Transplanted for Congestive Heart Falilure

The afterload dependence of the intracellular calcium transient in isolated working human myocardium was analyzed in both donor and recipient hearts of seven patients undergoing transplantation because of dilated cardiomyopathy. The intracellular calcium transient (recorded by the fura 2 ratio method), force development, and muscle shortening were simultaneously recorded in small (0.6x4.0-mm) electrically driven (60 beats per minute) trabeculas contracting at constant preload against varying afterloads. When the fibers contracted under isometric conditions, the intracellular calcium transients of normal and failing myocardium were similar. However, in dilated cardiomyopathy, stepwise afterload reduction and the concomitant increase in shortening amplitudes were associated with extraordinary alterations in the shape of the calcium transients: the amplitude rose, the time to peak was delayed, and at minimal afterloads, a long-lasting plateau was observed, he intracellular calcium transient of normal human myocardium is modulated during the performance of mechanical work.1)2 The ability to perform mechanical work (to shorten against a given afterload) was depressed in skinned myocardial fibers of patients with dilated cardiomyopathy, although the crossbridge cycling rate was normal.3 The intracellular calcium transient of intact working human myocardium of patients with dilated cardiomyopathy had not yet been analyzed. Measurements of calcium transients during the performance of mechanical work have now become possible, since new fluorescent dyes are available.4-7 For the measurement of intracellular calcium transients, the dual wavelength excitation method ("ratio method") and the fluorescent dye fura 2 were selected to minimize shortening artifacts.',4,6,8 Combined measurements of calcium, force, and shortening show for the first time that extraordinary alterations of the intracellular calcium transient occur in dilated cardiomyopathic myocardium during shortening. Materials and Methods