Epicardial Pacemaker Implantation for Complete Heart Block

Transcription

1 for Complete Heart Block Donald G. Mulder, M.D., and C. Gordon Frank, M.D. S udden death or progressive cardiac failure threatens life in the patient with complete heart block. The slow heart rate and relatively fixed cardiac output severely limits physical activities. Since medical therapy is seldom successful or reliable, electrical stimulation of the heart has been advocated increasingly. Thoracotomy with direct epicardial electrode implantation has been the standard procedure available in the past. More recently, pervenous techniques have provided an attractive alternative method, although the reliability of capture, incidence of complications, and longterm results have not as yet been documented. Such information pertaining to both pervenous and conventional methods of pacemaker implantation, is necessary to determine the role of each method in the management of these patients. It is the purpose of this report to present our experience over the past seven years at the U.C.L.A. Medical Center in treating patients with complete heart block by thoracotomy with epicardial pacemaker implantation. CASE MATERIAL Between 96 and February, 968, 60 patients with complete heart block have been operated upon at the U.C.L.A. Medical Center. There were 38 males and 22 females whose ages ranged from 3 months to 89 years. Forty-three patients (70%) were over 60 years of age. The heart block was thought to be related to coronary artery disease in 42 patients, in 4 cases it was congenital in origin, and in 4 others it followed a cardiac operation. No specific cause could be identified in 4 instances, while in the remaining 6 cases it was attributed to infection, and hypertensive or rheumatic heart disease. In these 60 patients, 45 operative procedures were performed which included 60 local procedures and 25 secondary thoracotomies (Table ). In the latter group were 6 patients who required one repeat thoracotomy, 2 who required two such procedures, and 4 patients who had from three to five secondary thoracotomies. From the Department of Surgery, University of California at Los Angeles Medical Center, Los Angeles, Calif. Supported in part by Los Angeles County Heart Association Grant No. 4 IG and U.S. Public Health Service Grant No. HE Accepted for publication July 5,

2 TABLE. Operation Thoraco tomy Primary Secondary reoperation 2 reoperations 3-5 reoperations Local procedures Pacer replaced Wire repair Pacer repositioned Number of operations (60 patients) OPERATIVE PROCEDURES IN PACEMAKER PATIENTS, 96 TO FEBRUARY, 968 No. of Patients Five different types of pacemakers were implanted. The two most commonly used were the Atricor synchronous unit (37 inserted at the initial operation and 29 as replacements) and the Medtronic asynchronous pacer (3 inserted at the initial operation and 25 as replacements). In the remaining 25, either a Ventricor, General Electric, or Electrodyne pacer was used. OPERA TIVE MANAGEMENT Each patient was given a trial of medical management which included the administration of atropine and sympathomimetic drugs such as isoproterenol. If this did not produce the desired response or was accompanied by adverse side effects, pacemaker implantation was recommended. Temporary transvenous pacing was used in those patients with marked symptoms or those who were in congestive heart failure. In the latter group, three to five days of pacing, along with the use of diuretics, fluid restriction, and correction of electrolyte disturbances, yielded significant improvement in the condition of these patients such that operation could be carried out under optimal circumstances. The standard technique for epicardial lead implantation through a left anterolateral thoracotomy was used in 64 instances, while a median sternotomy was performed in the remaining 2 cases. With the latter approach, the leads were usually attached to the right ventricle (and right atrium when a synchronous pacer was used). The pulse generator was placed most commonly in the left subcostal area, but occasionally the subpectoral region or other locations were used under certain circumstances. At the moment the permanent pacemaker was attached, the temporary pacer was turned off. It was left in situ for 24 hours or longer if intermittent capture was present and was then removed when the rhythm was stable. Antibiotics were not given routinely. RESULTS There were operative and 4 late deaths. Forty-four patients are alive with functioning pacemakers, while in child, who had undergone multiple procedures, the pulse generator was removed because of recurrent infections. She vol. 6, NO. 5, NOV.,

3 MULDER AND FRANK = PTS. OPERATED (60) = PTS. ALIVE (45) I YEARS SINCE ORIGINAL OPERATION FIG.. Long-term results in pacemaker implantation for complete heart block. Prolonged suruival with return to normal activity was achieved in most patients. Despite the need for multiple operative procedures, 75% of those operated upon 4 to 7 years ago are still alive. maintains an idioventricular rate of 48. The follow-up in these 60 patients has been complete. Despite the necessity for multiple operations in many of these patients, it is gratifying to note the appreciable long-term salvage which was achieved (Fig. ). Twenty-seven out of 38 patients (7%) are alive 2 years or more after operation, while 2 out of 6 patients (75%) have survived more than 4 years since their original pacemaker implantation. DEATHS The operative death was the result of intraoperative hemorrhage in a patient with complete heart block and severe mitral stenosis. Concomitant closed mitral commissurotomy was performed upon completion of an uneventful pacemaker implantation. The left atrium was torn during the digital manipulation of the valve. Although the bleeding was controlled, she died in the early postoperative period. Five of the 4 late deaths were of cardiac origin, although unrelated to the pacemaker (Table 2). Three were due to an acute myocardial infarction, 2 were the result of progressive cardiac failure, was related to sepsis, and in instance the cause of death was never determined. In addition, there were 7 patients who died of unrelated problems, including cerebrovascular accidents, cancer, hepatorenal failure, and pulmonary embolus. CAUSES OF PACEMAKER FAILURE There were 78 instances of pacemaker failure. Battery depletion accounted for 52 malfunctions, electrode failure due to wire fracture (7) or epicardial fibrosis (4) was the etiological factor in 2, while infection accounted for the remaining 5. RESULTS WITH SYNCHRONOUS PACER (ATRICOR) In recent years, the synchronous pacemaker (Atricor) has been used much more frequently than other types. Since 964, 66 of these units have been implanted in 43 patients. There have been 27 pacer failures, of which 22 were due to battery depletion. This was usually signaled by lack of P-wave synchrony. There were 0 deaths (previously alluded to), none of which were related to the pacemaker. Twenty-nine patients continue to be paced by an Atricor, while in 2 cases it has been replaced, in instance by a Ventricor and in the other by 426

4 TABLE 2. LATE DEATHS IN PACEMAKER IMPLANTATION FOR COMPLETE HEART BLOCK, 96 TO FEBRUARY, 968 Cause of Death Acute infarction Cardiac failure Unrelated Cerebrovascular accident Cancer Hepatorenal failure Pulmonary embolus Infection Unknown (? pacer related) 3 2 No a Medtronic unit. One patient (previously mentioned) survives with no pacemaker, while the remaining patient has had the Atricor unit removed and is being paced by a temporary transvenous unit. Battery depletion occurred in 22 units at between 9 and 35 months, with an average duration of function of 2 months. UNUSUAL COMPLICATIONS Rhythm. It is not uncommon for a patient in the early postoperative period following pacemaker insertion to have transient episodes of intermittent capture, extrasystoles, or other arrhythmias. When these occur later on, it frequently heralds pacer failure, and one of the more dramatic of such episodes is the runaway pacer. One patient in this group, previously reported [Z], experienced this complication when the pacemaker rate changed abruptly from a fixed rate of 68 to 400 per minute. Her ventricular response was 200 beats per minute. Following removal of her pacer, she was maintained by an external pacemaker until a new unit was implanted uneventfully. Ventricular fibrillation occurred in 2 patients after a synchronous pacemaker had been inserted. In neither instance was a temporary pacing stimulus being supplied which might have caused a competitive rhythm. However, in each instance, the cautery was being used to obtain hemostasis prior to chest closure. It seems most likely that inadequate electrical grounding of the patient made it possible for the fibrillation to occur. This is a potential hazard not experienced with the single shock of cardioversion, in which ventricular fibrillation rarely, if ever, results. Infection. Despite stringent precautionary measures, infection of the pacemaker unit occasionally does occur. This serious complication followed pacemaker implantation in an 8-year-old girl whose heart block developed during repair of an ostium primum atrial septa defect. She previously had had temporary pacing wires connected to an external unit. The subcutaneous pocket in the upper abdomen and possibly the wire tracts became infected. The unit was replaced at thoracotomy with a new pulse generator inserted in the opposite upper abdominal quadrant. This promptly became infected, necessitating removal of this unit and the insertion of an Atricor synchronous pacer through a left posterolateral thoracotomy. Because of the previously infected abdominal wall and inadequate chest-wall soft tissue to accept the pulse generator, it was placed retropleurally in the left chest as a last resort (Fig. 2). The child tolerated this surprisingly well and had an uncomplicated convalescence. Three months later, however, she was noted to have episodes of vol. 6, NO. 5, NOV.,

5 MULDER AND FRANK FIG. 2. The pulse generator in this child was placed in an intrathoracic position because of infection in the abdominal wall. A transvenous unit would be sed currently under such circumstances. bradycardia, and pacer malfunction was suspected. Increased pleural reaction and probable fluid collection was seen on chest x-ray. At reexploration, the pulse generator was found to have eroded into the pulmonary parenchyma, causing a bronchopleural fistula and empyema. The pacemaker was exteriorized (Fig. 3), and the empyema drained. The unit continued to malfunction, but the patient seemed to tolerate a stable rate of 48 to 50 beats per minute. Consequently, the FIG. 3. Bronchopleural fistula and ernpyema developed following intrathoracic implantation of the pulse generator, necessitating exteriorization of the unit and drainage of the infected space. 428

6 pacer and the wires were removed, and she continues to do quite well without pacemaker support. Traction Lead Dislocation. Pacemaker failure occurred abruptly in patient due to traction on his electrode wires. Over a period of months following pacemaker insertion, the pulse generator, which originally had been placed in the left upper quadrant, began to drift toward the iliac crest. X-rays revealed the wires to have wound around the pulse generator as it rotated in its descent. At reexploration, the leads were seen to have pulled free from the myocardium. A new unit was inserted uneventfully. DISCUSSION Chronic complete heart block is relatively rare. Even so, it has been estimated that new cases arise at an approximate rate of 50 per million population per year [4], suggesting an annual incidence of 8,000 new cases in the United States [5]. With the development of increasingly reliable pacemakers, it is now possible to prolong life in many of these patients who otherwise would die. The best reflection of the poor medical prognosis in patients suffering from chronic heart block is reported by Johansson [3]. In a group of 9 patients the -year medical mortality was 40%. By contrast, Chardack et al. [l] reported a series of 4 patients treated by pacemaker implantation with a total mortality over a 5X-year period of 28%. The present series of 60 patients, in whom the surgical mortality over a 7-year period was 25%, compares favorably. Pacemaker malfunction currently is caused almost exclusively by battery depletion. Previous problems with wire fracture and epicardial fibrosis seldom occur since the development of the coiled wire leads with the spike-footplate myocardial electrodes. Failure of other component parts in the circuitry is rare. There remains a difference of opinion as to whether one type of pacemaker is preferable to another. There are advocates of the fixedrate, synchronous, and demand types. Opinion also differs as to whether the pervenous method of stimulating the heart should be used in preference to direct implantation at thoracotomy. There are theoretical and practical advantages to each. A careful long-term evaluation of patients treated by different techniques should allow for a more accurate appraisal of the role of various pacemaker devices in the treatment of patients with chronic complete heart block. SUMMARY A 7-year experience at the U.C.L.A. Medical Center with the use of pacemakers with epicardial implantation of the leads in the treatment of complete heart block is presented. One hundred twenty-nine VOL. 6, NO. 5, NOV.,

7 MULDER AND FRANK pacers of 5 different types were inserted in 60 patients. There were operative death and 4 late deaths, none of which could be attributed to the pacemaker. A complete follow-up was obtained. Twenty-seven out of 38 patients (7%) are alive 2 years or more after operation, while 2 out of 6 patients (75%) have survived more than 4 years since their original pacemaker implantation. The selection of surgical candidates, operative management, and unusual problems encountered in this group of patients are discussed. REFERENCES Chardack, W. M., Gage, A. A., Federico, A. J., Schimert, G., and Greatbatch, W. The long-term treatment of heart block. Progr. Cardiovasc. Dis. 9:05, 966. Gaal, P. G., Goldberg, S. J., and Linde, L. Cardiac output as a function of ventricular rate in a patient with complete heart block. Circulation 30:592, 964. Johansson, B. W. Complete heart block: A clinical, hemodynamic and pharmacological study in patients with and without an artificial pacemaker. Acta Med. Scand. 80 (Suppl.):45, 966. Siddons, H., and Sowton, E. Cardiac Pacemakers. Springfield, Ill.: Thomas, 967. Sowton, E. Cardiac pacemakers and pacing. Mod. Conc. Cardiovasc. Dis. 36: 3,