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Left ventricular assist devices (LVADs) have been used for end-stage heart failure patients as a therapeutic option. The aortic valve plays a critical role in heart failure and its treatment with a LVAD. The cardiovascular-LVAD model is often used to investigate the physiological demands required by patients and predict the hemodynamic of the native heart supported with a LVAD. As it is a “ bridge-to-recovery ” treatment, it is important to maintain appropriate and active dynamics of the aortic valve and the cardiac output of the native heart, which requires that the LVAD pump be adjusted so that a proper balance between the blood contributed through the aortic valve and the pump is maintained. In this paper, we investigate how the pump power of the LVAD pump can affect the dynamic behaviors of the aortic valve for different levels of activity and different severities of heart failure. Our objective is to identify a critical value of the pump power (i.e., breakpoint ) to ensure that the LVAD pump does not take over the pumping function in the cardiovascular-pump system and share the ejected blood with the left ventricle to help the heart to recover. In addition, the hemodynamic often involves variability due to patients’ heterogeneity and the stochastic nature of the cardiovascular system. The variability poses significant challenges to understanding dynamic behaviors of the aortic valve and cardiac output. A generalized polynomial chaos (gPC) expansion is used in this work to develop a stochastic cardiovascular-pump model for efficient uncertainty propagation, from which it is possible to rapidly calculate the variance in the aortic valve opening duration and the cardiac output in the presence of variability. The simulation results show that the gPC-based cardiovascular-pump model is a reliable platform that can provide useful information to understand the effect of the LVAD pump on the hemodynamic of the heart.
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This content will become publicly available on February 1, 2026
Aortic stretch and recoil create wave-pumping effect: the second heart in the systemic circulation
Wave propagation in the heart tube is key to establishing an early pumping mechanism, as explained by impedance pump theory in zebrafish. Though initially proposed for embryonic blood circulation, the role of impedance-like behaviour in the mature cardiovascular system remains unclear. This study focuses on the understudied physiological mechanism of longitudinal displacement in the adult aorta caused by the long-axis motion of the heart. Using magnetic resonance imaging on 159 individuals, we compared aortic displacement profiles between a control group and those with heart failure, revealing a significant difference in aortic stretch between the two groups. Building on this clinical evidence, we conductedin vitroexperiments to isolate the effects of longitudinal aortic wave pumping by eliminating the pumping action of the heart. We identified three biomechanical properties of stretch-related longitudinal wave pumping that exhibit characteristics like impedance pump: (i) a nonlinear flow–frequency relationship, (ii) bidirectional flow, and (iii) the potential for both positive and negative flow at a fixed frequency, contingent upon the aorta’s wave speed dictating the wave state. Our results demonstrate for the first time that this mechanism generates a significant flow, potentially providing a supplementary pumping mechanism for the heart.
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- Award ID(s):
- 2145890
- PAR ID:
- 10579302
- Publisher / Repository:
- The Royal Society
- Date Published:
- Journal Name:
- Journal of The Royal Society Interface
- Volume:
- 22
- Issue:
- 223
- ISSN:
- 1742-5662
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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