ASSIST HEART

-DRIVING MECHANISM AND ITS CONTROL

Abstract

In this report, pulsatile air driven systems will be written. Because most of blood pumps for clinical use are air driven type and their driving mechanisms are usually composed of electromagnetic air valves and air pressure regulators. Positive/negative air pulses are generated from compressed air and vacuum air. The driving machine for clinical usage has three main points of arguments as follows.
1) DRIVING SYSTEM; As temporal usage of assist heart is today's clinical consensus, air driven system is the best choice from its controllability and its stability. In order to respond to the dynamic change of circulatory system, ECG synchronization and measurement of pump output are essential factors for controlling the driving system. Various kinds of driving mechanism and also various kinds of measurement method of pump output are developed today.
2)LOAD OF PUMP OUT; AT the temporal usage of assist device, the cannulation site and orifice and length of cannulae are decided most of the performance of the assist heart. The conventional cannulae for cardio-pulmonary bypass have very high internal hydraulic impeadances and if the cannulae orifice are less than 6mm at 41/min pump output, the driving positive pressure exceeds 300mmHg. Then, the hydraulic bench top test of the system must be essential before clinical application.
3)PERIPHERAL ARTERIAL RESISTANCE; AT clinical usage, the patient is usually inject many kinds of peripheral circulatory drugs. The controllability of circulatory system is completely diminished. Then, we must decide the total course of control procedure of driving parameters.