Nb. Ingels et al., LEFT-VENTRICULAR DIASTOLIC SUCTION WITH ZERO LEFT ATRIAL PRESSURE IN OPEN-CHEST DOGS, American journal of physiology. Heart and circulatory physiology, 39(4), 1996, pp. 1217-1224
We investigated left ventricular (LV) diastolic volume changes (suctio
n 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 +/- 1.4
4 mmHg before the clamp and fell to 0.74 +/- 0.61 mmHg (P < 0.0001) af
ter the clamp. During the first clamped beat a transmitral pressure gr
adient 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 sucti
on can be an important filling mechanism under conditions in which LV
end-systolic volume is reduced, e.g., reduced filling pressures, high
heart rates, exercise, or increased inotropic drive.