Blood clots prevent excess bleeding when a blood vessel is injured, inside or out. Generally, clots are broken down naturally by the body over time, but when this doesn’t happen, problems can arise. 

One such problem is deep vein thrombosis (DVT), the name for a condition in which blood clots form deep in a vein of the leg. DVTs can occur when a person is immobile for long periods of time, such as during an international flight or in a person with a spinal cord injury. DVTs can also happen in people who have health conditions associated with clot formation, such as cancer or an inherited blood disorder. 

A potential danger is that a blood clot can break off and travel to another area of the body. This is called an embolus. If an embolus travels to the lungs, it could block one of the pulmonary arteries, creating a pulmonary embolism, which is life-threatening. Pulmonary embolism is among the leading causes of death worldwide. 

If recognized, DVTs are typically treated with medications called blood thinners that dissolve them before they can become pulmonary embolisms. Not everyone can take these medications, however. Another option for potentially preventing blood clots from going to the lungs is called an inferior vena cava (IVC) filter. An IVC is a special basket-like filter to trap clots that can be inserted into the inferior vena cava, a large vein in the abdomen that carries blood from the lower to the upper half of the body to the heart. 

Doctors can implant an IVC filter permanently or temporarily, depending on the patient’s needs. “IVC filters can help to save lives, and it is important to remove IVC filters as soon as they’re no longer needed to reduce long-term complications,” says Hamid Mojibian, MD, director of cardiac CT/MR Imaging for Yale Medicine’s Department of Radiology & Biomedical Imaging.

Doctors try to dissolve or remove clots before they have a chance to become embolisms. The following conditions increase the risk for developing a pulmonary embolism:

• Family history of blood clotting disorders
• Surgery or injury (especially to the legs) that decreases mobility
• Paralysis or extended bed rest
• Previous history of blood clots
• Advanced age
• Smoking
• Obesity
• Cancer and cancer therapy
• Medical conditions such as heart failure, chronic obstructive pulmonary disease (COPD), high blood pressure, stroke, and inflammatory bowel disease
• Taking some medications, including birth control pills and estrogen replacement therapy
• Having enlarged veins in the legs (varicose veins)
• Not moving for long periods of time
• Pregnancy

The main treatment for blood clots in legs and prevention of pulmonary embolism is the use of blood thinners. Alternatively, IVC filters can be helpful for people with a history of developing blood clots, including those diagnosed with deep vein thrombosis and previous pulmonary embolism, as well as people who are immobile or have experienced a physical trauma and cannot take blood thinners. 

Below are conditions that would prohibit the use of blood thinners: 

• Digestive tract bleeding
• Brain bleed
• Recent brain or spinal cord surgery
• Hemorrhagic stroke
• Recent trauma
• Risk of fall due to age or other medical problems

To place an IVC filter, an interventionalist makes a small incision through the neck or groin and moves a thin, flexible tube (known as a catheter) through a vein. The catheter, carrying a collapsed filter, is sent through a blood vessel to the inferior vena cava. The filter remains after the catheter is removed, expanding to fit between the walls of the inferior vena cava. As blood circulates, the filter traps blood clots and prevents them from moving to the heart and lungs.

IVC filters come in permanent or temporary (retrievable) models. With new research showing a risk of fractured filters over long periods of time, raising the risk that a patient will develop a DVT, there has been an increase in the use of retrievable IVC filters. 

Retrievable IVC filters may be removed once the risk of a clot traveling to the heart and lungs passes, usually after about six months. If blood thinners are unusable and/or the risk of clots continues, a removable filter may remain in place for an extended period of time.  

Retrievable IVC filter should be removed according to manufacturer and clinical guidelines and assessment. 

These devices are placed and removed by an IR physician using precision image guidance. The removal procedure is done, usually on an outpatient basis, under light sedation. The process is similar to insertion. Through a very small puncture in the skin in the groin or neck, the interventional radiologist will insert a long tube (catheter) equipped with a removal device to the treatment area. 

Contrast dye material may be injected to help with visibility. Once the filter is removed, the vein in which the IVC filter was placed will be sealed. The catheter will be removed, and the skin puncture will be covered with a small bandage. This procedure usually takes about an hour.

Risks associated with IVC filter placement and removal include:

• Excess bleeding
• Infection
• Allergic reaction
• Damage to the blood vessel at the insertion site
• Blockage of blood flow to the vena cava
• Leg swelling
• A dislodged filter traveling to the heart or lungs
• Damage to other organs from a IVC filter puncture
• Continued risk of a blood clots
• Failure to remove the filter

“The latest technology in venous condition and IVC filter medicine is practiced at Yale Medicine. Expert physicians care for and guide patients with acute and chronic venous conditions for better health,” says Dr. Kim.

Yale Medicine IR experts treat patients in a cutting-edge, state-of the-art IR suite. Yale Medicine IR doctors use the latest technology to safely and effectively care for patients with venous thromboembolic conditions.

At Yale Medicine, the Interventional Radiology team is committed to follow every patient with an IVC filter to ensure timely removal of the filter and also to monitor any potential complications associated with IVC filter insertion.