An electrocardiogram (EKG) is a graphical representation of the electrical current of the heart. Electrodes are placed on the body that detect the rapid contraction of the heart muscle. If there are problems with the heart's function, an EKG detects the problem and represents it on paper.
Evaluate the P-wave. The P-wave is the first, small, rounded hump at the beginning of the EKG. This symbolizes the initial contraction of the right atrium of the heart. The atrium is a blood reservoir that passes its contents to the right ventricle. Normal readings are approximately 10 ms long.
Evaluate the QRS complex. The QRS complex is the large spike in the center of the graph. This is the contraction of the ventricles. Q-waves that are more than a fourth of the size of the S-wave indicate a possible myocardial infarction (heart attack).
Evaluate the PR-wave. The PR-wave is measured from the beginning of the P-wave to the beginning of the QRS complex. Normal results are approximately 120 ms. A PR-wave greater than 200 ms signifies a possible heart blockage.
Evaluate the ST segment. The ST segment connects the QRS complex and the final T-wave. This section is approximately 80 to 120 ms long, and abnormalities can mean ischemia or myocardial infarction.
Evaluate the T-wave. The T-wave is the last segment, and it signifies the relaxation of the ventricles. Poor T-wave values indicate coronary ischemia or central nervous system disorders.