[Dynamic cardiomyoplasty]

Between 1965 and 1995 the incidence of heart failure has been constantly rising and the mortality from this disease has increased fivefold. The introduction of ACE-inhibitors and of adrenergic beta-blockers have resulted in major symptomatic improvements in patients with mild to moderate heart failure. For end-stage disease, heart transplantation offers by now the only therapeutic option and yields excellent results. The permanent implantation of left heart assist-devices is just gaining increasing importance. Yet, both methods also have inherent drawbacks and may not be available to all patients, so that new methods are constantly evaluated. Cardiomyoplasty was introduced into clinical practice in 1985 by Alain Carpentier and since then more than 700 patients have been operated worldwide. After dissection of the latissimus dorsi muscle it is wrapped around the heart in a clockwise fashion (Figure 1). Two sensing electrodes are placed on the anterior aspect of the right ventricle and two stimulation electrodes between the proximal branches of the thoracodorsal nerve (Medtronic SP 5548). The electrodes are then connected with a burststimulator (Cardiomyostimulator, Medtronic 4710) (Figure 2). During the first 2 weeks following the operation the muscle is not stimulated in order to allow for the healing process. Thereafter, a stimulation protocol with a programmed, staged increase of the stimulation frequency is started, to induce transformation of the skeletal muscle into a "fatigue resistant" tissue. After 3 months the muscle is stimulated with every second heart beat (2:1 mode) with full burstimpulses containing 6 single impulses per burst for a duration of 185 ms (Figure 3). Cardiomyoplasty was conceived for patients in NYHA III and severely impaired myocardial function, in whom drug treatment does not produce the expected benefits. The criteria for patient selection are strictly followed, since it has been shown in the past, that the preoperative condition of the patient is of specific importance for the postoperative outcome. Contraindications are NYHA IV, advanced right ventricular dysfunction, secondary pulmonary hypertension (> 600 dyn x s x cm-5), LV end-diastolic diameter > 70 mm und AV-valve incompetence > Grad II. Between July 1985 und October 1996 647 patients received a cardiomyoplasty with the Medtronic Cardiomyoplasty System and the results from 438 patients were analyzed from the "Worldwide Cardiomyoplasty Study Group". One and 2 years following the operation NYHA-class had improved by one class in 41.9% and 53.3%, respectively, and by 2 classes in 38.1% and 30.5%, respectively. In 16% and 15% no improvement was found (Figure 4). Prospective investigation of the quality of life by a score revealed a considerable improvement in the level of daily activities and social interaction. In contrast, two years after the operation, only a small, but significant increase in LV-EF from 22.9 +/- 8.1% to 25.8 +/- 9.7% (p < 0.05) was shown. Heart rate, maximal O2-consumption, total exercise time, cardiac index, stroke volume and stroke work index did not change. According to the results of a recent FDA-study, in-hospital mortality was 12% between 1991 and 1993, and was reduced during a second phase starting 1994 to < 3%. One, 2 and 3-year survival of 349 patients who were in NYHA-III prior to the operation was 69%, 56% und 47%, respectively. 43 patients who were operated in NYHA IV exhibited considerably worse survival with only 48% after 1 year and 30% after 2 years, respectively. In a subgroup of 103 patients with a statistically low operative risk, 1, 2 and 3-year survival was 77%, 71% und 61%, respectively (Figure 5). As a mechanism of action the skeletal muscle wrap exerts some active improvement of systolic wall motion of the heart/skeletal muscle complex. However, probably more important is an acute and chronically persisting shift of the pressure-volume relation to the left. This process results in a "reverse remodel