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The Realization of a Pulsatile Implantable Impeller Pump with Low Hemolysis
Author(s) -
Qian K. X.,
Fei Q.,
Lin K. D.,
Pi K. D.,
Wang Y. P.
Publication year - 1989
Publication title -
artificial organs
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.684
H-Index - 76
eISSN - 1525-1594
pISSN - 0160-564X
DOI - 10.1111/j.1525-1594.1989.tb02853.x
Subject(s) - impeller , pulsatile flow , hemolysis , materials science , turbulence , biomedical engineering , specific speed , mechanics , physics , centrifugal pump , engineering , cardiology , medicine
A pulsatile implantable impeller pump with low hemolysis was developed without markedly increasing the complexity of the system compared with the nonpulsatile pump. The key to the question is to design a three‐dimensional impeller with twisted vanes, compacted by an axial helical spiral and a radial logarithmic spiral so as to reduce the turbulent shear in the pump as the impeller changes its rotations per minute periodically to generate a physiologic pulsatile flow. Both mathematic computation of velocity distribution in the impeller and geometric illustration of the velocity triangle at the top of the vane have demonstrated that the peripheral velocity variation of blood cells in a twisted impeller will be less than that in an untwisted impeller. Thus, the main mechanical factor of hemolysis in the impeller pump, namely, the turbulent shear, should be reduced because it is proportional to the product of velocity variations measured in two perpendicular directions. In the in vitro experiments, the pump delivered 4 L/min mean flow at 100 mm Hg mean pressure (pulsed between 80‐120 mm Hg) for more than 3 h in a circulatory model containing 700 ml of fresh citrated porcine blood. Every half hour, the free hemoglobin level in the plasma was tested, and the resulting index of hemolysis was about 0.020, slightly more than that of a nonpulsatile impeller pump developed in Shanghai. To compare hemolyses, the index of hemolysis of this pump is about !4 of that of the self‐made diaphragm pump and Va of that of the Polystan Pulsatile Pump. In the in vivo evaluations with dogs and goats, the pump was used as a left ventricular assistance device. The bypass ratio in all cases was adjusted to 40‐50% of the total flow. Approximately 30‐mm Hg reduction of left ventricular pressure and a 10% decrease of pressure rising rate were observed by asynchronous perfusion. The blood count and hematocrit reading of experimental animals decreased unremarkably during the survival time for up to 21 h, and the free hemoglobin level in the plasma remained under 50 mg/dl. The output of the pump was controlled by adjusting the mean voltage, and the pulsatile frequency has no effect on mean flow. The pump weighs 250 g (including a 190‐g motor).