BLOOD COAGULATION TIME CONTROL, DURING IN VIVO TESTS WITH THE AUXILIARY TOTAL ARTIFICIAL HEART (ATAH) IMPLANTED IN CALVES AS LEFT VENTRICLE ASSIST DEVICE

Abstract

Many research groups are studding new designs for Ventricle Assist devices (VAD) and Total Artificial Hearts (TAH). Common problems encountered by those groups are the device dimension, thrombus formation and the TAH control system. A miniaturized artificial heart is being tested in our laboratories, the Auxiliary Total Artificial Heart (ATAH). The ATAH is an electromechanically driven artificial heart with reduced dimensions (outer diameter is 85 mm and the thickness is 65 mm). Eighteen In Vivo tests were performed in calves with 80 ± 5 Kg of weight. The device was implanted as Left Ventricle Assist Device (LVAD) in their abdominal cavities in series with their native hearts to verify the device performance and operating functions. The implantations were performed connecting a flexible polymeric graft from the left ventricle apex to the artificial ventricle inlet port. From the LVAD outlet port, the blood was pumped to the descending aorta through another polymeric graft. During all the tests, heparin was administrated and the blood Activated Coagulation Time (ACT) was maintained in 400 ± 100 s by adjusting the heparin infusion flow. Important data were obtained with those tests. A strong relationship between the polymeric area and the heparin dosage was observed. The polymeric materials initiate the blood coagulation process that must be reversed by the anticoagulant (heparin). A relationship between the blood flow through the LVAD and the heparin infusion flow was observed.