The inferior vena cava (IVC) is a large vein that enters the bottom part of the heart. Venous blood from the lower portion of the body drains into the IVC. The IVC then returns blood back to the heart. An IVC filter is placed to help prevent the blood clots moving from the legs to the heart or lung. The idea behind using a filter in the IVC is to capture potential fatal pulmonary emboli at an anatomical location where they may pose less risk for the patient. Early filters, 1960's and 70's were, remained in the vein permanently. More recently, temporary or retrievable filters have been developed and are being widely used.