Changes in ventricular size and plasma renin activity after cardiac surgery in children.

Plasma renin activity and one-dimensional echocardiographic measurements of the left atrium and left ventricle as well as function indices were studied repeatedly in 20 children with various cardiopathies (ages: 9 months to 15 years) before and after corrective surgery. Nine children had tetralogy of Fallot, four had pulmonary stenosis, four had rheumatic heart disease, two had ventricular septal defect, and one had atrial septal defect. Plasma renin activity was normal preoperatively, but increased significantly immediately after surgery, was still significantly higher on the 12th postoperative day and returned to normal six to eight weeks after surgery. Patients with tetralogy of Fallot and pulmonary stenosis had higher plasma renin activity values than the others. There was a positive correlation between plasma renin activity and postoperative percentage change of the left ventricular dimension. In patients with tetralogy of Fallot and pulmonary stenosis, this meant that plasma renin activity became normal when the preoperatively small left ventricle reached its normal dimension. This adjustment occurred slowly over a period of two months. In rheumatic heart disease and left-to-right shunt lesions, plasma renin activities became normal when the preoperatively dilated left ventricle decreased in size towards normal values; the plasma renin activities of these patients had reached normal levels by the fifth postoperative day. The renin secretion is modulated by various factors: of these, ventricular size and pulmonary venous return seem to be of importance.