Key result
Full LVAD support significantly reduced maximum blood flow velocities in the left ventricular outflow tract to a median of 0.14 m/s compared to 0.50 m/s in unsupported hearts, revealing potential regions of stagnation.
Why the study?
Investigations of ventricular flow patterns during mechanical circulatory support have been limited to in vitro or in silico models that cannot fully replicate complex cardiac anatomy and contraction.
Does LVAD support alter ventricular flow patterns and velocities in the LVOT in an isolated beating porcine heart model?
Does LVAD support alter ventricular flow patterns and velocities in the LVOT in an isolated beating porcine heart model?
Absolute Event Rate: 0.14% vs 0.5%
p-value: p=0.001
Echo-PIV successfully visualized altered ventricular flow patterns during LVAD support in an ex vivo porcine model, demonstrating diminished LVOT washout and potential stagnation areas with increasing support.
May indicate LVOT stasis risk with full LVAD support; hypothesis-generating for thrombosis in patients and requires in vivo confirmation.
Investigations of ventricular flow patterns during mechanical circulatory support are limited to in vitro flow models or in silico simulations, which cannot fully replicate the complex anatomy and contraction of the heart. Therefore, the feasibility of using echocardiographic particle image velocimetry (Echo-PIV) was evaluated in an isolated working heart setup. Porcine hearts were connected to an isolated, working heart setup and a left ventricular assist device (LVAD) was implanted. During different levels of LVAD support (unsupported, partial support, full support), microbubbles were injected and echocardiographic images were acquired. Iterative PIV algorithms were applied to calculate flow fields. The isolated heart setup allowed different hemodynamic situations. In the unsupported heart, diastolic intra-ventricular blood flow was redirected at the heart's apex towards the left ventricular outflow tract (LVOT). With increasing pump speed, large vortex formation was suppressed, and blood flow from the mitral valve directly entered the pump cannula. The maximum velocities in the LVOT were significantly reduced with increasing support. For the first time, cardiac blood flow patterns during LVAD support were visualized and quantified in an ex vivo model using Echo-PIV. The results reveal potential regions of stagnation in the LVOT and, in future the methods might be also used in clinical routine to evaluate intraventricular flow fields during LVAD support.
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Aigner et al. (2019) studied Mechanical circulatory support (n=4). Left ventricular assist device (LVAD) support vs. Unsupported heart was evaluated on Maximum velocity in the left ventricular outflow tract (LVOT) (p=0.001). Full LVAD support significantly reduced maximum blood flow velocities in the left ventricular outflow tract to a median of 0.14 m/s compared to 0.50 m/s in unsupported hearts, revealing potential regions of stagnation.
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