The Annals of Thoracic Surgery, Vol 46, 430-437, Copyright © 1988 by The Society of Thoracic Surgeons
Impact of acute reduction in chronically elevated left atrial pressure on sodium and water excretion
RP Shannon, E Libby, D Elahi, RM Weintraub, RL Thurer, R Johnson and JY Wei
Charles A. Dana Research Institute, Beth Israel Hospital, Boston, MA 02215.
To test the hypothesis that a reduction in chronically elevated left atrial
pressure would decrease sodium and water excretion in humans, we studied 61
carefully selected patients who underwent cardiac surgery for valvular or
coronary artery disease or both. The immediate postoperative decrease in
left atrial pressure (from 16.7 +/- 1.0 to 9.4 +/- 0.4 mm Hg; p less than
0.001) was inversely correlated with postoperative urine output (r = -0.69;
p less than 0.001) and sodium excretion (r = -0.51; p less than 0.005).
There was no significant relationship between postoperative urine output or
sodium excretion and other hemodynamic or nonhemodynamic variables. A
significant postoperative decrease in plasma atrial natriuretic factor
(from 150 +/- 22 to 65 +/- 14 pg/ml; p less than 0.01) and increase in
plasma renin activity (from 2.5 +/- 0.6 to 8.7 +/- 3.2; p less than 0.05)
occurred in patients with a 7 mm Hg or greater postoperative decrease in
left atrial pressure. Thus, an acute reduction in left atrial pressure
results in significant reductions in urine output and sodium excretion, the
magnitude of which are related to the degree of reduction in left atrial
pressure.
