二维斑点追踪成像评价放射性心脏损伤模型兔左心室收缩功能

Two-dimensional speckle tracking imaging in evaluating left ventricular systolic function in rabbit models of radiation-induced heart disease

目的观察二维斑点追踪成像(2D-STI)评价放射性心脏损伤(RIHD)模型兔左心室收缩功能的价值。方法将55只雄性新西兰大白兔分为低剂量(20 Gy)组(n=22)、高剂量(40 Gy)组(n=22)及对照组(n=11),针对前2组建立RIHD模型、对照组实行假放射治疗(放疗)。于放疗前(T0期)、放疗后0周(T1期)、5周(T2期)及15周(T3期)行经胸超声心动图检查,采集图像后处死高、低剂量组各2只及对照组1只进行病理观察;于放疗后25周(T4期)完成经胸超声心动图检查后全部处死进行病理观察,将超声图像导入QLab 10软件,应用aCMQ进行分析。结果3组各期射血分数(EF)、短轴缩短率(FS)差异均无统计学意义(P均>0.05)。高剂量组前壁基底段(BA)、前壁中间段(MA)、侧壁中间段(MAL)、前间隔中间段(MAS)收缩期峰值纵向应变及应变率在T3期较同组前期及同期另外2组均降低(P均<0.05),T4期除后壁基底段(BIL)、下壁基底段(BI)、下壁中间段(MI)收缩期峰值纵向应变及应变率外,其余节段均较同组前期及同期另外2组降低(P均<0.05),T3、T4期整体应变及应变率均较同组前期降低(P均<0.05);低剂量组T4期BA、MA、MAL、MAS收缩期峰值纵向应变及应变率均较同组前期及对照组降低(P均<0.05)。光镜下高、低剂量组于T2期心肌开始呈现炎性渗出表现,随时间推移出现纤维化,血管壁增厚及炎性浸润,高剂量组重于低剂量组并于T4期出现坏死。结论2D-STI可较常规超声更早地定量评价RIHD模型兔左心室整体及节段收缩功能异常。

Objective To explore the value of two-dimensional speckle tracking imaging(2D-STI)for evaluating left ventricular systolic function in rabbit models of radiation-induced heart disease(RIHD).Methods Fifty-five male New Zealand white rabbits were divided into high dose group(40 Gy,n=22),low dose group(20 Gy,n=22)and control group(n=11).Rabbit models of RIHD were established in high and low dose groups,while rabbits in control group underwent sham radiotherapy.All rabbits were examined with transthoracic echocardiography before radiotherapy(T0),0 week(T1),5 weeks(T2)and 15 weeks after radiotherapy(T3),and the images were collected,and 2 rabbits in high and low dose groups and 1 in control group were killed to observe the pathological changes at each time points.The remained rabbits were all killed after radiotherapy and transthoracic echocardiography at 25 weeks(T4),and the pathological changes were observed.The images were imported to QLab 10 software and analyzed with aCMQ.Results No significant difference of ejection fraction(EF)nor fraction shortening(FS)was found among 3 groups at each time point(all P>0.05).In high dose group,the peak longitudinal strain and strain rate of basal anterior(BA),mid anterior(MA),mid anterolateral(MAL)and mid anterolateral(MAS)at T3 were lower than those of itself at the previous periods and of other 2 groups(all P<0.05),while except basal inferolate(BIL),basal inferior(BI)and mid inferior(MI),the peak longitudinal strain and strain rate at T4 were lower than those of itself at the previous periods and of other 2 groups(all P<0.05),and the global strain and strain rate at T3 and T4 were lower than those of itself before(all P<0.05).In low dose group,the peak longitudinal strain and strain rate of BA,MA,MAL and MAS at T4 were significantly lower than those of itself before and of control group(all P<0.05).The myocardium of high and low dose groups began to show inflammatory exudation at T2,with fibrosis,vascular wall thickening and inflammatory infiltration with time going,in high dose group were more serious than those in low dose group,and necrosis of high dose group occurred in T4.Conclusion 2D-STI could be used to quantitatively evaluate the systolic dysfunction of the whole left ventricle and segments in rabbit models of RIHD earlier than traditional ultrasound.