Isolated anomalous inferior vena cava with azygos drainage.

In a 79-year-old female with shortness of breath, catheterization via the femoral vein encountered difficulty entering the right heart; venography revealed anomalous drainage of the inferior vena cava via a dilated azygos vein permitting subsequent catheterization. Similar difficulties during catheterization merit consideration of this congenital anomaly, which is virtually always discovered in the pediatric population in association with other congenital anomalies. Its unique discovery at advanced age indicates its benignity as an isolated abnormality.