The duration of use of the present generation of disposable centrifugal blood pumps has been limited to 1 to 2 days due to the propensity for thrombus formation around the central bearing and/or shaft seals need to maintain rotor stability. For many patients undergoing short term post-cardiotomy support, duration of support up to two weeks is desirable for heart recovery. To eliminate the bearing problem, we have demonstrated in Phase I the operation of a non-contact, passively operated bearing using permanent magnet configurations for maintaining angular and radial stability of the rotor and hydrostatic pressure distribution over the surfaces of the rotor for axial stability. The pump configuration is compatible with the use of currently available external rotor drive units. Such a device is amenable to cardiac support without the use of anticoagulation. In the Phase H program, a comprehensive design optimization of the non-contact bearing, flow around the bearing, and pump configuration will be tested. Following this effort, non- contact bearing centrifugal pumps will be fabricated and tested in vitro for device performance, and tested in vivo to demonstrate minimal hemolysis and its anti-thrombogenic characteristics.
The potential application of the device is in approximately 300,000 cardiac surgery cases per year in the US which require cardiopulmonary bypass. The proposed device 'will be particularly appropriate for use in those patients requiring circulatory support extending beyond a few hours, into the range of a few weeks. These cases number approximately 10,000 to 20,000 annually in the US.
