I reduce arrhythmic death in survivors of cardiac arrest

Transcription

1 Methods of Implantable Cardioverter-Defibrillator- Pacemaker Insertion to Avoid Interactions Henry M. Spotnitz, MD, Gary Y. Ott, MD, J. Thomas Bigger, Jr, MD, Jonathan S. Steinberg, MD, and Frank Livelli, Jr, MD Departments of Surgery and Medicine, Columbia-Presbyterian Medical Center, New York, New York Experience with combined transvenous pacemaker and implantable cardioverter-defibrillator insertion in 21 patients is described. Special techniques are needed to avoid potentially lethal pacemaker-implantable cardioverter-defibrillator interaction. Separation between leads for the two devices should be maximized. The electrophysiologic criteria for successful device function can be met, even when some leads for both devices must be placed by a transvenous approach. (Ann Thorac Surg 1992;53:253-7) mplantable cardioverter-defibrillators (ICDs) markedly I reduce arrhythmic death in survivors of cardiac arrest [l-31. Because the majority of patients who are candidates for ICD implantation suffer from advanced heart disease [l, 21, some patients who undergo ICD implantation will also require permanent pacemakers for sinus bradycardia, sinus arrest, or atrioventricular block [4,5]. The indication for an ICD or pacemaker may also be discovered after one or the other has already been implanted. Maximum safety is promoted in combined implantation by making pacemaker output invisible to the ICD, thereby avoiding inappropriate ICD discharges and failure of the ICD to recognize and respond to ventricular fibrillation. We describe methods that we have found useful in achieving this goal. Material and Methods We have previously described our approach to ICD implantation [6]. These patients are generally, but not always [2, 31, survivors of cardiac arrest in whom antiarrhythmic drugs are ineffective, poorly tolerated, or untestable. The need for transvenous pacing may be discovered in the course of electrophysiologic testing for ICD implantation. Some patients who are candidates for an ICD will have previously undergone pacemaker insertion. Other patients will be discovered to need a pacemaker after ICD insertion. The technique described here is best suited for patients undergoing ICD insertion through a left thoracotomy without simultaneous coronary bypass grafting. General anesthesia, maintenance of heart rate with drugs or temporary pacing, excellent fluoroscopy, and Accepted for publication Aug 1, Presented in part at the annual meeting of the New York Society for Thoracic Surgery, Nov Dr Ott s present address is University of Oregon Health Sciences Center, Portland, OR. Dr Steinberg s present address is St. Luke s-roosevelt Hospital, New York, NY. Address reprint requests to Dr Spotnitz, Columbia-Presbyterian Medical Center, 630 West 168th St, New York, NY electrocardiographic monitoring are essential. Adhesive external defibrillation electrodes are applied to the anterior right chest and posterolateral left chest. A fluoroscopy table must be used, and careful positioning is required to allow successful fluoroscopy and left thoracotomy in the presence of adhesive external defibrillation electrodes. We begin with a standard approach to transvenous pacing, exposing a cephalic or other small venous branch through a 3- to 4-cm incision beneath the left clavicle. Pacing wires are introduced directly through a small venotomy or through a 7F strip-away percutaneous catheter introducer (No ; Daig Corp, Minnetonka, MN) passed over a small guidewire. Fluoroscopy is then used to insert ventricular or atrial pacing wires as needed. The pacemaker system must be bipolar [v. For ventricular pacing, we prefer two unipolar, positive fixation, screw-in permanent pacing electrodes (Model ; Intermedics, Inc, Freeport, TX) positioned close together in the outflow tract of the right ventricle (RV) or in the anterior RV, just across the tricuspid valve (Figs 1, 2). Adequacy of sensing and pacing thresholds is confirmed before installing the pacemaker generator. A pacemaker system analyzer is used to determine thresholds for each unipolar lead, seeking pacing thresholds of less than 0.7 V, an R wave greater than 5 mv, and impedance of approximately 500 R. The leads are then tested in the bipolar configuration, usually providing pacing thresholds and R-wave amplitude similar to the unipolar configuration, except that bipolar impedance is about 1,000 R. Both possible bipolar polarities are tested, and the configuration giving the lower pacing threshold is identified with a marking tie on the negative lead. The leads are connected to a bipolar pacing generator. An adapter is usually required for these connections, because most current pacemakers use in-line bipolar connectors. Y adapters (5 mm to vs-1 or is-1) are available from Medtronic, CPI, Telectronics, and other manufacturers. Similar techniques of insertion, testing, and connection of paired atrial leads are employed when atrial or dual by The Society of Thoracic Surgeons /92/$5.00

2 254 SPOTNITZ ET AL Ann Thorac Surg 1992;53:25>7 A C B Fig 1. Posteroanterior (A) and lateral (C) roentgenograms reveal transvenous bipolar VVI pacemaker and epicardial ZCD inserted by left thoracotomy in a 56-year-old woman. Schematic diagrams (B, D) identify two positive-fixation pacemaker leads in the right ventricle, two myocardial ICD rate-sensing leads, and two large extrapericardial patch leads. D chamber pacing is indicated. Leads are placed in the atrial appendage or lateral right atrium as required. A left anterolateral thoracotomy incision is then performed, usually excising a small (7 cm) segment of the fifth rib. IntrapericardiaYmyocardial rate-sensing electrodes and extrapericardial large patch electrodes for the ICD are installed. Alternatively, the rate-sensing leads and a spring-coil defibrillator lead may be inserted through the subclavian vein (see Fig 2). During transvenous pacing at maximum pacemaker output and pulse width, the electrograms in both the rate-sensing and morphology leads are examined to confirm that pacemaker spikes are less than 0.2 mv in amplitude or less than 5% of the QRS amplitude in the rate-sensing leads. If these criteria are not met, either the pacemaker or ICD leads are repositioned (Fig 3). After lead positioning, cardioversion thresholds are measured by our electrophysiologists (J.T.B., J.S.S., F.L.) in ventricular tachycardia (when inducible) and in ventricular fibrillation, with transesophageal or epicardial echocardiographic monitoring of wall motion and ejection fraction when possible, as we have described previously [4]. Defibrillation thresholds are measured with an external cardioverter defibrillator (CPI) and must be 20 J or less. External defibrillator backup and availability of internal paddles can be critical if thresholds are unexpectedly high. Implantable cardioverter-defibrillator lead configurations are adjusted until defibrillation thresholds are adequate. A hemostatic, abdominal subcutaneous pocket is fashioned through a left upper quadrant incision. The ICD leads are tunneled through the diaphragm and attached

3 Ann Thorac Surg 1992;53:25>7 SPOTNITZ ET AL 255 A C SprlnQ COII Defibrlllator Lead, SVC Blmlar Rate Sensing Bipolar Rate Sensing Lead, RV Apex B Large Patch Electrode. Leads, RV%utflow Tract Fig 2. Posteroanterior (A) and lateral (C) roentgenograms reveal transvenous bipolar VVZ pacemaker and ICD in a 60-year-old man with previous coronary artery bypass grafting. Schematic diagrams (B, D) identify leads. Two positive-fixation pacemaker leads are visible in the right ventricular outflow tract. Technical considerations led also to transvenous insertion of an endocardial, bipolar rate-sensing lead and a spring-coil defibrillator lead in the superior vena cava. One large patch was inserted in an extrapericardial location through a left thoracotomy. Successful function of this lead configuration is illustrated in Figure 4. (RV = right ventricular; SVC = superior vena cava.) D - to the ICD, which is activated and tested. Our experience encompasses AICD models AID-B (Intek) and Ventak models 1510, 1520, 1550, and 1600 (CPI). The most stringent test is successful ICD detection and cardioversion from ventricular fibrillation during magnet-forced asynchronous ventricular or asynchronous atrioventricular pacing at maximum pacemaker output and pulse width (Fig 4). The absence of double counting of pacing spikes and QRS complex during asynchronous ventricular or asynchronous atrioventricular pacing should also be confirmed by listening to the R-wave synchronous tones emitted when a magnet is applied to an activated ICD. Finally, the ICD is temporarily inactivated and all incisions are closed, incorporating a small left chest tube. The patient is generally awakened and extubated in the operating room. Epidural fentanyl analgesia is administered in the intensive care unit for 24 to 48 hours. All devices are again tested in the electrophysiology laboratory 1 week postoperatively before discharge. Results Our clinical experience includes 114 ICD system insertions since 1984, with one infarction-related perioperative

4 256 SPOTNITZ ET AL Ann Thorac Surg 1!392;5325>7 Fig 3. The pacing spikes illustrated in the left panel were judged unacceptably large in the rate-sensing leads. After repositioning, as shown on the right, the pacemaker spikes decreased in size, the amplitude of the native QRS increased, and the lead position was considered adequate. LA Initial Recordings - Output 8.lv PM Leads Repositioned - 8.lv mortality. At mean follow-up of 2.9 years, only one arrhythmic death may have occurred. Twenty-one of these patients have required ICDs in combination with pacemakers (19) or pacing leads (2). Pacemakers implanted consisted of 12 WI, 6 DDD, and one antitachycardia pacemaker. In 3 patients, the need for transvenous pacing was established and pacemaker insertion occurred weeks or months after ICD insertion. In 12 patients, ICD implantation was combined with pacemaker insertion (10) or lead insertion only (2) using the methods described. Five additional patients were referred for ICD insertion with previously inserted pacemakers; in 2 of these patients (DDD) satisfactory function of both devices was achieved by moving the ICD rate-sensing leads as far as possible to the posterolateral aspect of the left ventricle. The remaining 3 patients required new transvenous leads and testing, as described in the Material and Methods section. Fig 4. Successful test of leads illustrated in Figure 2. Continuous right ventricular bipolar pacing is forced by a magnet applied to the pacemaker. The pacing spikes do not prevent detection and cardioversion by the ICD. The pacing spikes are invisible except in the bipolar morphology lead (patch and superior vena cava electrodes), where they measure less than 0.4 mv. (AICD = automatic implantable cardioverter-defibrillator; VF = ventricular fibrillation; VOO = asynchronous ventricular.) - AlCD CardioverSiOn VF i Overall, we found it necessary to reposition or replace ventricular pacemaker leads four times-twice from the RV apex to the outflow tract and twice from outflow tract to the anterior RV, close to the tricuspid valve. In 1 patient with DDD pacing and chronically implanted unipolar leads in the right atrial appendage and RV apex, successful conversion to bipolar pacing was accomplished by placing a second unipolar lead close to the chronic leads and proceeding as described. We have found that either RV or right atrial pacing wires can cause interactions with ICDs. Accordingly, both lead systems must be individually tested. Comment The methods and testing described here were not used in one patient, our first pacemaker recipient, who received a bipolar DDD pacemaker. That patient is the only one in Rate Sensing Lead I f I I I I I I I I I I I I I Ill11 II I I I I I I I I I I I I I I I I I I I I I I I1 I I I I\ I I I I I I1 I I

5 Ann Thorac Surg 1992;5325>7 SPOTNlTZ ET AL 257 our series of 114 ICD recipients who may have suffered arrhythmic death. The circumstances of that event are not fully known, as the patient died while sleeping alone, at home. Nevertheless, that experience leads us to recommend that all steps to avoid pacemaker-icd interaction be followed stringently. Pacemaker-ICD interaction can cause either unnecessary ICD discharges or inappropriate ICD inhibition permitting sudden death [3]. Unnecessary ICD discharges can occur if the highly sensitive circuits of the ICD detect both the pacing spike and the QRS depolarization in W I pacing (double counting). Similarly, triple counting can occur (atrial spike, ventricular spike, and QRS) in DDD or DVI pacing. In both cases, a paced rate of 90 beats/min will exceed the common ICD rate cutoff of 173 and lead to ICD firing [ 81. More ominous is the potential problem in ventricular fibrillation. Ventricular fibrillation may not inhibit ventricular pacing [4]. The ICD may not detect ventricular fibrillation in the presence of unipolar ventricular pacing spikes if the amplitude of the pacing spikes substantially exceeds the low amplitude of the waves of ventricular fibrillation. The ICD thus may interpret pacemaker spikes as a normal ventricular rhythm, a phenomenon that has been observed in patients [4]. Other adverse ICD-pacemaker experiences described in the literature include potentially lethal reciprocal triggering of an ICD and antitachycardia pacemaker [8], inadvertent induction of ventricular tachycardia triggered by an "R on T" phenomenon during a pacemaker magnet test [8] or burst pacing [9], and transient sensing and pacing dysfunction of transvenous pacemakers after ICD discharges [4]. Many of these problems will be eliminated when devices integrating ICD and pacemaker functions in a single unit are released, hopefully within 2 to 3 years. Many difficulties of ICD-pacemaker interaction can be avoided with present, independent devices by making the pacemaker signals invisible to the ICD. Unipolar pacing is contraindicated in this setting because of the large pacing spikes generated [;7. Recently, it has been recommended that pacemakers implanted in ICD recipients should be capable of function only in the bipolar mode, because pacemakers capable of function in the unipolar mode could be inadvertently programmed to the unipolar mode or may use that mode as an indicator of battery depletion. The optimal lead configuration consists of bipolar RV endocardial pacing electrodes and bipolar left ventricular epicardial ICD electrodes. In-line bipolar pacemaker leads can be useful but are stiff in comparison with unipolar leads and, as we have observed, may not provide good R-wave amplitude in the outflow tract. The increased flexibility of unipolar positive-fixation leads promotes stability of pacemaker leads in locations such as the RV outflow tract and anterior RV, which we prefer. We have observed no displacement of more than 30 leads implanted in these locations with the technique and lead described. Others have also described successful experiences with outflow tract pacing [lo]. We have found moving the epicardial rate-sensing leads, described by others [8], useful to minimize ICD-pacemaker interaction. But we find the ability to move twin unipolar leads widely within the RV to be even more useful. This has even allowed endocardial ICD rate-sensing leads and pacemaker leads to be combined (see Fig 2). Successful operation of this lead configuration is illustrated in Figure 3. In summary, the need for simultaneous insertion of both an ICD and a permanent pacemaker is a problem created in part by delayed development of a single device capable of both functions. The techniques must be well understood, because bradycardic death in ICD recipients has been reported [5]. However, even when dual-function devices become available, special situations will arise that require familiarity with the techniques described. Detection of pacemaker spikes by the ICD can lead to either inappropriate ICD discharges or failure of the ICD to detect and fire in ventricular fibrillation. These problems can be avoided by use of bipolar pacemakers and lead configurations physically separating the lead systems. Supported in part by US Public Health Service grant HL References 1. Winkle RA, Mead RH, Ruder MA, et al. Long-term outcome with the automatic implantable cardioverter-defibrillator. J Am Coll Cardiol 1989;13: Lehman MH, Saksena S. NASPE policy statement. Implantable cardioverter defibrillators in cardiovascular practice: report of the policy conference of the North American Society of Pacing and Electrophysiology. 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