Left ventricular bypass: a new nonthrombogenic device with homograft aortic valves

Blood coagulation studies during six day heparinless venoarterial bypass in sheep

Heparinless venoarterial bypass (HL-VAB) was carried out in 16 sheep for 6 days, by means of a closed circuit tubing coated with nonthrombogenic polyurethane-polyvinyl-graphite (PPG) and a roller pump. Nine experiments were completed uneventfully. Seven sheep died during bypass. The causes of death were pneumonia (2), caseous granulomatous lung abscess (3) or abdominal abscess (1), and thromboembolism (1). The last complication was caused by inadverten trauma to the PPG coating at the time of tubing connection. In the animals in which HL-VAB was uneventful, no significant changes were noted in the hematologic studies including white blood counts, platelet counts, hematocrit, plasma fibrinogen levels, prothrombin time, thrombin time, activated partial thromboplastin time, Factors V and VIII, and free plasma hemoglobin levels. Inconsistant changes in the above parmeters were noted in the animals which died of complications. In conclusion, prolonged HL-VAB has no adverse effects on blood coagulation mechanism.

Heparinless left heart bypass for resection of thoracic aortic aneurysms

Our clinical experience employing heparinless left heart bypass for the resection of twenty-three thoracic aneurysms is presented. In our current technic of heparinless left heart bypass, plastic tubing coated with nonthrombogenic polyurethane-polyvinyl-graphite material and a conventional roller pump are employed. The reduced size of the aneurysm below the aortic clamp during bypass facilitates careful dissection of the aneurysm and the aorta. Twenty-two of twenty-three patients underwent successful thoracic aneurysmectomy with this technic. None had subsequent paraplegia and the postoperative blood loss was minimal. Heparinless left heart bypass is a simple and safe procedure to facilitate thoracic aneurysm resection.