Ingels N B, Daughters G T, Nikolic S D, DeAnda A, Moon M R, Bolger A F, Komeda M, Derby G C, Yellin E L, Miller D C
Department of Cardiovascular Physiology and Biophysics, Palo Alto Medical Foundation 94301, USA. (With the Technical Assistance of Cynthia E. Handen, Mary K. Zasio, and Erin M. Schultz.)
Am J Physiol. 1996 Apr;270(4 Pt 2):H1217-24. doi: 10.1152/ajpheart.1996.270.4.H1217.
We investigated left ventricular (LV) diastolic volume changes (suction inflows) with left atrial pressure (LAP) clamped to ambient pressure in six open-chest, anesthetized dogs. The left atrium was cannulated and connected to a servo pump, and LAP was clamped to a set point near 0 mmHg for four beats by withdrawing blood. LAP averaged 5.88 +/- 1.44 mmHg before the clamp and fell to 0.74 +/- 0.61 mmHg (P < 0.0001) after the clamp. During the first clamped beat a transmitral pressure gradient of 1.0 +/- 0.6 mmHg was observed, resulting in LV filling of 2.6 +/- 1.8 ml. Subsequent beats developed suction-driven (mean negative LV pressure: -1.5 +/- 1.3 mmHg; P < 0.005 vs. zero) LV filling of 4.5 +/- 2.8 ml/beat with a peak transmitral pressure gradient of 1.7 +/- 0.6 mmHg. These data are consistent with the hypothesis that LV suction can be an important filling mechanism under condition in which LV end-systolic volume is reduced, e.g., reduced filling pressures, high heart rates, exercise, or increased inotropic drive.
我们在六只开胸麻醉犬中，将左心房压力（LAP）钳夹至环境压力，研究左心室（LV）舒张期容积变化（抽吸流入量）。左心房插管并连接至伺服泵，通过抽血将LAP钳夹至接近0 mmHg的设定点，持续四个心动周期。钳夹前LAP平均为5.88±1.44 mmHg，钳夹后降至0.74±0.61 mmHg（P<0.0001）。在第一个钳夹心动周期中，观察到跨二尖瓣压力梯度为1.0±0.6 mmHg，导致左心室充盈2.6±1.8 ml。随后的心动周期出现抽吸驱动的左心室充盈（平均左心室负压：-1.5±1.3 mmHg；与零相比P<0.005），每搏充盈量为4.5±2.8 ml，跨二尖瓣压力梯度峰值为1.7±0.6 mmHg。这些数据与以下假设一致，即在左心室收缩末期容积减少的情况下，例如充盈压降低、心率加快、运动或心肌收缩力增强，左心室抽吸可能是一种重要的充盈机制。
