Electrocardiogram [ECG]
Electrocardiogram [ECG]
An electrocardiogram (ECG or EKG, from the German Electrokardiogramm) is a test that records the electrical activity of the heart. Analysis of the electrical activity can yield important diagnostic information like rate and regularity of heart beats, damage to the heart muscles and effects of drugs on the functioning of the heart.
The ECG was invented in 1903 by a Dutch doctor and physiologist, Willem Einthoven. He also invented the string galvanometer in 1901 and used it to measure the electrical activity of the heart. For his invention, Einthoven was awarded the Nobel prize in 1924. The basic principle of ECG has still remained the same and we still use the notation used by Einthoven. However, many advances have been made in this field. For example, computerized ECG machines have replaced cumbersome equipment. Not only are these machines more accurate, they are also much portable.
An electrocardiogram is performed by a health care professional and the resulting ECG is interpreted by a cardiologist. During the procedure, the patient is made to lie down on a bed or table and electrodes are placed on the arms, legs and chest. A special gel may be applied on the skin to increase conduction. These electrodes are connected to a machine that traces the electrical activity of the heart on a piece of paper. Based on the tracing obtained, the doctor makes diagnosis.
There are four components in the ECG tracing: the P-wave, the QRS complex, the ST segment and the T wave. The P-wave is a record of the electrical activity through the upper heart chambers. The QRS complex is a record of the electrical activity though the lower chambers. The ST segment occurs when the lower chambers (ventricles) are contracting and the T wave occurs when the lower heart chambers are relaxing electrically.
ECG is very safe and there is no reason why a patients cannot undergo ECG testing.
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