ARRHYTHMIAS AND CONDUCTION DISTURBANCES

Three-Year Outcome of a Nonthoracotomy Approach to Cardioverter-Defibrillator

Implantation in 189 Consecutive Patients

To date, no long-term clinical data have been published in patients undergoing a nonthoracoto- C linical experience with the automatic implantable

cardioverter-defibrillator (ICD) dates back to 1980 when the first automatic ICD system was implant-

my approach to cardioverterdefibrillator system ed into a human patient.’ In the first decade of clinical implantation. In the present report, 189 consecu- usage, the standard surgical approach used to implant tive patients prospectively underwent a stan- these systems most often involved a left thoracotomy to dardized approach to cardioverterdefibrillator place 2 epicardial patch electrodes directly on the myo- system implantation in which the nonthoracoto- cardium.2-‘0 Experience has shown that this approach is my configurations were tested first. If satisfacto- safe and associated with a low surgical mortality rate, ry defibrillation thresholds were not obtained, although morbidity related to the thoracotomy incision thoracotomy was performed during the same remains a major drawback.2-10 Long-term experience intraoperative session. A nonthoracotomy sys- has also shown that systems implanted via thoracotomy tem was successfully implanted in 149 of 189 are effective and reliable in treating patients with recur- patients (79%), with a higher success rate (90%) rent life-threatening ventricular arrhythmias.2-10 Begin- observed in patients who had more recent ning in 1990, nonthoracotomy systems for investigational implantations. The overall rate of complications implantation became available from 2 manufacturers.” associated with these systems was low (11%). Short-term results have shown that these systems may Over a mean follow-up of 12.5 f 9.3 months, 17 be successfully implanted in >70% of patients in whom patients (9%) died. Three-year total, cardiac, and this approach is first attempted,12J3 although long-term sudden death-free actuarial survival for all clinical experience with nonthoracotomy ICD systems is patients was 83 -c ll%, 80 +- 7%, and 94 + 2%, limited. Since nonthoracotomy systems are simpler to respectively. Three-year sudden deatlkfree actu- implant and have a high success rate, they are rapidly arial survival was higher in the nonthoracotomy evolving as the system of choice for most patients requir- than in the thoracotomy patients (97 + 2% vs 87 ing an ICD. The purpose of the present study is to report + 6%, p = 0.047), although total survival was our 3-year clinical experience in 189 consecutive patients similar (77 + 11% vs 93 f 7%, p = 0.77). These in whom a nonthoracotomy approach was frrst attempt- data suggest that a majority of patients (~80%) ed to implant a cardioverter-defibrillator system. requiring a cardioverterdefibrillator system can undergo implantation using a nonthoracotomy METHODS approach. Patients receiving nonthoracotomy Patients: Between September 1990 and November systems have 3-year outcomes comparable to 1993, a nonthoracotomy approach was initially used to those implanted via thoracotomy. If these implant an ICD system in 189 consecutive patients. A results are maintained, a nonthoracotomy total of 168 patients received implants at the Massachu- approach will supplant thoracotomy-implanted setts General Hospital and 21 patients at St. Peter’s Hos- systems as the preferred method because of the pital. Before implantation, all patients underwent cardiac simpler implant procedure and lower overall cost catheterization and appropriate noninvasive testing to involved. define underlying cardiac disease and left ventricular

(Am J Cardiol 1994;74:1011-1015) function. Baseline electrophysiologic testing was per- formed in all patients using standard techniques as pre- viously described. l4 In patients with inducible sustained ventricular arrhythmias, a mean of 1.8 k 1.4 antiar- rhythmic drug trials failed to suppress the arrhythmia before the ICD was implanted. In all, 56 patients (30%) were receiving antiarrhythmic drugs at the time of im- plantation (quinidine or procainamide [n = 211, mexile- tine [n = 61, sotalol [n = 191, and amiodarone [n = lo]).

Ross Brooks, MD, Hasan Garan, MD, David Torchiana, MD, Gus J. Vlahakes, MD, Stanley Dziuban, MD, John Newell, BA, Brian A. McGovern, MD, and Jeremy N. Ruskin, MD

From the Cardiac Arrhythmia Service, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; and St. Peter’s Hospi-

All ICDs were implanted as primary surgical procedures.

tal, Albany, New York. Manuscript received April 21, 1994; revised Transvenous lead electrode insertion: Transve-

manuscript received and accepted June 24, 1994. nous electrodes (CPI Endotak [Cardiac Pacemakers Inc., Address for reprints: Ross Brooks, MD, Cardiac Unit, Massachu- St. Paul, Minnesota] or Medtronic Transvene [Medtron-

setts General Hospital, Boston, Massachusetts 02114. ic Inc., Minneapolis, Minnesota]) were inserted preop-

NONTHORACOTOMY CARDIOVERTER-DEFIBRILLATOR IMPLANTATION 1011

TABLE I Comparison of Patients Implanted During Different Periods of the Study

First 63 Second 63 Last 63

Implant period g/90-392 6192-4193 4193-I 1193 EndotaklTransvene 21/42t 23/40# 36/27t’ Thoracotomy 18 (29)s 16 (25)# 6 (1 O)g Nonthoracotomy 45 (71)s 47 (75)# 57 (go)*’ Lead alone 8 (13)’ 17 (27)* 39 (62)* Follow-up (mos) 21 + 8.6’ 11 AZ 3.4* 3.1 ?1 1.9*

Age (Years) 62 i 13 62+11 62kll Gender (men/women) 49124 46/I 7 51112 Heart disease 59 (94) 62 (98) 62 (98) Coronary artery disease 41 (65) 44 (70) 37 (59) Prior myocardial infarction 38 (93) 40 (91) 31 (84) Prior CABG 25 (61)*” 15 (34)T 13 (35)” Dilated cardiomyopathy 12 (19) 8 (13) 18 (29) No heart disease 4 (6) 1 (2) 2 (3) Left ventricular ejection 0.40 f 0.16 0.38 f 0.15 0.37 + 0.15

fraction LVID (mm) 56 f IO 58 f 8 56 + IO Presenting arrhythmia

Ventricular fibrillation 33 (52)” 29 (46) 20 (32)n Sustained ventricular 20 (32) 20 (32) 29 (46)

tachycardia Nonsustained ventricular 7 (11) 10 (16) 8 (13)

tachycardia Induced arrhythmia

Ventricular fibrillation 21 (33)“* 13 (21) IO (16)“’ Sustained ventricular 27 (43)” 31 (49) 41 (65)”

tachycardia Noninducible 11 (18) 8 (13) 7 (11) Antiarrhythmic drugs 14 (22) 21 (33) 21 (33) Postop. hospital stay (days) 6.4 f 3 6.4 k 4 5.4 f 4 Complications 9 (14)t: 7 (II)* 4 (6)* Received ICD therapy 28 (44) 21 (33) 18 (29) Total deaths IO (16)5 6 (1’3 1 w *p <O.OOOl ; fp = 0.002; *p = 0.003, first and second 63 versus last 63; “p = 0.007: “p = 0.02; #p = 0.03; l *p = 0.04.

Numbers in parentheses are percentages. CABG = coronary artery bypass grafting; ICD = implantable cardioverter-

defibrillator; LVID = (echocardiographic) left ventricular internal dimension; Postop. = postoperative.

eratively in the pacemaker laboratory under fluoroscop- ic guidance using local anesthetic (n = 167), or at the time of pulse generator implantation in the operating room (n = 22). The 100 cm 12Fr tripolar Endotak lead consists of a tined distal tip for sensing and pacing, an adjacent distal coil electrode (electrode surface area = 295 sq mm [0064] and 379 sq mm [0074]), and a prox- imal coil electrode (electrode surface area = 617 sq mm) for cardioversion/defibrillation. The interelectrode dis- tance is fixed at 13 cm (model 0062 [n = 16]), 16 cm (model 0064 [n = 57]), or 18 cm (model 0074 [n = 71). The tripolar Transvene lead (model 6966 [n = 1051 or model 6936 [n = 41) consists of a 110 cm 10.5Fr screw- in tip, an adjacent sensing ring, and an adjacent 50 mm long distal coil electrode (electrode surface area = 290 sq mm). A separate 8Fr unipolar coil electrode (model 6963 [n = 1051 or model 6933 [n = 41) with an electrode surface area of 90 sq mm was inserted as the second car- dioversion-defibrillation electrode, with its tip generally positioned above the superior vena cava/right atria1 junc- tion. The left subclavian or cephalic vein was preferen- tially used for lead insertion (n = 180), whereas the right subclavian or cephalic vein was used less frequently (n = 9). Satisfactory R-wave amplitudes, slew rates, pac- ing thresholds, and lead resistances were obtained in all

patients. In patients undergoing lead insertion preoper- atively, the terminals of the electrodes were capped and buried in an infraclavicular pocket. Defibrillation thresh- old testing and pulse generator placement were per- formed in the operating room in all patients.

Surgical procedure and defibrillation threshold testing: There was an intention-to-treat all patients ini- tially with a nonthoracotomy system with crossover to thoracotomy only if satisfactory defibrillation energy re- quirements could not be obtained. In all patients, oper- ative testing was performed under general anesthesia. Patients were positioned on their right side with broad access to the left chest. The infraclavicular pocket was opened and the transvenous leads were connected to an external cardioverting device with adjustable energy out- put. A stepwise approach to defibrillation threshold test- ing was used as previously described in which the non- thoracotomy configurations were tested first.12 A minimal 10 J margin of safety between the defibrillation thresh- old and the maximal stored energy of the pulse genera- tor was required for implantation in all cases. In patients receiving a subcutaneous patch (CPI model 0063, elec- trode surface area 280 mm sq; Medtronic model 6999, electrode surface area 660 sq mm), the patch was implanted in a lateral or posterolateral position on the chest wall superficial to the latissimus dorsi muscle. If the nonthoracotomy system did not result in satisfactory defibrillation thresholds despite testing multiple config- urations, left thoracotomy was performed to place 21 extrapericardial patches which were used in conjunction with the transvenous lead(s) as previously outlined.12 The pulse generator was subsequently tested for appro- priate arrhythmia detection and defibrillator function, and implanted in a left paraumbilical subcutaneous pocket. An ICD was implanted during the same intraoperative session in 182 of 183 patients. Patients undergoing tho- racotomy were admitted to the surgical intensive care unit after operation, whereas most patients with a non- thoracotomy implantation returned to a monitored med- ical bed after brief observation in the recovery room.

Statistical analysis: Data are presented as mean + SD. Paired data were analyzed using the Student’s t test. Proportions were analyzed by Fisher’s exact test. Com- parison of group data was performed by l-way analysis of variance. Survival was compared with the use of BMDP program PlL using life-table analysis.15 Multi- variate predictors of thoracotomy were determined by a Cox proportional-hazards regression model.16 A p val- ue of 0.05 was considered statistically significant.

RESULTS Outcome and transvenous leads: Overall, a non-

thoracotomy system was successfully implanted in 149 of 189 patients (79%) with the manufacturer’s protocol (118 J for Transvene and 120 J for Endotak) satisfied in 92% of cases. Notably, the success rate was significantly higher in the last 63 patients than in the first 126 patients (90% vs 73%, p = 0.005, Table I). One hundred nine patients (58%) received a Medtronic Transvene system, and 80 patients (42%) received a CPI Endotak system (Table II). A comparison of the 2 systems involving monophasic pulse generators showed a trend toward a

1012 THE AMERICAN JOURNAL OF CARDIOLOGY@ VOLUME 74 NOVEMBER 15, 1994

higher nonthoracotomy success rate with the Endotak than with the Transvene system (85% vs 73%, p = 0.08, Table II). The success rate of nonthoracotomy implan- tation was also higher in patients receiving biphasic (n = 22) than in those receiving monophasic (n = 167) pulse generators, although not significantly so (88% vs 78%, p = 0.42).

Final electrode conligurations and implanted pulse generators: Overall, 64 of 149 patients (43%) received implants using a transvenous lead-alone configuration, while the other 85 patients (57%) required a 3-electrode configuration. The success rate of the transvenous lead- alone contiguration in conjunction with monophasic pulse generators was significantly higher with the Endo- tak than with the Transvene system (67% vs ll%, p <O.OOOl, Table II). In the 40 patients requiring thoraco- tomy, 6 different configurations were used, the most fre- quent of which (26 patients [65%]) involved a “hybrid” system incorporating a single left ventricular epicardial patch in conjunction with the 2 transvenous coil elec- trodes. Patients implanted with an Endotak lead system received 1 of 6 different pulse generators (Ventak 1600 [n = 361, Ventak 1550 [n = 91, Ventak 1555 [n = 91, Ven- tak P2 1625 [n = 161, Vent& PRX 1705 [n = 71, and Ventritex Cadence V-1OOC [n = 31). Patients implanted with a Transvene lead system received 1 of 3 different pulse generators: PCD 7217B (n = 104), Jewel 7219D (n = 4), and Ventritex Cadence V-1OOC (n = 1).

Predischarge implantable cardioverterdefibrill* tor testing: Predischarge ICD testing was performed in all patients. Ventricular fibrillation was induced in all patients and was terminated in 185 of 189 patients (98%), at or below the programmed maximal stored energy of the pulse generator. Four patients with nonthoracotomy systems and unsuccessful predischarge defibrillation testing underwent system revision. Three patients re- quired a thoracotomy, whereas the fourth patient was suc- cessfully managed after changing from a monophasic to a biphasic pulse generator.

Complications: There were no intraoperative com- plications. Overall, complications occurred in 21 patients (11%) in this series. Early complications occurring with- in the tirst postoperative month consisted of subcuta- neous. patch (n = 3) or pulse generator (n = 2) hematoma, embolic stroke (n = 2), subclavian vein thrombosis (n = l), pulse generator infection from Corynebacterium diphtheriae (n = l), dislodgement of the superior vena coil electrode (n = 2), dislodgement of the Medtronic tripolar lead (n = 4), high pacing threshold (n = l), and sensing failure (n = 1); the tripolar lead or superior vena cava electrode was replaced in each of these 8 patients. The infected patient was successfully managed using a prolonged course of intravenous antibiotics. Late com- plications occurring a mean of 19 months after implan- tation consisted of tripolar lead fracture (n = 2) and a severed superior vena cava coil electrode with emboliza- tion of the distal fragment into the right ventricle (n = 1). Each of these patients also required replacement of the damaged lead. One patient developed an infected ICD system 19.5 months after implantation and had the system removed. This infection was caused by Staphy- lococcus aureus and likely resulted from contiguous

TABLE II Comparison of Endotak and Transvene Systems

Endotak Transvene (n = 80) (n = 109) VZue

Nonthoracotomy (monophasic) 52 (85) 75 (73) NS Nonthoracotomy (monoibiphasic) 69 (86) 79 (72) 0.03 Nonthoracotomy (lead alone) 53 (66) 9 (11) 0.0001 Age (years) 61 +I2 61 413 NS Gender (women/men) 19161 18191 NS Coronary artery disease 56 (70) 73 (67) NS Left ventricular ejection fraction 0.39 ? 0.14 0.38 + 0.16 NS LVID (mm) 56 k8 57 * 9 NS Clinical ventricular fibrillation 45 (56) 37 (34) 0.002 Clinical ventricular tachycardia 20 (25) 54 (50) 0.001 Induced ventricular tachycardia 35 (44) 71 (65) 0.007 No antiarrhythmic drugs at implant 64 (80) 69 (63) 0.02 R-wave amplitude (mV) 13+5 15+6 0.01 Pacing threshold (V) 0.5 c 0.2 0.7 f. 0.3 0.0001 Lead resistance (ohms) 440+78 534+106 0.001 Defibrillation threshold (J) 15*5 19 +8 NS Complications 5 (6) 15 (14) NS Lead complications 1 (1) 8 (7) 0.08 Follow-up (mos) 11.6 k 12 12.8i-8 NS Received ICD therapy 26 (33) 41 (38) NS Total deaths 3 (4) 14 (13) 0.04 Sudden deaths 1 (1) 6 (6) NS

Abbreviations as in Table I. Numbers in parentheses are percentages.

spread of a lingular pneumonia to the left ventricular epi- cardial patch. Three patients (2 with nonthoracotomy systems) required a revision of their systems because of elevated defibrillation thresholds (2 after initiation of amiodarone therapy).

Implantable cardiovertelulefibrillator utilization during follow-up: During the follow-up period (12.5 f 9.3 months), 67 of 189 patients (35%) received appro- priate therapy for 21 arrhythmic episodes. The cumula- tive frequency of delivered therapy increased as a func- tion of time after implantation (Table I). A similar percentage of patients with nonthoracotomy and thora- cotomy-implanted systems received therapy over the fol- low-up period (34% vs 40%, p = NS). Patients with a history of sustained ventricular tachycardia received an&rhythmic therapy more frequently than those with a history of ventricular fibrillation (32 of 73 [44%] vs 22 of 83 [27%], p = 0.03). Notably, 10 of 25 patients (40%) with a clinical history of nonsustained ventricu- lar tachycardia received ICD therapy during the follow- up period.

Survival: There were no intraoperative deaths. There was 1 perioperative death from congestive heart failure occurring 16 days after implantation (0.5%). The remain- ing 188 patients were discharged alive, and have been followed for a mean of 12.5 + 9.3 months (range 2.5 to 63) after implantation. Two patients underwent removal of their system at the time of heart transplantation. Six- teen patients (9%) died during the follow-up period (mean 7.7 + 6.3 months, range 0.7 to 25.3). There were 7 sudden, 6 nonsudden cardiac, and 3 noncardiac deaths during the follow-up interval. Three-year total, cardiac, and sudden death-free actuarial survival for all patients was 83 f ll%, 88 + 7%, and 94 + 2%, respectively (Fig- ure 1). Three-year sudden death-free actuarial survival in the nonthoracotomy group was higher than in the tho- racotomy group (97 f 2% vs 87 + 6%, p = 0.047, Fig-

NONTHORACOTOMY CARDIOVERTER-DEFIBRILLATOR IMPLANTATION 1013

ure 2), although cardiac and total survival were lower (83 f 11% vs 95 f 5%, p = 0.50 and 77 + 11% vs 83 rt: 7%, p = 0.77, respectively, Figure 3). Three-year sudden death-free survival was not significantly different for the CPI compared with the Medtronic patient groups (97 + 3% vs 92 + 3%, p = 0.45).

DISCUSSION There are 3 main findings of this study: (1) The 2

nonthoracotomy ICD systems evaluated are comparable and can be implanted in ~80% of patients in whom this system is attempted as the first approach. (2) The rate of complications associated with the use of nonthoracoto- my systems is low. (3) The outcome of patients with nonthoracotomy systems after 3 years of follow-up is comparable to that observed in patients with thoraco- tomy-implanted systems.

Success rate of nonthoracotomy implantation: To date, the published clinical experience with nontho- racotomy ICD systems has been limited to reports involv- ing smaller numbers of patients.17-24 Our overall success rate of nonthoracotomy implantation (79%) is compara- ble to that reported by Trappe et all7 (83%) and Blake- man et a123 (77%) in smaller patient groups using simi- lar systems. Hauser and co-workers13 reported a success rate of 72% from pooled CPI Endotak data. Notably, we observed a significantly higher success rate in the group

100 ---- ~.7.~~.:..~ _ _ _ . . . . . . -x...ir‘7.T.;i.7.~ . . . . . . . . . . . . . . . . . . . . . . ------ ---

60-

8 m-

i f 3” 0,

............ Sudden Deaths

----- Cardiac Deaths

- Total Deaths

OO I 9 18 27 36 MONTHS

IGURE 1. Actuarial total, cardiac, and sudden death-free survival in all 189 patients.

----- Nonthoracotomy

- Thoracotomy

I*. 9 18 27 36

MONTHS

FIGURE 2. Actuarial sudden death-free survival in the nonthoracotomy and thoracotomy groups. At 3 years, the sudden death-free survival was 97% for the nontho- racotomy group and 87% for the thoracotomy group (p = 0.047).

of patients with more recent implantations, compared with the earlier groups (90% vs 73%, p = 0.005, Table II). Also, the success rate of the transvenous lead-alone configuration has increased steadily over the 3-year peri- od (Table I). The higher success rate in patients who have had more recent implantations is not attributable to (1) obvious differences in the patients undergoing im- plantation at different times in this series (Table I), (2) important differences in the placement of the transve- nous lead or subcutaneous patch during the different implant periods, or (3) differences in the implant crite- ria accepted. The factors accounting for this difference are not completely known, although routine testing of both transvenous electrode polarities, the more frequent use of biphasic pulse generators in which the nonthora- cotomy success rate is very high, and possibly, a greater use of the Endotak lead with a higher overall success rate, may have been contributory (Table II).

Complications in patients with nonthoracotomy systems: The low rate of complications observed in patients with nonthoracotomy systems attests to the sim- pler approach involved. Most complications were lead- related and represent a “learning curve” associated with the placement of the transvenous leads or subcutaneous patches, or both. These problems were significantly less frequent in the group with more recent implants (Table I). Although no deaths resulted from these problems, morbidity was nevertheless significant in that the tripo- lar or superior vena cava electrode had to be replaced in all of the involved patients. Fractures that occurred in the tripolar lead (n = 2) and superior vena cava coil elec- trode (n = 1) a mean of 19 months after implantation are of greater potential concern. These problems were most probably related to compression at the costoclavicular junction. 25 Fractured conductors or damaged insulators, or both, in patients with ICDs may cause inappropriate discharges (as seen in 2 of our patients) or failure to defibrillate, which fortunately did not oc~ur.~~~* As the duration of follow-up increases in patients receiving transvenous ICD systems, whether wear and tear prob- lems of the larger tripolar lead or subcutaneous patch will be observed more frequently remains to be seen.

Outcome of patients with nonthoracotomy sys- tems: Survival of patients with ICDs implanted using a nonthoracotomy approach will ultimately be measured

100 ---- --- ----------,

I w- L - - - - - - - - -

- - - - - Nonthoracotomy

- Thoracotomy

2u-

I I

OO 9 1s 27 36

MONTHS

FIGURE 3. Actuarial total survival in the nonthoracotomy and thoracotomy groups. At 3 years, the total survival for the 2 groups was similar (77% vs 83%, p = 0.77).

1014 THE AMERICAN JOURNAL OF CARDIOLOGY@ VOLUME 74 NOVEMBER 15, 1994

against’those with conventional thoracotomy-placed sys- tems in which long-term follow-up now exceeds 10 years. Over a comparable follow-up period to ours, the sudden death-free survival rates in published series of patients with thoracotomy-implanted ICDs ranges be- tween 91% and 95%, with overall survival rates of 62% to 82%.2-10 The comparable 3-year sudden deatl-free and overall survival rates in the present series (Figures 2 and 3) suggests that nonthoracotomy systems are as effective and reliable as thoracotomy-implanted systems in treating patients with recurrent life-threatening ven- tricular arrhythmias, and supports their widespread use in patients who require ICDs.

Study limitations: The transvenous lead(s) were common to both groups of patients, and the difference between the 2 groups was mainly due to the placement of 21 epicardial electrodes in the thoracotomy patients. Therefore, the thoracotomy group in the present series may not be directly comparable to previous groups undergoing a “planned” thoracotomy, particularly when 2 epicardial electrodes are used in a majority of patients. However, 37% of the patients undergoing thoracotomy in the present series in fact had 2 epicardial patches placed. Moreover, the use of the 2 transvenous electrodes in conjunction with a single epicardial patch (hybrid con- figuration) used in 65% of patients is analogous to the “spring-patch” configuration used in conventional tho- racotomy series, which accounts for between 29%7 and 81%l” of patients implanted in large series, including 66% of those reported previously at our institution.2 In the present study, there was an intention-to-treat all patients initially with a nonthoracotomy system using a standardized implantation technique, with crossover to thoracotomy only if the nonthoracotomy approach was unsuccessful. Even though the clinical features of the patients forming the 2 groups were similar in most respects, comparison of the nonthoracotomy and thora- cotomy groups in the present study is limited by the lack of a randomized design, and the results of this compar- ison must be interpreted cautiously with this limitation in mind.

Clinical implications: Our data show that a high rate of successful implantation may be achieved with exist- ing nonthoracotomy systems. As experience with newer lead systems and biphasic pulse generators increases, the success rate will further increase, and may ultimately reach 90% to 95% in routine cases. Our 3-year experi- ence indicates that currently available nonthoracotomy systems can be implanted with a low rate of complica- tions and are reliable and effective in controlling recur- rent ventricular arrhythmias. Patients with nonthoraco- tomy systems also have survival comparable to those receiving thoracotomy-implanted systems. Because they are simpler to implant, and are associated with less post- surgical morbidity and lower overall cost,12 they should be considered the system of tirst choice for the majori- ty of patients requiring an ICD.

1. Mirowski M, Reid PR, Mower MM. Termination of malignant ventricular arrhythmias with an implanted automatic defibrillator in human beings. N Engl J Med 1980;303:322-326. 2. Kelly PA, Cannom DS. Garan H, Mirabal GS, Hathome SW, Hwvitz RJ, Vla-

h&es GJ, Jacobs ML, Ilvento JP, Buckley MJ, Ruskin JN. The automatic implantable c~dioverter-defibrillator: efficacy, complications and survival in patients with malig- nant ventricular arrhythmias. J Am Cd Car&d 1988; 11: 1278-1286. 3. Myerburg RJ; Luceri RM, Thurer R, Cooper DK, Zaman L, Interian A, Fer- nandez P, Cox M, Glicksman F, Castellanos A. Time to fzst shock and clinical outcome in patients receiving an automatic implantable cardioverter-defibrillator. J Am CoN Cardiol 1989;14:508-514. 4. Tchou PJ, Kadri N, Anderson J, Caceres JA, Jazayeri M, Akhtar M. Automatic implantable cardioverter defibrillators and survival of patients with left ventricular dysfunction and malignant ventricular arrhythmias. Ann Intern Med 1988;109: 529-534. 5. Man&s AS, Tat-DeGuzman W, Lee MA, Rastegar H, Haffajee CI, Hung SKS, Estes NAM. Clinical experience in seventy-seven patients with the automatic implantable cardioverter defibrillator. Am Heart J 1989; 118:445450. 6. Kim SG, Maloney JD, Pinski SL, Choue CW, Ferrick KJ, Roth JA. Gross J, Brodman R, Furman S, Fisher JD. Influence of left ventricular function on survival and mode of death after implantable defibrillator therapy (Cleveland Clinic Foun- dation and Mont&ore Medical Center Experience). Am .I Cardiol 1993;72: 1263-1267. 7. Wiie RA, Mead RH, Ruder MA, Gaudiani VA, Smith NA, Buch WS, Schmidt P, Shipman T. Long-term outcome with the automatic implantable caxlioverter- defibrillator. J Am CoN Car&l 1989;13:1353-1361. 8. Fogoros RN. Elson JJ, Bonnet CA, Fiedler SB, Burkholder JA. Efftcacy of the automatic implantable cardioverter-defibrillator in prolonging survival in patients with severe underlying cardiac disease. JAm Coil Cardiol 1990,16:381-386. 9. Reid PR, Griffith LSC, Platia EV. The automatic implantable cardioverter-defib- rillator: 5-year clinical experience. In: Breithardt G, Borggrefe M, Zipes DP, eds. Nonphannacologic Therapy of Tachyanhytbmias. Mt. Kisco, NY: Futura Publish- ing, 1987:4774X5. 10. Echt DS, Armstrong K, Schmidt P, Oyer PE, St&on EB, Winkle RA. Clini- cal experience, complications, and survival in 70 patients with the automatic implantable cardioverter-defibrillator. Circulation 1985;71:289-296. 11. Saksena S, Parsonnet V. Implantation of a cardioverter-defibrillator without thoracotomy using a triple electrode system. JAMA 1988;259:69-72. 12. Brooks R, Gaxm H, Torchiana DF, Vlahakes GJ, Jackson G, Newell J, McGov- ern BA, Ruskin JN. Determinants of successful nonthoracotomy cardioverter-defib- rillator implantation: experience in 101 patients using two different lead systems. .I Am Co11 Cardiol 1993;22:1835-1842. 13. Hauser RG, Kurschinskj DT, McVeigh K, Thomas A, Mower MM. Clinical results with nonthoracotomy ICD systems. PACE 1993;16:141-148. 14. Wilbur DJ, Garan H, Fink&t& D. Out-of-hospital cardiac arrest: use of elec- trophysiologic testing in the prediction of long-term outcome. N Engl J Med 1988;318:19-24. 15. Brown MB, Dixon WJ. BMDP Statistical Software 1990. PlL. Los Angeles: University of California Press. 16. Brown MB, Dixon WJ. BMDP Statistical Software 1990. P2L. Los Angeles: University of California Press. 17. Trappe HJ, Klein H, Fieguth H-G, Kielblock B; Wenzlaff P, Lichtlen PR. Ini- tial experience with a new hansvenous defibrillation system. PACE 1993;16: 136140. 16. Block M, Hammel D, Isbmch F, Borggrefe M, Wietholt D, Hachenberg T, Scheld HH, Breithardt G. Results and realistic expectations with transvenous lead systems. PACE 1993;15:665-670. 19. McGowan R, Maloney J, Wilkoff B, Simmons T, Khoury D, McAlister H, Morant V, Castle L. Automatic implantable cardioverter-defibrillator implantation without thoracotomy using an endocardial and submuscular patch system J Am Coil Car&l 1991;17:415421. 20. Bardy GH, Troutman C, Poole JE, Kudenchuk PJ, Dolack GL, Johnson G, Hofer B. Clinical experience with a tiered-therapy multiprogrammable ant&- rhythmia device. Circulation 1992;85:1689-1698. 21. Jordaens L, Trouerbach JW, Vertongen P, Herregods L, Poelaert J, Van Nooten G. Experience of cardioverter-defibrillators inserted without tboracotomy: evalua- tion of transvenously inserted intracardiac leads alone or with a subcutaneous axil- lary patch. Br Heart J 1993;69:14-19. 22. Yee R, Klein GJ, Leitch JW, Guiraudon GM, Guiraudon CM, Jones DL, Nor- ris C. A permanent transvenous lead system for an implantable pacemaker car- dioverter-defibrillator. Circulation 199285: 19%2.04. 23. Blakeman BP, Sullivan HJ, Montoya A, Calandra D, Wilber D, Ollshansky B, Kall J, Koop D, Pifarre R. Nonthoracotomy lead system for implantable defibxil- later. J Thorac Cardiovasc Surg 1993; 106: 1040-1047. 24. Lindemans FW, Biinsbergen EV, Connolly D. European Transvene PCD Study. Maastricht, The Netherlands: B&ken Research Center, 1991:5-39. 25. Magney JE, Flynn DM, Parsons JA, Staplin DH, Chin-Purcell MV, Milstein S, Hunter DW. Anatomical mechanisms explaining damage to pacemaker leads, defibrillator leads, and failure of central venous catheters adjacent to the sterno- clavicular joint. PACE 1993;16:445-457. 26. Troup PJ. Implantable cardioverters and defibrillators. In: O’Rourke RA, Craw- ford MH, eds. Current Problems in Cardiology. Chicago: Year Book Medical Pub- lishers, 1989;XIV:673-815. 27. Tulle NG, Saksena S, Km1 RB. Management of complications associated with first generation endowdial defibrillation lead systems for implantable cardiovert- er-defibrillators. Am J CardioL 1990;66:41 l-415. 26. Marchlinski FE, Flares BT, Buxton AE. The automatic implantable cardioverter defibrillator: efficacy, complications, and device failures. Ann intern Med 1986; 104: 481489.

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