治疗超声波对心肌收缩力的影响及分布研究

目的 通过体外低强度超声波辐照左室心肌,旨在探索超声波对心肌收缩力的影响及分布特征。方法 8只新西兰大白兔,采用0.75w的脉冲超声波从心尖区朝向左室长轴方向辐照50分钟,将兔依据辐照前后分为A、B两组,M型超声在左室中段短轴切面测量EF值,分别检测两组左室基底段、左室中段、心尖段及整体圆周心肌内层应变,分别计算两组对应节段心肌辐照前后的应变差值并进行比较。结果 EF值B组较A组增强(p<0.05),左室基底段、左室中段及心尖段圆周心肌内层应变B组大于A组,两组应变差值左室心尖段与基底段及中段具有统计学意义。结论 体外低剂量超声波辐照左室心肌可产生明显的正性肌力作用,且靠近超声发射区的左室心尖段增加更显著。

Effect and distribution of therapeutic ultrasoundon myocardial contractility

Objective To explore the effect and distribution of ultrasound on myocardial contractility , left ventricular myocardium was irradiated by low intensity ultrasound in vitro. Methods Eight New Zealand white rabbits were irradiated with 0.75w pulsed ultrasound from the apical region towards the long axis of the left ventricle for 50 minutes. The rabbits were divided into groups A and B according to the pre and post irradiation. The EF value was measured by M-mode ultrasound in the short axis section of the middle left ventricle. The inner myocardial strains of the left ventricular basal segment, the left ventricular middle segment, the apical segment and the whole circumference of the two groups were measured respectively. The strain differences of the corresponding segments of the two groups before and after irradiation were calculated and compared. Results The EF value in group B was higher than that in group A (P < 0.05). The myocardial inner layer strain of left ventricular basal segment, left ventricular middle segment and apical segment in group B was greater than that in group A. the strain difference between the two groups was statistically significant. Conclusion Low dose ultrasound irradiation in vitro could produce significant positive inotropic effect on left ventricular myocardium, and the increase of left ventricular apical segment near the ultrasound emission area was more significant.