Division of Cardiology, The Labatt Family Heart Centre, The Hospital for Sick Children and University of Toronto, Canada.
J Appl Physiol (1985). 2020 Jun 1;128(6):1677-1683. doi: 10.1152/japplphysiol.00775.2019. Epub 2020 May 21.
Right ventricular (RV) function impacts clinical outcomes after surgical repair of Tetralogy of Fallot (rTOF). However, assessment of RV function remains difficult. We investigated the RV myocardial systolic-to-diastolic (S/D) duration ratio derived from strain imaging time intervals to characterize RV myocardial performance, exploring its relation with peak oxygen consumption during exercise (V̇o) and cardiac magnetic resonance-derived RV dilation and function in rTOF. We retrospectively analyzed 76 children with rTOF and 42 normal controls. The RV myocardial S/D duration ratio was measured from RV global and regional 2D speckle tracking longitudinal strain. Time from QRS onset to peak systolic strain was defined as the systolic duration. The S/D duration ratio was calculated and corrected for heart rate (HR). Postsystolic shortening (PSS) duration was defined as shortening time after cessation of pulmonary systolic antegrade flow. The RV myocardial S/D duration ratio, corrected or uncorrected for HR, was significantly higher in rTOF vs. controls (1 ± 0.3 vs. 0.8 ± 0.2, = 0.004) in relation to prolonged PSS. The HR-corrected myocardial S/D duration ratio correlated weakly with RV ejection fraction (EF, = -0.37, = 0.001) and V̇o ( = -0.32, = 0.042). In multiregression analysis, RV EF was independently associated with the myocardial S/D duration ratio. The RV myocardial S/D duration ratio is a parameter of RV myocardial performance and efficiency, incorporating elements of systolic and diastolic performance, mechanical dyssynchrony, and PSS. The S/D duration ratio is associated with exercise capacity and RV dysfunction in rTOF. This is the first study to assess right ventricular myocardial performance using the systolic-to-diastolic duration ratio derived from 2D strain. Seventy-six children with repaired Tetralogy of Fallot were evaluated. Echocardiographic data were correlated with cardiac magnetic resonance and peak oxygen consumption during exercise. The results show the right ventricular myocardial systolic-to-diastolic duration ratio incorporates systolic and diastolic performance, electromechanical dyssynchrony, and postsystolic shortening and is associated with exercise capacity in repaired Tetralogy of Fallot.
右心室（RV）功能影响法洛四联症（rTOF）手术后的临床结果。然而，RV 功能的评估仍然很困难。我们通过应变成像时间间隔来研究 RV 心肌的收缩-舒张（S/D）持续时间比，以描述 RV 心肌的性能，探讨其与 rTOF 患者运动时峰值耗氧量（V̇o）和心脏磁共振衍生的 RV 扩张和功能的关系。我们回顾性分析了 76 例 rTOF 患儿和 42 例正常对照者。从 RV 整体和局部二维斑点追踪纵向应变测量 RV 心肌 S/D 持续时间比。从 QRS 起始到收缩期应变峰值的时间定义为收缩期持续时间。计算并校正心率（HR）后的 S/D 持续时间比。收缩后缩短（PSS）持续时间定义为肺动脉收缩前向血流停止后的缩短时间。与延长的 PSS 相比，rTOF 患者的 RV 心肌 S/D 持续时间比校正或未校正 HR 均显著升高（1 ± 0.3 比 0.8 ± 0.2， = 0.004）。校正 HR 后的心肌 S/D 持续时间比与 RV 射血分数（EF， = -0.37， = 0.001）和 V̇o（ = -0.32， = 0.042）呈弱相关。多元回归分析显示，RV EF 与心肌 S/D 持续时间比独立相关。RV 心肌 S/D 持续时间比是 RV 心肌性能和效率的一个参数，包含收缩和舒张性能、机械不同步和 PSS 的元素。S/D 持续时间比与 rTOF 患者的运动能力和 RV 功能障碍相关。这是第一项使用从二维应变中得出的收缩-舒张持续时间比评估右心室心肌性能的研究。评估了 76 例修复后的法洛四联症患儿。超声心动图数据与心脏磁共振和运动时峰值耗氧量相关。结果表明，右心室心肌的收缩-舒张持续时间比包含收缩和舒张性能、机电不同步以及收缩后缩短，并与修复后的法洛四联症患者的运动能力相关。
