Coronary arteries supply oxygen-rich blood to the heart. When they have a buildup of cholesterol in the arterial wall, this is considered coronary heart disease (CHD). It is often referred to as atherosclerosis. CHD can cause significant morbidty and mortality. If you have been diagnosed with having elevated cholesterol, you are at risk for developing CHD.
Exercise Stress Test
This test is performed when there is a moderate suspicion of coronary heart disease. A cardiologist, a doctor who specializes in the heart, places electrodes on the skin that will monitor the heart's electrical activity. The test is usually performed on a treadmill or an exercise bike. During exercise, the heart demands more oxygen, and thus more blood is needed to move through the coronary arteries to supply the heart with the oxygen that it requires. When there is buildup of cholesterol, or atherosclerosis, the arteries are unable to deliver the oxygen that the heart requires, and the heart is strained. The heart manifests this strain in an electrical impulse that the cardiologist can detect with the electrodes.
Stress Echocardiogram
Sometimes when the cardiologist is concerned about the way in which the heart muscle is contracting during exercise, an echocardiogram will be performed immediately after the exercise component of the test. An echocardiogram is a test in which a trained technologist or a physician utilizes a machine that emits sound waves. The sound waves enter the body and then bounce off of the heart. The machine detects the sound waves that were bounced off the heart and creates a picture that a cardiologist is able to interpret.
Nuclear Imaging
Nuclear imaging utilizes the administration of radioactive dye that is given intravenously. A special type of camera, called a gamma counter, is used to measure the amount of blood flow in the coronary arteries while the patient is at rest. The patient is then made to exercise or is given another medication that will cause dilation or opening of the coronary arteries and then is re-imaged with the gamma counter. The two images are compared to determine the extent of the coronary artery disease.
Coronary Angiography
Coronary angiography is the most invasive test, as it involves placement of a catheter or a small tube in an artery in the leg that is then fed into the coronary artery. Dye is then injected, and, using special X-rays called fluoroscopy, the cardiologist is able to visualize the arteries. This test has been the gold standard since its broad acceptance in the 1960s, but it is invasive. Another benefit is if the coronary artery disease, atherosclerosis, is found to be blocking more than 70 percent of the artery, then angioplasty and stent placement may be performed at the same time as the diagnostic study.
Computed Tomography and Cardiac Magnetic Resonance Imaging
These non-invasive tests use computed tomography or magnetic resonance imaging to visualize coronary arteries. These tests have been in use only since the 1990s but are becoming more common as the technology evolves. A recent analysis, published in the February 2010 issue of the "Annals of Internal Medicine," compared the two different types of images and determined that computed tomography was more accurate than magnetic resonance imagining in determining if there was significant coronary heart disease.
References
- "Annals of Internal Medicine"; Meta-analysis: Noninvasive Coronary Angiography Using Computed Tomography vs. Magnetic Resonance Imaging; Georg Schuetz, Niki Zacharopoulou, et al; February 2010
- "Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine (7th Edition)"; Peter Libby, MD, Robert O. Bonow, MD, Douglas L. Mann, MD, Douglas P. Zipes, MD, editors; 2005
