Device performance and durability of the C-TAH were tested in mock circulations and on durability bench tests. In vitro studies exposing the blood-contacting materials of the device to circulating fresh human blood verified the hemocompatibility of these materials [7]. Subsequent animal studies in a calf model were used to validate hemocompatibility and device performance in a physiological environment up to 10 days of support [8].

Standard two-dimensional thoracic computer tomography (CT) scans of potential candidates for C-TAH placement are analyzed preoperatively to ensure that the device fits in the thoracic cavity. From the 2D scans, a three-dimensional (3D) model of the thorax and its structures is created. The native heart is then replaced with a 3D model of the C-TAH. The inflow areas of the 3D model are placed at the right and left atrioventricular junctions and the outflow areas at the pulmonary artery and aorta. Based on these placements and the resulting position of the 3D model relative to the chest wall and diaphragm, the implanting surgeon determines whether the device fits (◘ Fig. 55.3).

The bioprosthetic surfaces of the device, the atrial suture flanges, and the biological valves are preserved in glutaraldehyde. During the initial phase of the surgical procedure, these surfaces are carefully rinsed with heparin-containing saline according to a validated procedure.

The CARMAT TAH is implanted in orthotopic position. The pericardial space is accessed through a median sternotomy and a midline vertical incision of the pericardial sac. Cardiopulmonary bypass (CPB) is established with direct bicaval cannulation and an outflow cannula in the ascending aorta. After cross clamping, the native ventricles are excised up to the left and right atrioventricular junctions. The aorta and the pulmonary artery are transected just distally from the valve commissures. The diameter of the atrioventricular orifices is measured with sizing tools (30-35-40-45 mm). Bioprosthetic flanges with a circular central opening reinforced by a silicon ring are cut to size and sutured onto the mitral and tricuspid orifices. The silicone ring of each flange is connected to a single titanium interface device with two central openings. The C-TAH, with the inflow valves in place, is then clicked onto the interface device with the silicone rings ensuring hermetic sealing. Next, the aortic conduit (Dacron, 30 mm diameter) containing the outflow valve is sutured to the distal aorta. Finally, the pulmonary conduit (Dacron, 30 mm diameter) with outflow valve is sutured to the distal pulmonary artery. Both arterial suture lines are left open to facilitate deairing.

The percutaneous driveline leaves the C-TAH just ventral of the interface device and is tunneled to exit the skin at the lower right abdominal quadrant. The driveline is then connected via the ERM and an external cable to the controller and hospital care console. The C-TAH can now be switched on for deairing of the device’s ventricles.

Deairing cannulas are inserted through the suture lines of the aortic and pulmonary conduits and connected to open syringes, in which CPB suction lines can be placed. After unsnaring the caval cannulae, the C-TAH is switched on with beat rate 10/min and stroke volume 30 ml to eject the remaining air through the deairing cannulas, with local CO₂ insufflation. The pump rate can be manually increased but high pressure on the suture lines should be avoided. When deairing is completed (eventually confirmed by echo), the aorta clamp is removed. Weaning of CPB is done with decreasing CPB flow while increasing the prosthesis output. Guided by the left atrial and central venous pressure, the clinician can set the pump rate, the left ventricular stroke volume, and the ratio between the right and left ventricular stroke volume. When the C-TAH has obtained full flow, CPB is stopped and protamine injected. Meticulous hemostasis is performed; the pericardium and sternum are closed, leaving drains in place.