A vena cava filter using thermal shape memory alloy. Experimental aspects.

Surgical ligation of the vena cava in the treatment of pulmonary embolism is already being superseded by devices introduced via a peripheral vein. A new metal alloy (nitinol) with unique memory characteristics forms the basis of an experimental device which promises even greater safety, simplicity and speed of introduction. It is inserted as a straight thin wire via the small bore catheter used for angiographic diagnosis. Upon reaching the lumen of the inferior vena cava and sensing body temperature, it reverts to its preset complex filter shape and locks into place permanently. It will trap further thromboemboli from the pelvis or lower limbs.