RELATION OF ELEVATED PLASMA ENDOTHELIN IN CONGENITAL HEART-DISEASE TOINCREASED PULMONARY BLOOD-FLOW

Endothelin-1 (ET), a potent vasoconstrictor pepetide, has been found t o be elevated in children with pulmonary hypertension associated with congenital heart defects. To evaluate the effects of pulmonary blood f low on ET concentrations, 5 ml blood samples were obtained peripherall y at cardiac catheterization from 35 patients, ages 0.13 to 17 years ( median 2). Plasma was extracted and ET measured by radioimmunoassay. P atients were classified into 2 groups based on the presence (group A) or absence (group B) of increased pulmonary blood flow defined as a Qp /Qs greater-than-or-equal-to 1.5. When the 13 patients (37%) in group A were compared with the 22 patients (63%) in group B there were no si gnificant differences in age, cardiac index, or pulmonary and systemic resistances. ET concentrations were significantly higher in group A p atients (median 3.25, range 0 to 16.5 vs median 0, range 0 to 6.35 pg/ ml; p less-than-or-equal-to 0.05). Pulmonary blood flow and pulmonary artery pressure were also higher in group A patients (p less-than-or-e qual-to 0.01). When patients within group A were subdivided into those with and without pulmonary hypertension, no difference was present in their ET concentrations (mean/SD: 4.4/4.3 vs 4.0/6.4 pg/ml, p = NS). Thus, ET is elevated in patients with congenital heart disease associa ted with left-to-right shunts and it appears that this increase is rel ated to increased pulmonary blood flow independent of pulmonary artery pressure.