myocardia ischemia Pulseless Electrical Activity • Hypothermia • Thyrotoxicosis • Respiratory failure with hypoxia • Electrolyte abnormality • Alcohol • Massive pulmonary embolus • Acidosis • Sick sinus syndrome • Tachycardia • PACs • Cardiac rupture • Decreased vagal tone • Massive myocardial infarction Atrial Flutter • Increased sympathetic tone • Pulmonary-respiratory arrest • Chronic hypertension • Myocardial infarction • Hemothorax • Valvular heart disease • Hypoxia • Tension pneumothorax • Left ventricular hypertrophy • Hypovolemia • Prolonged acidosis • Coronary artery disease • Fever • Decreased availability of calcium • Diabetes • Anxiety • Sepsis • CHF • Pain • Severe CHF • Post-op revascularization • Hypothyroidism with elevated TSH • Hyperkalemia • Digitalis toxicity • Exercise • Hypothermia • Pulmonary embolism • Caffeine • Drug ingestion (TCA, digoxin, Ventricular tachycardia calcium and beta blocker in Supraventricular tachycardia • Coronary heart disease overdosage) • Digoxin toxicity • Structural heart disease • Post defibrillation PEA • Catecholamines • Caffeine Torsades de Pointes • Gender (more common in males 2:1) • Congenital elongated QT intervals • Antiarrhythmic drugs • Electrolyte imbalances

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History complexes. Pulse volume is diminished or absent • Not all symptoms may be present during PVC • Client may note irregular heartbeat • Palpitations Ventricular tachycardia: ECG abnormal, rhythm may be regular or irregular. There are no • Chest discomfort comprehensive ECG criteria for diagnosing VT, • Shortness of breath but the presence of a rate • Dizziness > 150 bpm, wide and bizarre QRS complexes, • Diaphoresis atrioventricular dissociation and presence of • Weakness fusion beats, suggest ventricular tachycardia. • Syncope Hypotension, dyspnea, diaphoresis may also be • Nausea present.

Physical Findings Torsades de pointe: ECG abnormal, rhythm Sinus bradycardia: ECG normal, heart rate regular or irregular. QRS complexes appear to < 60 bpm. A heart rate below 40 bpm is usually a change appearance and size, looks like they are junctional rhythm originating in the . twisting. Hypotension, dyspnea, diaphoresis may Look for irregular PR intervals to determine heart also be present. block or sick sinus syndrome. Ventricular fibrillation: ECG abnormal, : ECG normal, heart rate > 100 unintelligible, no identifiable waves, complexes or bpm, blood pressure constant rhythms. No heart rate detectable, hemodynamically very unstable. PSVT (Atrioventricular nodal re-entrant tachycardia): ECG abnormal - rhythm regular, Differential Diagnosis fast, atrioventricular block usual as seen by a • Multifocal atrial tachycardia prolonged PR interval, systolic BP constant, • Sinus tachycardia with multiple premature atrial electrical alternans rare contractions • Sick sinus syndrome SVT (Orthodromic atrioventricular re-entrant • Wolfe-Parkinson-White syndrome tachycardia): ECG abnormal - rhythm regular, • Atrioventricular block atrioventricular block not present, systolic BP constant, electrical alternans common especially at high heart rates Complications • Heart failure Atrial fibrillation: ECG abnormal, rhythm • Myocardial infarction irregular, P waves not visible, systolic BP • Cerebrovascular accident changing. At high rates there is risk of developing • Thromboembolism Wolfe-Parkinson-White syndrome in some • Wolff-Parkinson-White syndrome individuals - look for delta waves on the Q wave • Cardiac arrest (slurred QRS) Diagnostic Tests Atrial flutter: ECG abnormal, ventricular rhythm • 12 lead ECG is usually regular, P waves have a well defined • Arrange for 24-hour Holter monitoring saw-tooth pattern. If rate is • Bloodwork - TSH, CBC, INR, PTT CK, < 120 bpm, there may be no symptoms, if > 120 Troponin T bpm, there may be hemodynamic instability

Premature ventricular contractions (PVC): ECG normal with occasional wide and bizarre QRS

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Management Pharmacologic Interventions Goals of Treatment Initial treatment prescribed only by a physician. • Convert to sinus rhythm • Relieve symptoms Selection of treatment modality should be based • Prevent recurrence on underlying pathophysiology. • Prevent complications (e.g. CHF, MI, Chronic atrial fibrillation is also treated with life-threatening dysrhythmias) anticoagulants such as warfarin. Appropriate Consultation Therapy is started as soon as possible if there is a Consult a physician if client has abnormal ECG history of underlying heart disease. pattern, refractory atrial fibrillation, suspicion of Wolff-Parkinson-White or "sick sinus" syndrome. Monitoring and Follow-Up For clients taking antiarrhythmic agents, liver Nonpharmacologic Interventions • enzyme levels should be measured during first Identify and remove any contributing factors. 4-8 weeks of therapy Client Education • Clients with risk factors for cardiac complications of therapy should undergo ECG • Teach client and family members the signs of during first weeks of therapy and every 3-6 hemodynamic compromise, including rapid months thereafter heart rate, unexplained weight gain, worsening dyspnea on exertion or in the night, decreased • Clients taking digoxin should be monitored exercise tolerance carefully for toxic effects • Teach client about long-term medication and its • Evaluate INR on a regular basis to monitor side effects therapeutic response to warfarin Referral Medevac clients with hemodynamic instability.

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