背向散射积分技术评价硝酸甘油对犬顿抑心肌收缩功能延迟保护

Evaluation of nitroglycerin delay protection effect on myocardial stunning contraction function using integrated backscatter

目的探讨背向散射积分技术定量评价硝酸甘油对犬顿抑心肌收缩功能的延迟保护。方法20只健康成年杂种犬随机分成缺血再灌注组(A组)和硝酸甘油组(B组),缺血及再灌注阶段检测室壁增厚率(WT)及心动周期变异幅度(CVIB),图像平均强度(AII)的动态变化。实验结束后对心肌组织行病理检查。结果缺血时两组相应区域心肌CVIB和WT明显减低,曲线形态不规则。再灌注后有逐渐恢复趋势。CVIB的动态变化与WT相似,二者具有较好的相关性。再灌注120min时B组收缩功能抑制分别较对照组减少了34%,30%。应用小剂量多巴酚丁胺后两组相应区域心肌运动增强。AII,标化AII在不同观测时间点之间的差异均无显著性意义。结论背向散射积分技术中的CVIB可用于检测顿抑心肌的收缩功能,多巴酚丁胺负荷试验结合背向散射积分技术可检测顿抑心肌的收缩功能储备,硝酸甘油对犬顿抑心肌收缩功能具有延迟保护作用。

Objective To investigate the nitroglycerin delay protection effect on myocardial stuning contraction function using integrated backscatter. Methods Twenty anesthetized dogs were randomly divided into two groups： in group A （10 dogs）, the anterior descending coronary artery was blocked for 20 min, and reperfused for 120 min. In group B （10 dogs）, nitroglycerin was given intravenously, after 24 h by followed the same step as group A. During ischemia and reperfusion, Dog was injected at reperfusion 30 min, cyclic variation of integrated backscatter （CVIB）, average image intensity （AⅡ）, standardized All, and wall thickening （WT） were measured. The correlations between CVIB and WT were analyzed. Gross pathologic specimen was stained with Evans blue （EB） and Triphenyl Tetrazolium Chloride （TTC） after test. Results CVIB and WT decreased significantly at reperfusion 0 min, and these parameters recovered gradually with prolonging reperfusion period, WT and CVIB variation tendencies were similar. CVIB correlated well to WT. CVIB and WT were higher in group B than in group A at reperfusion 120 min, contraction function inhibition decreased 34% and 30% in group B than in group A. AⅡ and standardized AⅡ were not remarkably variable during the reperfusion. With the Dob injection, the CVIB and WT were increased remarkably. Conclusion CVIB can quantitatively evaluate the variations of contraction function in stunning myocardium. Nitroglycerin can induced delay protection on contraction function of myocardial stunning.