Key result
Orienting LVAD inflow cannula toward the mitral valve minimizes blood stasis, potentially reducing thrombosis risk.
Why the study?
LVADs are associated with thromboembolic events potentially related to intraventricular flow changes around the inflow cannula, but the effect of cannula positioning on thrombosis risk is unclear.
Does LVAD inflow cannula orientation toward the mitral valve reduce regions of low flow and low shear compared to other orientations in a patient-specific LV model?
Does LVAD inflow cannula orientation toward the mitral valve reduce regions of low flow and low shear compared to other orientations in a patient-specific LV model?
Computational modeling suggests that orienting the LVAD inflow cannula toward the mitral valve minimizes low flow and low shear regions, potentially reducing thrombosis risk.
May minimize stasis with mitral orientation in models; hypothesis-generating and requires prospective human validation before practice change.
Left ventricular assist devices (LVADs) have been increasingly used as a therapy for patients with end-stage heart failure. However, a growing number of clinical observations have shown that LVADs are associated with thromboembolic events, which are potentially related to the changes in intraventricular flow. Particularly, the flow fields around the inflow cannula (IC) of the LVAD. In this study, a fluid structure interaction (FSI) simulation was conducted to evaluate the hemodynamics of a patient specific left ventricle (LV) with varying LVAD IC orientations. The LV model was obtained from computed tomography scans and modeled to have contraction and relaxation during cardiac cycles following available experimental data of LV volume changes. The LV of the patient was assumed to have an end systolic volume of 223.7 mL and a stroke volume of 46.4 mL. Four different IC positions were considered: towards the (1) septum; (2) aortic valve (AV); (3) mitral valve (MV) and (4) inferior wall (IW). The potential thrombus growth around the IC was assumed to be caused by blood stagnation regions with low velocity (<5 mm/s) and low shear rate (<60/s) flow. Mean velocity magnitudes and low blood velocity regions around the IC were numerically obtained. To quantitatively compare the thrombosis risks of the four simulation cases, the time-averaged volumes of the low-velocity regions and the low shear rate regions were calculated. The intraventricular volumes of low velocity zones based on IC orientation are 1.42 mL toward the septum, 1.14 mL toward the AV, 0.93 mL toward the MV, and 1.24 mL toward the IW. The intraventricular volumes of low shear regions based on IC orientation are 11.54 mL toward the septum, 11.15 mL toward the AV, 9.24 mL toward the MV, and 10.7 mL toward the IW. IC orientation toward the MV results in lower volumetric regions of low flow and low shear within the ventricle, which consequently may lead to a reduced risk of thrombus formation.
No takes yet. Share an insight, caveat, or question.
He et al. (2021) studied End-stage heart failure (n=1). LVAD inflow cannula orientation vs. Alternative orientations (septum, aortic valve, inferior wall) was evaluated on Intraventricular volumes of low velocity zones and low shear regions. Orienting the LVAD inflow cannula toward the mitral valve resulted in the lowest intraventricular volumes of low velocity (0.93 mL) and low shear (9.24 mL) regions, potentially reducing thrombosis risk.
Synapse has enriched 3 closely related papers on similar clinical questions. Consider them for comparative context: