Indications
A DVT is a blood clot (thrombus) within a vein of the leg. Patients are at risk for a DVT if they are inactive for a long period of time (such as during a long airline flight or if they are suffering from a prolonged illness). In addition, damage to the blood vessels as a result of surgery or an injury can put patients at risk for clot formation. Cancer and genetic problems that result in clotting abnormalities can also put patients at risk for DVT. Other risk factors for DVT include obesity, a history of heart problems, pregnancy, and the use of birth control pills.
Formation of a DVT within the legs can lead to leg swelling and aching. The leg can become quite painful when walking or when it is touched. In addition, the leg can feel warm or become red in color. A small blood clot in the leg may not cause any symptoms. A DVT is dangerous because clots in the legs can potentially travel through the veins to the lungs. When a clot reaches the lungs, it is known as a pulmonary embolism, which can cause severe breathing problems. That is why prompt diagnosis and treatment of a DVT is so important. In addition, DVT can damage the vein wall and the valves inside of the vein, leading to what is known as a post-thrombotic syndrome. When this occurs, there can be abnormal pooling of blood in the leg, chronic leg pain, fatigue, swelling, and possibly skin ulcers. Some form of this can occur in as many as 60-70% of patients with a DVT. This is the reason why many physicians are becoming more aggressive in their treatment of DVT.
Procedural Details
When a DVT is suspected, an ultrasound is typically the first test that is performed. This is a painless test that usually takes less than 30 minutes to perform. During this test, the sonographer places the ultrasound transducer on the leg and images the veins of the leg from the groin to the calf. It is possible to directly visualize blood flow and clot within a leg vein using ultrasound. Historically, a test known as a venogram was used for a diagnosing a DVT, but this has been essentially replaced with ultrasound. Today, venography is reserved for patients who have difficulty undergoing an ultrasound examination (usually due to large legs) or who have had an ultrasound examination that was unable to definitely conclude if a DVT is present. An interventional radiologist performs this test. It involves placing a small needle into a vein in the foot and then injecting an x-ray dye into the veins. This enables the veins to be directly observed with x-rays, which typically allows for a definitive diagnosis of DVT to be made.
Once the diagnosis of a DVT has been made, a discussion will take place regarding treatment. DVTs are most commonly treated with blood thinners (also known as anticoagulation). This medication prevents the formation of new blood clots. It should be taken every day as prescribed; you will likely have to take the medicine for 3-6 months, but possibly longer depending on your risk factors. Antiocoagulation medications can be taken in pill form or may require an injection. Some medications require regular blood tests to monitor its effectiveness. Your doctor will discuss the options with you.
Catheter-directed thrombolysis is performed by Albany IR and is best performed as soon as possible after a DVT is diagnosed. Prior to the procedure, some patients may receive a CT scan of the head to make sure that there is not an increased risk for bleeding. During this procedure, a small catheter (tube) is placed directly into the affected vein, usually from behind the knee. Once the catheter is in place, a drug can be administered directly into the clot in order to dissolve the clot. New devices are now available which can disrupt the clot in order to facilitate delivery of the drug directly into the thrombus. These devices also allow for the removal of the clot through the catheter. By removing the clot, it is hoped there will be less damage to the vein and therefore fewer symptoms associated with a post-thrombotic syndrome. Once the clot is dissolved and/or removed, it may be possible to see if there is any narrowing within the vein. This can subsequently be treated with angioplasty or placement of a stent within the narrowed vein. Often patients need to spend the night in the intensive care unit (ICU) while the drug to dissolve clot is being given.
This image is from a venogram prior to DVT thrombolysis. It shows that there is an occlusion of the superficial femoral vein due to a DVT.
This image is from a venogram prior to DVT thrombolysis showing extensive thrombus in the pelvis, specifically within the external iliac and common iliac veins.
This image is from a venogram after catheter-directed thrombolysis showing flow restored to the previously-occluded superficial femoral vein.
This image is from a venogram after catheter-directed thrombolysis showing that flow has been restored to the external iliac and common iliac veins which previously contained extensive clot.
Results
There are several studies that have evaluated outcomes after the endovascular treatment of DVT. It has been shown that 90% of patients can be treated successfully, meaning that flow in the vein is restored and symptoms are improved (Oklu R and Wicky S, 2013) In general, these studies have shown documented patency rates of up to 75-85% at 1 year (Amin VB and Lookstein RA, 2014). In addition, catheter-directed treatment of DVT has been shown to improve quality of life and reduce the incidence of post-thrombotic syndrome (Comerota AJ, et al, 2000).