Contractile State of the Heart Characterized by Force‐Velocity Relations in Variably Afterloaded and Isovolumic Beats
Contractile State of the Heart Characterized by Force‐Velocity Relations in Variably Afterloaded and Isovolumic Beats
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可变后负荷和等容搏动中以力-速度关系为特征的心脏收缩状态
DOI：
10.1161/01.res.18.2.149
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发表时间：
1966
影响因子：
20.1
通讯作者：
E. Braunwald
中科院分区：
文献类型：
--
作者：
J. Ross;J. Covell;E. Sonnenblick;E. Braunwald
以类似于在离体肌肉中所采用的方式，即，通过连续的，可重复的变化，在后负荷单独，从一个恒定的舒张末期容积。用电磁流量计测量左室射血率，计算左室壁张力、心肌纤维和收缩成分的缩短速度。通过分析射血早期的等容点，缩短速度，活动状态持续时间和瞬时肌肉长度的其他两个决定因素所产生的影响被最小化。通过外推法获得的Vmax和最大张力的变化清楚地表明了基本力-速度关系的变化。去甲肾上腺素和成对的电刺激导致这种关系向右偏移，在任何张力下速度都增加，急性心力衰竭则向左偏移，在任何张力下速度都降低。在单次等容收缩期间计算的张力与速度相关的曲线中也出现了类似的变化。有人建议，这些关系的确定扩展了心室性能的传统定义，最大速度以及最大强度相对于肌肉长度的变化的估计提供了直接的信息有关的完整心脏的收缩状态的改变。
Relations between tension and the velocity of shortening in the intact left ventricle of the dog were examined in a manner analogous to that employed in isolated muscle, i.e., by serial, reproducible variations in the afterload alone, from a constant end diastolic volume. Sudden increases or decreases in the aortic pressure during diastole were produced, and ejection rate was measured with an electromagnetic flowmeter; LV wall tension and the shortening velocities of the myocardial fibers and the contractile elements were then calculated. By analyzing isovolume points early in ejection, effects resulting from two other determinants of shortening velocity, duration of active state and instantaneous muscle length, were minimized. Shifts in the basic force-velocity relation with alterations in Vmax, obtained by extrapolation, and maximum tension were clearly demonstrated. Norepinephrine and paired electrical stimulation caused a shift in this relation to the right, with increases in velocity at any tension, and acute heart failure produced a shift to the left, with decreases in velocity at any tension. Similar shifts were also apparent in curves relating tension to velocity, calculated during single isovolumic contractions. It was suggested that determination of these relations expands traditional definitions of ventricular performance, and that estimation of changes in maximum velocity as well as maximum strength relative to muscle length provides direct information concerning alterations in the contractile state of the intact heart.