An original inflow cannula for paracorporeal assist devices

Cannulae for paracorporeal ventricular assist devices have been clinically shown to be limiting factors in optimal circulatory support. A new inflow cannula has been manufactured according to an original silicone rubber molding process, permitting a hemocompatible inner surface. The cannula is 200 mm in length, with a 10 mm internal diameter. The wall is 3 mm thick and reinforced by a stainless steel spiral spring embedded in the silicone. An external ring permits adequate interface between the cannula and the endocardial surface of the atrium. A compliant external segment on the inflow cannula, free of any spiral spring, allows adjustment of vacuum to optimal values, thus avoiding inflow obstruction. The cannula has been tested during 1 to 5 days of left ventricular bypass in calves (n = 15). A Symbion AVAD, Utah 85 VAD, or Centrimed pumps were used. Adequate heparinization was maintained throughout. Paracorporeal flow was 0.045 L min-1 kg-1. In vivo evaluation was made by hemodynamic studies and the incidence of thromboembolism. The cardiac cavities, cannulae, and peripheral vessels were carefully searched for thrombi and emboli at autopsy. The atrium, the interface between atrium and silicone cannula, and the cannula itself were found free of any deposit. This aspect differed from that observed previously with available PU or PVC cannulae.