Esmaeilzadeh Maryam, Poorzand Hoorak, Maleki Majid, Sadeghpour Anita, Parsaee Mozhgan
Iran Cardiovascular Research Institute, Department of Echocardiography, Tehran, Iran.
J Tehran Heart Cent. 2011 Winter;6(1):24-30. Epub 2011 Feb 28.
The right ventricular (RV) dyssynchrony has not been studied extensively and the existing literature has established the effect of cardiac resynchronization therapy (CRT) on the left ventricular (LV) dyssynchrony, but there is a dearth of data on the effect of CRT on the forgotten ventricle. We sought to evaluate the presence of mechanical right ventricular dyssynchrony in patients with systolic heart failure, selected for CRT, and track the changes early afterward utilizing the longitudinal strain analysis.
Thirty-six patients with severe left ventricular systolic dysfunction, candidated for CRT, were enrolled in this study. Mechanical dyssynchrony was assessed using tissue Doppler echocardiography. The time interval between the onset of the QRS to the peak systolic longitudinal strain at the RV free wall and the septum was obtained. The RV mechanical delay was calculated as the absolute value of the difference in the time-to-peak measurements between the RV and septum. The RV dyssynchrony was defined as the calculated delay in strain imaging, which was ± 2 SD above the mean value for the control subjects (20 cases). The RV function was evaluated using the RV fractional area change (RVFAC), tricuspid annulus plane systolic excursion (TAPSE), and peak systolic strain values of the RV free wall. Four to 7 days after CRT implantation, echocardiographic reevaluations were done.
The calculated cut-off value for the RV dyssynchrony was 41.5 msec, according to which the pre-CRT analysis specified two patient groups: Group 1 (16 cases) with RV dyssynchrony and Group 2 (20 patients) without RV dyssynchrony. Significant improvement in the RV dyssynchrony was noted in Group 1 after CRT (30 ± 28.9 msec vs. 68.8 ± 21 msec; p value < 0.01 vs. 14 ± 10 msec vs. 19 ± 16.5 msec; p value = 0.18 respectively). A significant correlation was found between the severity of the RV dyssynchrony and peak systolic strain in the RV free wall (r = -0.5; p value < 0.05). No significant relation was found between the RV dyssynchrony and right ventricle fractional area change (RVFAC), LV mechanical dyssynchrony, time-to-peak systolic strain in the RV free wall, QRS width, or morphology. In Group 1, the peak systolic strain increased insignificantly (p value = 0.15 for the basal segment; p value = 0.20 for the mid segment). A moderately significant correlation was found between the RV mechanical delay before CRT vs. the post-CRT values (r = 0.4; p value = 0.01).
Early after CRT, the RV mechanical delay can improve and the significant improvement is seen in patients with baseline RV mechanical dyssynchrony.
右心室（RV）不同步尚未得到广泛研究，现有文献已证实心脏再同步治疗（CRT）对左心室（LV）不同步的影响，但关于CRT对被忽视的心室的影响的数据却很匮乏。我们试图评估入选CRT治疗的收缩性心力衰竭患者中机械性右心室不同步的存在情况，并利用纵向应变分析追踪术后早期的变化。
本研究纳入了36例重度左心室收缩功能障碍且适合CRT治疗的患者。使用组织多普勒超声心动图评估机械性不同步。获取QRS波起始至右心室游离壁和室间隔收缩期纵向应变峰值之间的时间间隔。右心室机械延迟计算为右心室与室间隔达峰时间测量值之差的绝对值。右心室不同步定义为应变成像计算得出的延迟，其高于对照组（20例）平均值±2个标准差。使用右心室面积变化分数（RVFAC）、三尖瓣环平面收缩期位移（TAPSE）和右心室游离壁收缩期峰值应变值评估右心室功能。CRT植入后4至7天进行超声心动图复查。
右心室不同步的计算临界值为41.5毫秒，据此CRT术前分析将患者分为两组：第1组（16例）存在右心室不同步，第2组（20例）无右心室不同步。CRT术后第1组右心室不同步有显著改善（分别为30±28.9毫秒对68.8±21毫秒；p值<0.01对14±10毫秒对19±16.5毫秒；p值=0.18）。右心室不同步的严重程度与右心室游离壁收缩期峰值应变之间存在显著相关性（r = -0.5；p值<0.05）。右心室不同步与右心室面积变化分数（RVFAC）、左心室机械不同步、右心室游离壁收缩期达峰时间、QRS波宽度或形态之间未发现显著关系。在第1组中，收缩期峰值应变无显著增加（基底段p值=0.15；中间段p值=0.20）。发现CRT术前与术后右心室机械延迟之间存在中度显著相关性（r = 0.4；p值=0.01）。
CRT术后早期，右心室机械延迟可改善，且基线存在右心室机械不同步的患者有显著改善。
