组织多普勒成像技术对不同心肌肥厚模型大鼠心功能的研究

目的探讨组织多普勒成像(TDI)技术对不同心肌肥厚模型大鼠心脏舒张功能评价的可行性。方法将25只大鼠采用两种方法制备心肌肥厚模型,分别为自发性高血压心肌肥厚组(SH)15只和以缩窄腹主动脉形成的心肌肥厚组(SAAC)10只,并以10只正常Wistar Kyoto大鼠作为对照组,比较各组血压、心率、体重、组织多普勒和常规超声心动图心功能指标的变化。结果SH和SAAC组血压及心率均高于对照组(P<0.05),各组间体重差异无统计学意义。SH和SAAC组心肌厚度均大于对照组(P<0.05),其前后壁厚度均大于2.0mm;SH及SAAC组左心室收缩末期内径(LVEDs)均小于对照组(P<0.05);3组间左心室射血分数(LVEF)和短轴缩短率(LVFS)差异无统计学意义。SH和SAAC组二尖瓣环后室间隔侧TDI各峰值均较对照组增高(P<0.01),而收缩期与舒张期峰值速度比值(Ea/Aa)减低;SH和SAAC两组相比,二尖瓣环TDI各个指标之间差异均无统计学意义(P>0.05)。大鼠二尖瓣口血流频谱和二尖瓣环TDI频谱在心率增快时,失去正常的舒张期双峰形态,呈现为单峰状;两者融合率均随心率增快而增加,且均在心率350次/min时出现双峰融合率明显增加。但TDI二尖瓣环频谱的融合率远远小于二尖瓣口血流频谱(29%和63%)。结论大鼠二尖瓣环后间隔Ea/Aa是反映早期心室舒张功能变化的敏感指标;两组心肌肥厚大鼠模型心腔变化和TDI指标改变类似。二尖瓣环TDI指标在评价大鼠舒张功能方面优于二尖瓣血流指标。

Evaluation of left ventricular function with different myocardial hypertrophy models in rats using tissue Doppler imaging

Objective To evaluate the left ventricular diastolic function in different myocardial hypertrophy rats using tissue Doppler imaging(TDI) and to define its feasibility.Methods Thirty-five 14-16 weeks male rats were assigned to divide into 3 groups:spontaneously hypertensive rats(SH,n=15),suprarenal abdominal aortic coarctation rats(SAAC,n=10) and Wistar Kyoto rats(WKY,n=10) as the control.Tail-cuff blood pressure,heart rate and body weight were measured in all the 3 groups.Echocardiography with TDI was performed for left ventricular function evaluation in all the rats.Results The blood pressure and heart rate in both SH and SAAC were higher than that of the control group.There were no significant difference of body weight among the 3 groups(P>0.05).Compared with WKY group,the left ventricular wall thickness in both SH and SAAC were increased significantly(P<0.05).The anterioposterior thickness was 2.0 mm.The left ventricular end systolic diameters of SH and SAAC were less than that of the control group.There were no significant difference of ejection fraction and fractional shortening among the 3 groups(P>0.05).The early and late diastolic peak velocity of the mitral annulus(Ea and Aa) in myocardial hypertrophy rats were increased while the ratios(Ea/Aa) were decreased(P<0.05).There was no significant difference of echocardiographic and TDI parameters between SH and SAAC groups(P>0.05).The phenomena of the fusion of E with A waves of transmitral flow or at mitral annulus were both increased when the heart rate increased,especially when the heart rate was more than 350 b/min,while the mitral annular tissue Doppler imaging demonstrated less fusion of Ea and Aa at rapid heart rates than at transmitral flow.Conclusions The index of Ea/Aa at mitral annulus could demonstrate the early changes of left ventricular diastolic function in hypertrophy rats and mitral annular tissue Doppler imaging showed less fusion of Ea and Aa wave even at rapid heart rate.There was no significant difference between echocardiograpic and TDI parameters in SH and SAAC groups.