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目的探讨犬急性心肌梗死后左心室局域心肌等容舒张期、快速充盈期在长轴方向的舒张运动特点。方法对24只急性心肌梗死犬在定量组织速度成像(QTVI)条件下采集冠状动脉结扎前、结扎后4h心尖二腔心、心尖四腔心及心尖五腔心切面各3个心动周期动态图像,并应用QTVI定量分析功能对梗死前、后左心室各节段长轴方向的运动特点进行分析。取样容积分别置于基底部、乳头肌水平、心尖部心内膜水平的左心室前壁(AW)、下壁(IW)、侧壁(LW)、后室间隔(PS)、前室间隔(AS)和后壁(PW),分别记录舒张早期峰值速度(Ve)、等容舒张期峰值速度(Vivrp),包括等容舒张期负向及正向峰值速度(Vivrp1,Vivrp2)及对应时间(T1,T2),并计算等容舒张期平均加速度(a)。结果急性心肌梗死后受累节段的Ve明显低于正常时的相应节段(P＜0.05或P＜0.01)；受累节段Vivrp1下降(P＜0.05),而Vivrp2无明显变化(P＞0.05)。心尖部梗死节段AW、AS的a大于正常时的相应节段(P＜0.05或P＜0.01),而相邻及相对节段LW、PS和IW、PW的a则小于正常时的相应节段(P＜0.01)；中部梗死节段AW、AS的a大于正常时的相应节段(P＜0.05),相邻PS的a则小于正常时的相应节段(P＜0.01)；基底部与梗死节段相邻的PS、AS、AW的a也小于正常时的相应节段(P＜0.05或P＜0.01)。结论QTVI能敏感、直观,且无创定量评价左心室局域心肌舒张功能,对早期诊断急性心肌梗死具有重要价值。
Objective To investigate the characteristics of diastolic motion in the direction of long axis during left ventricular regional myocardial isovolumic diastolic and rapid filling in dogs after acute myocardial infarction. Methods Twenty-four acute myocardial infarction (AMI) dogs were collected at 4 hours after coronary artery ligation and 3 weeks after coronary artery occlusion. Four dynamic images of cardiac apex, apical four-chamber and apical five-chamber were collected under quantitative tissue velocity imaging (QTVI) The QTVI quantitative analysis was used to analyze the characteristics of long axis of left ventricular before and after infarction. The volume of the sample was placed at the basal portion, papillary muscle level, apical endocardial level of left ventricular anterior wall (AW), inferior wall (IW), lateral wall (LW), posterior septum (PS) AS) and posterior wall (PW) were recorded. The peak diastolic velocity (Ve), the peak isovolumic peak velocity (Vivrp), including the negative and positive peak velocity of isovolumic relaxation (Vivrp1, Vivrp2) and corresponding time T1, T2), and calculate the average isokinetic diastolic acceleration (a). Results The Ve of affected segments after acute myocardial infarction were significantly lower than those of normal segments (P <0.05 or P <0.01). Vivrp1 of affected segments decreased (P <0.05), but Vivrp2 had no significant change (P> 0.05) . The a, a and c values of AW and AS in the apical infarct segment were higher than those in the normal segment (P <0.05 or P <0.01), while those in the adjacent and relative segments LW, PS and IW and PW were less than those in the normal (P <0.01). In the middle infarction segment, the a and a values of AW and AS in the infarcted segment were higher than those in the normal segment (P <0.05), while those in the adjacent PS were less than those in the normal segment (P <0.01) The PSAs, ASs, and AWs adjacent to the infarct segment were also smaller than those of the normal segment (P <0.05 or P <0.01). Conclusion QTVI can be sensitive, intuitive and non-invasive quantitative assessment of left ventricular regional myocardial diastolic function, early diagnosis of acute myocardial infarction has important value.