Performance Comparison between Two Types of Miniature Axial Flow Pumps for Children

Miniature axial flow pump (M-AFP) is a ventricular assist device that supports the failing ventricle in advanced stage heart failure. In the past several years, we have developed two types of M-AFP aiming for children. In this paper, mechanical performance of them are tested and analyzed in order to help us find out their differences in nature. A simulative circulative apparatus is designed that can be used to quantitatively predict the mechanical characteristic parameters of the pumps and their relationship. Under the condition of load pressure invariance, we mainly test the change of blood flow with these two pumps respectively. The type A has a volume of 47ml; with external diameter of 26mm and length of 72mm. The simulative cardiac flow attains 3-4L/min under the pressure of 100mmHg, which is enough to assist the left ventricular of children. In all the two pumps, rotate speed of impeller and flow rate of blood present positive mutuality with pressure invariance. Besides, comparing with type A, the type B has smaller volume, and it is much easier for type B to increase rotate speed of the pump and comparably reduce energy consumption. Apart from the characters of smaller volume and simpler configuration, the output of miniature axial blood pump has achieved required pressure and blood flow. We still have the possibility to improve the blood pump by reducing energy consumption and increasing efficiency. The performance test and comparison in simulative circulation apparatus that is out of body is very important for improvement of blood pump. It can accelerate the development of mechanical assistant therapy and increase the cure rate of heart failure for children.