Blood Clots in Legs: A Case Study
What happens when a person develops a blood clot in their leg?
This patient came in with severe swelling in his left leg, which began about 3 days ago. It started out with swelling in his lower leg the day following a drive from Dallas to Wichita, KS. Over the past two days, the swelling got a lot worse, to the point where it's painful for him to walk. He can get from his bedroom to the bathroom, but by the time he gets there, he's dragging his leg and says it feels very heavy. And he has a “throbbing sensation”, which makes him want to sit down and elevate his leg.
This is a scan of a severe blood clot visible in a patient’s leg.
Question: What is going on here?
To understand what is going on in this case, you need to understand the difference between arteries and veins. Arteries take blood away from the heart and deliver it to the rest of the body and brain. Veins bring the blood from the extremities back to the lungs. Then oxygen is attached, delivered to the left side of the heart, and pumped throughout the body. In short, arteries take blood away from the heart and veins bring blood back to the lungs and heart.
If a clot develops in an artery, the area downstream (called the watershed area) is deprived of its blood supply. If the clot is in the brain, this results in a massive stroke. But if the clot is in an artery in the arm or leg? Patients will experience severe pain beyond the clot because those muscles are not getting the blood flow that they need. This is an emergency situation because the clot needs to be removed in order to restore blood flow to the muscles downstream.
Leg muscles can sustain decreased blood flow longer than the muscles in the heart. A heart attack victim has similar severe discomfort in their chest when they are having a heart attack. This acute blockage in the artery is called a myocardial infarction, or STEMI. Loss of blood supply to the heart results in severe ischemia and tissue death. The heart muscle, called the myocardium, is far less tolerant than the skeletal muscles in the legs. STEMI patients are treated immediately in the Cath lab where the artery can be opened and re-perfused immediately.
In this case, the problem is in the patient's vein near his left hip.
What is a DEEP VEIN THROMBOSIS (DVT)?
There are basically two sets of veins in the legs. One is a set of deep veins that we cannot see; the other set is are veins closer to the surface. These become apparent in the standing position because blood is pumping to the lungs back against the flow of gravity. When a DVT occurs there is only one pathway back to the lungs. If this pathway gets blocked, then the blood fails to drain, and the extremity develops severe swelling with pain and becomes uncomfortable with walking or weight bearing.
In this case, the patient waited a few days before coming to the hospital. The condition was diagnosed in the emergency room and confirmed with an ultrasound exam showing blood clots in the vein extending all the way up to the central vein called the inferior vena cava, which you can see in the diagram below. If these clouds continue to travel through the right side of the heart and into the lungs, the patient can present in critical shock with low blood pressure and severe shortness of breath. The problem almost always begins in the deep leg veins.
To treat DVT, we use a procedure called aspiration thrombectomy. This procedure is new. Before, we could only dissolve the clot by dripping medication through a catheter that has to stay on the leg overnight. It took considerably longer and was less effective. Our patient at Kansas Vascular will go home from the hospital on blood thinners the day after the aspiration thrombectomy procedure.
Why do blood clots form in the first place?
We don't always know what causes the clots, however certain situations predispose us to forming blood clots. This is especially true if you have a history of previous blood clots. Prolonged sitting as on a long flight leads to pooling in the extremities and exposes people to DVT.
This can also happen to patients who are in the hospital for several days, especially after an operation. That is why doctors recommend intermittent compression, pumping of the legs, and, often times, a blood thinner until the patient fully recovers to prevent clotting.
Patients with cancer are also predisposed to form blood clots. If a person develops a DVT for no identifiable reason, we exclude underlying malignancy by asking questions pertaining to other body systems and investigating them according to our suspicion. This is especially true if a patient presents with recurrent DVT.
What could go wrong If a clot goes undetected or under treated?
An untreated or inadequately treated clot almost always leads to severe chronic leg swelling. Many other problems are related to swelling and infection, as well as skin conditions. People with massive clots that end up in the lungs can also be treated with a catheter through the groin to remove the clot. But the more quickly the patient is seen, the greater the likelihood that they can recover. Untreated pulmonary emboli result in failure on the right sided pumping chamber of the heart, which ultimately results in congestive heart failure.
James A.M. Smith, DO, is board certified by the American Board of Vascular Medicine and the American College of Osteopathic Internists. He practices cardiovascular medicine and intervention at Kansas Vascular Medicine.
