Deep vein thrombosis
What is deep vein thrombosis?
Deep vein thrombosis (DVT) is the formation of blood clots in veins that move blood from various parts of the body back to the heart and lungs. DVT is caused by a combination of factors: change in blood flow, injury to a vein, and/or development of a medical condition which increases the likelihood of forming blood clots. People at increased risk of DVT include those who have been immobilized for long periods (bed rest, hospitalization, long plane flights); have had recent surgery, recent trauma, cancer, current infection, a history of previous DVT, or have a family history of DVT.
Deep vein thrombosis is often seen in the limbs, and most commonly occurs in the deep veins of the legs. A clot can block blood flow and cause blood congestion behind it. With this blockage holding back blood flow, patients experience swelling, pain, redness, warmth, and tenderness to the touch at the calves and thighs. Anyone experiencing these symptoms must see a physician immediately.
Interventional radiologists are board-certified physicians in minimally invasive, catheter-based treatments that address conditions such as deep vein thrombosis. These less invasive methods are often less painful, better tolerated and have quicker recovery time than conventional surgery.
Mechanical treatment of deep vein thrombosis comes in various forms: mechanical thrombectomy, angioplasty, and stent placement. With each treatment, an interventional radiologist makes a small incision to access the femoral vein (the large vein in the leg). Guided by live x-rays, the doctor inserts a catheter (a thin plastic tube) through the vein to the DVT site.
With mechanical thrombectomy, the interventional radiologist guides a device through the femoral vein to the DVT site. Once there, the doctor uses the device to mechanically break up the clot into smaller pieces and remove the clot pieces.
Another option includes the use of angioplasty, in which a balloon is inserted into the vein containing the DVT and expanded in order to open up blood flow through the vein. The interventional radiologist also may opt to use a stent, a tiny expandable tube that props open the vein and prevents it from narrowing again.
With extensive deep vein thrombosis, an interventional radiologist may offer pharmacologic thrombolysis—a treatment that uses medications to dissolve clots. Pharmacologic thrombolysis can be done by two methods: The interventional radiologist makes a small incision in the groin to access the femoral vein (the large vein in the leg) and uses live x-rays to guide a catheter (a thin plastic tube) to deliver medication directly to the site of the DVT clot. Or, the doctor can use the “systemic” method, in which the medication is introduced into the bloodstream far from the DVT site and then flows through the body. The care team, which can include an interventional radiologist, will monitor the effectiveness of treatment by using imaging, such as ultrasound, computerized tomography (CT) scan, and/or venogram.
Pairing catheter-directed treatment with mechanical clot disruption allows the interventional radiologist to use lower doses of the clot-busting medication, which potentially decreases side-effects such as bleeding. Results from the NIH-sponsored ATTRACT Trial help identify which patients may benefit most from the combination treatmemt of pharmacomechanical catheter-directed thrombolysis with blood-thinning drugs. This helps interventional radiologists and other health care professionals deliver effective care by eliminating unnecessary treatments for certain patients.
IVC filters and DVT
Some patients are not able to undergo anticoagulation therapy (treatment that uses medications to reduce the body’s ability to form clots) because of factors such as an increased risk of bleeding. With these individuals, an interventional radiologist can offer treatment using a device called an inferior vena cava (IVC) filter, which acts like a clot filter and prevents clots from traveling through the body and reaching vital organs such as the lungs. IVC filters can either be permanent or retrievable, which can be removed after the threat of DVT or pulmonary embolism goes away. It’s important that patients regularly follow-up with their interventional radiologists for re-evaluation and planning of IVC filter removal when appropriate.
SIR is currently participating in the PRESERVE Trial, the first large-scale, multi-specialty, prospective clinical study to evaluate the use of inferior vena cava (IVC) filters and related follow-up treatment in the United States. This five-year study is sponsored by IVC Filter Study Group Foundation, which is a joint collaboration between the Society of Interventional Radiology (SIR) and the Society for Vascular Surgery (SVS).