LONG-TERM FOLLOW-UP (12 TO 35 WEEKS) AFTER DYNAMIC CARDIOMYOPLASTY

Objectives. To obtain information on the long-term effects of dynamic cardiomyoplasty on hemodynamics and muscle histology, this surgical me thod was evaluated in goats. Background. Dynamic cardiomyoplasty has b een introduced as a new method to treat patients with severe cardiac f ailure. Methods. In 24 goats, the left latissimus dorsi muscle was wra pped around the heart. The muscle was then subjected to progressive el ectrical stimulation. In 16 goats, invasive transesophageal Doppler ec hocardiographic measurements and histologic evaluation of the latissim us dorsi muscle were performed at greater-than-or-equal-to 12 weeks af ter the wrapping. Results. Only two goats showed an increase in aortic and left and right ventricular pressures concomitant with increased a ortic flow during latissimus dorsi muscle stimulation both before and after induction of cardiac failure using imipramine. This was accompan ied by a preserved latissimus dorsi muscle structure and nearly comple te transformation to type I muscle fibers. The remaining 14 goats show ed extensive lipomatosis in the latissimus dorsi muscle, with severe i ntimal hyperplasia and proliferation of smooth muscle cells in the wal ls of the thoracodorsal artery and its branches. An increase in endone ural and endomysial connective tissue was observed, with some goats sh owing destroyed nerve branches near the electrodes. These findings dif fered from those observed after long-term electrical stimulation of go at latissimus dorsi muscle in situ. Conclusions. Dynamic cardiomyoplas ty is of use in the treatment of severe heart failure if the histologi c structure of the wrapped latissimus dorsi muscle remains intact. Lon g-term results in goats suggest that the current approach used in dyna mic cardiomyoplasty may lead to deterioration of the wrapped muscle.