Data_Sheet_1_Effect of transcatheter edge-to-edge repair device position on diastolic hemodynamic parameters: An echocardiography-based simulation study.PDF

BackgroundTranscatheter edge-to-edge repair (TEER) has developed from innovative technology to an established treatment strategy of mitral regurgitation (MR). The risk of iatrogenic mitral stenosis after TEER is, however, a critical factor in the conflict of interest between maximal reduction of MR and minimal impairment of left ventricular filling. We aim to investigate systematically the impact of device position on the post treatment hemodynamic outcome by involving the patient-specific segmentation of the diseased mitral valve.
Materials and methodsTransesophageal echocardiographic image data of ten patients with severe MR (age: 57 ± 8 years, 20% female) were segmented and virtually treated with TEER at three positions by using a position based dynamics approach. Pre- and post-interventional patient geometries were preprocessed for computational fluid dynamics (CFD) and simulated at peak-diastole with patient-specific blood flow boundary conditions. Simulations were performed with boundary conditions mimicking rest and stress. The simulation results were compared with clinical data acquired for a cohort of 21 symptomatic MR patients (age: 79 ± 6 years, 43% female) treated with TEER.
ResultsVirtual TEER reduces the mitral valve area (MVA) from 7.5 ± 1.6 to 2.6 ± 0.6 cm2. Central device positioning resulted in a 14% smaller MVA than eccentric device positions. Furthermore, residual MVA is better predictable for central than for eccentric device positions (R2 = 0.81 vs. R2 = 0.49). The MVA reduction led to significantly higher maximal diastolic velocities (pre: 0.9 ± 0.2 m/s, post: 2.0 ± 0.5 m/s) and pressure gradients (pre: 1.5 ± 0.6 mmHg, post: 16.3 ± 9 mmHg) in spite of a mean flow rate reduction by 23% due to reduced MR after the treatment. On average, velocities were 12% and pressure gradients were 25% higher with devices in central compared to lateral or medial positions.
ConclusionVirtual TEER treatment combined with CFD is a promising tool for predicting individual morphometric and hemodynamic outcomes. Such a tool can potentially be used to support clinical decision making, procedure planning, and risk estimation to prevent post-procedural iatrogenic mitral stenosis.

背景：经导管缘对缘修复术（Transcatheter edge-to-edge repair, TEER）已从一项创新技术发展为二尖瓣反流（mitral regurgitation, MR）的成熟治疗策略。然而，TEER术后医源性二尖瓣狭窄的风险，是实现最大程度减少二尖瓣反流与最小程度损害左心室充盈这两个治疗目标之间利益冲突的关键影响因素。本研究旨在通过对病变二尖瓣进行患者特异性分割，系统探究装置位置对术后血流动力学结局的影响。
材料与方法：对10例重度二尖瓣反流患者（年龄：57±8岁，女性占比20%）的经食管超声心动图影像数据进行分割，并采用基于位置的动力学方法，在三个不同位置对患者模型进行虚拟TEER治疗。对干预前后的患者解剖结构进行预处理，以用于计算流体动力学（computational fluid dynamics, CFD）仿真，并在舒张峰期采用患者特异性血流边界条件进行模拟。仿真分别在模拟静息状态与应激状态的边界条件下开展。将仿真结果与21例接受TEER治疗的有症状二尖瓣反流患者队列的临床数据进行对比（该队列患者年龄：79±6岁，女性占比43%）。
结果：虚拟TEER治疗可将二尖瓣瓣口面积（mitral valve area, MVA）从7.5±1.6 cm²降至2.6±0.6 cm²。装置中央定位时的MVA较偏心定位时小14%。此外，与偏心定位相比，中央定位时的残余MVA预测性更佳（决定系数R²=0.81 vs. 0.49）。尽管治疗后因二尖瓣反流减轻使平均流量降低了23%，但MVA的减小仍导致舒张期最大流速显著升高（术前：0.9±0.2 m/s，术后：2.0±0.5 m/s），跨瓣压力梯度也显著升高（术前：1.5±0.6 mmHg，术后：16.3±9 mmHg）。平均而言，装置置于中央位置时的流速较外侧或内侧定位时高12%，压力梯度高25%。
结论：虚拟TEER治疗联合计算流体动力学仿真是一种颇具前景的工具，可用于预测个体的形态计量学与血流动力学结局。该工具有望辅助临床决策、手术规划以及风险评估，从而预防术后医源性二尖瓣狭窄。