A vena cava filter is a medical device which is used to reduce the risk of experiencing a pulmonary embolism (PE), an event in which a large clot enters the lungs. Pulmonary emboli can cause serious medical problems, including death, and a number of approaches can be used to make patients less susceptible to a PE, including the implantation of a vena cava filter. If a doctor recommends that such a device should be implanted, it can be performed as an outpatient procedure in a hospital or clinic.
The vena cava is a large vein which brings blood from the lower body to the heart. In patients with clotting disorders or the presence of clots in the lower body, these clots can work their way up the vena cava to the lungs and heart, which is not desired. Anticoagulant medications are often used to manage clotting or to break up clots, but these drugs do not always work, and some patients are at high risk of a PE due to the presence of existing clots, in which case a doctor may recommend a vena cava filter.
This medical device looks a little bit like an umbrella, with arms which catch clots so that they cannot travel up the vena cava. The filter is usually installed in the inferior vena cava, the part of the vein which runs through the abdomen, and it is inserted through a blood vessel in a minor invasive procedure.
Before the filter is inserted, a radiologist injects contrast dye which is used to determine the best placement. Then, the filter is carefully maneuvered into place and left there. Contrast dye will be injected again to confirm that the vena cava filter is placed correctly. Local anesthetic is usually used for the procedure, and the patient may be given antianxiety medications to relax. In some instances, general anesthesia may be used for a vena cava filter placement.
Many vena cava filters are designed to be left permanently in place. The doctor will monitor the patient's condition to confirm that the filter is still working, and to make any necessary adjustments in the patient's treatment plan as needed. Other filters are removable, with a design which can be collapsed to pull the filter into a catheter so that it can safely be pulled from the body. A removable vena cava filter may be used in circumstances when a doctor thinks that the device will be required on a temporary basis only, rather than in the long term.