Shi Hao-ying, Wang Fang, Meng Wei-dong, Zhang Feng, Sun Ya-ping, Sun Bao-gui
Department of Cardiology, Affliated First People's Hospital, Shanghai Jiao Tong University, Shanghai 200080, China.
Zhonghua Xin Xue Guan Bing Za Zhi. 2005 Nov;33(11):1002-5.
Right ventricular apical pacing may induce cardiac desynchronize and deteriorate left ventricular systolic performance. We hypothesized that right ventricular outflow tract (RVOT) pacing could produce better mechanical synchrony and left ventricular contraction.
We enrolled nine patients without structural heart disease who underwent electrophysiological studies. The pacing sites (right apex, low septum, free wall and septum of RVOT of the right ventricle) were defined with fluoroscopy and ECG. The atrioventricular sequential pacing was applied every 5 minutes in a random order at a rate of 120 bpm. Tissue Doppler imaging was carried out with GE VIVID 7 for off-line analysis at each pacing site. The global systolic contraction amplitude (GSCA) was calculated as the average shortening amplitude of all 16 segments of left ventricle.
The GSCA during pacing was 5.76 mm +/- 0.66 mm at free wall of RVOT and 5.66 mm +/- 1.00 mm at septum of RVOT, respectively. The GSCA at both sites was significantly higher than that at apical pacing 4.82 mm +/- 0.94 mm (P < 0.05) or low septum pacing 4.82 mm +/- 1.06 mm (P < 0.05). Moreover, segmental displacement analysis showed that the longitudinal displacement of lateral, posterior, and inferior walls significantly decreased at apical pacing compared with RVOT pacing, although no difference could be demonstrated in anterior and septum walls. Accordingly, the curve of the myocardial displacement at apical or low septum pacing was M-shaped, and had a negative wave at the end of the diastole in lateral, posterior, and inferior walls. The tissue velocity during isovolumic contraction period was also higher than systolic tissue velocity in these walls. The phenomenon could seldom be seen at RVOT pacing.
RVOT pacing in patients without structural heart disease is associated with more favorable immediate myocardial contraction and mechanical synchrony compared with right apical pacing or low septum pacing.
右心室心尖部起搏可能会导致心脏失同步，并使左心室收缩功能恶化。我们推测右心室流出道（RVOT）起搏可产生更好的机械同步性和左心室收缩。
我们纳入了9例无结构性心脏病且接受电生理研究的患者。通过荧光透视和心电图确定起搏部位（右心室心尖部、低位间隔、游离壁和右心室流出道间隔）。以120次/分钟的频率，每5分钟以随机顺序进行房室顺序起搏。使用GE VIVID 7在每个起搏部位进行组织多普勒成像以进行离线分析。计算左心室所有16个节段的整体收缩幅度（GSCA），即平均缩短幅度。
在起搏期间，RVOT游离壁的GSCA分别为5.76 mm±0.66 mm，RVOT间隔为5.66 mm±1.00 mm。这两个部位的GSCA均显著高于心尖部起搏时的4.82 mm±0.94 mm（P<0.05）或低位间隔起搏时的4.82 mm±1.06 mm（P<0.05）。此外，节段位移分析显示，与RVOT起搏相比，心尖部起搏时侧壁、后壁和下壁的纵向位移显著降低，尽管前壁和间隔壁未显示出差异。因此，心尖部或低位间隔起搏时心肌位移曲线呈M形，侧壁、后壁和下壁在舒张期末有负向波。这些壁在等容收缩期的组织速度也高于收缩期组织速度。在RVOT起搏时很少见到这种现象。
与右心室心尖部起搏或低位间隔起搏相比，无结构性心脏病患者的RVOT起搏与更有利的即时心肌收缩和机械同步性相关。
