Warren Swee, MD, MPH, a Vascular and Interventional Radiologist at South Florida Vascular Associates, in Coconut Creek, FL, talks about a state-of-the-art device that melted away a potential killer.
What is DVT?
Dr. Swee: DVT or a deep vein thrombosis is essentially a clot that forms in the deep veins of the leg. Initially it will present as pain and swelling in the leg, which can increase over several days. It’s usually identified with a simple test in which an ultrasound probe is placed over the veins of the leg. DVT is a tremendous public health problem in the United States with almost six thousand cases diagnosed every year. Although the initial problem with the pain and swelling can resolve it, it also places patients at significant risk of a pulmonary embolism, which is when a part of that clot breaks off and travels to the lungs and that can be life threatening. It’s estimated that up to a hundred thousand patients every year will die of pulmonary embolism.
What does a pulmonary embolism do?
Dr. Swee: It breaks off from the legs and travels up the pelvis through the abdomen, through the heart and into the pulmonary artery, which is the main vessel that supplies oxygen to the lungs for transport. Without blood going to your lungs it can be fatal.
How often do you see DVT patients coming in here?
Dr. Swee: We see DVT patients quite frequently. Typically they’re relatively simple DVT’s with an isolated clot behind the knee or in a portion of the vessel along the thigh. In rarer cases the clot can travel up across the thigh in to the pelvis and even in to the abdomen. Those are much more severe cases.
What is the size of a normal clot?
Dr. Swee: Typically anywhere from an inch to six inches or so is-- would be a typical clot size.
The clot basically cuts off the circulation to the rest of the vein?
Dr. Swee: Correct. It prevents drainage of the blood from the leg from going up through that vessel. Usually that’s what causes the swelling because you’re unable to drain blood from the leg, but over time if a patient is placed on the proper anticoagulation, some of the clot will melt away on its own. The body will form collateral or side channels around the blocked segments.
How do you take care of the clot?
Dr. Swee: Most cases of deep vein thrombosis are treated with just blood thinners. The pain and swelling usually will resolve within a week or so.
As long as you catch it early enough the danger might be minimized?
Dr. Swee: The blood thinners is twofold. One is to prevent the clot from becoming bigger and second to help stabilize the clot so that pieces don’t break off and go to the lungs.
What is the biggest one you’ve seen?
Dr. Swee: Mr. Cunha has a very large clot. His is about a two and a half foot clot that starts below the level of the knee and extends all the way up his thigh into his pelvis and into the lower abdomen. Those clots don’t respond as well to blood thinners because they’re so massive.
How often do you see that?
Dr. Swee: We probably see that maybe once every few months, if that.
How do you survive when you have a clot that big?
Dr. Swee: The blood is no longer liquid. It’s solidified into almost a jelly like substance, and plugs up the vessels instead of allowing flow. It causes immediate swelling but the body does have a lot of capacity to somehow move blood around the actual blockage through their side channels.
So when you get to a point where it’s two and a half feet long what’s the next attack?
Dr Swee: Those patients are in particular at risk of throwing clots to their lungs. If they are treated only with conservative measures, they tend to have debilitating pain and swelling in their legs often for the rest of their lives. They can develop something called post thrombotic syndrome, in which the clot damages valves within the veins. With damage to the valves, it causes you to have this horrendous pain and swelling. What we can do now is use a catheter called the EKOS catheter, which has really revolutionized the way we as interventional treat large blood clots. A small catheter is essentially inserted through the skin into the clotted vessel and positioned there. Within a coaxial system, there is a wire, which is an ultrasound wire, and together this allows simultaneous deliver of ultrasound energy and clot busting medications to allow breaking up the clot much more quickly and safely compared to standard techniques.
How does the EKOS work?
Dr. Swee: The catheter itself has hundreds of holes in it which allow the clot buster to be delivered directly in to the clot. At the same time the ultrasound core wire delivers ultrasound energy, which causes a vibration, which allows the clot busting medication to better penetrate the clot.
In Mr. Cunha's case, if this wasn’t around what would be the other option?
Dr. Swee: The standard technique is to put a catheter in with a lot of side holes, which is can also deliver clot busting medication but without the ultrasound energy. That can work also, but it can take almost double the time. Time counts when we’re treating clot because we’re delivering a very powerful clot busting medication that has a lot of side effects. There could be bleeding from other parts of your body and the worse scenario would be bleeding into your brain, which can be fatal.
How often have you been able to use this now?
Dr. Swee: I’ve used this catheter in about a half a dozen cases, including clot in the leg vessels, and also clot up in the pulmonary arteries. When a clot breaks off and becomes a pulmonary embolism, the catheter can actually be advanced all the way up through the heart from the groin and positioned inside the pulmonary artery.
What is the clot busting drug that you use?
Dr. Swee: There are several different ones that can be used. The one that we typically use is called TPA or tissue plasma activator.
Once Mr. Cunha was diagnosed with his huge blood clot, what was the step after that?
Dr. Swee: Once we reviewed some more imaging we found out that the clot was not just in his leg but it actually went up in to his pelvis and abdomen. We performed the procedure in a hospital endovascular suite under an x-ray machine. He essentially was positioned on his stomach to allow access to his vein right behind his knee. Using ultrasound guidance we advanced the needle into that vein and then through that hole threaded the catheter into the clot. We positioned it under x-ray guidance and then started dripping the clot busting medication into the clot to dissolve it. In Mr.Cunha’s case because this clot was almost five weeks old, it took longer than most cases. It took two days to finally melt the clot away. But he had a fantastic result and dramatic improvement in his leg swelling and pain.
What was his recovery like?
Dr. Swee: The patient is transported to the ICU where they’re monitored carefully for any complications from the clot busting medication. If they do well then they’re brought down the next morning and then we do a check by injecting x-ray dye in to the vessel to see how much clot is still there. If there’s still clot then we’ll send the patient back up to ICU and continue the drip and the ultrasound energy and then bring them back the next day.
Between the ICU and the actual procedure how long are you busting the clot?
Dr. Swee: The actual procedure to get the catheter in is actually pretty quick. It takes about twenty minutes or so to get the catheter where it needs to be. The catheter stays inside the body until the clot is dissolved totally.
What added benefit does the ultrasound give you?
De. Swee: The ultrasound allows the clot busting medication that’s being dripped through the catheter to better penetrate the clot and allows for more surface area between the clot busting medication and the clot. That essentially allows for much quicker dissolving of the clot and decreases the overall amount of clot busting medication that we need to use.
What are the risks?
Dr. Swee: This actually allows us to use this sort of treatment on patients that previously were not candidates, because they couldn’t tolerate several days of clot busting medication. By using this device we can decrease the time it takes to do the procedure and also the amount of clot busting medication.
It’s pretty amazing that Mr. Cunha was left with no disability.
Dr. Swee: Over five weeks he was basically hobbling around and just in constant pain. But about a day or two after the clot was dissolved he was almost back to normal.
What was his recovery time?
Dr. Swee: Following the procedure he stayed in the hospital for an additional week in order to thin his blood to an appropriate level and then after that he was sent home and walking quite comfortably.
Has he had to take anything since?
Dr. Swee: He’s going to be on lifelong blood thinners.
Once you’ve had a clot that big, are you at risk for another?
Dr. Swee: The biggest risk for him is re-developing a clot in the same place.
What has it done to the vein now? Having such a massive clot how stable is it?
Dr. Swee: The vein now that the clot has been melted away is very resilient. In his case his veins should essentially come back to their normal configuration. He may have some mild damage to the valves, but certainly not anywhere near the damage that would have been caused if the clot was not removed.
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