Miller W P, Liedtke A J, Nellis S H
Am J Physiol. 1986 Apr;250(4 Pt 2):H606-11. doi: 10.1152/ajpheart.1986.250.4.H606.
Pulsus alternans has previously been ascribed to variations in end-diastolic fiber length and/or an alternating contractile state. In six paced, whole blood-perfused, intact, working pig hearts, left ventricular internal diameters were measured with ultrasonic crystals, and left ventricular pressures were measured with a micromanometer-tipped catheter. Pulsus alternans was induced with propranolol (24-51 micrograms X kg-1 X min-1). End-systolic pressure-diameter relationships were determined during pulsus alternans from a series of consecutive, variably volume-loaded beats using a previously described technique. Beats analyzed prior to any change in loading conditions revealed a left ventricular pressure of 62.7 +/- 8.7 mmHg for the strong beats and 55.2 +/- 7.0 for the weak beats (P less than 0.050). The end-diastolic diameter prior to the stronger beats was larger than that prior to the weaker beats (24.80 +/- 2.73 vs. 23.82 +/- 2.82 mm, P less than 0.025), but there was no significant difference in the corresponding end-diastolic pressures. The maximum dP/dt of the strong beats was 1,275 +/- 249 mmHg/s compared with 1,038 +/- 222 for the weak beats (P less than 0.025). The slope of the end-systolic pressure-diameter relationship, which provides an index of contractility independent of end-diastolic diameter, averaged 42.3 +/- 6.4 mmHg/mm for the strong beats and 24.4 +/- 6.8 for the weak beats (P less than 0.025). These data support an alternating contractile state as an independent mechanism for pulsus alternans in the intact animal.
交替脉以前被归因于舒张末期纤维长度的变化和/或交替的收缩状态。在6个经起搏、全血灌注、完整的工作猪心脏中，用超声晶体测量左心室内径，用微测压导管测量左心室压力。用普萘洛尔（24 - 51微克×千克⁻¹×分钟⁻¹）诱发交替脉。使用先前描述的技术，在交替脉期间，从一系列连续的、不同容量负荷的搏动中确定收缩末期压力-直径关系。在负荷条件发生任何变化之前分析的搏动显示，强搏动的左心室压力为62.7±8.7 mmHg，弱搏动的左心室压力为55.2±7.0 mmHg（P<0.050）。强搏动之前的舒张末期直径大于弱搏动之前的舒张末期直径（24.80±2.73对23.82±2.82毫米，P<0.025），但相应的舒张末期压力没有显著差异。强搏动的最大dP/dt为1275±249 mmHg/s，而弱搏动的最大dP/dt为1038±222 mmHg/s（P<0.025）。收缩末期压力-直径关系的斜率提供了一个独立于舒张末期直径的收缩性指标，强搏动的平均斜率为42.3±6.4 mmHg/mm，弱搏动的平均斜率为24.4±6.8 mmHg/mm（P<0.025）。这些数据支持交替的收缩状态是完整动物中交替脉的一种独立机制。
