Diagnosis of Coronary Artery Disease (CAD) and Angina
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Since ]]>high cholesterol]]> is a risk factor for CAD, doctors will look for evidence of elevated cholesterol, such as a collection of fatty tissue near the eyes. Your doctor will also listen for extra sounds in the heart, known as murmurs or gallops, which may suggest heart disease.
Increased levels of total cholesterol, triglycerides, and blood sugar are risk factors for CAD, as are increased levels of homocysteine and c-reactive protein. Angina may be precipitated or worsened by ]]>anemia]]> , ]]>overactive thyroid]]> , and kidney failure. Testing for the presence/quantity of heart muscle enzymes in the blood may indicate heart muscle damage.
During an ]]>EKG]]> , Electrodes are attached to your skin to record the electrical activity of your heart. This test can identify heart rhythm problems and damage to your heart caused by a previous ]]>heart attack]]> . During anginal attacks, the EKG may show specific changes. Using this test to diagnose CAD has its limitations because other heart problems can also cause changes in the heart’s electrical waves.
]]>Stress test]]> will show how well the heart is functioning. Depending on your health, you may take a stress test involving exercise (sometimes on a treadmill) or take medication that will increase blood flow to the heart. You may be hooked up to an EKG or other heart monitor. If the exercise or medication causes an increased need for blood flow that the blood vessels diseased by CAD cannot accommodate, the EKG will appear abnormal. Also, a radioactive tracer can be injected so the doctor will be able to see which parts of the heart are not getting an adequate blood supply.
With this test, your doctor can see damaged areas of the heart and examine the heart’s pumping action. A small amount of radioactive material is injected into one of your veins, usually in the arm. The healthy heart muscle takes up this material. Then, a scanning camera reads where the material does or does not show up. This determines which areas of the heart muscle have been previously damaged.
A variety of imaging techniques may be used to examine the heart muscle after the radioactive material has been injected. These include: scintigraphy, computed tomography (CT) scan, ]]>magnetic resonance imaging]]> (MRI), ]]>positron emission tomography]]> (PET) scan, and single-photon emission computerized tomography (SPECT) imaging. Nuclear scanning can be performed with the patient at rest, immediately following exercise, or after the administration of a medication that simulates the stress of exercise.
During an ]]>echocardiogram]]> , an ultrasound image of the heart demonstrates the heart muscle's movement with each heartbeat. When the heart doesn’t get enough blood, the walls of the heart show irregular motion. The echocardiogram can be performed at rest, during exercise, or after the administration of medication that simulates the stress of exercise.
A ]]>coronary angiography]]> is the most accurate way to measure the severity of CAD. It is also the most expensive and invasive method. A thin tube (catheter) is put into an artery of the arm or leg and passed through the body into the arteries of the heart. A dye is injected through the catheter and into the heart’s arteries. Several ]]>x-ray]]> images are taken. These pictures will show the amount of blockage caused by ]]>atherosclerosis]]> .
Developing technologies include the following:
- ]]>Magnetic resonance angiography (MRA)]]> —The MRA test uses MRI technology to identify coronary artery blockages. This technique has its limitations and is not commonly used.
- ]]>Electron beam CT scan (EBCT)]]> —This is a “heart scan” that uses some radiation to detect tiny calcium deposits in the lining of the coronary arteries. This technique is appealing because it is not invasive, physically exerting, or risky. However, results can often be incorrect or misleading, so research is still being done on EBCT.
- ]]>Computed tomography angiography (CTA)]]> —CTA uses 64 slice CT imaging—along with an IV contrast injected in the hand or arm—to image the coronary arteries and look for blockages. This test is similar to coronary angiography, but poses less risk because there is no need for an invasive catheter placement.
American Heart Association website. Available at: http://www.americanheart.org/presenter.jhtml?identifier=1200000 .
Libby P, Braunwald E. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, PA: WB Saunders; 2007.
HeartInfo.org website. Available at: http://www.heartinfo.org .
Last reviewed July 2010 by ]]>Michael J. Fucci, DO]]>
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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