Definition: Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.
Input: Abstract: Recurrent pulmonary embolism from the lower extremities or pelvis, despite anticoagulation, often requires interruption of the inferior vena cava (IVC). We report two patients in whom interruption of the IVC failed to ameliorate symptoms. Both patients demonstrated a previously unrecognized duplication of the IVC. We stress the importance of excluding abdominal venous anomalies prior to interrupting the IVC using surgical or percutaneous methods.

Duplication of the inferior vena cava in thromboembolic disease.