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An electrocardiography, also known as and EKG or ECG is a medical diagnostic technique that records cardiac electrical impulses. The impulses that are recorded are the impulses that precede cardiac muscle contractions. This painless procedure is frequently used for diagnosis of coronary artery disease, heart rhythm disturbances, and inflammation of the protective cardiac membrane. The electrocardiography may also detect the presence of a past heart attack and can indicate if a person is having one at that time.
Typically, the electrocardiograph begins with the connection of electrodes to certain areas of the chest, ankles, and wrist. These electrodes are then connected to the recording machine. As the machine picks up electrical impulses, the results are recorded on rolling graph paper. The EKG can be taken in a doctor's office, in the emergency room, or even in the home with the use of a portable cardiac monitor called a Holter monitor. This monitor records the electrical impulses and heart rhythms on a 24-hour basis.
Sometimes, certain factors can interfere with the reliability of the electrocardiograph test. Stress and anxiety can cause a rapid and irregular heart rate that would not normally be present under normal circumstances. In addition, consumption of certain medications such as cold and allergy medications may skew results because they stimulate the heart. Generally, people who drink coffee and consume other foods and drinks containing caffeine may have abnormal electrocardiograph results.
Frequently, cardiac medications called beta blockers can mask certain conditions of the heart. Typically beta blockers slow and regulate the heart rate. Many times when the beta blocker is discontinued, the heart rhythm and rate will revert back to abnormal. It is important to tell the health care provider when taking a beta blocker, or any cardiac medication while undergoing an electrocardiograph evaluation. Pacemakers also slow and regulate the heart, which may also show up on the electrocardiograph as an abnormality.
Generally, based on results of the electrocardiograph, other cardiac tests may be recommended. If the test shows an abnormality, an echocardiogram may be suggested. This test uses sound waves that are bounced off the cardiac structures to visualize the heart, valves, and vessels. In addition, a stress test may be needed to determine if a coronary blockage is present. The electrocardiograph can suggest the presence of cardiac ischemia, which may indicate a blockage.
The electrocardiograph test sometimes elicits false positive or false negative results. Because the test is not foolproof, it is important to supplement it with a thorough physical examination and medical history. Sometimes, cardiac enzyme blood tests will be done to rule out the presence of a myocardial infarction, or heart attack. When the cardiac muscle is damaged, cardiac enzymes slough off into the blood stream and are revealed in this blood test. A combination of diagnostic tests are often needed to rule out cardiac events.