Pulmonary arteriovenous malformation (PAVM) is common after cavopulmonary anastomosis. PAVMs appear on chest X-ray film as diffuse opacity in one or both lungs. Angiographically, it appears as spidery diffuse vascularity with near simultaneous opacification of pulmonary arteries and veins.
Singhi, A. K., & Kumar, R. K. (2009). Pulmonary arteriovenous malformations after cavopulmonary anastomosis. Annals of Pediatric Cardiology, 2(2), 177–178. https://doi.org/10.1016/S0003-4975(99)00407-5