Non-Invasive Mapping of Intraventricular Flow Patterns in Patients Treated with Left Ventricular Assist Devices

Abstract

Introduction: In patients with advanced heart failure, refractory to medical therapy, treatment with left ventricular assist devices (LVADs) decreases mortality and improves quality of life. However, the success of LVAD therapy is hampered by complications such as thrombosis and right ventricular heart failure. Understanding the interactions between the heart, vascular bed and the LVAD might help improve pump settings and decrease the rate of complications. We recently developed 2D echo color Doppler velocimetry (echo-CDV), a novel echocardiographic modality to map blood flow inside the LV and its changes during the cardiac cycle. Hypothesis: We hypothesize that echo-CDV can be used to non-invasively characterize the effect of LVAD support in LV hemodynamics, in order to help understand the ventricular-vascular-LVAD interplay. Our overarching goal is to use this tool to optimize device and patient management. Methods: We used echo-CDV to image LV flow patterns at baseline LVAD speed and during a ramp test in patients with ongoing LVAD support (Heartmate II, N = 6). We tracked diastolic vortices and mapped LV blood stasis. We compared flow features with data from patients with dilated cardiomyopathy (DCM) not treated with an LVAD. Results: Compared to patients with DCM and no LVAD support (panel A), the flow pattern during LVAD support (panels B-C) had a less prominent diastolic vortex ring, and transited directly from the mitral valve to the cannula forming a straight path. The changes elicited by LVAD support displaced blood stasis regions from the LV apex towards the base along the antero-septal and infero-posterior walls. Quantitative metrics of blood stasis were sensitive to the LVAD speed, with different trends in different patients (compare panels B and C). Conclusions: Using 2D echo-CDV in patients with ongoing LVAD treatment yields detailed information about the effect of this treatment on LV flow patterns and blood stasis. This new methodology could potentially be used in combination with standard echo, hemodynamics and clinical information to find the LVAD setting that optimizes LV flow transport and minimizes stasis for each patient.