Evaluation of a minimally invasive cardiac function estimator for patients with rotary VAD support

Ventricular pressure-volume relationship or Emax is a reliable index to assess the healthy status of the ventricle. Determining this index usually involves invasive pressure and flow measurements or expensive echo cardiographs. If an indirect index of Emax can be identified from the measurements of a ventricular assist device (VAD) without any indwelling sensor, this would facilitate an effective way to monitor the healthy condition of the patient's heart while the patients are under VAD support. This index can also be used to determine the control strategy of VAD operation and gradually wean the patient from the mechanical circulatory support. In this paper, an amplitude detector was used to determine the amplitude of pump flow through a rotary VAD using data from a computer simulation and from in-vivo experiments. This amplitude depicts a strong correlation with Emax, and thus, can be used as an indirect index to monitor a VAD patient's cardiac function.