Masuda T, Takeda K, Okamura A, Tamano K, Nakamura Y, Yagi S
Department of Medicine, Dokkyo University School of Medicine, Tochigi.
J Cardiol. 1993;23(4):371-8.
A new contractility index (Ec) is proposed based on the slope of the left ventricular (LV) end-systolic force-length relationship. The Ec values of normal human hearts are relatively constant. The present study investigated the Ec values of 16 cases of heart failure in 11 patients with old myocardial infarction and 5 with dilated cardiomyopathy in NYHA functional class 1 to 3. The LV end-systolic pressure (Pes) and dimension (Des) were estimated simultaneously by intraarterial cannulation and LV echocardiography. The LV pressure decreased from 111 +/- 17 to 90 +/- 14 mmHg after intravenous infusion of nitroglycerin. The LV Fes-Des relationship was found to be nearly linear and the slope (Ec) and extrapolated dimension intercepts (Do) were obtained as 60 +/- 22 g/cm and 2.7 +/- 1.2 cm, respectively. The values of Ec and Do were both proportional to the baseline Des value. Our model predicts that the Ec value reflects intracellular peak Ca2+ concentrations ([Ca2+]) of the myocardium and/or myosin ATPase activity. The present results suggest that the working myocardium of a failing heart increases [Ca2+] and/or myosin ATPase activity to compensate for depressed LV pump function due to myocardial damage.
基于左心室（LV）收缩末期力-长度关系的斜率，提出了一种新的收缩性指数（Ec）。正常人心脏的Ec值相对恒定。本研究调查了11例陈旧性心肌梗死和5例扩张型心肌病患者（纽约心脏协会心功能分级为1至3级）共16例心力衰竭患者的Ec值。通过动脉插管和左心室超声心动图同时估计左心室收缩末期压力（Pes）和尺寸（Des）。静脉输注硝酸甘油后，左心室压力从111±17 mmHg降至90±14 mmHg。发现左心室Fes-Des关系近乎线性，斜率（Ec）和外推尺寸截距（Do）分别为60±22 g/cm和2.7±1.2 cm。Ec和Do值均与基线Des值成正比。我们的模型预测，Ec值反映心肌细胞内的峰值Ca2+浓度（[Ca2+]）和/或肌球蛋白ATP酶活性。目前的结果表明，衰竭心脏的工作心肌会增加[Ca2+]和/或肌球蛋白ATP酶活性，以补偿因心肌损伤导致的左心室泵功能下降。
