Elevated atrial natriuretic peptide after the Fontan procedure.

ABSTRACT

To assess the response of atrial natriuretic peptide (ANP) to rapidly changing right atrial pressures in vivo, we measured ANP levels in 15 patients undergoing the Fontan procedure and compared them with control levels in nine patients undergoing cardiac surgery for lesions not associated with atrial hypertension. There were no significant differences in preoperative ANP levels 57 +/- 15 pg/ml for patients undergoing the Fontan procedure, 43 +/- 8 pg/ml for control patients. There was no significant change in ANP during surgery or in the postoperative period in control patients. In contrast, ANP increased significantly to 333 +/- 70 pg/ml (p less than .0025) after establishment of right atrial-pulmonary artery continuity with the Fontan procedure and was related to right atrial pressure, which increased from 5 mm Hg before to 14 mm Hg after the Fontan procedure (p less than .001). There was no significant change in left atrial pressure. During the first postoperative day, ANP levels fell to 141 +/- 34 pg/ml (p less than .01) but later increased to 290 +/- 80 pg/ml (p less than .025), a finding that may suggest depletion of a readily releasable intracellular pool of ANP before mobilization of a storage pool. There was no direct relationship between ANP levels and effusions in patients undergoing the Fontan procedure. Pharmacologically significant increases in ANP occur in patients undergoing the Fontan procedure, correlating with increased right atrial pressures, but the relationship between ANP and the fluid derangements after the procedure remains unclear.