Programmed Speed Reduction Enables Aortic Valve Opening and Increased Pulsatility in the LVAD-Assisted Heart

Area of Science:

• Cardiovascular Engineering
• Medical Device Technology
• Hemodynamics

Background:

• Aortic valve opening (AVO) is crucial during left ventricular assist device (LVAD) support to prevent valve dysfunction.
• Continuous LVAD support can lead to valve fusion, incompetence, and thrombosis.
• The programmed low speed algorithm (PLSA) offers intermittent AVO by temporarily reducing LVAD speed.

Purpose of the Study:

• To evaluate the efficacy of the PLSA in achieving AVO during LVAD support.
• To assess the hemodynamic effects of PLSA-induced AVO in a mock circulatory loop.
• To determine the impact of PLSA on aortic valve function and blood flow patterns.

Main Methods:

• Utilized a HeartMate II LVAD with a PLSA controller in a mock circulatory loop.
• Measured left ventricle and aortic pressures, LVAD speed, and total aortic flow.
• Tested PLSA under varying cardiac function settings (low and medium) and LVAD speeds.

Main Results:

• PLSA at 10 krpm dropping to 7 krpm for 6s dwell time achieved AVO in all tested cardiac functions with minimal cardiac output changes.
• AVO frequency was not dependent on opening area or systolic duration, which decreased with increased LVAD support.
• Aortic pulsatility index significantly increased in the aortic root and distal aorta during PLSA, indicating improved blood mixing and AVO.

Conclusions:

• PLSA effectively facilitates AVO during LVAD support across different hemodynamic conditions.
• PLSA enhances aortic blood mixing and pulsatility, potentially mitigating risks associated with continuous LVAD support.
• The PLSA controller demonstrates a viable strategy for improving hemodynamics and valve function in LVAD patients.