SYMPATHETIC ACTIVITY IN CHILDREN UNDERGOING BALLOON VALVULOPLASTY OF PULMONARY STENOSIS

We studied the influence of balloon valvuloplasty on alpha- and beta-a drenoceptor densities, plasma catecholamine, and cAMP levels in childr en and infants with pulmonary stenosis before and 10 min after balloon dilatation, employing as controls children undergoing transcatheter o cclusion of patent ductus arteriosus (PDA) with Q(p)/Q(s) ratio < 1.5. In the PDA group, the alpha-adrenoceptor density (B-max) was 3.75 +/- 0.72 fmol/10(7) cells (n = 15) before occlusion and remained unchange d at 3.35 +/- 0.47 fmol 10 min thereafter. In the pulmonary stenosis p atients (n = 31), the receptor density was 59% higher (p < 0.05) befor e, and decreased to PDA levels 10 min after, the procedure. The contro l beta-adrenoceptor density was 64.8 +/- 11.0 fmol/10(6) cells before, and 71.2 +/- 13.2 fmol 10 min ater, occlusion. In the study group, th e density was 23% lower (p < 0.07) and increased to the PDA levels 10 min after the dilatation. Compared with the PDA, pre- and postdilatati on plasma norepinephrine levels were not significantly changed; epinph rine was slightly elevated before, but increased by 73% after dilatati on; dopamine was 80% (p < 0.05); and cAMP was 37% higher before, and r emained elevated at 70 and 23% above the PDA values after, the procedu re. Accordingly, alpha-adrenoceptor density is significantly elevated in children with pulmonary stenosis and decreases significantly immedi ately after balloon valvuloplasty. On the other hand, beta-adrenocepto r density is attenuated and increases toward normal levels after the p rocedure. The immediate reversal of the receptor levels after balloon valvuloplasty suggests that this procedure exerts acute effects on the sympathetic functional level in this disease.