犬右心耳和右室心尖起搏左心室心肌力学状态的超声斑点追踪成像对比研究

目的 采用超声斑点追踪成像技术评价急性心肌缺血前后右心耳起搏与右室心尖起搏模式下左心室心肌力学状态.方法 结扎冠状动脉左前降支建立急性心肌缺血比格犬模型.获取14只开胸犬急性心肌缺血前后窦性心律及两种起搏状态的标准左心室长轴切面;分别测量和计算左心室整体长轴应变及18节段长轴峰值应变、应变达峰时间、应变达峰时间标准差;进行不同研究者间和研究者自身重复性相关分析.结果 ①急性心肌缺血前起搏:右心耳和右室心尖起搏时左心室整体应变均小于窦性心律(P＜0.05).右室心尖起搏时后间隔节段峰值应变均小于右心耳起搏和窦性心律(P＜0.05);右心耳起搏时前间隔心尖及中间节段应变达峰时间均较右室心尖起搏延后(P＜0.05);左室18节段应变达峰时间标准差在窦性心律、右心耳起搏和右室心尖起搏模式下呈递增趋势(P＜0.05).②急性心肌缺血后起搏:右心耳和右室心尖起搏时左心室整体应变小于窦性心律(P＜0.05),右室心尖起搏时后间隔中间及基底节段峰值应变均小于右心耳起搏和窦性心律(P＜0.05);右心耳起搏时后间隔中间及基底节段应变达峰时间均较右室心尖起搏和窦性心律延后(P＜0.05);左室应变达峰时间标准差在窦性心律、右心耳起搏和右室心尖起搏间差异均无统计学意义(P＞0.05).③同一切面节段峰值应变在不同研究者间r=0.810,P＜0.001;研究者自身r=0.837,P＜0.001.结论 急性心肌缺血前后右心耳起搏及右室心尖起搏均未能使左心室心肌力学恢复至正常实性心律的有效和同步状态.

Comparison study of longitudinal left ventricular myocardial mechanical pattern during right atrial appendage pacing and right ventricular apical pacing using ultrasonic speckle tracking imaging in vivo

Objective To evaluate the myocardial mechanical pattern of left ventricle(LV)before and after acute myocardial ischemia during right atrial appendage pacing(RAA-P)and right ventricular apical pacing(RVA-P)using ultrasonic speckle tracking imaging(STI).Methods Left anterior descending coronary artery was ligated for acute myocardial ischemia in open-chest beagle canine models(n=14).The two dimensional apical views in LV were acquired during normal sinus rhythm(NSR),RAA-P and RVA-P before and after acute myocardial ischemia.The longitudinal global strain(ε),18 segmenal peak strain,time to peak longitudinal strain(Te)and 18 segmental time to peak longitudinal strain-standard deviation(Tε-18SD) of LV were measured and calculated.Reproducibility correlation analysis was performed.Results ①Before acute myocardial ischemia:the global ε of LV during RAA-P and RVA-P were lower than that during NSR(P＜0.05).The peak ε at interventricular septum during RVA-P was lower than that during NSR and RAA-P(P＜0.05);Tε of anterior septum at apical and middle level during RVA-P was shortened than that during RAA-P(P＜0.05).Tε-18SD of LV increase progressively between NSR,RAA-P and RVA-P(P＜0.05).②After acute myocardial ischemia:the global ε of LV during RAA-P and RVA-P were lower than that during ischemical sinus rhythm(ISCH-SR)(P＜0.05).The peak ε of interventricular septum at middle and basal level during RVA-P was lower than that during ISCH-SR and RAA-P(P＜0.05).The Tε of interventrieular septum at middle and basal level during ISCH-SR and RVA-P was shortened than that during RAA-P(P＜0.05).There was no significant difference of LV Tε-18SD during ISCH-SR,RAA-P and RVA-P.③There was a reasonable reproducibility for the measurement of LV segmental peak ε for both interobserver(r=0.810,P＜:0.001)and intraobserver(r=0.837,P＜0.001).Conclusions Both RAA-P and RVA-P couldn't achieve a normal LV mechanical pattern before and after myocardial ischemia.