Atrial natriuretic peptide and atrial pressures in newborns with transposition of the great arteries.

The relation of atrial pressure to atrial plasma concentration of atrial natriuretic peptide (ANP) was studied in four newborns undergoing catheterization because of transposition of the great arteries. In three patients, mean left atrial pressure clearly exceeded right atrial pressure (12 +/- 7 vs. 2 +/- 3 mmHg; mean +/- SD). In one patient mean atrial pressures were identical (4 mmHg). In all patients the ANP concentration in the left atrium exceeded that of the right (833 +/- 464 vs. 415 +/- 366 pg/ml; mean +/- SD). There was a significant (r = 0.97; p less than 0.01) correlation between pressure and ANP concentration in the left atria. In the right atria, no linear correlation existed between pressure and ANP concentration. ANP concentration in the left atrium decreased after a lowering of the left atrial pressure by atrial septostomy. In these patients, the left atrium seems to be the main source of circulating ANP.