Ventricular Flow Field Visualization During Mechanical Circulatory Support in the Assisted Isolated Beating Heart

Area of Science:

• Cardiovascular Research
• Biomedical Engineering
• Medical Imaging

Background:

• Investigating ventricular flow during mechanical circulatory support is challenging due to limitations of in vitro and in silico models.
• Accurately replicating the heart's complex anatomy and contraction is crucial for understanding blood flow dynamics.

Purpose of the Study:

• To evaluate the feasibility of echocardiographic particle image velocimetry (Echo-PIV) for visualizing and quantifying cardiac blood flow in an isolated working heart model with a left ventricular assist device (LVAD).
• To analyze how different levels of LVAD support affect intraventricular flow patterns and hemodynamics.

Main Methods:

• An isolated working heart setup was used with porcine hearts and implanted LVADs.
• Microbubbles were injected, and echocardiographic images were acquired during unsupported, partial, and full LVAD support.
• Iterative particle image velocimetry (PIV) algorithms were applied to calculate flow fields.

Main Results:

• Echo-PIV successfully visualized and quantified cardiac blood flow patterns in an ex vivo model.
• In unsupported hearts, diastolic flow was redirected towards the left ventricular outflow tract (LVOT).
• Increasing LVAD support suppressed vortex formation, directed flow into the pump cannula, and reduced velocities in the LVOT, revealing potential stagnation regions.

Conclusions:

• Echo-PIV is a feasible method for evaluating intraventricular flow fields during LVAD support in an ex vivo setting.
• The study provides novel insights into how LVADs alter cardiac hemodynamics.
• This technique holds potential for clinical application in assessing flow patterns during mechanical circulatory support.