DYNAMIC CARDIOMYOPLASTY

Between 1965 and 1995 the incidence of heart failure has been constant ly rising and the mortality from this disease has increased fivefold. The introduction of ACE-inhibitors and of adrenergic beta-blockers hav e resulted in major symptomatic improvements in patients with mild to moderate heart failure. For end-stage disease, heart transplantation o ffers by now the only therapeutic option and yields excellent results. The permanent implantation of left heart assist-devices is just gaini ng increasing importance. Yet, both methods also have inherent drawbac ks and may not be available to all patients, so that new methods are c onstantly evaluated. Cardiomyoplasty was introduced into clinical prac tice in 1985 by Alain Carpentier and since then more than 700 patients have been operated worldwide. After dissection of the latissimus dors i muscle it is wrapped around the heart in a clockwise fashion (Figure 1). Two sensing electrodes are placed on the anterior aspect of the r ight ventricle and two stimulation electrodes between the proximal bra nches of the thoracodorsal nerve (Medtronic SP 5548). The electrodes a re then connected with a burststimulator (Cardiomyostimulator(TM), Med tronic 4710) (Figure 2). During the first 2 weeks following the operat ion the muscle is not stimulated in order to allow for the healing pro cess. Thereafter, a stimulation protocol with a programmed, staged inc rease of the stimulation frequency is started, to induce transformatio n of the skeletal muscle into a ''fatigue resistant'' tissue. After 3 months the muscle is stimulated with every second heart beat (2 : 1 mo de) with full burstimpulses containing 6 single impulses per burst for a duration of 185 ms (Figure 3). Cardiomyoplasty was conceived for pa tients in NYHA III and severly impaired myocardial function, in whom d rug treatment does not produce the expected benefits. The criteria for patient selection are strictly followed, since it has been shown in t he past, that the preoperative condition of the patient is of specific importance for the postoperative outcome. Contraindications are NYHA IV, advanced right ventricular dysfunction, secundary pulmonary hypert ension (> 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 6 47 patients received a cardiomyoplasty with the Medtronic Cardiomyopla sty System and the results from 438 patients were analyzed from the,,W orldwide Cardiomyoplasty Study Group''. One and 2 years following the operation NYHA-class had improved by one class in 41,9% and 53,3%, res pectively, and by 2 classes in 38,1% and 30,5%, respectively. In 16% a nd 15% no improvement was found (Figure 4). Prospective investigation of the quality of life by a score revieled 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. Hea rt rate, maximal O-2-consumption, total exercise time, cardiac index, stroke volume and stroke work index did not change. According to the r esults of a recent FDA-study, in-hospital mortality was 12% between 19 91 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 pr ior to the operation was 69%, 56% und 47%, respectively. 43 patients w ho were operated in NYHA IV exhibited considerably worse survival with only 48% after 1 year and 30% after 2 years, respectively. In a subgr oup 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 mec hanism of action the skeletal muscle wrap exerts some active improveme nt of systolic wall motion of the heart/skeletal muscle complex. Howev er, probably more important is an acute and chronically persisting shi ft of the pressure-volume relation to the left. This process results i n a ''reverse remodeling'' of the insufficient heart with an improveme nt of the ''contractility reserve'' (Figure 6).