Identifying Physiologically Significant Pumping State Transitions in Implantable Rotary Blood Pumps Used as Left Ventricular Assist Devices: An In-Vivo Study
NEW SOUTH WALES UNIV SYDNEY (AUSTRALIA) SCHOOL OF BIOMEDICAL ENGINEERING
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The VentrAssist implantable rotary blood pump IRBP is a centrifugal pump that uses a hydrodynamic bearing to support its impeller. The pump is to be used as a left ventricular assist device LVAD. Varying pump speed can control the degree of left ventricular assistance. By increasing impeller speed, it is possible to transition from the normal physiological state of ventricular ejection VE to a state where the aortic valve remains closed AC throughout the cardiac cycle. Using the non-invasive parameter of instantaneous impeller speed in an ovine experimental model N3, we investigated state transitions. The cardiovascular system of the animal was perturbed by pharmacological intervention or by exsanguination. A total of six pump speed set point changes that caused physiological state transitions VE to AC were examined. A state transition index STI derived originally from data obtained in an in-vitro mock loop setup was found to be directly applicable in the in-vivo studies and showed statistically significant pO.0005 reliability in differentiating between no change in state and change in state. These data indicate that the STI may be a valuable mechanism to in optimal LVAD control.
- Anatomy and Physiology
- Medicine and Medical Research