Development of a pneumatic VAD drive unit aiming at compact wearable type

Abstract

The purpose of this work is to develop an ultra-compact wearable pneumatic drive unit for ventricularassist device. The drive unit weighing 1.8kg consists of a brushless DC motor, a crankshaft, a cylinder-piston, noncircular gears and air pressure regulation valves. The reciprocating motion of the cylinder-piston generates the air pressure which drives the blood pump. The noncircular gears generate systolic ratio and the air pressure regulation valves regulate the maximum and minimum air pressure in the cylinder-piston. The drive unit was tested in an overflow type circulation mock test and a chronic animal test using a Toyobo blood pump of 70mL of stroke volume. The mock test showed that the maximum fl ow rate was more than7L/minat100bpm. The Holstein calf weighing 62kg with the drive unit on his back survived for 30 days in good general condition. The pumping rate and the systolic ratio were set at 80bpm and 53%. The average bypass flow and the average electric power consumption were maintained at 3.9+/-0.9L/min and 12+/-1W. These results indicate that developed drive unit has a potential to become a mechanical circulatory support system of the human heart.