Spaccavento L J, Grassman E D, Briesblatt W M, Schwartz R S
Cardiology Service/SGHMMC, Wilford Hall USAF Medical Center, Lackland AFB, San Antonio, Texas.
Angiology. 1990 Jun;41(6):486-91. doi: 10.1177/000331979004100611.
The constant of elastance (E-MAX) is determined by measuring continuous left ventricular pressure and volume changes during the cardiac cycle. To evaluate the effect of myocardial ischemia on contractility, E-MAX was measured from serial pressure volume loops at baseline, with atrial pacing-induced ischemia, and after the administration of intravenous nitroglycerin with repeat pacing. Ten patients undergoing cardiac catheterization for presumed coronary artery disease were evaluated by this method. The severity of the coronary artery disease was graded angiographically by using the Gensini coronary score. In 8 of the 10 patients there was a significant decrease in E-MAX during atrial pacing (P less than .05). With the administration of nitroglycerin there was an attenuation of the ischemic effect previously noted with pacing. In 3 of the 10 patients administration of nitroglycerin produced a further decrease in E-MAX with ischemia. All 3 patients had a significantly lower Gensini coronary score with a well-developed, visible coronary collateral network. The authors' results indicate that continuous pressure volume loop analysis is possible using the nuclear stethoscope. Significant ischemic changes are seen with atrial pacing, which are relieved by the administration of nitroglycerin, except in the presence of coronary collaterals.
弹性常数（E-MAX）通过测量心动周期中连续的左心室压力和容积变化来确定。为评估心肌缺血对收缩性的影响，在基线、心房起搏诱导缺血时以及静脉注射硝酸甘油后重复起搏时，从系列压力容积环测量E-MAX。采用此方法对10例因疑似冠状动脉疾病接受心导管检查的患者进行评估。通过使用Gensini冠状动脉评分对冠状动脉疾病的严重程度进行血管造影分级。10例患者中有8例在心房起搏期间E-MAX显著降低（P<0.05）。使用硝酸甘油后，先前起搏时出现的缺血效应有所减轻。10例患者中有3例在使用硝酸甘油后，缺血时E-MAX进一步降低。所有3例患者的Gensini冠状动脉评分均显著较低，且有发育良好、可见的冠状动脉侧支网络。作者的结果表明，使用核听诊器进行连续压力容积环分析是可行的。心房起搏时可见明显的缺血变化，除存在冠状动脉侧支外，硝酸甘油给药可缓解这些变化。
