COMPARISON OF PULSED AND CONTINUOUS DOPPLER IN THE FLOW MEASUREMENT OF LEFT HEART ASSIST DEVICE (LHAD)

Abstract

Mechanical ventricular assistance is a valuable adjunct in the treatment of post cardiotomy left ventricular power failure and cardiogenic shock following myocardial infarction.
Our institute has been engaged in the design, development and in-vivo evaluations of pneumatically-actuated Left Heart Assist Device (LHAD).
A continuous monitoring system of pump flow changes is absolutely necessary to have the adequate drive and control of LHAD.
Experiments were designed to evaluate flow measurements using ultrasonic pulsed Doppler (PD) and continuous wave form Doppler (CWD) methods during LHAD pumping in the mock circulation.
Pneumatic source controls were changed from 200mmHg to 50mmHg to measure several flow changes by the PD and CWD methods.
The correlation between actually measured flow and PD (r=0.96) and CWD (r=0.99) were evident.
This results showed that both PD and CWD were stable and reliable method to determine the LHAD flow as the continuous monitoring system.
In the comparison of PD and CWD, CWD system is a very simple, not expensive and easy to fabricate the flow probe around the inflow or outflow tube of LHAD.
These results indicate that the continuous wave form Doppler method is useful as a non-invasive method for monitoring the LHAD flow.