冠脉血流显像技术评价缺血预适应对冠脉反应性充血的影响

Assessment of the effect of ischemic preconditioning on coronary reactive hyperemia by coronary flow Doppler imaging

目的:应用冠脉血流显像技术评价缺血预适应对冠脉反应性充血的影响。方法:将16条杂种犬分为二组:反复三次短暂性缺血预处理组(IP组,n=8)以及在预处理之前静脉注射NOS抑制剂L-NAME组(L-NAME组,n=8)。应用冠脉血流显像程序取前降支远端血流频谱。分别在基础状态、最后一次预适应后5分钟进行短暂性冠脉结扎(20s)和再松放(反应性充血),自短暂性结扎前起连续记录血流频谱,测量基础状态和最大充血状态下峰值速度、速度时间积分以及充血开始至最大充血时的时间(DPT)。计算充血时最大峰值血流速度与基础速度比值、速度时间积分比值(即PRV∶BV和VTIPR∶VTIBASE)。测算左室射血分数(EF)。结果:IP组缺血预适应后各反应性充血指标明显低于基础状态,而L-NAME组预适应后仅VTIPR∶VTIBASE低于基础状态,而DPT和PRV∶BV差异无显著性意义。结论:应用冠脉血流显像技术可以发现缺血预适应后反应性充血的改变,反应性充血量减少,但充血率增快,充血率与NO合成有关。

Objective:The study was performed to evaluate the effect of ischemic preconditioning on the coronary reactive hyperemic response and further exploit the role of nitric oxide (NO)in the process.Methods:Sixteen mongrel dogs were di-vided into two groups:three cycles of transient ischemia interrupted by transient reperfusion (IP group),infusion of L-NAME (a selective NO synthase inhibitor)before preconditioning (L-NAME group).To measure the following indices:peak velocity and flow integral.Reactive hyperemic response were induced respectively at baseline and5minutes after the last cycle of pre-conditioning.Coronary flow spectrum in the distal left anterior descending artery (LAD)was recorded continuously during the whole course.The following indices were measured and calculated:peak velocity and velocity time integral both at baseline and during maximal hyperemia and their ratio (PRV∶BV and VTI PR ∶VTI BASE ),time to maximal hyperemia (DPT).Blood samples were also taken from coronary vein to measure the endothelin (ET)level at the two time.Results:The indices reflecting the reactive hyperemic volume change (PRV∶BV and VTI PR ∶VTI BASE )decreased at5minutes after the last cycle preconditioning in the two groups.DPT became smaller after the ischemic preconditioning.Inhibition of NOS could reversed this change.Coro-nary venous ET levels determined by radioimmunological method after the last cycle of ischemia did not change significantly in the two groups.Conclusion:After preconditioning the reactive hyperemic flow volume and time to maximal hyperemia was reduced.Hyperemic rate was related with the synthesis of NO.