急性心肌缺血早期心室舒张功能的损害
李云霞, 杨绿化, 雷孝光, 程立仁
湖南医学院生理教研室. 湖南
摘要
用长度计和多导仪记录狗左心室胸面近心外膜层心肌的长度,长度变化速率(dL/dt),压力-长度环和心肌作功量等项指标,从心肌运动功能的角度探讨急性心肌缺血早期心室内压最大下降速率(-dP/dt-max)降低的机理。实验结果表明:(1)阻断冠状动脉左前降支(LAD)后5s 左右,-dP/dt-max 降到最低值时,LVEDP 和心肌舒张末期长度相应增加,此时非缺血区心肌(n=8)收缩增强,作功量增加,长度曲线、dL/dt 曲线和压力-长度环的时相关系正常;而缺血区心肌(n=16)收缩功能减弱,并出现射血晚期和舒张早期的反向异常运动(由缩短转为延长),故长度曲线反向膨出,压力-长度环由正常的逆钟向环变为“8”字形顺钟向环,心肌作功降低并转为负功;(2)阻断LAD后,在-dP/dt-max降低并达到最低值时,-dP/dt-max瞬间的心肌缩短速率(dL/dt)也逐渐降低并转为负值(-dL/dt),此时长度曲线和压力一长度环尚无可见的变化。
关键词: 力-长度环; 长度计; 局部心肌缺血; 阻断冠脉; 节段心肌长度
Left ventricular dysfunction in early stage of regional myocardial ischemia
Li Yunxia, Yang Luhua, Lei Xiaoguang, Cheng Liren
Department of Physiology, Hunan Medical College. Hunan, China
Abstract
Acute regional myocardial ischemia was produced in seven open-chest anesthetized dogs by occlusion of the, left anterior descending artery (LAD) at the point just below the origin of its first branch. In order to assess the regional myocardial function, two mercury-filled length gauges were sutured on the epicardium in both the ischemic and the non-ischemic areas, respectively. The segmental myocardial length (SL), the first derivative of length change (dL/dt), the pressure-length (P-L) loop, and other left ventricular function parameters were recorded on an 8-channel polygraph and an oscilloscope. The stroke work of the segmental myocardium (SM) was calculated, based on the P-L loop. In all the experiments, the LVEDP and SM end-diastolic length increased significantly after the onset of LAD occlusion and at the point when the -dP/dt-max decreased to its nadir at the fifth second. At this time, the non-ischemic SM (n=8) work increased, however, the phasic configurations of the length curve, the dL/dt curve and the P-L loop were unchanged, but the ischemic SM (n=16) work decreased rapidly and even became negative. During the late ejection and early. Relaxation period, there was an ,abnormal SM elongation, the normal .anti-clczckwise rectangular P-L loop changed to an,8-shaped loop or even in a clockwise pattern. Furthermore, under the control condition, at the point of-dP/dt-max, the rate of SM shortening (dL/dt) reached its maximum (dL/dt-max). After, LAD occlusion, when the -dP/dt-max decreased and reached its nadir, the dL/dt-max decreased gradually and finally became a negative value (-dL/dt-max). Afterward, the -dL/dt-max became larger, but did not correlate with the -dP/dt-max, and preceded the -dP/dt-max. These results indicate that the abnormal movement of ischemic myocardium first appears in the isovolumic relaxation period. This might be a reasonable explanation for the decrease in -dP/dt-max and left ventricular dysfunction during the early stage of ischemia.
Key words: Pressure-length loop;Length gauge;;;
收稿日期: 录用日期:
通讯作者: E-mail:
引用本文:
李云霞, 杨绿化, 雷孝光, 程立仁. 急性心肌缺血早期心室舒张功能的损害[J]. 生理学报 1985; 37 (1): .
Li Yunxia, Yang Luhua, Lei Xiaoguang, Cheng Liren. Left ventricular dysfunction in early stage of regional myocardial ischemia. Acta Physiol Sin 1985; 37 (1): (in Chinese with English abstract).