Biomechanical Hearts

Abstract

Background-As shown previously in goats, clenbuterol increased the power of electrically conditioned skeletal muscle ventricles (SMVs) of clinically relevant size (150 mL), which were constructed around a mock system. They pumped against a pressure of 60 to 70 mm Hg immediately during surgery and up to several months after, finally at Ͼ1 L/min. SMVs without clenbuterol administration failed. Thus, we expected that clenbuterol-supported SMVs might become integrated into the circulation by a 1-step operation instead of the 2-step procedure required up to now. Methods and Results-In adult Boer goats (nϭ5), latissimus dorsi muscle was wrapped around a polyurethane chamber of 150 mL that was connected to the descending aorta. This muscular flow-through pumping chamber containing a stabilizing inner layer (called a biomechanical heart [BMH]) was formed and immediately made to work against a systemic load with the support of clenbuterol (5ϫ150 g/wk). During surgery, the mean stroke volume of BMHs was 53.8Ϯ22.4 mL. One month after surgery, in peripheral arterial pressure, the mean diastolic (P MD ) and minimal diastolic (P min ) pressures of BMH-supported heart cycles differed significantly from unsupported ones (P MD ϭϩ2.9Ϯ1.1 mm Hg [PϽ0.04], P min ϭϪ2.4Ϯ0.9 mm Hg [PϽ0.04]). After BMH-supported heart contractions, the subsequent maximal rate of pressure generation, dP/dt max , increased by 20.5Ϯ8.1% (PϽ0.02). One BMH, catheterized 132 days after surgery, shifted a volume of 34.