Dufva Melanie J, Truong Uyen, Tiwari Pawan, Ivy Dunbar D, Shandas Robin, Kheyfets Vitaly O
1 Department of Bioengineering, University of Colorado Denver, USA.
2 Department of Pediatrics, Section of Cardiology, Children's Hospital Colorado, USA.
Pulm Circ. 2018 Jul-Sep;8(3):2045894018791352. doi: 10.1177/2045894018791352. Epub 2018 Jul 13.
The right ventricle and left ventricle are physically coupled through the interventricular septum. Therefore, changes in the geometry and mechanics of one ventricle can directly affect the function of the other. In treatment of pediatric pulmonary arterial hypertension, the left ventricle is often overlooked, with clinical focus primarily on improving right ventricular function. Pediatric pulmonary arterial hypertension represents a disease distinct from adult pulmonary arterial hypertension based on etiology and survival rates. We aimed to assess left ventricular torsion rate in pediatric pulmonary arterial hypertension and its role in right ventricular dysfunction. Cardiac magnetic resonance images with tissue tagging were prospectively acquired for 18 pediatric pulmonary arterial hypertension (WHO class I) patients and 17 control subjects with no known cardiopulmonary disease. The pulmonary arterial hypertension cohort underwent cardiac magnetic resonance within 48 hours of clinically indicated right heart catheterization. Using right heart catheterization data, we computed single beat estimation of right ventricular end-systolic elastance (as a measure of right ventricular contractility) and ventricular vascular coupling ratio (end-systolic elastance/arterial afterload). Left ventricular torsion rate was quantified from harmonic phase analysis of tagged cardiac magnetic resonance images. Ventricular and pulmonary pressures and pulmonary vascular resistance were derived from right heart catheterization data. Right ventricular ejection fraction and interventricular septum curvature were derived from cardiac magnetic resonance. Left ventricular torsion rate was significantly reduced in pulmonary arterial hypertension patients compared to control subjects (1.40 ± 0.61° vs. 3.02 ± 1.47°, P < 0.001). A decrease in left ventricular torsion rate was significantly correlated with a decrease in right ventricular contractility (end-systolic elastance) ( r = 0.61, P = 0.007), and an increase in right ventricular systolic pressure in pulmonary arterial hypertension kids ( r = -0.54, P = 0.021). In both pulmonary arterial hypertension and control subjects, left ventricular torsion rate correlated with right ventricular ejection fraction (controls r = 0.45, P = 0.034) (pulmonary arterial hypertension r = 0.57, P = 0.032). In the pulmonary arterial hypertension group, interventricular septum curvature demonstrated a strong direct relationship with right ventricular systolic pressure ( r = 0.7, P = 0.001) and inversely with left ventricular torsion rate ( r = -0.57, P = 0.013). Left ventricular torsion rate showed a direct relationship with ventricular vascular coupling ratio ( r = 0.54, P = 0.021), and an inverse relationship with mean pulmonary arterial pressure ( r = -0.60, P = 0.008), and pulmonary vascular resistance ( r = -0.47, P = 0.049). We conclude that in pediatric pulmonary arterial hypertension, reduced right ventricular contractility is associated with decreased left ventricular torsion rate.
右心室和左心室通过室间隔在解剖结构上相连。因此，一个心室的几何形状和力学变化可直接影响另一个心室的功能。在小儿肺动脉高压的治疗中，左心室常常被忽视，临床主要关注改善右心室功能。小儿肺动脉高压在病因和生存率方面与成人肺动脉高压是不同的疾病。我们旨在评估小儿肺动脉高压患者的左心室扭转率及其在右心室功能障碍中的作用。前瞻性地获取了18例小儿肺动脉高压（世界卫生组织I级）患者和17名无已知心肺疾病的对照受试者的带有组织标记的心脏磁共振图像。肺动脉高压队列在临床指示的右心导管检查后48小时内接受心脏磁共振检查。利用右心导管检查数据，我们计算了右心室收缩末期弹性（作为右心室收缩性的指标）和心室血管耦合比（收缩末期弹性/动脉后负荷）的单搏估计值。通过对标记的心脏磁共振图像进行谐波相位分析来量化左心室扭转率。心室和肺动脉压力以及肺血管阻力来自右心导管检查数据。右心室射血分数和室间隔曲率来自心脏磁共振检查。与对照受试者相比，肺动脉高压患者的左心室扭转率显著降低（1.40±0.61°对3.02±1.47°，P<0.001）。左心室扭转率的降低与右心室收缩性（收缩末期弹性）的降低显著相关（r=0.61，P=0.007），并且与小儿肺动脉高压患者右心室收缩压的升高相关（r=-0.54，P=0.021）。在肺动脉高压和对照受试者中，左心室扭转率均与右心室射血分数相关（对照受试者r=0.45，P=0.034）（肺动脉高压r=0.57，P=0.032）。在肺动脉高压组中，室间隔曲率与右心室收缩压呈强正相关（r=0.7，P=0.001），与左心室扭转率呈负相关（r=-0.57，P=0.013）。左心室扭转率与心室血管耦合比呈正相关（r=0.54，P=0.021），与平均肺动脉压呈负相关（r=-0.60，P=0.008），与肺血管阻力呈负相关（r=-0.47，P=0.049）。我们得出结论，在小儿肺动脉高压中，右心室收缩性降低与左心室扭转率降低有关。
