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User's Guide to Cardiovascular Imaging By Les Fleischer, M.D., Cardiology at White-Wilson Medical Center 
The easiest way to understand cardiovascular imaging tests is to consider the question to be answered about the part of the heart at issue. Organize the heart anatomically. The heart is a muscle that contracts. It has valves to keep the blood flowing in the right direction. There is an electrical system to stimulate the heart to beat and arteries that bring blood and oxygen to nourish the heart muscle itself. We can only image the heart muscle, the valves, and the arteries. When we hear a heart murmur, there may be a problem with one of the heart valves. We visualize heart valve function using an echocardiogram. The echo machine shines sound waves through the chest wall and senses their reflection from various heart tissues. We gather information regarding the valve structure and function, as well as the pumping capability of the heart itself and can also measure pressures in the heart chambers. When we want to investigate heart or valve function in a patient with heart failure or shortness of breath, the echocardiogram is the best choice. The test is painless and takes about an hour with no IV needed. What it does not do is directly see the coronary arteries. Heart attacks are the most common cause of death in this country and many cardiac imaging procedures are aimed at uncovering and analyzing cholesterol blockages in the coronary arteries, the arteries that bring blood to the heart. Initially, when we suspect a blockage in an artery we ask our patient to undergo a stress test, usually by walking on a treadmill. We analyze the electrocardiogram but may also use the echo or inject radioactivity to see the heart walls better. Areas with blocked arteries show up on the stress echocardiogram as a part of the heart that does not contract well during exercise. When we use radioactivity during a stress test, a cardiolyte stress test, we look for areas of the heart muscle that do not show up well during stress, signaling a lack of blood to the area, a blockage in the artery. Some patients have no symptoms, yet we suspect that they have cholesterol buildup in their arteries but not severe enough to cause chest pain. We can image the damaged arteries by using a coronary calcium score xray, an outpatient procedure, taking less than 30 seconds. When cholesterol buildup damages an artery, it heals and calcifies the area. Thus, arteriosclerosis can be seen on the x-ray. In cases in which the arteries are heavily calcified, we might consider doing a stress test to see if any of the calcified areas block the arteries. Since about 30% of all heart attacks are painless, coronary calcium scoring is an excellent screening test for patients with a family history of coronary artery disease or with several risk factors for the disease. The gold standard for evaluating blockages in the coronary arteries is the cardiac catheterization or coronary angiography. This involves a day in the hospital with a catheter insertion into an artery, usually in the groin. Although risks are low, they are still present. The catheterization shows us the blockages, where they are, and how tight they are. It may lead to placement of a stent in the artery or bypass surgery. Recently, we have introduced coronary CT angiography on the Panhandle. This procedure is an outpatient CT scan, taking roughly an hour, and involves no hospital stay. Patients can return to work the same day. Coronary CT angiography can visualize most coronary arteries and is an excellent technique in patients with bypass grafts or who have stress tests that do not lead to a clear answer. Although not appropriate for all patients, it is easier, safer, and quicker than a heart catheterization and can clear up many questions regarding the presence, absence, and extent of coronary artery blockages. It is also a quick screening test for both obscure abnormalities of the coronary arteries and areas of the heart chambers poorly seen by other techniques. |
| Did
you know? |
| Coronary
heart disease and stroke death rates have decreased by 30 percent
since 1999. Follow this link to learn more about the American Heart
Association’s recent findings regarding heart disease and stroke. Learn More About the American Heart Association's research and findings. |
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