Acute sternal opening after cardiac surgery in children: effect on plasma atrial natriuretic peptide.

Plasma atrial natriuretic peptide (ANP) was measured immediately before and 15 minutes after re-opening of the sternotomy and delayed sternal closure were performed to alleviate possible myocardial compression in 3 children. As acute re-opening of the sternotomy is a rare occurrence our sample size was necessarily small. ANP increased following the procedure in all 3 patients, and this was significant (p less than 0.02) when compared to plasma levels obtained from 9 children who underwent sternotomy prior to elective cardiac surgery. Following acute re-opening of the sternotomy there was an increase in median urine output and a decrease in median central venous pressure. Our results illustrate that it is atrial wall stress rather than intra-atrial pressure that determines release of ANP, and in addition suggest ANP may be a factor in the rapid clinical improvement following delayed sternal closure for atypical tamponade in children.