位移曲线对犬正常及心肌梗死模型左室心肌局域功能的评价

Evaluation of left ventricular myocardial regional function in normal and myocardial infarction of mongrel dogs with displacement curve

目的通过研究犬心肌梗死模型左室局域心肌的位移曲线特征,寻求在生理和病理情况下评价心肌功能的合理量化指标。方法27只犬采用开胸结扎冠状动脉左前降支复制心肌梗死模型;分别采集结扎前后心尖长轴不同切面(二腔、四腔、五腔)的各三个完整心动周期动态多普勒组织速度图;应用EchoPACPC外置数字超声工作站同步获取左室心肌不同节段心肌组织位移曲线,记录每一位移曲线上长轴方向收缩期位移峰值及达峰值时间,计算等容舒张期开始时间、等容收缩期时间、等容舒张期时间。结果正常心肌位移曲线呈现规律性变化;梗死后前间隔、前壁各节段、后间隔近心尖部运动位移峰值与结扎前相比明显减低(P≤0.001);心梗后等容舒张期时相较结扎前明显延长(P<0.05)。结论位移曲线可以定量评价心肌梗死后局域心肌运动异常;位移峰值降低、等容舒张期时相延长可能是评价局部心肌梗死后局域心肌运动异常的早期敏感指标。

Objective To study the features of normal and infracted left ventricular regional wall motion of mongrel dogs with displacement curve, to investigate its suitable and quantitative standards of evaluating myocardial function in physiological and pathophysiological conditions. Methods Twenty-seven of the left anterior descending coronary arteries of mongrel dogs were ligated with opened chest surgery under systemic anesthesia. Activity Doppler tissue images of three cardiac cycles were obtained on apical views (2-chamber, 4-chamber, 5-chamber) before and after myocardial infarction. EchoPAC PC off-line digital ultrasound workstation was used to analyze the displacement curve at different myocardial segments of the left ventricle. All of displacement curve peaks on long axis and the time to peak were recorded. The time of starting isovolumic relaxation, and the duration of isovolumic contraction and relaxation were calculated. Results Displacement curve showed regularity in normal subjects. In myocardial infarction, peaks of all segments of anterior septum, anterior wall, apex and posterior septum were significantly lower than that in healthy subjects (P≤0.001). The duration of isovolumic relaxation was prolonged than that in healthy subjects (P<0.05). Conclusion Regional wall motion abnormalities in myocardial infarction were able to be evaluated with displacement curve. The descended peak of displacement and/ or the prolonged duration of isovolumic diastole may be the early sensitive indicators of regional wall motion abnormalities in myocardial infarction.