EDN1 and atrial septal defect: At 12 months after transcatheter closure there was still a significant difference in ET-1 levels both in the peripheral artery (0.049 ± 0.025 vs. 0.49 ± 0.17, p < 0.001) and in the peripheral vein (0.054 ± 0.027 vs. 0.40 ± 0.19, p < 0.001) between patients with closed ASD and healthy volunteers.