T lator (ICD) in the nonpharmacological treatment of

Transcription

1 Implantation of Cardioverter Defibrillators in the Post-S ternotomy Patient Ralph J. Damiano, Jr, MD, Andrew H. Foster, MD, Kenneth A. Ellenbogen, MD, Mark A. Wood, MD, Bruce S. Stambler, MD, William J. Welch, MD, and Andrew S. Wechsler, MD Divisions of Cardiothoracic Surgery and Cardiology, Medical College of Virginia, Richmond, Virginia In an attempt to minimize the hazards of redo sternotomy or thoracotomy in patients who have undergone previous cardiac procedures, a technique has been developed for cardioverter defibrillator implantation that involves dissection through a left subcostal incision and placement of extrapericardial defibrillation patches. This approach was used in 22 consecutive patients who required an implantable cardioverter defibrillator 4 to 156 months after previous median sternotomy. Defibrillation threshold energy was less than or equal to 20 J in every patient. Ninety-one percent of patients were extubated during the first 24 hours and were transferred out of the intensive care unit by the second postoperative day. One patient died of an acute myocardial infarction 3 days postoperatively (1/22, 4.5%). It was necessary to replace one lead for mechanical failure of an adapter, one patch required repositioning, and 1 patient needed drainage of a persistent pleural effusion (3122, 13.6%). No further complications occurred during 3 to 27 months of followup. Advantages of the subcostal approach included prompt extubation, a single incision, and minimal morbidity. This approach is safe and effective, and is the method of choice for implantation of a cardioverter defibrillator in patients who have undergone prior sternotomy. (Ann Thorac Surg 1992;53:978-83) he precise role of the implantable cardioverter defibril- T lator (ICD) in the nonpharmacological treatment of sudden cardiac death and malignant ventricular arrhythmias continues to evolve as clinical experience expands and device technology becomes more sophisticated. As implantations of the device become more frequent, a number of refinements in surgical technique have been reported [l, 21. The surgical approaches for primary ICD insertion include median sternotomy 13-51, left thoracotomy [MI, and subxiphoid [9] or subcostal [lo, 111 techniques. Patients who have undergone previous open heart operations, particularly those with patent aortocoronary bypass grafts, present the surgeon with additional technical difficulties with conventional implantation techniques because of the presence of postoperative adhesions and the potential risks of graft, cardiac, or great vessel injury. To minimize the hazards of standard redo sternotomy or thoracotomy in patients who have undergone previous cardiac procedures, a technique for placement of an ICD has been developed that involves dissection through a left subcostal incision and use of extrapericardial defibrillation patches. This report describes the operative technique Presented at the Thirty-eighth Annual Meeting of the Southern Thoracic Surgical Association, Orlando, FL, Nov 7-9, 1991 Dr Foster s present address is Department of Thoracic and Cardiovascular Surgery, University of Maryland Hospital, Room N4W91, Baltimore, MD Address reprint requests to Dr Damiano, Division of Cardiothoracic Surgery, Medical College of Virginia, MCV Station, Box 645, Richmond, VA and the results of its application in 22 consecutive patients undergoing implantation of the device after previous median sternotomy. Material and Methods Patient Population During the 26-month period from July 1989 to September 1991, 128 automatic cardioverter defibrillators were implanted at the Medical College of Virginia and McGuire Veterans Administration Hospitals, Richmond, VA, by one attending surgeon (R.J.D.). Twenty-two (17%) of these devices were implanted after previous median sternotomy, and these patients form the basis of this report. All data are expressed as the mean & the standard error of the mean. The duration between the previous cardiac procedure and ICD placement ranged between 4 and 156 months with a mean of 52 * 9 months. The majority of the patients were men (21/22); the mean age was 62 k 7 years (range, 44 to 77 years). All patients except 2 had ischemic heart disease, and of these 20, 18 (90%) had ejection fractions equal to or less than Overall mean ejection fraction was 0.27 & Seventeen patients had undergone previous coronary artery bypass grafting, 4 of whom had had two previous coronary revascularization procedures. The left internal mammary artery had been used in 2 of these patients. Four patients had undergone combined coronary artery bypass and valve replacement procedures. Two patients without coronary artery disease had had valve replacement for rheumatic valvular disease by The Society of Thoracic Surgeons /92/$5.00

2 Ann Thorac Surg 1992;53: DAMIANO ET AL 979 Fig 1. The left subcostal incision is performed as depicted in the inset. The diaphragm and pericardium are exposed by upward retraction of the costal margin. The most common indication for use of the ICD was the presence of ventricular tachycardia that remained inducible despite drug therapy (20/22 patients, 91%). Two patients were seen following a documented clinical episode of ventricular fibrillation and had noninducible arrhythmias in the electrophysiological laboratory. Operative Technique All patients received a first-generation cephalosporin intravenously on call to the operating room. They were positioned supine on a fluoroscopy table with external defibrillation patches and electrocardiographic leads in place. Cardiopulmonary bypass was available, and a perfusionist was on standby. General orotracheal anesthesia was employed. A high-dose narcotic, musclerelaxant anesthesia technique was used. Central venous access and invasive monitoring were used in all patients. The skin preparation involved the chest, abdomen, and both groins. The chest was prepared laterally to the table level to allow for pleural tube placement when needed. The left subcostal skin incision was begun at the xiphoid process and carried one to two fingerbreadths below and parallel to the costal margin (Fig 1). The anterior rectus fascia and muscle were divided at this level using electrocautery to achieve hemostasis. A pocket was created beneath the rectus muscle inferiorly and laterally and packed with a sponge soaked in antibiotic solution. Cephalad retraction of the left costal margin using an upper-hand retractor or ring-type self-retaining retractor was necessary to expose the plane of dissection underlying the xiphoid process. The dissection was carried Fig 2. Defibrillation patch electrodes are positioned extrapericardially along both lateral margins of the heart. through the diaphragm at and to the left of the midline under direct vision with the use of a fiberoptic headlight. The costal attachments of the diaphragm were either bluntly separated or sharply divided. The anterior mediastinum was exposed, and the diaphragmatic surface of the right ventricle or the overlying pericardium, when present, was identified. The dissection was continued anteriorly and laterally in the extrapericardial space. The areas between the pericardium and the right and left pleura were carefully dissected. An area large enough to accommodate the surgeon s hand was necessary to place the flattened defibrillator patches along the extrapericardial borders of the heart (Fig 2). The defibrillation patches were placed such that the cathode lay over the lateral left ventricular pericardium and the anode over the lateral wall of the right atrium and ventricle. Silk ligatures were used to fix the defibrillation patches to the pericardium, even though surrounding adhesions often confined the patches securely between the lungs and pericardium. In our initial experience, epicardial screw-in electrodes were positioned after dissection of a small area of the diaphragmatic surface of the right ventricle. Although this surface was often relatively free from adhesions, care was taken to avoid injury to the ventricle or bypass grafts. Bipolar epicardial screw-in leads were placed approximately 1 cm apart into a nonscarred area of exposed myocardium. To avoid unnecessary dissection around the heart and the possibility of ventricular laceration or graft injury in these patients with a previous sternotomy, transvenous pacing and sensing electrodes became preferred to epicardial leads. A transverse left subclavicular incision 1 to

3 980 DAMIANO ET AL Ann Thorac Surg 1992;53: Fig 3. The completed procedure with a transvenous endocardial lead tunneled down to the subcostal incision and the generator implanted beneath the rectus muscle. The patches are positioned between the pericardium and the pleura. 2 cm long was performed. A 100-cm bipolar endocardial lead was inserted into the left subclavian vein using the Seldinger technique. The lead was positioned fluoroscopically in the right ventricular apex, and routine pacing and sensing variables were examined. Both active and passive fixation leads were employed. Active fixation leads were favored (9/10 patients) because of our concern regarding dislodgment of tined leads during defibrillation testing. The lead was securely fixed to the pectoralis fascia with a nonabsorbable ligature to eliminate the possibility of migration. The lead then was tunneled through the subcutaneous tissue to the subrectus generator pocket (Fig 3). Defibrillation threshold testing was performed using a standardized protocol. Testing was begun at 20 J, and shock energy was decreased until the defibrillation threshold was defined. Warm saline solution was instilled into the chest, and all metal retractors were removed before shock delivery. Defibrillation was performed at full lung inflation to maximize contact of the patches with the pericardium. At least 2 minutes were allowed for hemodynamic stabilization between each test. Defibrillation patch configuration was considered acceptable only if three consecutive defibrillations were successful at less than or equal to 20 J. The defibrillator generator was then connected, interrogated, activated, and tested. If bleeding at the epicardial surface of the right ventricle had occurred, a soft closedsuction mediastinal drain was left in place; otherwise no drain was used. The ICD was deactivated and placed beneath the rectus muscle. Meticulous hemostasis was obtained after generous irrigation with antibioticcontaining saline solution. If either hemithorax had been entered, a pleural tube was used for drainage. The diaphragm was reapproximated to the costal margin. The anterior rectus fascia was closed with a continuous nonabsorbable suture, and this was followed by closure of the subcutaneous tissue and skin. Fluoroscopy was used to confirm proper patch position and verify satisfactory placement of the endocardial lead in the right ventricular apex before the patient left the operating room. Postoperatively antiarrhythmic medications were restarted on an individual basis. Antibiotic administration was continued for 24 hours or until the pleural tubes were removed. Extubation was often performed in the operating room but was delayed when there had been prolonged defibrillation testing or when the patient had not completely metabolized the anesthetic agents. Postoperative pain was treated with epidural narcotics, supplemented intravenously as needed. The ICD was activated immediately after completion of the procedure. The patients were monitored in an intensive care unit for at least 24 hours. The patients then were transferred to the ward and had telemetry monitoring and resumption of activity as tolerated. Before discharge, ICD testing in the electrophysiological laboratory was performed in every patient on the fifth to seventh postoperative day. Patients were examined by the operating surgeon in the clinic 2 and 6 weeks after hospital discharge. Subsequent routine examinations were performed by the electrophysiologists. Results Operative Results Adequate defibrillation energy thresholds were obtained in each patient. Mean defibrillation energy was 16 & 5 J (range, 7 to 20 J). The most commonly employed configuration was a large patch on the left lateral border of the pericardium as the cathode and an anodal patch in the right lateral position (19 patients). In 3 patients, lateral positioning was not successful, and patches were placed in extrapericardial anterior and posterior positions to achieve adequate thresholds. Standard ICD devices were implanted in most patients (CPI Ventak model 1550 [Cardiac Pacemakers, Inc, St. Paul, MN], 9 patients; CPI Ventak model 1600, 2). A high-output ICD (CPI Ventak model 1555) was implanted in 1 patient with ventricular fibrillation at electrophysiological study and a defibrillation threshold of 20 J. Epicardial screw-in rate-sensing leads were placed on the diaphragmatic surface of the right ventricle in 12 patients. Transvenous endocardial leads were placed in 10 patients and became our preferred lead for patients receiving devices with antitachycardia pacing (Telectronics model 4210 [Telectronics Pacing Systems, Inc, Englewood, CO], 8 patients) or bradycardia support (Telectronics model 4203, 2 patients). R-wave amplitude ranged from 6 to 35 mv (mean amplitude, 17 * 2 mv). Pacing threshold at a pulse width of 0.5 ms ranged between 0.5 and 1.9 V (mean threshold, 0.9 k 0.2 V).

4 Ann Thorac Surg 1992;53: DAMIANO ET AL 981 These variables were not significantly different between endocardial and epicardial leads. Only 6 of the 22 patients had the pericardium closed at the time of the initial procedure. There was no appreciable difference in the difficulty of the dissection between patients who had previously open and those with previously closed pericardiums. There were no instances of intraoperative damage to bypass grafts, and no patient required a sternotomy or thoracotomy. Early Postoperative Results Most of the patients (13/22, 59%) were extubated on the evening of ICD insertion and nearly all (20/22, 91%), by the first postoperative day. These 20 patients were all transferred out of the intensive care unit within the following 24 hours. Atrial tachyarrhythmias prevented transfer and ICD activation until the third postoperative day in 1 patient, and repeated episodes of ventricular tachycardia in another delayed transfer until the fifth postoperative day. Extubation was delayed until the third day in 1 patient who received excessive fluid and was treated for pulmonary edema. Chest tube drainage was minimal (mean amount, 200 f 58 ml; range, 0 to 900 ml), with tube removal by the first postoperative day in all but 2 patients. Bilateral drainage tubes were necessary in 7 patients, and single tubes in 13 patients. No chest tubes were required in 2 patients. Although left basilar atelectasis was common, clinical pneumonia or critically impaired ventilatory function was not seen after use of the subcostal approach. One patient required readmission for drainage of a symptomatic left pleural effusion 3 weeks after cardioverter defibrillator implantation. Two patients had to be returned to the operating room. One ICD was revised on the fifth postoperative day for oversensing related to a mechanical lead problem involving a fractured adapter. Buckling of a defibrillation patch was noted on a predischarge chest roentgenogram in 1 patient, and the patch was repositioned on postoperative day 10. There was 1 perioperative death (1/22, 4.5%). It occurred 3 days after ICD placement and was related to an acute anterior myocardial infarction. This patient had undergone combined five-vessel coronary artery bypass grafting and mitral valve replacement 4 months earlier. Postmortem examination demonstrated occlusion of two grafts and an acute infarction. There were no other complications in this group of patients. Formal electrophysiological testing was conducted before discharge and confirmed ICD function in each patient. Most patients (16/22, 73%) were either discharged home or transferred for further medical workup by the tenth postoperative day (range of hospital stay, 6 to 23 days). Lute Postoperative Results Patients have been followed for intervals of 3 to 27 months after hospital discharge. No patient has been lost to follow-up. During this period there has been only 1 death. It was due to a documented noncardiac cause and was not an arrhythmia-related death. Comment It is estimated that more than 24,000 patients have received ICDs to date, and it can be assumed that with further technological advances, the number of implantations will continue to increase dramatically [12]. As implantation of the device becomes more commonplace, more patients will be seen who have undergone prior cardiothoracic procedures. Early techniques for implantation of the cardioverter defibrillator emphasized the need to obtain generous operative exposure in an expeditious and safe matter [7]. The left anterior thoracotomy approach was the most commonly employed technique [2, 6-8, 131. Many centers even preferred a median sternotomy for primary implantation [3-51. However, as experience increased, some surgeons became convinced that more limited approaches carried a lower morbidity and mortality. Watkins and associates [9] introduced the subxiphoid approach in This approach obviated the need for thoracotomy or sternotomy but employed two separate incisions: a subxiphoid incision to place intrapericardial patches and epicardial wires and a second incision for the generator pocket. Excellent results were obtained with this more limited approach [ 141. The subcostal thoracotomy, introduced by Parsonnet and colleagues [15] in 1965, was initially used for pacemaker electrode insertion. Lawrie and associates [lo, 161 first used the subcostal approach for ICD placement in This approach employed only a single incision for patch and generator placement and has been used with excellent results for primary ICD insertion. Patients who have undergone prior sternotomies for cardiac procedures represent an additional technical challenge because of the presence of postoperative adhesions and the potential risks of bypass graft, cardiac, or great vessel injury. Although the left thoracotomy approach has been endorsed for patients with prior sternotomy [7, 171, this technique has several disadvantages. It results in a painful, cosmetically unattractive incision, can be difficult in patients with prior internal mammary artery grafts, and requires a separate incision for generator implantation. A redo median sternotomy also cames potential hazards [18,19]. Lytle and colleagues [19] demonstrated that the risk of redo sternotomy, especially in the presence of patent internal mammary grafts, is appreciable. The subcostal approach has several advantages in a patient with a prior sternotomy. Patch placement can be performed in either anterior-posterior or lateral-lateral extrapericardial locations through a single, cosmetically superior incision. Postoperative adhesions from previous procedures can be avoided, thus minimizing the potential risks of graft, cardiac, or great vessel injury. Either transvenous endocardial or epicardial pacing or sensing leads can be easily placed. There were no serious problems with bleeding or graft injury with epicardial lead placement using this approach, although as our experience increased, the endocardial pacing or sensing lead was favored because it eliminated the need for dissection inside the pericardium. In all instances, an adequate

5 982 DAMIANOETAL Ann Thorac Surg 1992; defibrillation configuration could be achieved with this approach in our 22 consecutive patients. The operative mortality of ICD placement as a primary procedure ranges from 1.2% to 4.5% in collected large series [ Patients with depressed left ventricular function have been shown to have an increased mortality rate. Kim and associates [30] reported an early mortality rate of 11% in patients with a left ventricular ejection fraction of less than 0.30 compared with 0% in those with preserved ventricular function. Other studies [31, 321 examined patient subsets with depressed left ventricular function and found a similar pattern. There was only 1 death in our series, and it was secondary to an acute myocardial infarction. Although the series is small, this is considered an acceptable result in this high-risk group of patients, all of whom had undergone prior cardiac procedures and 81% of whom had ejection fractions less than or equal to The reported incidence of early complications after primary ICD insertion by median sternotomy or thoracotomy ranges from 6% to 30% [ Some groups [9, 10, 141 showed a substantial decrease in complication rates for the less invasive subcostal or subxiphoid approaches for primary ICD insertion. This report confirms these findings in a high-risk population of patients who have undergone previous sternotomy. The early complication rate in this series was low (3/22,13.6%), and there were no instances of infection, erosion, or bleeding. The subcostal approach also resulted in a very low incidence of pulmonary complications in these patients (1/22,4.5%). In a previous report [25], 29% of patients had pulmonary complications after ICD placement. In the present series, the single pulmonary complication was a minor one involving a persistent pleural effusion. In summary, this series supports the utility and advantage of the subcostal approach for ICD insertion in patients who have undergone a previous sternotomy. The less invasive subcostal approach avoids adhesions and the potential risks of graft, cardiac, or great vessel injury. The difficulties associated with redo sternotomy or thoracotomy are avoided. With appropriate retraction, subcostal exposure yielded satisfactory flexibility for defibrillation patch placement. There was minimal morbidity in this high-risk group of patients, allowing prompt extubation and ambulation. The subcostal approach is considered to be a safe and effective technique and is our method of choice for ICD insertion in patients with a previous sternotomy. References Winkle RA, Stinson EB, Echt DS, Mead RH, Schmidt P. Practical aspects of automatic cardioverter/defibrillator implantation. Am Heart J 1984;108: Hammon JW. The role of the automatic implantable cardioverter-defibrillator in the treatment of ventricular tachycardia. Semin Thorac Cardiovasc Surg 1989;1: Brodman R, Fisher JD, Furman S, et al. Implantation of automatic cardioverter defibrillators via median sternotomy. PACE 1984; Porterfield JG, Porterfield LM, Bray L. Long-term community hospital experience with the internal defibrillator. PACE 1991;14: Blakeman BM, Wilber D, Pifarre R. Median sternotomy for implantable cardioverter/defibriilator. Arch Surg 1989; Mirowski M, Reid PR, Mower MM, et al. Termination of malignant ventricular arrhythmias with an implanted defibrillator in human beings. N Engl J Med 1980;303: Watkins L, Mirowski M, Mower MM, et al. Automatic defibrillation in man. The initial surgical experience. J Thorac Cardiovasc Surg 1981;82: Winkle RA, Stinson EB, Bach SN, et al. Measurement of cardioversion/defibriillation threshold in man by a truncated exponential waveform and an apical patch-superior vena caval spring electrode configuration. Circulation 1984;69: Watkins L Jr, Mirowski M, Mower MM, et al. Implantation of the automatic defibrillator: the subxiphoid approach. Ann Thorac Surg 1982; Lawrie GM, Griffin JC, Wyndham CRC. Epicardial implantation of the automatic implantable defibrillator by left subcostal thoracotomy. PACE 1984; Lawrie GM, Wright-Hargis J, Lin HT, et al. High defibrillation threshold with the AICD. management with a right atrial patch electrode (Abstract). J Am Coll Cardiol 1988;11: Damiano RJ Jr. Implantable cardioverter defibrillators: current status and future directions. J Cardiac Surg (in press). 13. Troup PJ. Implantable cardioverters and defibrillators. Curr Probl Cardiol 1989;12: Watkins L, Levine J. Smart electronic devices in the treatment of cardiac arrhythmias. In: Karp RB, ed. Advances in cardiac surgery; vol 2. St. Louis; Mosby-Year Book, 1990: Parsonnet V, Gilbert L, Zucker IR, et al. Subcostal, transdiaphragmatic insertion of a cardiac pacemaker. J Thorac Cardiovasc Surg 1965;49: Lawrie GM, Morris GC Jr, Howell JF, DeBakey ME. Left subcostal insertion of the sutureless myocardial electrode. Ann Thorac Surg 1976;21: Siclari F, Klein H. Automatic implantable cardioverter defibrillator implantation after previous open heart surgery: subcostal incision and small left anterior thoracotomy. PACE 1990;13: Dobell ARC, Jain AK. Catastrophic hemorrhage during redo sternotomy. Ann Thorac Surg 1984;37: Lytle BW, Loop FD, Cosgrove DM, et al. Fifteen hundred coronary reoperations. Results and determinants of early and late survival. J Thorac Cardiovasc Surg 1987;93: Tchou PJ, Kadri N, Anderson J, et al. Automatic implantable cardioverter defibrillators and survival of patients with left ventricular dysfunction and malignant ventricular arrhythmias. Ann Intern Med 1988;109: Winkle RA, Mead H, Ruder MA, et al. Long-term outcome with the automatic implantable cardioverter-defibrillator. J Am Coll Cardiol 1989;13: Hargrove W, Josephson M, Marchlinski F, Miller JM. Surgical decisions in the management of sudden cardiac death and malignant ventricular arrhythmias. Subendocardial resection, the automatic internal defibrillator, or both. J Thorac Cardiovasc Surg 1989; Palatianos G, Thurer RJ, Cooper DK, et al. The implantable cardioverter-defibrillator: clinical results. PACE 1991;14: Watkins L, Taylor NA. The surgical aspects of automatic cardioverter-defibrillator implantation. PACE 1991; Kelly PA, Cannon DS, Garan H, et al. The automatic implantable cardioverter defibrillator: efficacy, complications and survival in patients with malignant ventricular arrhythmias. J Am Coll Cardiol 1988;11:

6 Ann Thorac Surg 1992:53: DAMIANO ET AL Borbola T, Denes P, Ezri M, Hauser RG, Serry C, Goldin MD. The automatic implantable cardioverter defibrillator: clinical experience, complication and follow-up in 25 patients. Arch Intern Med 1988;148:70-6. Myerberg R, Luceri R, Thurer R, et al. Time to first shock and clinical outcome in patients receiving an automatic implantable defibrillator. J Am Coll Cardiol 1989; Fogoros R, Elson J, Bonnet C. Actuarial incidence and pattern of occurrence of shocks following implantation of the automatic implantable cardioverter defibrillator. PACE 1989;12: Manolis AS, Tan-DeGuzman W, Lee MA, et al. Clinical experience in seventy-seven patients with the automatic implantable cardioverter defibrillator. Am Heart J 1989;118: Kim SG, Fisher JD, Furman S, et al. Benefits and risks of implantable defibrillators in patients with poor left ventricular function [Abstract]. PACE 1991;14:641. Axtell K, Tchou P, Akhtar M. Survival in patients with depressed left ventricular function treated by implantable cardioverter defibrillator. PACE 1991;14: Marchena E, Chakko S, Fernandez P, et al. Usefulness of the automatic implantable cardioverter defibrillator in improving survival of patients with severely depressed left ventricular function associated with coronary artery disease. Am J Cardiol 1991; DISCUSSION DR JOHN M. KRATZ (Charleston, SC): We have not tried this approach but may try it as a new procedure before doing it on a post-sternotomy patient. In some of the patients we operate on in this situation, the pericardium is closed; in some, it is partially open; and in some, wide open. During your presentation, I was trying to imagine a patient with a pericardium wide open. Sometimes we do not know because the patient was operated on elsewhere some time ago. Does that affect the efficacy of this approach, or can you find yourself actually not looking at the pericardium but at the heart while you are dissecting a widely opened pericardium? DR DAMIANO: I think that is an excellent question. In most of the patients, it is fairly easy to identify at least one of the borders of the pericardium because you are coming up from below and through the diaphragm. It is fairly evident that after you divide the diaphragmatic muscle, you are usually on the pericardial surface of the heart. It is important to perform the dissection right under the xiphoid process. I am sure you have had a lot of experience with redo coronary bypass procedures, and there usually is a space overlying the diaphragmatic surface of the right ventricle, even if the pericardium has been left widely open. I think it is important to carefully identify when you go through the diaphragm. If you do not see the pericardium, you know you need to carry your dissection in an anterolateral direction. The key to this approach is both staying anterior, hugging the costal margin, and moving laterally as quickly as possible after you divide the diaphragm. This does not present a very difficult clinical problem. I think the advantage of this approach, certainly with the use of transvenous endocardia1 leads, is that there is no requirement for any dissection around the heart and no chance of injuring the vein or internal mammary grafts. DR LYNN H. HARRISON (New Orleans, LA): That was a very nice presentation. These patients were very sick, as they always are, and you got them through splendidly. I do have a couple of points to raise. It seems to me that one of your premises is that these patients were able to be separated from the ventilator sooner by virtue of this technique, yet a substantial percentage of them were intubated, I gather, overnight. In addition, division of the rectus as well as a portion of the diaphragm represents a lot of muscle cutting. If an anterior thoracotomy is used with a muscle-splitting procedure, it seems that we do not cut quite that much muscle, and postoperative pain with the anterior incision has not been an unwieldly problem. Finally, I noticed you had one problem with a lead fracture. With the technique that you described, as I understand it, you are tunneling that lead subcutaneously, passing it over the costal margin, which is one of the techniques that is associated with a lead-fracturing problem. Would you comment on that? DR DAMIANO: Those are excellent points. I am not sure whether this technique really offers a substantially earlier extubation compared with standard techniques, and I really did not mean to imply it. About 70% of our patients were extubated immediately after the operation. I think the biggest single limiting factor in early extubation of these patients is a lack of cooperation between the surgeon and the anesthesiologist. I would like to emphasize that epidural narcotics are important in terms of limiting the immediate postoperative pain. Having had experience with both the thoracotomy and the subcostal incision, I think the latter is a little bit less invasive and less painful, though, as you point out, there is pain with this incision. However, I do not think there is much pain from the splitting of the costal attachments of the diaphragm. Those of you who have used this approach know that usually that can be done very easily, almost with a finger, and we are not talking about a very thick muscular attachment. There is some pain in dividing the rectus muscle. In some patients, we have actually been able to separate the rectus muscle and slip the device in, and I think with some of the newer device designs this will probably become the norm rather than the exception. These defibrillators are bulky, and their rectangular design does not lend itself to being squeezed between the muscle fibers of the rectus. Some of the newer defibrillators have oval shapes that are much easier to insert. Another advantage of the subcostal approach is that it requires only one incision. Certainly our patients seem to be a lot happier with a single incision in a cosmetically acceptable place than with a thoracotomy scar and a separate subcostal incision required for a standard implantation. I think that with the advent of nonthoracotomy systems, things may be changing. In many of the post-sternotomy patients, a nonthoracotomy approach presents a very viable option. Since we prepared this presentation, we have performed ncnthoracotomy implantation in 2 patients with excellent results.