An electrocardiogram (ECG) is a medical test done to record the electrical activity of the heart. It is a non-invasive procedure that can be done quickly. An abnormal ECG may be caused by a variety of factors, including an arrhythmia, or a faster or slower than normal heartbeat. Other causes may include a defect in the heart muscle, heart failure, and coronary artery disease.
Within the heart, an electrical signal travels from the upper chamber to the lower chamber, making the heart contract, or beat. Several conditions may change the electrical signal in the heart. An electrocardiogram is one of the first steps to determine problems with the heart. ECG results are available immediately after the procedure, which may help the doctor make a quick diagnosis and begin treatment.
Additional reasons for an abnormal ECG include a current, impending, or past heart attack. Myocardits, which is inflammation of the heart, can also cause ECG abnormalities. Enlargement of the heart and heart valve disease may also lead to abnormal ECG results.
Chemical imbalances in the blood may also cause an ECG to be abnormal. Chemicals in the blood, such as potassium and sodium, are known as electrolytes. The electrolytes are needed for proper heart function. If the levels of certain electrolytes change and become either abnormally high or abnormally low, the heart’s electrical activity may be affected. These changes in electrical activity can lead to an abnormal ECG.
An abnormal electrocardiogram may also be caused by some type of congenital defect in the heart. This type of heart problem is present from birth. Several heart defects may result in an abnormal ECG, such as narrowed valves, holes in the heart, and right ventricular hypertrophy. In some cases, symptoms may not be present, and a person is not aware of the situation until he has an abnormal electrocardiogram.
It is important to understand that although an ECG can detect an abnormal heart rhythm, it may not identify the cause. For instance, an ECG may show tachycardia, which is a fast heart rate, but there are many causes of this abnormal rhythm. After an abnormal ECG, additional tests may be needed determine the cause of the abnormality. Other tests, such as an echocardiogram, stress test, blood work, or a cardiac catheterization, may be needed to determine the cause of an abnormal electrocardiogram.