A portable electrocardiogram (ECG) is a diagnostic medical tool that detects, displays and records electrical activity in the heart. By positioning electrodes on the body in standardized locations, information about many heart conditions can be learned by looking for characteristic patterns on the readout. Electrocardiograms are used in doctors' offices, hospitals, clinics and anywhere cardiac care is offered. A portable ECG might be used on an ambulance or at a temporary clinic or screening location.
An ECG is sometimes referred to as an EKG after the German translation, elektrokardiogramm, because the term "ECG" can be commonly confused with other medical terms, such as electroencephalogram or echocardiogram. An ECG is a noninvasive recording procedure, and there are no risks involved. No electricity passes through the patient's body from the machine, and there is no danger of getting an electrical shock.
A portable ECG can be used to check the electrical activity of the heart when a patient is experiencing unexplained chest pain, which could be caused by a heart attack, angina or pericarditis, which is when the sac around the heart becomes inflamed. It might also shed light on symptoms of heart disease, such as fainting; dizziness; shortness of breath; or quick, irregular heartbeats. Portable ECG readouts might also provide information on how effective medications are and whether they are causing any side effects that might affect the heart.
During an ECG, the patient lies on his or her back. The portable ECG technician places three to 10 disposable electrodes on the patient's arms, legs and chest. These are connected to the ECG monitor, which detects the electrical impulses in different areas of the patient's body and heart and traces the activity onto a strip of paper as lines and waves. The procedure can take less than five minutes.
The ECG readout consists of up to 12 leads, or lines that represent the heart's electrical impulses. Up to six views are generated by the electrodes placed on the arms and legs, and up to six are generated by the electrodes placed on the chest. From these views, various cardiac abnormalities can be attributed to specific parts of the heart. ECG technicians are trained to note abnormalities in the various wave forms and interpret their causes. Treatment can then be administered based on cardiac algorithms.
Each heartbeat's electrical activity is described as a "complex" consisting of three parts: the P wave, the QRS complex and the T wave. The P wave shows the electrical impulse as it travels across the heart's atria. The QRS complex represents the impulse as it moves across the ventricles. The T wave shows the ventricular muscle's recovery period after it has been stimulated.