MECHANICAL-PROPERTIES OF AORTAS AND PULMONARY-ARTERIES OF CALVES IMPLANTED WITH CARDIAC PROSTHESES

Left ventricular assist devices (LVAD) were implanted in calves 3-months old between the natural left ventricular apices and middle descending aortas, while total artificial hearts (TAH) were implanted to replace the natural heart ventricles. The stiffness and strength of upper and lower descending aortas obtained from the calves implanted with the LVADs for 1-2 months were signficantly lower than those of nonpumped control calves, accompanied by local detachment and damage of endothelial surfaces, while the mechanical properties of the aortas from TAH-implanted calves were very similar to those of the control calves. However, the decreased stiffness and strength of the aortas in the LVAD-implanted calves were recovered to the control levels by pumping for another 1 month or by the pump removal. These characteristic changes in aortic mechanics and structures by LVAD pumping for an intermediary duration are ascribed to the distortion of blood flow produced around the anastomosis of the pump outflow conduit to the descending aorta.