A 52 year old male patient presented with an acute inferior myocardial infarction. His past medical history was unremarkable, and he was well up to 12 hours before presentation. He initially made an uneventful recovery during the first day, but on the second day postinfarction he developed symptomatic bradycardia necessitating temporary cardiac pacing, which was inserted via the right femoral vein under fluoroscopy. The pacing electrode catheter reached the right ventricular apex with an abnormal course (left panel), which forced us to consider an inferior vena cava (IVC) anomaly. On the seventh day of admission, three dimensional reconstructed multislice computed tomography of the whole thorax and abdomen delineated the complete absence of the right IVC trunk. The postrenal part of the IVC was present and transposed to the left side of the vertebral column, juxtaposing with the abdominal aorta (right panel). The other segments of the IVC—that is, the hepatic, prerenal, and renal parts—were also missing. The left renal vein drained directly into the left paravertebrally located IVC; by contrast, the right renal vein drained into the right azygos vein. Because of the absence of the hepatic segment of the IVC, all hepatic veins entered the inferior part of the right atrium. The enlarged right azygos vein joined the right superior vena cava at the right paratracheal space. All venous blood flow except from the hepatic veins entered the heart through the azygos and superior vena cava. This anatomical variant associated with renal vein drainage anomalies was consistent with IVC interruption and azygos continuation.

We describe an unusual case of an adult patient with IVC interruption and azygos continuation, in whom any symptoms or signs of complications of this anomaly were absent. This disorder has been described mainly as an incidental finding associated with a number of congenital malformations, especially with polysplenia syndrome. This anomaly is encountered in at least 65% of these patients. The incidence of congenital anomalies of the IVC is, however, less than 1% in individuals who have no other congenital malformation.