Hemodynamics on abrupt stoppage of centrifugal pumps during left ventricular assist

A magnetically suspended centrifugal pump (MSCP), developed for long-term v entricular assist, is reliable and durable because it has no shaft or seal. However, with nonvalve pumps such as a MSCP, regurgitation occurs when the y accidentally stop without cannula clamping. We investigated the hemodynam ics during temporary stoppage of a MSCP being used as a left ventricular as sist system (LVAS), comparing two inflow cannulation sites. In four sheep ( weight, 35-45 kg), microspheres were injected into the left main coronary a rtery to induce heart failure, An outflow cannula was sutured onto the desc ending aorta, and two inflow cannulae were inserted into the left atrium an d the left ventricle. The MSCP was stopped with both the left ventricular c annula and left atrial cannula damped, and the hemodynamics and P-V loops w ere recorded. Each cannula was then unclamped in order, and similar paramet ers were recorded. LVEDP increased at unclamping of the left ventricular ca nnula (ULVC), and rose further at unclamping of the left atrial cannula (UL AC). Aortic pressure did not change at ULVC, but decreased at ULAC. The eff ective systemic flow that subtracted the regurgitant flow through the MSCP from left ventricular output was half at ULVC and almost 0 at ULAC. When st opping centrifugal pumps without circuit clamping, hemodynamic deterioratio n is less at ULVC than at ULAC. This finding suggests that left ventricular inflow cannulation is recommended to allow more time in emergency situatio ns.