Acute functional changes of platelets in left ventricular assist in a dog model.

Left ventricular assist bypass was performed in nine dogs using pneumatically actuated blood pumps fabricated of segmented polyurethane and heparinized hydrophilic polyurethane (H-USD) newly developed so as to render excellent antithrombogenicity. The survival of the dogs ranged from 1 to 82 days. In all cases, significant reductions in platelet count and in platelet aggregability were observed. Simultaneously, severe hemorrhage from the anastomosed descending aorta occurred four to six hours after the pump implantation. This hemorrhage, leading to death, was not related to systemic heparinization, but was closely related to the mechanical impairment of platelets by the pumping operation. Five days after the pump implantation, complete recovery of the platelet aggregability was observed and no further hemorrhage occurred in the dog that survived for 82 days.