The influence of left ventricular filling pressure on atrial contribution to cardiac output.

The influence of left ventricular filling pressure on the atrial contribution filling pressure and atrial contribution was seen in studies done at baseline (PCW (r=-.53, p less than .025), as well as in studies done after PCW was modified by volume expansion and/or nitrates (r=-.53, p less than .005). At baseline, atrial contribution averaged 9.3 +/- 1.3 c.c./M.2 in patients with PCW less than 20 mm. Hg, while it was only 2.4 +/- 1.2 c.c./M.2 in patients with PCW greater than or equal to 20 mm. Hg (p less than .005). Atrial contribution was significantly greater in patients who had no history of heart failure when they were volume loaded to a PCW above 20 mm. Hg than in patients with impaired ventricular function whose baseline PCW was above 20 mm. Hg. Thus, atrial contribution tends to be less effective in augmenting cardiac output when filling pressure is already elevated, particularly in patients with impaired left ventricular function.