Use of aortic valvo-pumps placed in valve annulus for long-term left ventricular assist.

To provide better anatomical fit and physiologic adaptation, three aortic valvo-pumps with different dimensions were developed. Each pump has a rotor with an impeller and drive magnets and a stator consisting of a motor coil with iron core and an outflow guide vane. The devices had outer diameters of 21 mm, 23 mm, and 25 mm, respectively, and weighted 27 g, 31 g, and 40 g, respectively. Laboratory testing demonstrated that the rotating speed for maintaining a diastolic pressure of 80 mm Hg at zero flow rate should be 17500 rpm, 15000 rpm, and 12500 rpm, respectively; the largest flow at these same speeds will be 5 l/min, 7 l/min, and 10 l/min, respectively, with approximately 50 mm Hg pressure head increase. Therefore, these three pumps may meet the hemodynamic requirements of patients with body weights of 40-60 kg, 60-80 kg, and 80-100 kg. The first in vivo trial exhibited that the 25 mm valvo-pump can be sewn onto the aortic valve annulus of a 80 kg body weight pig without harm to adjacent organ functions. The devices occupy no additional anatomic space and deliver the blood directly from ventricle to the aorta, thus producing less physiologic disturbance to the natural circulation. Neither connecting conduits nor bypass circuits are necessary, thus eliminating the most dangerous sites of thrombosis in traditional left ventricular assist devices.