Aneurysm

Destination Unknown: It is not known where a moving blood clot will land. If the clot attaches to a small vessel and stops the blood flow, it can cause a stroke.

An aneurysm is a bulge in a blood vessel. The bulge can be equal in size around the vessel (think of a snake digesting a rat), one-sided, or shaped like a balloon with a small neck from a vessel connected to it. The equal-sized and one-sided aneurysms are generally corrected by removal from the vessel, with a graft inserted in their place. This is considered major surgery, especially when the aneurysm is in the aorta. A balloon aneurysm is more common in the brain than elsewhere and is a frequent cause for a “bleed” stroke if it ruptures. The corrective action often taken is to place a metal clip around its neck and clamp off the aneurysm. With the blood supply cut off, the aneurysm will be absorbed by the body over time. The tissue will grow over the clip, keeping it in place. Modern clips are nonmagnetic, so they are safe if the patient has a magnetic resonance imaging (MRI) exam.

How Is an Aneurysm Detected?
An aortic aneurysm is often first detected with the oldest instrument in the physicians’ practice: a stethoscope. As physicians listen to the heart, they will move the instrument down the left side of the chest to listen for an echo in the sound. If they hear an echo, they will schedule an ultrasound first, and then possibly an angiogram or a computed tomography (CT) exam. A brain aneurysm cannot be heard, but the symptoms are often headaches and loss of some motor skills, balance, or vision. The final diagnosis will be made by an angiogram or CT of the brain.

Angiogram
An angiogram is the study of a vessel. “Angio” and “angi” are base words for blood or lymph vessels, and they often have “arterio,” for artery, or “veno,” for venous, as a prefix. An angiogram is generally done with a fluoroscope image, as a radiopaque liquid—often called a contrast—is injected into the vessel and its movements are followed visually on the fluoroscope.

Generally, the radiologist will introduce a catheter into the vein or artery to be studied and advance the catheter toward the area of interest. These catheters are marked every 10 cm, so the physician knows how far the catheter has gone into the body.

When the contrast liquid is injected, either by a power injector or a syringe, the radiologist watches the movement. If an aneurysm is present, the contrast liquid will spread out and then come back to the normal width of the vessel. If a blockage—called a coarct or clot—is present, the contrast liquid will narrow at that point. Think of this as looking down on a body of water from a plane. A lake would be an aneurysm, and a clot would be a narrow opening or dam.

When the aneurysm or blockage is seen, the radiologist will often take a spot film or a series of films using the rapid film changer, or puck, to document what appears on the screen. Instead of using a spot film or puck, the old multi-format camera would store four to 12 images on a film. Many of these studies are now done on the MRI or CT and are called CT or MRI “with contrast.” While the basic procedure is similar, this is not a cardiac catherization.

Some of the most common problems with an angiogram are infections; stroke, if the catheter breaks off part of the blockage; vessel perforation, where the catheter is pushed though the wall of the vessel; and a reaction to the contrast media.

Finding and Correcting a Coarct
As with the aneurysm, the stethoscope is often the instrument used to detect a coarct. The physician will listen to the carotid artery on both sides of the patient’s neck. Signs of a potential blockage include a difference in the sound levels detected between the sides, and a diminishing of the volume progressing up the neck.

For the femoral vessels, both artery and vein, the same basic procedure of listening for varying sound levels is used. The next step is generally the use of a high-frequency Doppler, 9.1 MHz, in which the physician follows the vessels and listens for varying sounds. If problems are found, an angiogram would be the definitive diagnostic tool.

Common Coarct Symptoms
For the carotid artery, warning signs are motor-skill deterioration, memory problems, and balance problems, to name a few. For the femoral artery, indications include weakness in the limbs, problems walking, cold feet, and cramps. If the coarct is in the vein, it is probably a thrombus or clot. The symptoms include swelling, as the venous return is slowed, causing blood to pool in the lower legs. Clots in the legs are common as people age and their physical activity and muscle tone diminish. Sitting for long periods of time can also cause clots to form. This is why you should do exercises or get up and walk when you are on a long airplane flight.

Fixing the problem varies with the location of the blockage and the patient’s age and condition. Treatment can range from a simple solution of prescribing drugs, to replacing the vessel with a graft or transplant, and to performing various less-invasive procedures in-between.

Prevention of coarcts and clots is the best action that can be taken. Preventive steps include medication to lower a patient’s cholesterol, which helps prevent plaque deposits from forming in blood vessels; some improvement can also be gained with dietary changes. Blood thinners are often prescribed to help prevent and dissolve clots. The use of elastic stockings is another preventive measure for some hospital patients, as is the use of the sequential compression unit.

Another problem with high cholesterol is that it can contribute to the formation of stones in the gallbladder. Since these stones are composed of cholesterol, they often do not show up on an x-ray; however, they are often confirmed using ultrasound. 24x7

David Harrington, PhD, is director of staff development and training at Technology in Medicine (TiM), Holliston, Mass, and is a member of 24x7’s editorial advisory board.