Nikolas Marquez-Maya (Bioengineering Undergraduate) received the Provost’s Award: Engineering at SRS, which took place from March 2-3, 2018 at the Conrad Prebys Aztec Student Union. Nikolas, along with lab mates Ricardo Montes and Saniya Salim, presented their research conducted through the Cardiovascular Bioengineering Laboratory, directed by Dr. Karen May-Newman. Below is the abstract from their research:
Previous clinical studies have identified cannula malposition as a significant risk for pump thrombosis. Thrombus development is a consequence of altered flow dynamics, which can produce areas of flow stasis or high shear that promote coagulation. The goal of this study was to measure the effect of LVAD inflow cannula angle on the left ventricle (LV) flow field using a mock circulatory loop, and identify flow-based indices that are sensitive measures of cannula malposition for potential clinical use. Experimental studies were performed using a mock loop with a customized silicone model of the dilated left ventricle and the EVAHEART® LVAS. The velocity field of the LV midplane was measured with particle image velocimetry for two levels of LVAD support. A transparent inflow cannula was evaluated in the standard orientation, parallel to the septum, and an angled orientation rotated 15° toward the septum under matched hemodynamic conditions. Vortex structures were analyzed from the vorticity of the measured velocity, and localized stasis calculated in a region of interest within the inflow cannula and combined with a map of normalized pulsatile velocity. The velocity fields revealed increased apical stasis and lower pulsatility with a small angulation of the inflow cannula. A large change in vortex dynamics with the angled cannula was observed, doubling the size of the CCW vortex while reducing the kinetic energy provided by LVAD support. A statistically significant decrease in average and systolic velocities within the LVAD inflow cannula were found with cannula angulation, suggesting an increased resistance that affects primarily systolic flow and thus is exacerbated with increased LVAD support. These results distinguish the flow field changes of cannula angle from those associated with LVAD pump thrombus, which identified a significant reduction in diastolic, not systolic, inflow cannula velocity. These common echocardiographic indices offer the opportunity for immediate clinical application during ramp study assessment. Optimized cannula positioning may be determined pre-operatively using imaging techniques and these analyses to develop patient-specific surgical recommendations such as inflow cannula insertion depth and angle.