[Biomechanical heart and cardiovascular support]

A surgical association between skeletal muscle and heart muscle dates back to experiments at the beginning of this century. Initially, the use of skeletal muscles aimed at plastic reconstructions of myocardial defects and enhancement of myocardial blood flow. The application of the contractile force of the skeletal muscle failed because of skeletal muscle fatigue. In the late sixties, investigations in muscle physiology demonstrated the "functional plasticity" of muscle tissue: Chronic electrical stimulation induces a transformational process of the cellular organelles, the metabolism, the fiber proteins and the calcium regulatory systems which results in "fatigue resistance" of the muscle. This was is a prerequisite for the application of skeletal muscles for continuous support of the circulation. Biomechanical support of the heart and the circulation is experimentally performed as skeletal muscle ventricles, chronic extraaortic counterpulsation and ventricular and atrial cardiomyoplasty. The electrical stimulation is performed with "burst" impulses, in order to increase the force and the length of contraction. The first clinical application of ventricular cardiomyoplasty is attributed to the French surgeon Alain Carpentier. Clinical investigations show that cardiomyoplasty results in an impressive symptomatic improvement of the patients clinical condition with only moderate changes of objective hemodynamic parameters. Further research will investigate the clinical applicability of the other, thus far only experimental techniques of biomechanical support. The introduction of cardiomyoplasty has induced great scientific interest in all forms of skeletal muscle circulatory support. Close collaboration between basic researchers and clinical investigators is of utmost importance for further developments in this field. The combined international research effort can be expected to yield considerable progress within the forthcoming years.