The importance of skeletal muscle fiber orientation for dynamic cardiomyoplasty.

Dynamic cardiomyoplasty has been performed clinically to provide a substitute for myocardium, to assist dyskinetic ventricles, and to benefit patients with Chagas disease or dilated cardiomyopathy. Encouraging results have been observed for the patients; however, a conclusive experimental study is not available. How to use conditioned skeletal muscle for maximal augmentation of cardiac function in an appropriate animal model is the goal of this study. Dogs were used for heart failure induction, for single versus burst muscle stimulation, and for cardiac function augmentation. Muscle transformation was documented by histochemical evaluations. Propranolol infusion (3 mg/kg) induced temporary heart failure for 4 to 6 hours with significantly decreased cardiac output and blood pressure. Dynamic cardiomyoplasty significantly improved hemodynamic function during induced heart failure with better improvement by multiple (burst) stimulation as compared with single stimulation. Skeletal muscle fiber orientation is a critical factor for the success of this procedure. Our results indicated that skeletal muscle fiber oriented circumferential to the heart and perpendicular to the ventricular septum is the preferred procedure for dynamic cardiomyoplasty.