INFLUENCE OF LEFT-VENTRICULAR FILLING PRESSURE ON ATRIAL CONTRIBUTION TO CARDIAC-OUTPUT

The influence of left ventricular filling pressure on the atrial contribution to cardiac output was evaluated in 18 patients. An inverse relationship between filling pressure and atrial contribution was seen in studies done at baseline (PCW (r = -.53, p < .025), as well as in studies done after PCW was modified by volume expansion and/or nitrates (r = -.53, p < .005). At baseline, atrial contribution averaged 9.3 ± 1.3 c.c./M.2 in patients with PCW < 20 mm. Hg, while it was only 2.4 ± 1.2 c.c./M.2 in patients with PCW ≥ 20 mm. Hg (p < .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. © 1979.