Key result
A compliant mock aorta demonstrated healthier physiologic pressure waveforms, steadier downstream flow, and reduced energetic demands on the pump compared to a rigid aorta in an ex-vivo flow loop.
Why the study?
Demand for heart transplants exceeds supply, and ex-vivo heart perfusion systems require investigation into flow loop fluid mechanics and the effect of mock aortic tubing compliance on pump performance.
Does a compliant mock aorta reduce energetic demands on the pump compared to a rigid aorta in an ex-vivo flow loop?
Does a compliant mock aorta reduce energetic demands on the pump compared to a rigid aorta in an ex-vivo flow loop?
Using a compliant mock aorta in an ex-vivo heart perfusion system produces more physiologic flow and reduces energetic demands on the pump, supporting its integration into EVHP systems for donor heart evaluation.
Should not yet change EVHP practice; leaves open clinical translation of compliant-aorta benefits.
Demand for heart transplants far exceeds supply of donated organs. This is attributed to the high percentage of donor hearts that are discarded and to the narrow six-hour time window currently available for transplantation. Ex-vivo heart perfusion (EVHP) provides the opportunity for resuscitation of damaged organs and extended transplantation time window by enabling functional assessment of the hearts in a near-physiologic state. Present work investigates the fluid mechanics of the ex-vivo flow loop and corresponding impact on cardiac performance. A mechanical flow loop is developed that is analogous to the region of the EVHP system that mimics in-vivo systemic circulation, including the body's largest and most compliant artery, the aorta. This investigation is focused on determining the effect of mock aortic tubing compliance on pump performance. A custom-made silicone mock aorta was developed to simulate a range of in-vivo conditions and a physiological flow was generated using a commercial ventricular assist device (VAD). Monitored parameters, including pressure, tube distension and downstream velocity, acquired using time-resolved particle imaging velocimetry (PIV), were applied to an unsteady Bernoulli analysis of the flow in a novel way to evaluate pump performance as a proxy for cardiac workload. When compared to the rigid case, the compliant mock aorta case demonstrated healthier physiologic pressure waveforms, steadier downstream flow and reduced energetic demands on the pump. These results provide experimental verification of Windkessel theory and support the need for a compliant mock aorta in the EVHP system.
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Cameron et al. (2020) studied Heart transplantation / Ex-vivo heart perfusion. Compliant mock aorta vs. Rigid mock aorta was evaluated on Pump performance (proxy for cardiac workload). A compliant mock aorta demonstrated healthier physiologic pressure waveforms, steadier downstream flow, and reduced energetic demands on the pump compared to a rigid aorta in an ex-vivo flow loop.
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