Inferior Vena Cava (IVC) filters are placed in a patient’s vena cava to prevent blood clots from traveling to the heart and lungs. If a blood clot travels to the heart or lung, it could be fatal. An IVC filter can either be permanent or retrievable. Permanent filters are made of stainless steel and titanium. Retrievable filters are made out of nitinol. Pieces of retrievable filters can break off and travel to the heart and lungs. A piece of filter that breaks off can be fatal or cause serious injury. About 250,000 IVC filters are implanted into patients each year. Eleven different companies sell IVC filters in the United States.