An electrocardiogram is a common diagnostic procedure used to record the electrical activity of the heart. The test creates a visual tracing that allows medical professionals to assess the organ’s rhythm and overall function. Both ECG and EKG refer to this identical, non-invasive test. They represent the same process of capturing the heart’s electrical signals to provide insight into cardiac performance.
The Difference Between ECG and EKG
The acronym ECG is derived from the English term, “Electrocardiogram,” using the Greek root “cardio” for heart. EKG, however, originates from the German word, Elektrokardiogramm, reflecting the test’s early development in German-speaking countries. Although ECG is the internationally standardized abbreviation, EKG remains widely used, particularly in the United States. This continued use helps prevent potential confusion with the similar-sounding medical acronym, EEG, which stands for electroencephalogram, a test that measures brain activity.
How the Electrocardiogram Works
The electrocardiogram functions by detecting and recording the tiny electrical impulses generated by the heart muscle as it contracts and relaxes. The procedure requires the placement of small, sticky patches called electrodes onto the patient’s skin, typically on the chest, arms, and legs. These electrodes are connected by wires (leads) to the recording machine.
In a standard test, ten electrodes capture the heart’s electrical potential from twelve different angles or “leads.” The machine amplifies these minute electrical signals and translates them into a continuous wave pattern on paper or a digital screen. The equipment only measures the body’s natural electricity and does not send any electrical current into the patient. The resulting graph plots voltage against time, providing a detailed visual representation of the heart’s electrical cycle. The patient is asked to lie still for a brief period to ensure the most accurate recording without movement interference.
Identifying Cardiac Function
The wave patterns produced by the electrocardiogram correspond directly to the stages of the heart’s electrical activity during a single beat. The P wave represents the electrical activation, or depolarization, of the atria, the heart’s upper chambers. Following this is the QRS complex, which signifies the depolarization of the ventricles, the heart’s main pumping chambers. The T wave marks the repolarization, or electrical recovery, of the ventricles, preparing them for the next beat.
By analyzing the shape, timing, and duration of these waves and the intervals between them, physicians can gather significant diagnostic information. Deviations from normal patterns can indicate issues such as an irregular heart rate (arrhythmias) or problems with the electrical conduction pathway. The test can also reveal signs of inadequate blood flow to the heart muscle or a previous heart attack.