EDITORIAL

Implanted electronic devices at endoscopy: advice in a gray area

In the course of a busy open-access endoscopy calendar, significant distance from the area of treatment. However, it is not uncommon for a gastroenterologist to encounter data are sparse and manufacturers’ guidance is generally ei- a patient who has an implanted medical device. What to ther highly restrictive or nonexistent. Endoscopists are do? Should the presence of the device influence the perfor- therefore advised to acknowledge presence of the device mance of the scheduled procedure? Should any particular and counsel patients regarding the uncertain but likely precautions be taken? Does awareness and acknowledge- safety. ment of the device engender any additional liability? Once Greater concern exists for performance of endoscopy in noted, are measures available to reduce the risk for the pa- patients with the various devices that either maintain critical tient? Unfortunately, we have very few objective data to functions or prevent critical events of a life-threatening guide us through these practical, everyday concerns. In nature (ie, the cardiac devices and perhaps selected this issue of GIE, a newly updated Technology Review article neurologic stimulators). Unfortunately, even for cardiac provides a discussion of the broad issues that are raised by performance of endoscopy and electrosurgical therapies in patients with implanted electronic devices.1 This document has received significant input from members of the national Implanted electronic devices are now used to Heart Rhythm Society (HRS) and has been adopted by treat a wide array of cardiac, neurologic, and boards of both the HRS and the ASGE. Although the Tech- nology Review article provides formal advice to endoscop- sensory problems, but for most of them, there ists, it is worth independently noting the relatively is neither experience nor objective data re- subjective basis for the recommendations and how one garding their interactions with electrosurgical might easily adopt the most pertinent guidance. current used during endoscopy. Implanted electronic devices are now used to treat a wide array of cardiac, neurologic, and sensory problems, among others. Several new devices are described each year, and many are used in only a small number of patients. pacemakers and defibrillators, the data are few and most Hence, for most device types, there is neither experience advice is based on theoretical concerns and a small number nor objective data regarding their interactions with electro- of intraoperative events.1 surgical current. For these devices, generic precautions in- In a recent, very informal survey of almost 20 clinicians clude the following: (1) ascertaining general type and practicing in various settings, including academic centers, location of the device; (2) determining whether the device community hospitals, and ambulatory endoscopy facili- can be inactivated or turned off during endoscopy to pro- ties, only a few responders acknowledged taking specific tect both the device and the patient; (3) striving to avoid precautions in patients with implanted pacemakers. Defi- use of electrosurgical current in tissue, perhaps favoring in- brillators generated a bit more concern and uncertainty, jection or clip applications, particularly when the implanted with few clinicians describing standard policies for care. electronic device cannot be inactivated; and (4) when elec- Undoubtedly these clinicians mirror practices across the trosurgical current is required, using the most localized country and likely represent hundreds or even thousands form (bipolar rather than monopolar if appropriate) in of procedures performed in patients with implanted car- short bursts at lower energy, preferably at a distance from diac devices without incident. Nevertheless, the downside the implanted device. These precautions are likely ade- to malfunction or injury related to interactions during quate for most intermittently active implanted devices of electrosurgical therapy may be significant, and the near a noncritical nature, particularly when they are located a ubiquity of implanted cardiac devices makes lack of aware- ness a frail defense. Accepting that premise, do these de- vices require greater precautions than noted above for the Copyright ª 2007 by the American Society for Gastrointestinal Endoscopy noncritical devices distant from the thorax? Yes and no: it 0016-5107/$32.00 depends on the implanted device, the patient, and the an- doi:10.1016/j.gie.2007.02.015 ticipated therapy. www.giejournal.org Volume 65, No. 4 : 2007 GASTROINTESTINAL ENDOSCOPY 569 Editorial Petersen

Precautions to be taken with all patients with implanted maker functions. The advice of the patient’s rhythm cardiac devices include all of those listed above for generic specialist should be sought for those patients who are pace- devices as well as use of continuous electrocardiographic maker dependent and have dual function devices, because monitoring, if this is not already a standard for all patients programmed responses to application of a ring magnet vary in the unit. In general, all pacemakers can be left on, with among the implanted defibrillators and may be detrimental. or without conversion to a continuously paced mode (as After endoscopic procedures that include the use outlined below), and most defibrillators should be inacti- of a ring magnet on a pacemaker or the inactivation of vated for procedures with anticipated use of electrosurgical a defibrillator, and before patient discharge, the cardiac de- currents, after initiating rhythm monitoring. vice should be reactivated or assessed for normal function. For pacemakers, brief consideration should be given to For pacemakers, this can often be done telephonically, as the patient’s reliance on the implanted device. Among patients frequently do from home. For defibrillators, this re- patients with cardiac pacemakers, approximately 20% are quires brief return of the specialty nurse to the recovery dependent on their pacemaker for moment-to-moment area. maintenance of adequate rhythm and hemodynamics. For many practices, particularly in hospital settings, the This group of patients has a greater risk in the event of de- measures outlined in the accompanying review are already vice malfunction than those with a usually adequate native standard. For others, perhaps more so in free-standing cen- rhythm whose pacemakers are implanted to guard against ters, they pose modest logistical issues. In the future, unifor- intermittent profound episodes of bradycardia. Pacemaker mity in control mechanisms for the defibrillators would ease dependency is most obviously apparent when cardiac the uncertainty for practitioners and potential risks for the rhythm monitoring demonstrates a predominantly paced patient. It is hoped that better outcomes data will be forth- rhythm. Conservative guidance in the Technology Review coming regarding the more commonly used devices and article suggests that we should identify patients who are that better data-driven guidance will be provided by manu- pacemaker dependent in advance and use modest addi- facturers for the uncommon devices. In the meantime, tional precautions to ensure sustained pacemaker awareness and attention to the modest principles above function when they require prolonged use of electrocau- should minimize risk and enhance patient safety. tery. Alternatively, while not strongly advocated, similar precautions could be taken for use of electrocautery in all patients with implanted pacemakers. Placement of a ring magnet directly over a pacemaker site DISCLOSURE forces a continuous paced beat. This should be used only briefly for the few minutes during which electrocautery is The author has no pertinent conflicts of interest. actually being delivered, particularly when treating in close proximity to the heart and/or when using prolonged bursts Bret T. Petersen, MD of energy, as in the delivery of argon coagulation to broad Advanced Endoscopy Unit areas or during endoscopic mucosal resection or polypec- Gastroenterology and Hepatology tomy of broad lesions or thick pedunculated stalks. Mayo Clinic College of Medicine Inactivating defibrillators before endoscopy prevents Rochester, Minnesota, USA their inadvertent delivery of a cardioverting shock in re- sponse to electrosurgical currents. This requires pre- and postprocedure adjustments by a cardiovascular rhythm spe- REFERENCE cialist, nurse, or technician using transcutaneous control devices, as well as continuous monitoring during the unpro- 1. American Society of Gastrointestinal Endoscopy. Endoscopy in patients tected interval. Some defibrillators have integrated pace- with implanted electronic devices. Gastrointest Endosc 2007;65:563-70.

570 GASTROINTESTINAL ENDOSCOPY Volume 65, No. 4 : 2007 www.giejournal.org TECHNOLOGY STATUS EVALUATION REPORT

Endoscopy in patients with implanted electronic devices

The ASGE Technology Committee provides reviews of BACKGROUND existing, new, or emerging endoscopic technologies that have an impact on the practice of gastrointestinal endos- Endoscopy is commonly performed in patients with im- copy. Evidence-based methodology is used, with a MED- planted electronic devices. Electrocautery is used in many LINE literature search to identify pertinent clinical endoscopic procedures. Endoscopists must be familiar studies on the topic and a MAUDE (Food and Drug Ad- with the potential for patient injury or interference with ministration Center for Devices and Radiological device function as a result of endoscopic intervention. Health) database search to identify the reported compli- This article will address the risks and the appropriate man- cations of a given technology. Both are supplemented by agement strategies for endoscopy and the use of electro- accessing the ‘‘related articles’’ feature of PubMed and by cautery in patients with implanted electronic devices, scrutinizing pertinent references cited by the identified including the following: (1) cardiac devices (pacemakers studies. Controlled clinical trials are emphasized, but and defibrillators), (2) neurostimulators (deep brain, gas- in many cases data from randomized controlled trials tric, spinal cord, sacral nerve, and urinary bladder stimula- are lacking. In such cases, large case series, preliminary tors), and (3) drug-infusion pumps (chemotherapy and clinical studies, and expert opinions are utilized. Techni- pharmacotherapy infusion pumps) (Table 1). Other risks cal data are gathered from traditional and Web-based of GI endoscopy in patients with implanted electronic de- publications, proprietary publications, and informal vices that are unrelated to electromagnetic interference communications with pertinent vendors. are not addressed. Guidance regarding potential risks re- Technology Status Evaluation Reports are drafted by 1 lated to infection,1 performance of wireless capsule endos- or 2 members of the ASGE Technology Committee, re- copy,2 or wireless pH monitoring3 is available in other viewed and edited by the committee as a whole, and ap- guidelines or technology evaluations. proved by the Governing Board of the ASGE. When financial guidance is indicated, the most recent coding data and list prices at the time of publication are pro- TECHNICAL ISSUES vided. For this review, the MEDLINE database was searched through September 2006 for articles related to Electrocautery use during GI endoscopy endoscopy in patients with implanted electronic devices Electrocautery involves the application of radiofre- by using the keywords ‘‘gastrointestinal endoscopy’’ quency current in a unipolar or bipolar/multipolar fashion and ‘‘electrocautery’’ paired with ‘‘pacemaker,’’ ‘‘defi- to cut and/or coagulate tissues. In unipolar cautery, cur- brillator,’’ ‘‘ICD,’’ and each of the miscellaneous noncar- rent passes from the active electrode of the electrosurgical diac devices. In addition, this document also received device, through the patient to a distant return electrode review and contributions from physician representatives (grounding pad), and back to the generator. During bipolar of the Heart Rhythm Society (Washington, DC). and multipolar cautery, current flows from 1 or more elec- Technology Status Evaluation Reports are scientific re- trodes located on an electrosurgical device through imme- views provided solely for educational and informational diately adjacent tissue and returns to 1 or more electrodes purposes. Technology Status Evaluation Reports are not on the same instrument. During electrocautery, the resis- rules and should not be construed as establishing a legal tance to flow of current generates heat, which enables standard of care or as encouraging, advocating, requir- electrocoagulation or electrosection (cutting effect). Coag- ing, or discouraging any particular treatment or pay- ulation occurs with short bursts of relatively low-energy cur- ment for such treatment. rent, whereas cutting uses continuous current generating high temperatures, which cause cell explosion and evapora- tion.4 Newer-generation electrosurgical generators use programmable blends of coagulation and cutting current. The most common applications of monopolar cautery Copyright ª 2007 by the American Society for Gastrointestinal Endoscopy include the performance of endoscopic polypectomy (pri- 0016-5107/$32.00 marily in the colon or the stomach) and endoscopic doi:10.1016/j.gie.2006.09.001 sphincterotomy of the biliary or pancreatic sphincters at www.giejournal.org Volume 65, No. 4 : 2007 GASTROINTESTINAL ENDOSCOPY 561 ASGE technology status evaluation report

TABLE 1. Device classes and devices

Patient controlled functions Sensing Voltage Alter programming Device class Device capabilities On-off or rate for electrocautery?

Cardiac

Pacemakers Yes, most No No Situational, see text ICD Yes No No Yes, with specialty input Neurostimulators DBS No Yes No See text GES No Yes Yes See text Other neurostimulators No Most yes Most yes Yes (spinal cord, peripheral nerve, urinary bladder, cochlear) Medication delivery pumps Pharmacologic agents No No Most no Most no (eg, narcotics,

Lioresal, PGI2) Chemotherapeutic No No Most no Most no agents (floxuridine)

the major or minor papillae in the duodenum. ‘‘Hot bi- source comes in direct contact with the body (eg, electro- opsy’’ is a special form of polypectomy in which monopo- cautery or defibrillation). Radiated EMI occurs when the lar cautery is used to simultaneously coagulate and ablate body is placed in an EMF (eg, magnetic resonance imag- the base of small polyps during sampling.5 Monopolar cau- ing). Variables related to endoscopic or surgical electro- tery is also used during the application of argon plasma cautery devices that determine the likelihood of coagulation for control of hemorrhage or for ablation of interference with implanted devices include the intensity mucosal lesions, such as vascular malformations or resid- of the generated EMF, the frequency and waveform of ual polyp tissue.6 In this ‘‘noncontact’’ technique, the mo- the signal, the distance between the electrocautery appli- nopolar circuit is completed by passage of current via cation and the leads of the implanted device, and the ori- a stream of argon ions from the device tip to the tissue. entation of the leads with respect to the EMF.8 Cutting In most monopolar applications, the duration of cautery current may be more likely to cause EMI than coagula- is controlled by stepping on a foot pedal for the desired tion current.9 Because bipolar and multipolar devices in- intervals of !1 second to 10 seconds or more. duce only a limited flow of current beyond the site of Bipolar and multipolar cautery are used during direct ap- application, a very localized EMF is generated and EMI plication of ‘‘bicap’’ probes for control of local hemorrhage is less likely compared with monopolar devices. Use of from ulcers or other vascular lesions.7 Power application electrocautery can induce an EMF as high as 60 V/m. Vari- can vary from brief pulses of!1 second to continuous appli- ables that determine the sensitivity of an implanted de- cation. The Olympus heat probe (Olympus Optical Co, Ltd, vice to an EMF include the presence and the number Tokyo) is a nonconductive hemostatic probe with a Teflon- of leads, the distance between the anode and the cath- coated tip that is heated by an internal electrical resister. No ode of the implanted device (smaller distance in bipolar current is passed through the tissues to either a local or dis- leads vs unipolar leads), and the programmed sensitivity tant electrode; hence, the induced electromagnetic field of the device to an electrical signal. Implanted devices (EMF) (see below) is negligible. that use bipolar sensing are less likely to experience EMI.10 Principles of electromagnetic interference Theoretically, EMI generated by an electrosurgical Electromagnetic interference (EMI) refers to the effect instrument on an implanted device can be manifested in of an EMF on the function of any electronic device. EMI the following ways10: occurs as a result of 2 forms of EMF: conducted and radi- 1. The signal may be interpreted as physiologic or patho- ated. Conducted EMI occurs when an electromagnetic physiologic, temporarily inhibiting or triggering output.

562 GASTROINTESTINAL ENDOSCOPY Volume 65, No. 4 : 2007 www.giejournal.org ASGE technology status evaluation report

For example, the signal could be sensed as intrinsic car- ICDs successfully terminate VF in over 98% of epi- diac electrical activity, with inhibition of a pacemakers sodes9,10 and have been shown to reduce mortality.11 output or as ventricular fibrillation (VF) resulting in dis- The indications for ICD use are expanding and now in- charge of an implantable cardioverter-defibrillator (ICD). clude not only patients with a history of ventricular ar- 2. The signal may be interpreted as noise, temporarily or rhythmia but those found at risk because of left permanently causing the device to revert to a mode ventricular dysfunction.16-18 This device consists of a pulse preset by the manufacturer. generator and 1 or more leads for pacing and defibrillation 3. High levels of current may pass though the implanted electrodes. The pulse generator has a titanium case that leads and damage the contiguous tissue. houses a battery, voltage converters, capacitors, and other 4. A continuous train of electrical impulses may be con- electronic capabilities of a pacemaker. Current ICD de- ducted down the leads of an implanted device and vices weigh 50 to 100 g, have a 30- to 70-mL volume, cause inappropriate stimulation of the target tissue, and are usually implanted in the anterior pectoral loca- such as ventricular or atrial fibrillation with pacemakers tion, similar to a pacemaker.19 Some patients who have re- or ICDs. tained older epicardial or endocardial ICD systems or who 5. High levels of current may cause irreversible loss of bat- have no upper-extremity venous access may have a gener- tery power or permanent destruction of the device. ator implanted in the abdomen, usually in the left upper Because of the very different nature of the devices, car- quadrant above the rectus muscle. Current-generation diac devices, neurostimulators, drug-infusion pumps, and ICDs can perform all pacemaker functions, including bi- other devices will be considered separately in this report. ventricular pacing; some patients with ICDs are also pace- For further discussion of EMI and the potential interaction maker dependent, usually because of concomitant AV with implanted cardiac devices, the reader is referred to block. recent reviews of the subject.11-13 Situations 3, 4, and 5 ICDs sense ventricular rate (R-R interval) by using above are very unlikely to occur in modern pacemakers a true or modified bipolar-sensing electrode, usually im- and ICDs unless the current source is applied in very planted on the endocardial surface of the right ventricle. close proximity to the pulse generator or the lead elec- ICDs detect ventricular tachyarrhythmias by sensing trodes, which is unlikely to occur in GI endoscopic a number of R-R intervals above a rate threshold for a given procedures. duration, all these variables are programmable. Typical tachycardia detection criteria are rates higher than 150 to 200 bpm for 3 to 5 seconds. Ventricular tachycardia CARDIAC DEVICES (VT) and VF events that meet detection criteria are treated by the delivery of antitachycardia pacing (ATP) for VT, Two major classes of cardiac-rhythm–management de- countershocks for VT or VF, and antibradycardia pacing vices are commonly used: pacemakers and ICDs. These as needed for a short time after delivery of a counter devices have significantly different risks for abnormal func- shock. Patients may also use the antibradycardiac pacing tion or injury and, hence, differing recommendations for functions of the ICD chronically. The specific criteria for their management during the use of electrocautery. arrhythmia detection, cardioversion, and defibrillation Cardiac pacemakers may be programmed in asynchro- vary between models and manufacturers, and are pro- nous modes (where the pacemaker paces but does not grammable.14 The signal caused by electrocautery is sense the atria or ventricle or both chambers) or synchro- 1600 times greater than the sense threshold of the ICD nous modes (capable of sensing the atrial or ventricular and, hence, can be detected as VT or VF by ICDs if the impulse or both). All currently implanted pacemakers signal is sufficiently close to the sensing electrode and have programmable features (including, eg, control over prolonged to meet programmed detection criteria pacing mode, rate, stimulus output, sensitivity, rate- (D. Ruzin, Medtronic Inc, written communication, Octo- responsiveness), the nature of which depends on the type ber, 2005). of pacemaker used.14 The sensing thresholds of pace- makers (as low as 0.1 mV) are well below the EMFs in- Safety issues with cardiac devices duced by use of electrosurgical therapy, that is, Published data regarding safety of endoscopic electro- electrosurgical current applied near pacemakers may be cautery use in patients with implanted cardiac pacemakers easily sensed as intrinsic cardiac electrical activity.15 Pace- are limited and anecdotal. Two case series with limited makers are implanted in patients for a variety of indica- numbers of procedures report safe use of electrocautery, tions, most commonly sinus-node dysfunction and without specific precautions during endoscopy in patients atrioventricular (AV) block. The term ‘‘pacemaker depen- with pacemakers.20,21 Serious adverse events related to dent’’ is used to refer to patients who require cardiac pac- the endoscopic application of electrocautery in patients ing most or all of the time to maintain a physiologically with pacemakers have not been reported. adequate heart rate. This situation most commonly occurs Adverse events occurring during the use of intraopera- in patients with a high-degree or a complete AV block. tive electrocautery in patients with a pacemaker have www.giejournal.org Volume 65, No. 4 : 2007 GASTROINTESTINAL ENDOSCOPY 563 ASGE technology status evaluation report decreased as a consequence of the increasing use of bipo- the cardiac device make, model, type (eg, single chamber, lar leads and improved pacemaker design, but they still dual chamber, biventricular), indication for the device, occur.22-29 Reports of intracardiac device malfunction in degree of pacemaker dependence, and the patient’s un- this setting include pacing inhibition, pacing triggering, derlying heart rhythm. For those with an ICD, a history automatic mode switching, spurious tachyarrhythmia de- of device utilization to treat VT and VF is also useful. tection,30 electrical reset,11,12 myocardial burns,13 VF,31 Such patients are usually followed at regular intervals the runaway pacemaker syndrome,24 and irreversible loss (every 3-6 months) in specialized device clinics and/or of output.32 Although the likelihood is low, transient pace- by heart rhythm specialists trained in device management. maker inhibition during actual delivery of electrocautery The patient’s cardiology provider should be able to pro- could occur, with resulting severe bradycardia or asystole vide these data, as well as information regarding how in patients dependent on a pacemaker. the patient’s device will respond to a magnet and advice In theory, electrosurgical cautery in patients with ICDs regarding whether and how the patient’s device should could elicit inappropriate countershocks by the pulse be reprogrammed during the procedure. generator, ATP, suspension of arrhythmia detection, or Pacemaker interrogation and reprogramming immedi- permanent damage/malfunction of the implanted device. ately before and after the procedure allows control over However, there are no published reports of these events the pacemaker rate but is not always feasible in all practice during endoscopy or surgery. The absence of such reports settings and clinical situations because of a lack of avail- may be because of a general practice of temporarily inac- ability of qualified personnel to perform this task. In some tivating ICDs during procedures in which electrocautery is practice settings, transtelephonic monitoring may be per- used. Two series report experience with electrosurgical formed to check basic pacemaker function. Internet-based devices in a total of 4 dogs and 48 patients. There was uni- home monitoring of some ICDs has recently become form absence of sensing of the electrosurgical signal or available. In the future, similar monitoring of pacemaker ICD charging, reprogramming, malfunction, or dam- and ICD function in the postprocedure setting may be age.33,34 Despite the lack of reported events because of possible. EMI, the potential risks of electrocautery should be con- Patients who are pacemaker dependent patients (ie, sidered in patients with ICDs undergoing an endoscopy those with complete AV block) and are undergoing endos- and appropriate precautions taken. copy in which prolonged electrocautery (especially unipo- lar) is anticipated may require temporary (via magnet application) or permanent reprogramming of the pace- Management of patients with cardiac devices maker to an asynchronous mode (VOO or DOO). In gen- Because of limited available data on the safety and ef- eral, a magnet held or taped in the proper position over fectiveness of different strategies for cardiac-device man- a pacemaker generator will result in asynchronous pacing agement during endoscopy, as well as different features at a constant rate prespecified by the manufacturer (gen- available in different cardiac-device makes and models, erally 70 to 100 bpm). The principal advantage of magnet universal recommendations applying to all patients in all application is ease of use and reversibility of the interven- practice settings cannot be made at the present time. A tion. One disadvantage is that pacemakers with magnet Practice Advisory for the Perioperative Management of rates near 100 bpm may not be well tolerated by some pa- Patients with Cardiac Rhythm Management Devices,35 tients at rest. The magnet response varies among manu- based upon a survey by the American Society of Anesthe- facturers and device models. siology (ASA), provides a useful review of the subject even Most patients with modern pacemaker systems who are though few points of broad consensus were achieved. not pacemaker dependent (ie, patients with infrequent Manufacturers’ Web sites and device-specific literature symptoms because of intermittent sinus-node dysfunc- are helpful sources of guidance regarding interventions tion) will not require temporary or permanent pacemaker in patients with implanted devices. Manufacturers’ recom- reprogramming for endoscopic procedures. Indeed, some mendations are often based on anecdotal case series and patients with normal intrinsic heart rhythm will become reports of pacemaker malfunction during surgery but not symptomatic if programmed to asynchronous pacing during GI endoscopy specifically. In the absence of data, mode, because of palpitations or diminution of cardiac the theoretical risk for significant morbidity led some output. In addition, although extremely rare, the potential manufacturers to issue recommendations that electrocau- for asynchronous-pacing–induced proarrhythmia is pres- tery or other therapies that generate EMFs should be ent. If pacemaker reprogramming is not performed, oper- avoided whenever possible in patients with implanted de- ators should be prepared to recognize and manage vices. At the present time, the preponderance of data sup- infrequent responses to electrocautery, such as ventricular port the safe use of electrocautery in patients who have pacing at the upper rate limit (because of rate-responsive pacemakers and ICDs, with proper precautions. behavior or ventricular tracking of sensed signal on the For patients with either pacemakers or ICDs, periproce- atrial channel), mode switching, and noise reversion to dural planning should include obtaining information on an asynchronous pacing mode. In general, these

564 GASTROINTESTINAL ENDOSCOPY Volume 65, No. 4 : 2007 www.giejournal.org ASGE technology status evaluation report responses, if they occur, will be transient and limited to ICD interrogation and reprogramming to suspend the period during which electrocautery is applied. tachycardia detection and/or therapies have been recom- For patients with ICDs, a principal concern regarding mended as the optimal solution to prevent the potential the use of electrocautery is the potential for triggering in- risk of inappropriate ICD therapies during use of electro- appropriate ICD therapy. Inappropriate ATP during sinus cautery.37 One limitation of this approach is the need to rhythm may induce VT or VF in a susceptible patient. have qualified personnel available to perform the task im- ICD discharges, especially repetitive discharges in an mediately before and after the procedure. During this pe- awake patient, may be psychologically traumatic, may in- riod of inactivation, Patients with an ICD are not protected duce arrhythmia or cause hemodynamic instability, and by the device and, hence, must be monitored continu- may cause physical injury because of sudden muscle ously in a setting where VT/VF can be immediately recog- contraction or reactive patient movement during a delica- nized and treated with external defibrillation. If external te procedure. Although such adverse events have not defibrillation is required, attempts should be made to been reported in patients undergoing endoscopy, the avoid placing the external defibrillator pads or paddles di- potential for such events nonetheless exists and may be rectly over the ICD generator, but immediate resuscitation underreported. Furthermore, the absence of reported of the patient should be the first consideration. Finally, en- adverse events may also be because of the widespread doscopy facilities that use an approach of ICD reprogram- practice of temporary ICD inactivation for such ming should establish a fail-safe protocol for ensuring that, procedures. in patients with an ICD, the ICD is appropriately reprog- A magnet properly applied over the pulse generator of rammed after the procedure and that no patient ever most ICD models will result in suspension of tachycardia leaves the monitored setting with the ICD inappropriately detection and/or ICD therapies, while the magnet is in inactivated. Several patient deaths from VT/VF have been place, without affecting pacemaker function. Although documented because of this preventable medical error.38 magnet use is attractive because of its simplicity and The patient with the ICD who is also dependent on the ease of reversibility, there are several limitations to the ap- pacemaker function of the ICD represents a particular proach of magnet application in this setting: challenge, because magnets do not affect the pacing func- 1. In some ICD models made by 1 manufacturer (Guidant tion of most ICDs, and many ICDs cannot be programmed Corp, St. Paul, Minn), the ICD response to a magnet to an asynchronous pacing mode because of manufacturer can be programmed by prolonged magnet application concerns about interference with VT/VF detection. Accord- to either permanently disable ICD therapies, temporar- ingly, particular care should be taken with electrocautery in ily disable ICD therapies while the magnet is in place, these patients, and preprocedure consultation with a cardi- or to ignore a magnet entirely. For these devices, one ologist or a heart-rhythm specialist may be advisable. cannot know how these devices will respond to a mag- net without knowing how this feature is programmed. Summary recommendations for cardiac The potential to permanently inactivate ICD therapies devices with a magnet exists with these devices, with at least By recognizing that the paucity of published clinical 2 documented sudden death.36 data favoring any given approach, that the availability of 2. Unlike a pacemaker response to a magnet, where asyn- heart rhythm specialty support varies by geographic re- chronous pacing can be easily observed, it is more dif- gion and practice setting, and that the variation in practice ficult to ascertain whether the magnet is properly currently exists in this area, the following general recom- positioned over an ICD. The proper position varies mendations are made to minimize the risks to patients among different device manufacturers and models, with implanted cardiac devices who are undergoing endo- and while some devices emit a tone when a magnet scopic procedures that require the use of electrocautery. is placed properly, others provide no feedback to prove d In all patients with implanted cardiac devices. proper placement. B Determine the type of cardiac device, indication for 3. Even if initially placed properly, a magnet may move the device, the patient’s underlying cardiac rhythm, out of place during the procedure, especially if patient and degree of pacemaker-dependence before endos- repositioning is required. In part for these reasons, the copy. Most patients carry wallet cards that identify 2005 ASA Practice Advisory ‘‘cautions against the use of the device make and model, with manufacturer con- a magnet over an ICD.’’35 It should be recognized, how- tact numbers. Contacting the patient’s cardiologist ever, that alternative approaches also have limitations or heart rhythm specialist and/or the device manu- and that no adverse events from magnet use during facturer may be helpful, especially in concert with endoscopy have been reported. Furthermore, some the evaluation by an on-site heart rhythm specialist endoscopy facilities with proper training, experience, or device nurse. and heart rhythm specialty support have a long record B Use continuous electrocardiographic rhythm moni- of using magnets for this purpose, without adverse toring in addition to pulse oximetry during the events. procedure. www.giejournal.org Volume 65, No. 4 : 2007 GASTROINTESTINAL ENDOSCOPY 565 ASGE technology status evaluation report

B Have appropriate equipment for resuscitation, cardi- than 14,000 implants had been performed worldwide39; oversion, and defibrillation immediately available. however, there is a potential for increasing use, because This should include an external defibrillator with the annual incidence of Parkinson’s disease ranges from transcutaneous pacing capability. 500,000 to 1 million people in the United States.40 The B Consider the use of endoscopic devices with limited DBS measures 61 Â 76 Â 13.4 mm, weighs 83 g, and is or no EMF (such as noncautery thermal probes or housed in a titanium-alloy body. The device electrodes are bipolar/multipolar probes). stereotactically placed in various areas of the brain. The B Use the lowest effective power output and the brief- lead is tunnelled subcutaneously down the side of the skull est application of the electrocautery device possible. where it meets the extension wire just behind the ear. The B Place grounding pads a good distance from the extension is then tunnelled down the neck and into the pulse generator and leads, such that the implanted anterior chest-wall location, where it is connected to device and leads are not between the cautery source the neurostimulator. The patient can activate and deacti- and the grounding pad. vate the neurostimulator by placing a magnet on the over- B Avoid use of cautery near implanted devices (Some lying skin. The DBS also provides telemetry data and can investigators advise avoiding therapy within 15 cm). be set in either a unipolar or bipolar configuration. d Most patients with cardiac pacemakers may undergo The gastric electrical stimulation (GES) system (En- routine uses of electrocautery (eg, polypectomy, hemo- terra Therapy; Medtronic) is indicated for stimulation of stasis) with no alterations in management. gastric motility in the treatment of patients with chronic, d For patients who are pacemaker dependent and in whom intractable (drug refractory) nausea, and vomiting sec- prolonged electrocautery is anticipated (eg, treatment of ondary to gastroparesis of either diabetic or idiopathic gastric antral vascular ectasia or radiation proctitis) con- etiology. It was approved by the Food and Drug Adminis- sider reprogramming the pacemaker to an asynchronous tration, with a humanitarian-device exemption in 2000.41 mode via application of a magnet over the pulse genera- An evolving indication in the literature is its possible tor during the use of electrocautery. use for morbid obesity. The device has a programmable d For patients with an ICD in whom the use of any electro- battery-operated neurostimulator42 that weighs 42 g and cautery may be anticipated, consultation with a cardiolo- measures 55 Â 60 Â 10 mm. Single or dual leads are tun- gist or a heart-rhythm specialist is recommended. nelled subcutaneously from the neurostimulator in the Deactivation of the ICD function by qualified personnel anterior abdominal wall to the gastric serosal surface should be considered. Continuous rhythm monitoring where unipolar or multipolar function stimulation is should be used throughout the interval that the ICD delivered. is deactivated. If deactivated, the ICD should be reprog- Other neurostimulation devices (peripheral nerve, spi- rammed as soon as possible after the procedure and be- nal-cord stimulators, urinary bladder, and cochlear) are fore cessation of monitoring or dismissal. similar in principals and have similar designs. d If the patient with an ICD is also pacemaker dependent and the ICD cannot be reprogrammed to an asynchro- nous mode and prolonged cautery application may be IMPLANTED INFUSION PUMPS required, then strongly consider the use of bipolar cau- tery or a device with no EMF. Implanted infusion pumps are indicated when therapy involves the constant, chronic intrathecal, epidural, or intravascular infusion of pharmacologic agents (eg, nar- NEUROSTIMULATORY DEVICES cotic, floxuridine, baclofen, and prostaglangin I2 [PGI2]). These implantable devices store and dispense drugs at Neurostimulators are implantable devices that deliver a constant flow rate set during the manufacturing process electrical stimulation to selected tissues, such as the brain, or a programmable rate that can be set by the physician. spinal cord, neural plexuses, gastric serosa, urinary blad- Programmable pumps are battery powered, whereas con- der, cochlea, and potentially other end organs. The de- stant-flow pumps have a propellant chamber. Both have vices generally consist of an electrical source, extension a pump drive and a central reservoir fill port. Certain wires, and 1 or more leads that deliver the electrical stim- models have an optional catheter-access port that is ulus. Most of the neurostimulatory devices have simple ex- used for diagnostic purposes. ternal modules for patient control of various settings, including the ‘‘on-off’’ function and voltage output. Safety issues in patients with neurostimulators The deep brain stimulator (DBS) (Activa Control Ther- and infusion pumps apy; Medtronic, Inc, Minneapolis, Minn)39 delivers electri- Safety data are almost nonexistent for the recently de- cal stimulation to selected areas of the brain for control of veloped neurologic and gastric stimulators and infusion aberrant brain signals in the management of Parkinson’s pumps. One report described the development of left- disease and other movement disorders. By 2004, more sided paresthesias in a patient with a DBS who underwent

566 GASTROINTESTINAL ENDOSCOPY Volume 65, No. 4 : 2007 www.giejournal.org ASGE technology status evaluation report repeated dermatologic surgery by using monopolar elec- Summary recommendations for noncardiac trocautery with or without the use of a dispersive plate. devices With the use of a battery-operated cautery device the The type of electronic device, the indication for the de- symptoms did not recur.43 Another case reported the vice, and whether normal physiology is critically dependent use of a battery-operated electrocautery device, without upon the device should be determined. Most patients production of neurologic symptoms in a patient with carry wallet cards that identify the device make and aDBS.44 A survey of the Maude database revealed 1 case model, with manufacturer contact numbers. Contacting report of DBS where a patient was ‘‘shocked’’ during the patient’s device specialist and/or the manufacturer the use of monopolar electrocautery.45 may be helpful in planning device management during Industry guidance and device inserts for the Activa and after the procedure. DBS, Enterra GES Systems suggest that electrocautery d Consider the use of endoscopic devices with limited or can cause the following: (1) temporary neurostimulator no EMF (such as noncautery thermal probes or bipolar/ device malfunction that presents as suppression of output multipolar probes). and/or reprogramming to reset parameters; (2) induced d Use the lowest effective power output and the briefest currents within leads, yielding symptoms of shocking or application of the electrocautery device possible. jolting and potential injury; and (3) electrode heating, d Place grounding pads a good distance from the device’s with a risk of focal tissue injury (Mr Curt Sponberg, Safety generator and leads, so that the implanted device and Representative, Medtronic Inc, personal written communi- leads are not between the cautery source and the cation, August, 2006).46,47 grounding pad. Permanent malfunction from electrocautery is unex- d Avoid the use of cautery near implanted devices. pected, and temporary malfunction can be mitigated by d For patients with DBS and GES devices, consult the pri- turning off the device during the procedure in which mary device specialist before considering inactivation of electrocautery will be used. Induced currents in im- the device output. planted leads may develop whether the device is turned d For patients with spinal cord and most other peripheral on or off. The level of EMFs necessary to cause a malfunc- neurologic stimulation devices, have the patient zero tion or induced currents has not been determined. Elec- the voltage output and then turn off the device before trode heating may be mitigated by limiting contact use of electrocautery. currents to !6 mA for 10 seconds or 18 mA for 1 second (C. Sponberg, personal communication). Correlation of these levels to outputs of clinical devices has not been CONCLUSIONS investigated. There is also no published literature regarding the safe Implanted electronic devices are increasingly encoun- use of electrocautery in patients with implanted infusion tered during GI endoscopy. Endoscopists must be aware pumps. The manufacturer’s System Components Clinical of the risks for patient injury and device damage or malfunc- Reference Manual states the following. ‘‘Testing indicates tion and must take precautionary steps to minimize the risk electrocautery is unlikely to damage the pump; however, if for their patients. The published data are quite limited. Fur- electrocautery is necessary near the pump, then follow ther studies should address the risk of adverse events re- these precautions: (1) use only bipolar cautery, and (2) lated to electromagnetic interference during GI endoscopy. if unipolar cautery is necessary, then do not use high-volt- age modes, keep the power settings as low as possible, and keep the current path (ground plate) as far away REFERENCES from the pump and catheter as possible.’’48 Recommendations for the use of electrocautery in pa- 1. Hirota WK, Petersen K, Baron TH, et al. Guidelines for antibiotic pro- phylaxis for GI endoscopy. Gastrointest Endosc 2003;58:475-82. tients with any of the noncardiac devices are based 2. Ginsberg GG, Barkun A, Bosco J, et al. Wireless capsule endoscopy. upon principles similar to those for cardiac devices, as Gastrointest Endosc 2002;56:621-4. well as on manufacturers’ guidance (Table 1). As with car- 3. Chotiprasidhi P, Liu J, Carpenter S, et al. ASGE technology status eval- diac devices, guidance should be sought from both manu- uation report: wireless esophageal pH monitoring system. Gastroint- facturers and the physician specialist managing the device est Endosc 2005;62:485-7. 4. Slivka A, Bosco J, Barkun A. Electrosurgical generators. Gastrointest En- application for the given patient. In general, the neurosti- dosc 2003;58:656-60. mulators for regions outside of the central nervous sys- 5. American Society for Gastrointestinal Endoscopy. Polypectomy de- tem, particularly those involving the spinal cord and vices. Gastrointest Endosc 2007. In press. peripheral nerves or organs, can be reduced to zero volt- 6. Ginsberg GG, Barkun AN, Bosco JJ, et al. The argon plasma coagulator. age output and then shut off entirely. Some devices can be Gastrointest Endosc 2002;55:811-4. 7. Nelson DB, Barkun AN, Block KP, et al. Endoscopic hemostatic devices. inactivated but cannot be adjusted downward to zero. Gastrointest Endosc 2001;54:833-40. Specialty physician input should be sought before inacti- 8. Sager DP. Current facts on pacemaker electromagnetic interference vating the DBS or the GES system. and their application to clinical care. Heart Lung 1987;16:211-21. www.giejournal.org Volume 65, No. 4 : 2007 GASTROINTESTINAL ENDOSCOPY 567 ASGE technology status evaluation report

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Intraoperative pacemaker dys- Poonputt Chotiprasidhi, MD function caused by the use of electrocautery during a total hip arthro- Julia Liu, MD plasty. J Arthroplasty 1998;13:599-602. Lehel Somogyi, MD 33. Wilson JH, Lattner S, Jacob R, et al. Electrocautery does not interfere *Heart Rhythm Society representatives. with the function of the automatic implantable cardioverter defibrilla- This document is a product of the Technology Assessment Committee. The tor. Ann Thorac Surg 1991;51:225-6. document was reviewed and approved by the Governing Board of the 34. Fiek M, Dorwarth U, Durchlaub I, et al. Application of radio- American Society for Gastrointestinal Endoscopy. frequency energy in surgical and interventional procedures: are

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