Electrocardiogram, often shortened to ECG or EKG, tests the electrical conduction system of the heart. The heart beats in response to electrical impulses that spread through the heart. An EKG tracing records electrical impulses on a piece of paper that shows the rhythm, rate and timing of electrical signals that travel through the heart. Abnormal EKG tracings indicate temporary or permanent problem within the heart that can range from inconsequential to life-threatening.
Procedure
EKGs cause no pain and take only a few minutes to do. Wires attached to electrodes are fastened to the skin in several places to transmit electrical impulses. The impulses record on EKG tracing paper, special paper broken down into small squares, each representing .04 seconds, RNCeus.com explains. The EKG measures the P wave, the first bump, which represents contraction of the atria, the top chambers of the heart. The QRS complex represents contraction of the ventricle, the lower chambers of the heart. T waves represent the resting stage or repolarization of the ventricles. Each electrode records activity in different areas of the heart, so the tracings from each lead look different.
Findings
The duration of the electrical impulses, the direction of the waves and the time between certain points all indicate normal or abnormal activity on the EKG. The time between the R waves, the rising V-shaped points, indicates the number of times the heart beats each minute, with 60 to 100 being the normal range. A faster heart rate, called tachycardia, can occur from exertion, certain drugs or from heart problems, while a slow heart rate can occur from blockage in the conduction system, certain medications or athletic conditioning. Abnormally short or long lapses between other points measured on the EKG or inverted waves indicate abnormalities of the heart.
Interpretation
Medical personnel can assess the abnormal changes on the EKG to determine where the problem in the heart originates and what might be causing the problem. A heart attack, for example, might first appear on the EKG as abnormally tall T waves, and later show as an S-T elevation, the website Ambulance Technician Study, explains. Irregularities in the space between R waves represent arrhythmias, irregular heartbeat. Atrial fibrillation, a quivering of the atrium rather than a forceful contraction, has no normal P wave but rather a series of small irregular bumps before the QRS wave. Heart blocks have abnormally long spaces between different waves.
Treatment
Treatment of an abnormal EKG tracing depends on the findings, but might include medication, surgery, cardioversion, in which a mild shock is delivered to the heart to correct an abnormal rhythm, and pacemaker implantation to correct arrhythmias through a mild shock.
Complications
Many EKG findings have no clinical significance, such as tachycardia right after exercise. Others, such as premature ventricular contractions, which feel like an extra "thud" in the chest, occur only occasionally in most people. Abnormal EKG readings require follow-up with a cardiologist to assess the importance of the changes, since an abnormal EKG can indicate serious malfunction of the heart.
