RV adaptation to increased afterload in congenital heart disease and pulmonary hypertension

BackgroundThe various conditions causing a chronic increase of RV pressure greatly differ in the occurrence of RV failure, and in clinical outcome. To get a better understanding of the differences in outcome, RV remodeling, longitudinal function, and transverse function are compared between patients with pulmonary stenosis (PS), those with a systemic RV and those with pulmonary hypertension (PH).Materials and methodsThis cross-sectional study prospectively enrolled subjects for cardiac magnetic resonance imaging (CMR), functional echocardiography and cardiopulmonary exercise testing. The study included: controls (n = 37), patients with PS (n = 15), systemic RV (n = 19) and PH (n = 20). Statistical analysis was performed using Analysis of Variance (ANOVA) with posthoc Bonferroni.ResultsPS patients had smaller RV volumes with higher RV ejection fraction (61.1±9.6%; p2 peak/kg% (pConclusionsRV remodeling and function differed depending on the etiology of RV pressure overload. In contrast to the RV of patients with PS or a systemic RV, in whom sufficient stroke volumes are maintained, the RV of patients with PH seems unable to compensate for its increase in afterload completely. Key mediators of RV dysfunction observed in PH patients, were: prolonged RV free wall shortening, resulting in post-systolic shortening and intra-ventricular dyssynchrony, and decreased transverse function.

研究背景：多种导致右心室（Right Ventricle, RV）压力慢性升高的病因，在右心室衰竭的发生风险及临床结局上存在显著差异。为更深入明确此类结局差异的机制，本研究对比分析了肺动脉瓣狭窄（Pulmonary Stenosis, PS）患者、系统性右心室患者及肺动脉高压（Pulmonary Hypertension, PH）患者的右心室重构、纵向功能与横向功能。

材料与方法：本项横断面研究前瞻性招募受试者，接受心脏磁共振成像（Cardiac Magnetic Resonance Imaging, CMR）、功能超声心动图及心肺运动试验。研究纳入的受试者包括：对照组（n=37）、PS患者（n=15）、系统性右心室患者（n=19）及PH患者（n=20）。统计分析采用方差分析（Analysis of Variance, ANOVA）结合事后Bonferroni检验。

结果：PS患者的右心室容积更小，右心室射血分数更高（61.1±9.6%；与系统性右心室患者、PH患者相比均p<0.001）。对照组受试者的峰值摄氧量为28.7±6.3 mL O₂/min/kg，PS患者为22.1±4.8 mL O₂/min/kg，系统性右心室患者为18.3±3.2 mL O₂/min/kg，PH患者为12.9±2.6 mL O₂/min/kg（所有组间比较均p<0.001）。峰值做功量在对照组为178±32 W，PS患者为142±25 W，系统性右心室患者为119±18 W，PH患者为92±15 W（p<0.001）。与PS患者及系统性右心室患者相比，PH患者的心室-动脉耦联受损。PS患者与系统性右心室患者的纵向功能得以保留，而PH患者的纵向功能显著降低；与对照组、PS患者及系统性右心室患者相比，PH患者的横向功能显著下降。右心室游离壁纵向应变在对照组为-21.3±3.2%，PS患者为-20.8±2.9%，系统性右心室患者为-19.7±3.1%，PH患者为-14.2±2.7%（p<0.001）。85%的PH患者可观察到收缩后缩短，而PS患者为0%，系统性右心室患者为5%，对照组为7%。室内不同步在PH患者中的发生率显著高于其他三组。

结论：右心室重构与功能异常取决于右心室压力超负荷的病因。与能够维持足够每搏输出量的PS患者及系统性右心室患者的右心室不同，PH患者的右心室似乎无法完全代偿其后负荷的增加。PH患者中观察到的右心室功能障碍的关键介导因素包括：延长的右心室游离壁缩短，进而导致收缩后缩短与室内不同步，以及横向功能下降。