Control of the pressure flow relationship with a magnetically suspended centrifugal pump in a chronic animal experiment.
A magnetically suspended centrifugal pump (MSCP) has been developed for long-term ventricular support. Effective torque to blood of the MSCP is exactly proportional to a motor current because of no friction inside the MSCP. The authors have devised new driving modes using these characteristics and applied it to a chronic animal experiment. Three driving modes were compared: 1) a constant rotational speed (N), 2) a constant motor current (I), and 3) a controlled motor current (CI). In two of nine sheep, the MSCPs were operated by the N and in seven by the I mode. The motor current and the rotational speed were always monitored. The CI mode was studied by altering the resistance of the vessels. In the I mode, the rotational speed varied depending upon the pressure head, and the slope of the pressure-flow (P-Q) relationship was steeper than that of the N mode, so that the pump flow was stabilized. In the CI mode, in which the motor current increased to compensate for the decrease in pump flow as the rotational speed increased, the P-Q slope was effectively controlled when the resistance was changed. The MSCP was able to control the P-Q slope without monitor of the pump flow. Various driving modes could be selected according to changes in resistance.
Nishimura
K
K
Department of Cardiovascular Surgery, Faculty of Medicine, Kyoto University, Japan.
Tsukiya
T
T
Akamatsu
T
T
Kono
S
S
Yamada
T
T
Ban
T
T
D000818:Animals; D001698:Biomedical Engineering; D001783:Blood Flow Velocity; D001794:Blood Pressure; D005069:Evaluation Studies as Topic; D006353:Heart-Assist Devices; D008280:Magnetics; D011474:Prosthesis Design; D012756:Sheep; D013997:Time Factors