右心声学造影时间-强度曲线参数与心肌运动指数评价右心收缩功能的实验研究

目的　探讨心腔声学造影时间-强度曲线( TIC)各项参数与心肌运动指数定量评价右心收缩功能的价值。方法　对1 0只犬分别在基础状态及注射心得安后心功能减退状态下经股静脉重复注射5 %声振白蛋白注射液,剂量0 .0 8ml/kg。于心尖四腔切面观察右心室造影剂的充盈及清除,采用拟合曲线定量分析方法获取心腔声学造影TIC各项参数,并分析各项参数在不同的心功能水平的差异。应用多普勒超声心动图分别在基础状态及注射心得安后心功能减退状态下记录三尖瓣舒张期和右心室流出道收缩期脉冲多普勒血流频谱,测量心肌运动指数( MPI,即Tei指数) ,MPI为心室等容舒张期时间及等容收缩期时间之和与心室射血时间的比值。结果　随心功能的减退,TIC各项参数中时间常数( k)明显减小,而造影剂峰值强度减半时间( HT)及造影剂平均渡越时间( MTT)明显延长,P值均小于0 .0 0 1。时间常数( k)与心肌运动指数( MPI)明显负相关,相关系数为- 0 .76。结论　右心腔声学造影时间-强度曲线参数与MPI在定量评估右心收缩功能时具有重要价值

Evaluation of Right Ventricular Systolic Function Using Contrast-enhanced Right Ventricular Time-intensity Curve and Myocardial Performance Index: An Experimental Study

Objective To study the right ventricular systolic function with contrast-enhanced time intensity curve (TIC) and to explore the relationship between the curve parameters and myocardial performance indices(MPI).Methods 5% sonicated human albumin was injected intravenously in doses of 0.08ml/kg at baseline and at decreased cardiac function after propranolol injection in 10 dogs.Four chamber view was observed for wash in and wash out of the contrast agent from the right ventricle.The parameters of TIC were obtained by curve fitting.The parameters were analysed in different cardiac function states.MPI (Tei index) defined as the sum of isovolumic relaxation time and isovolumic contraction time divided by ejection time,was measured from Doppler velocity profiles recorded at tricuspid inflow and right ventricular outflow on echocardiography at baseline and after cardiac function was decreased.Results Among the parameters derived from TIC,the time constant (k) was decreased significantly along with the decrement of cardiac function (P<0.001),but the half-time of descendant peak intensity and the mean-transit-time of wash out were increased significantly (P<0.001).Time-constant (k) strongly related to MPI(r=-0.76).Conclusions The parameters derived from TIC with right ventricular contrast enhancement related with MPI on assessment of right ventricular systolic function.