The contractile state as the major determinant in the evolution of left ventricular dysfunction in the spontaneously hypertensive rat.
The contractile state as the major determinant in the evolution of left ventricular dysfunction in the spontaneously hypertensive rat.
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收缩状态是自发性高血压大鼠左心室功能障碍演变的主要决定因素。
DOI：
10.1161/01.res.53.6.767
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发表时间：
1983
影响因子：
20.1
通讯作者：
Braunwald,E
中科院分区：
文献类型：
--
作者：
Mirsky,I;Pfeffer,JM;Pfeffer,MA;Braunwald,E
雌性自发性高血压和血压正常大鼠在6，12，18和24个月的年龄进行了研究，以确定哪些特征的心肌性能预示着左心室功能障碍的发病。峰值射血分数指数来自峰值每搏输出量（体内容量负荷）和被动压力-容量关系的测量。根据压力-容积数据计算心肌刚度常数（km，增量模量-应力关系的斜率，EINC = km sigma）、心腔刚度常数（kc，心腔刚度-压力关系的斜率，dP/dV = kcP）和10 mm Hg时的左心室腔室容积与室壁容积比），并根据射血分数指数-后负荷关系评估收缩状态。在血压正常的大鼠，心肌硬度常数不受年龄的影响，而在自发性高血压大鼠，心肌硬度常数保持在正常范围内，直到18个月，在这个时候发生了显着增加心肌硬度指数。自发性高血压大鼠的基线和最大心脏指数和射血分数指数在6 - 18个月内正常，但在24个月时明显降低。心脏功能的这种降低与左心室腔室刚度常数的降低有关，即，kc.在心肌硬度增加时发生的心腔硬度降低是由于腔体尺寸增加大于心肌硬度增加。正常血压大鼠的左心室腔室壁容积比不受年龄的影响，而在自发性高血压大鼠，这一比例显着下降了18个月。射血分数指数-后负荷关系，即，6个月和12个月大的自发性高血压大鼠的收缩状态的测量与所有年龄的血压正常大鼠的测量相似。然而，自发性高血压大鼠的收缩状态在18个月时出现抑制，并在24个月时进一步抑制。这种收缩状态的异常在心脏性能恶化之前是明显的，如基线和最大心脏指数降低和左心室扩张所反映的。因此，收缩状态（射血分数指数-后负荷关系）是自发性高血压大鼠左心室功能障碍最敏感的指标。
Female spontaneously hypertensive and normotensive rats were studied at 6, 12, 18, and 24 months of age to determine which characteristics of myocardial performance herald the onset of left ventricular dysfunction. Peak ejection fraction index was derived from measurements of peak stroke volume (in vivo volume loading) and passive pressure-volume relations. The myocardial stiffness constant (km, slope of the incremental modulus-stress relation, EINC = km sigma), chamber stiffness constant (kc, slope of the chamber stiffness-pressure relation, dP/dV = kcP), and left ventricular cavitary volume-to-wall volume ratio at 10 mm Hg) were calculated from the pressure-volume data and the contractile state was assessed from the ejection fraction index-afterload relations. In the normotensive rats, the myocardial stiffness constant was not affected by age, whereas, in the spontaneously hypertensive rats, the myocardial stiffness constant remained within normal limits until 18 months, at which time a significant increase in this index of myocardial stiffness occurred. Baseline and maximal cardiac indices and ejection fraction index of spontaneously hypertensive rats were normal from 6 to 18 months, but were markedly reduced at 24 months. This reduction in cardiac performance was associated with a decrease in the left ventricular chamber stiffness constant, i.e., kc. This decreased chamber stiffness, which occurred at a time when myocardial stiffness was increased, was due to a greater increase in cavity size than in myocardial stiffness. The left ventricular cavity-to-wall volume ratio of normotensive rats was not affected by age, whereas, in the spontaneously hypertensive rats, this ratio markedly declined by 18 months. The ejection fraction index-afterload relations i.e., a measure of the contractile state, of the 6- and 12-month-old spontaneously hypertensive rats were similar to those of the normotensive rats of all ages. However, a depression in the contractile state of the spontaneously hypertensive rats occurred at 18 months and was further depressed at 24 months. This abnormality of the contractile state was evident before the deterioration of cardiac performance, as reflected in a decrease in baseline and maximal cardiac indices, and dilation of the left ventricle occurred. The contractile state (ejection fraction index-afterload relation) is thus the most sensitive indicator of left ventricular dysfunction in spontaneously hypertensive rats.