Pericardium-Lined Skeletal Muscle Ventricles: Up to Two Years' In-Circulation Experience

Abstract

Background. Skeletal muscle ventricles (SMVs) are autologous pumping chambers constructed from skeletal muscle. Skeletal muscle ventricular rupture and thromboembolism have complicated chronic models of this method of skeletal muscle cardiac assist. Methods. The SMVs were constructed from the latissimus dorsi muscle in 10 dogs. The inner surface of each SMV was lined with autologous pericardium harvested at the time of SMV construction. After a 3-week period of vascular delay and 6 weeks of electrical conditioning to convert the muscle to a fatigue-resistant state, SMVs were connected to the descending thoracic aorta and stimulated to contract during cardiac diastole. Results. Initial hemodynamics revealed that SMV contraction at 33 Hz increased diastolic pressure 24.7% (60.8 ± 7.3 mm Hg versus 80.3 ± 8.8 mm Hg). Skeletal muscle ventricle relaxation decreased presystolic pressure 14.4% (59.9 ± 7.7 mm Hg versus 51.3 ± 7.5 mm Hg) and decreased peak systolic pressure 4.1% (90.2 ± 7.3 mm Hg versus 86.5 ± 5.8 mm Hg). Hemodynamics were assessed at 1 to 2 weeks, then at 1, 2, 3, and 6 months, and at 6-month intervals thereafter. Hemodynamic performance remained stable for the duration of this study. After 2 years of pumping continuously in circulation, SMV contraction resulted in a 34.8% augmentation of diastolic pressure (63.6 ± 6.6 mm Hg versus 85.3 ± 6.4 mm Hg), a 17.2% decrease in presystolic pressure (54.7 ± 3.73 mm Hg versus 45.3 ± 4.1 mm Hg), and a 4.2% decrease in peak systolic pressure (95.3 ± 10.4 mm Hg versus 91.3 ± 12.3 mm Hg). Three dogs survived to 2 years with the SMVs in circulation. No animal showed evidence of thromboembolism during serial echocardiography or at autopsy and no SMVs ruptured. Conclusions. These data demonstrate that SMVs can provide effective hemodynamic assist over an extended period without specific complications related to the SMVs.