Embolism

An embolism is an obstruction or blockage in a vessel caused by an embolus—who said only lawyers and politicians are good at doublespeak? The majority of extremity embolisms occur in the thigh, groin, or knee area, with a few in the shoulder, elbow, or lower arm. The more common embolisms are: air, caused by an injury to the lung, such as a puncture wound or an “oops” during cardiac bypass surgery, where air gets into the system due to a leak in the tubing; atheroma or cholesterol; cellular matter from degenerating tissue; from an old injury; fat; or bone marrow from a broken bone, which is common after auto accidents.

 Air is a common embolism, caused by an injury to the lung, such as a puncture wound, or when air gets into the system due to a leak in the tubing during cardiac bypass surgery.

The removal of a clot is called a thromboembolectomy, (“thrombo” means clot, “embolol” means blockage, and “ectomy” means removal), and it is done during an angiogram. The clot is located, and a catheter is introduced downstream of the clot and advanced to the clot. On the end of the catheter is a small corkscrew that is pushed into the clot. When the clot is captured, the catheter is slowly withdrawn, pulling the clot out of the vessel and the body. Using suction through the catheter is another option. A third option is to use a laser beam down the catheter to vaporize the clot. A problem with all of these is the potential for some of the clot to break off and travel to other parts of the body, causing additional emboli to form. In patients prone to embolus, a filter is placed in the inferior vena cava, which is the vein that returns blood to the heart from the lower part of the body. The filter is introduced via a catheter and is opened like an umbrella. Then, it is pulled back so its tips lodge into the vessel walls. The catheter is disconnected and withdrawn, leaving the filter in place. When a filter is placed in a patient, that person will, most likely, have to take blood-thinning medication for the rest of his or her life. Blood thinner is a misleading description of the drug, as it does not dilute the blood volume but slows the clotting times. The most common of these drugs is aspirin.

A common procedure in the lower extremity is called, in shorthand, a fem-pop, which is a replacement graft or surgical repair of the femoral artery to the popliteus muscle (the quad muscle in the thigh). This is major surgery; and while bilateral grafts are not common, they can happen. During the recovery period, the patient may alternate between a sequential compression unit and a constant passive motion to help with both blood return and muscle tone.

Repairing blocked carotid arteries is a little more involved, because they feed blood to the brain. There are two: one on each side of the neck; and one on the split, or bifricate, near the base of the skull. The gold standard is to open the neck to expose the artery and clamp off the artery above and below the coarct. The first problem is that the blood supply to that side of the brain has been clamped off, so an electroencephalogram (EEG) is taken to see how the brain is functioning. The vessel with the coarct is removed, and a graft is sown in place. The clamps are then released, and the blood flow is checked. Another EEG will be done. Once the first graft is working, the other side will be done. A percentage of these patients do suffer a stroke during the procedure.

Alternate techniques being applied to both femoral and carotid blockages include using a laser beam to vaporize the obstruction, possibly creating a gas embolism; or using the “Roto-Rooter” method, where a catheter with rotary cutters on the tip is pushed up against the blockage and “tunnels” through it. With this method, there needs to be a suction port near the cutters to bring the debris out of the body. A third option, and growing fast in popularity, is the stent. This is a metal-mesh device that may be coated with a drug to prevent clotting. It is placed on the end of a catheter that is brought into position using angiography. Once in place, it is expanded to create a clear passageway through the blockage. The stent is becoming an option for the “cabbage,” or coronary-artery-bypass graft, which is the most common “open-heart” surgical procedure. Stents can be done on an outpatient basis in many cases; they are less expensive than invasive procedures, and their long-term results are good. By using a coated stent, the body will not attack the metal; and the coating prevents, or at least greatly slows, any clotting that could occur in the area.

As with any surgery, the possibility for emboli to travel to the brain and cause a stroke is always a possibility. Strokes, also called cerebral vascular accidents, are one of two types: a bleed, caused by a ruptured or leaking aneurysm; or a blockage, caused by a clot. Treatment of the two types of strokes is very different. For a bleed stroke, treatment is an operation. For a blockage, if diagnosed quickly, a computed tomography is the diagnostic tool of choice. In addition, it can be treated with a drug called TPA, which will dissolve the clot. TPA is also used for heart attacks that are caused by a clot, but the window of effectiveness is short—2 to 4 hours for either a stroke or a heart attack—from the onset of symptoms. So, if you have symptoms, get to a hospital quickly and get diagnosed, as your recovery will be much quicker and the results will be much better. 24×7

David Harrington, PhD, is director of staff development and training at Technology in Medicine (TiM), Holliston, Mass, and is a member of 24×7’s editorial advisory board.