Animal studies with the Carmat bioprosthetic total artificial heart

The Carmat bioprosthetic total artificial heart (TAH) contains bioprosthetic blood-contacting surfaces, and is designed for orthotopic cardiac replacement. In preparation for clinical studies, we evaluated the TAH performance and its effects on end-organ function in an animal model.

Twelve female Charolais calves, 2-3 months of age and weighing 102-122 kg, were implanted with the TAH through a mid-sternotomy to ensure an adequate anatomic fit. The intended support duration was 4-10 days. Haematological values, creatinine, bilirubin and lactate levels were measured and mean arterial and central venous pressure, central venous oxygen saturation and TAH parameters were monitored.

The calves were placed in a cage immediately postoperatively, and extubated on postoperative day 1 in most cases. Average support duration was 3 days, with 4 of 12 calves supported for 4, 4, 8 and 10 days. The initial procedures were used to refine surgical techniques and postoperative care. Pump output ranged from 7.3 to 10 l/min. Haemodynamic parameters and blood analysis were within acceptable ranges. No device failures occurred. No anticoagulation was used in the postoperative phase. The calves were euthanized in case of discomfort compromising the animal well-being, such as respiratory dysfunction, severe blood loss and cerebral dysfunction. Device explant analysis showed no thrombus formation inside the blood cavities. Histological examination of kidneys showed isolated micro-infarction in 2/12 animals; brain histology revealed no thromboembolic depositions.

The Carmat bioprosthetic TAH implanted in calves up to 10 days provided adequate blood flow to organs and tissues. Low levels of haemolysis and no visible evidence of thromboembolic depositions in major organs and device cavities, without the use of anticoagulation, may indicate early-phase haemocompatibility of the TAH.