斑点追踪显像技术用于评价压力负荷改变致犬左心室扭转功能的影响

Evaluation of Left Ventricular Twist in Beagles with Different Pressure Loading Using Speckle Tracking Imaging

目的：探讨压力负荷改变对犬左心室扭转功能的影响.方法：6只雌性比格犬经股静脉注射甲氧明[5～10 μg/（kg·min）]和酚妥拉明[5～10 μg/（kg· min）],分别建立压力负荷的增加和下降模型.分别采集基线状态和压力负荷改变时的二维超声图像,采用斑点追踪显像（speckle tracking imaging,STI）技术评估左心室扭转和解旋,并行左心导管检查.结果：与基线状态相比,注射甲氧明后左心室收缩末期容积（end systolic volume,ESV）减小,射血分数（left ventricular ejection fraction,LVEF）增加;注射酚妥拉明后左心室舒张末期容积（end diastolic volume,EDV）减小、ESV增加、LVEF降低,差异均有统计学意义（P＜0.05）.与基线状态相比,注射甲氧明后左心室心尖、心底及整体峰值扭转角度（peak twist angle,Ptw）增加,左心室心尖、心底及整体扭转角度达峰时间（time to peak twist angle,tPtw）延迟;注射酚妥拉明后左心室心尖、心底及整体Ptw减小,左心室心尖、心底和整体tPtw延迟,差异均有统计学意义（P＜0.05）.与基线状态相比,注射甲氧明和酚妥拉明后的左心室收缩压（left ventricular systolic pressure,LVSP）和舒张末压（left ventricular end diastolic pressure,LVEDP）升高,左心室压力最大上升及下降速率（±dp/dtmax）下降,差异均有统计学意义（P＜0.05或P＜0.01）.注射甲氧明（r=0.656,P=0.03）和酚妥拉明（r=0.701,P=0.02）后的整体Ptw均与左心室收缩功能指标（＋dp/dtmax）呈正相关.结论：犬左心室心尖、心底及整体Ptw随压力负荷改变而改变,STI技术可以有效评估压力负荷改变对犬左心室扭转功能的影响.

Objective：To explore left ventricular twist in beagles with different pressure loading using speckle tracking imaging （STI）.Methods：In 6 female beagles,methoxamine [5-10μg/（kg · min）] and phentolamine [5-10 μg/（kg · min）] were injected by femoral vein,and the ascending and descending models of left pressure loading were established,respectively.Two dimensional echocardiography images were recorded under baseline conditions and after pressure loading change.Twist-related parameters were measured by STI,and left ventricular catheterization was performed simultaneously.Results：Compared with that under baseline condition,end systolic volume（ESV） of left ventricle decreased and left ventricular ejection fraction（LVEF） was increased with methoxamine,and end diastolic volume（EDV） was decreased,ESV was increased and LVEF was decreased with phentolamine.The differences were statistically significant（P＜0.05）.Compared with that under baseline condition,peak twist angle（Ptw） was increased in left ventricular apex,base and global segments,while time to peak twist angle （tPtw） was delayed with methoxamine.Ptw was decreased in left ventricular apex,base and global segments,while tPtw was delayed with phentolamine,and the difference were statistically significant （P＜0.05）.Compared with baseline condition,left ventricular systolic pressure（LVSP） and left ventricular end-diastolic pressure（LVEDP） was increased and ± dp/dtmax was decreased with methoxamine and phentolamine,the difference were statistically significant（P＜0.05 or P＜0.01）.Ptw in global segments was significantly positively correlated with ＋ dp/dtmax under methoxamine condition（r =0.656,P =0.03） and phentolamine condition（r=0.701,P=0.02）.Conclusions：Ptw in left ventricular apex,base and global segments in beagles changes along with the different pressure loading.STI is useful in evaluating left ventricular twist in beagles with different pressure loading.