Urotensin II (U-II) is a vasoactive peptide that has been highly conserved throughout evolution. U-II has been described as the most potent vasoconstrictor yet identified.¹ The identification in humans of immune reactive U-II in plasma, the U-II receptor, and U-II expression in the myocardium, arterial system, and kidney and the elevation of U-II in important disease states such as hypertension and congestive heart failure suggest that U-II may be an important mediator in the regulation of cardiovascular function.^1–4

U-II has never been investigated in children with congenital heart disease (CHD) and in those undergoing cardiac surgery requiring cardiopulmonary bypass (CPB). The objective of this study was twofold. Firstly, we compared plasma U-II in children with CHD with concentrations in healthy children; and secondly, we examined the 24 hour profile of U-II in children undergoing open heart surgery.

PATIENTS AND METHODS

Forty children undergoing surgery for CHD were recruited, of whom 20 had low or normal preoperative pulmonary blood flow (LNF group; undergoing valve repairs, relief of outflow tract obstruction, tetralogy of Fallot repair, Fontan operations, and arterial switch operation) and 20 had high preoperative pulmonary blood flow (HF group; undergoing closure of septal defects). In the HF patients, preoperative angiotensin converting enzyme inhibitors were being taken by five children, diuretics by seven, and digoxin by one child. Seventeen of the children with CHD underwent modified ultrafiltration (MUF) after CPB, according to institutional protocols. Twenty children without cardiopulmonary or renal disease who were undergoing day case surgical procedures were also recruited for the study (controls).

In controls, a single blood sample was taken after induction of anaesthesia. In …