Systemic endothelial dysfunction in adults with cyanotic congenital heart disease

Secondary erythrocytosis results in increased shear stress in cyanotic congenital heart disease (CCHD), which may modify the balance between vasodilators and vasoconstrictors and affect systemic endothelial function. Because no data are available on systemic vasomotion, systemic endothelial function and nitric oxide (NO) availability were investigated in CCHD patients.

Responses to arterial endothelium-dependent (acetylcholine [Ach]) and -independent (sodium nitroprusside [SNP]) vasodilation, NO synthase blockade (NG-monomethyl-L-arginine [L-NMMA]), endothelin-1 (ET-1), and ET-1 receptor blockade by BQ-123 in 11 CCHD patients (O2 saturation <90%; mean+/-SD, 79+/-1%; mean+/-SD age, 39+/-2 years) were compared with those in 10 age-matched healthy referents by using forearm venous occlusion plethysmography. Resting forearm blood flow (FBF) was lower in CCHD patients than in referents (2.4+/-0.2 versus 3.5+/-0.4 mL.min(-1).100 mL(-1) of forearm volume [FAV], P<0.05). Although the response to SNP was similar in both groups (CCHD, 2.0+/-0.3 to 8.3+/-1.0; referents, 3.6+/-0.7 to 11.9+/-1.2 mL.min(-1).100 mL(-1) of FAV; P>0.1), the response to Ach was markedly reduced in CCHD (maximal increase in FBF, 2.8+/-0.8 versus 37.5+/-4.4 mL.min(-1).100 mL(-1) of FAV; P<0.0001). l-NMMA was less effective in CCHD (decrease in FBF, 25+/-6% versus 40+/-4%; P<0.05). ET-1 caused less vasoconstriction in the CCHD group (-25+/-9% versus -51+/-7%, P<0.05), but the response to BQ-123 was similar in both groups (32+/-9% versus 27+/-9%).

Systemic endothelial dysfunction is evident in CCHD patients as shown by strikingly reduced endothelial vasodilation to Ach. The response to exogenous ET-1 is reduced, possibly because of elevated endogenous ET-1 levels, but the effects of endogenous ET-1 on arterial tone are not enhanced, as indicated by the similar response to ET-1 blockade.