Transapical left ventricular bypass with local heparinization for prolonged circulatory support

Extracorporeal left ventricular assistance with prostacyclin and heparinized centrifugal pump

A temporary left ventricular assist system utilizing an improved left atrial catheter and centrifugal pump was developed and tried in 22 anesthetized sheep to test the hypothesis that prostacyclin (PGI2) and ionically bound heparin-coated surfaces could prevent thrombosis in this perfusion system without inhibiting soluble, circulating coagulation factors. Sheep were perfused at 53.6 ml/kg/min (standard error, 1.5) from left atrium to aorta for two hours. The pump maintained flow at left atrial pressures of 3 to 4 mm Hg. As expected, systemic heparin inhibited coagulation, mildly activated platelets, and prevented thrombosis in uncoated perfusion circuits and wounds. Infusion of PGI2 (30 ng/kg)min) without systemic heparin or heparin-bonded extracorporeal surfaces prevented platelet activation and did not alter coagulation measurements; however, bleeding times increased and thrombi formed in every circuit. When heparin was ionically bound to all extracorporeal surfaces, infusion of PGI2 completely prevented thrombosis within the circuit, inhibited platelet activation, and did not alter coagulation measurements. Blood spontaneously clotted in three of six thoracotomy wounds during perfusion. When PGI2 infusion was stopped, heparin-coated surfaces alone failed to prevent thrombosis within the system in 3 of 5 animals. The combination of PGI2 infusion and heparin-coated extracorporeal surfaces prevents thrombosis within the perfusion circuit without inhibiting soluble coagulation factors. This method, using the assist system, overcomes many of the implementation and bleeding problems associated with other temporary left ventricular assist devices.