Stein P A, McBride C G, Sabbah H N
Cardiovasc Res. 1975 Jan;9(1):29-37. doi: 10.1093/cvr/9.1.29.
During isovolumic contraction, there is a calculabe compression of the blood within the ventricle. Energy is expended by the ventricle during isovolumic contraction, and some of it is transferred to the blood in the form of elastic compression. The rate of energy transfer (power) and acceleration of energy transfer (rate of change of power) during isovolumic contraction were calculated based upon considerations of the energy of compression. In anaesthetized dogs, the isovolumic energy of compression was 42 plus or minus 6 (mean plus or minus SE) dyn cm; peak isovolumic power was 1,400 plus or minus 300 dyn cm sec-1; and peak rate of change of power was 56,000 plus or minus 15,000 dyn cm sec-2. During states of augmented contractility induced by isoproterenol, the peak acceleration of energy expeniditure (peak rate of change of power) increased to 126,000 plus or minus 33,000 dyn cm sec-2 (p smaller than 0.001). Conversely, with a reduction of contractility induced by propranolol, the peak isovolumic rate of change of power decreased to 30,000 plus or minus 5,700 dyn cm sec-2 (p smaller than 0.001). The peak rate of change of power was unaffected by changes of the afterload. A trend, however, suggests that it may be affected by preload. The derivations of the isovolumic energy of compression, power, and rate of change of power are based upon firm principles of fluid dynamics. No assumptions related to ventricular geometry, synergy of contraction, or characteristics of muscle fibers are implied. Because of its physiological meaning and the theoretical validity of its derivation, an expression such as the isovolumic peak rate of change of power, when utilized as an index of ventricular performance, would appear to be of value.
在等容收缩期，心室内的血液会受到可计算的压缩。心室在等容收缩期消耗能量，其中一部分以弹性压缩的形式传递给血液。基于压缩能量的考虑，计算了等容收缩期的能量传递速率（功率）和能量传递加速度（功率变化率）。在麻醉犬中，等容压缩能量为42±6（均值±标准误）达因厘米；等容峰值功率为1400±300达因厘米秒⁻¹；峰值功率变化率为56000±15000达因厘米秒⁻²。在异丙肾上腺素诱导的收缩力增强状态下，能量消耗的峰值加速度（峰值功率变化率）增加到126000±33000达因厘米秒⁻²（p＜0.001）。相反，在普萘洛尔诱导的收缩力减弱时，等容峰值功率变化率降至30000±5700达因厘米秒⁻²（p＜0.001）。功率的峰值变化率不受后负荷变化的影响。然而，有一种趋势表明它可能受前负荷的影响。等容压缩能量、功率和功率变化率的推导基于流体动力学的坚实原理。未隐含与心室几何形状、收缩协同作用或肌纤维特性相关的假设。由于其生理意义及其推导的理论有效性，诸如等容峰值功率变化率这样一种表达式，当用作心室功能指标时，似乎具有价值。
