Left ventricular outflow obstruction predicts increase in systolic pressure gradients and blood residence time after transcatheter mitral valve replacement

Adelaide De Vecchi,Ioannis Ntalas,Vinayak Bapat,David Marlevi,Jonathon Leipsic,Steven A Niederer,David A Nordsletten,Ronak Rajani

doi:10.1038/s41598-018-33836-7

Abstract

Left ventricular outflow tract (LVOT) obstruction is a relatively common consequence of transcatheter mitral valve replacement (TMVR). Although LVOT obstruction is associated with heart failure and adverse remodelling, its effects upon left ventricular hemodynamics remain poorly characterised. This study uses validated computational models to identify the LVOT obstruction degree that causes significant changes in ventricular hemodynamics after TMVR. Seven TMVR patients underwent personalised flow simulations based on pre-procedural imaging data. Different virtual valve configurations were simulated in each case, for a total of 32 simulations, and the resulting obstruction degree was correlated with pressure gradients and flow residence times. These simulations identified a threshold LVOT obstruction degree of 35%, beyond which significant deterioration of systolic function was observed. The mean increase from baseline (pre-TMVR) in the peak systolic pressure gradient rose from 5.7% to 30.1% above this threshold value. The average blood volume staying inside the ventricle for more than two cycles also increased from 4.4% to 57.5% for obstruction degrees above 35%, while the flow entering and leaving the ventricle within one cycle decreased by 13.9%. These results demonstrate the unique ability of modelling to predict the hemodynamic consequences of TMVR and to assist in the clinical decision-making process.

Highlights

With the success of transcatheter aortic valve (AV) implantation for patients at high surgical risk, attention has been cast on transcatheter therapies for the mitral valve (MV)[1]
Our results show that an Left ventricular outflow tract (LVOT) obstruction greater than 35% is associated with deleterious effects on ventricular hemodynamics following transcatheter mitral valve replacement (TMVR), including a significant increase in ventricular afterload and in the blood volume residing inside the ventricle for more than two cycles
By combining imaging and computer modeling we have provided a tool to predict LVOT obstruction post-TMVR and to quantify the impact of varying degrees of obstruction on ventricular afterload and blood residence times, providing a link between anatomical and hemodynamics parameters

Summary

Introduction

With the success of transcatheter aortic valve (AV) implantation for patients at high surgical risk, attention has been cast on transcatheter therapies for the mitral valve (MV)[1]. These techniques vary from balloon and self-expanding AV used in the mitral position, to newer devices specific to the MV, to Valve-in-Valve interventions for failed bioprosthetic devices[2,3,4]. This, in conjunction with the displacement of the anterior MV leaflet towards the AV, introduces a risk of left ventricular outflow tract (LVOT) obstruction as it involves a taller frame protruding inside the left ventricle (LV)[5,6]. In the current study we sought to evaluate the utility of combining this technique with computer models to simulate blood flow dynamics in TMVR patients and to predict the ventricular response to LVOT obstruction

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Results

Discussion

Conclusion