Abnormal development of the inferior vena cava and its implications on distal venous drainage during cardiac surgery and other clinical entities

Congenital anomalies of the inferior vena cava (IVC) are caused by an abnormal persistence or regression of embryonic precursor veins; they are usually incidental findings on imaging studies. These rare conditions have a 0.6% prevalence in individuals with congenital heart diseases and 0.3% in healthy patients. The purpose of this paper was to report two cases of interruption of IVC with hemiazygos continuation and its implications during surgery, highlighting that after recognizing this anomalous drainage the surgeon should be prepared to change the surgical strategies, especially in cardiovascular surgery, in order to obtain adequate circulatory flows or surgical exposure where venous cannulation could be difficult. We have also reported two cases of healthy patients with the same isolated IVC anomaly with no clinical repercussions, which can develop in the future.