Resting EKG

The EKG is a routine test for heart symptoms. It provides information on heart rate and rhythm and on the electrical activity of the atria and ventricles.

The EKG, the heart’s electrical tracing

When electrical excitation from the sinus node spreads through the heart, a weak current is generated. That current cannot be measured at the body surface. The heart muscle does change its electrical properties when it contracts. These voltage changes can be recorded with electrodes on the chest wall or on the arms and legs. The resulting tracing is the electrocardiogram, or EKG. It has a typical waveform with the following meaning:

• the P wave shows atrial contraction
• the QRS complex shows ventricular contraction
• the T wave shows ventricular relaxation

Recording of cardiac activity

The EKG records the heart’s electrical activity and displays it as a curve. The signals are picked up with electrodes (small metal plates) on the arms, legs and chest. The EKG device amplifies them and shows them on a screen or prints them on paper.

During a resting EKG you lie relaxed on an examination couch. The EKG is a routine test for heart symptoms. It provides information on heart rate and rhythm and on the electrical activity of the atria and ventricles. The EKG cannot always estimate the severity of a heart condition such as heart failure, but it often gives clues to the underlying cause.

EKG changes

Typical EKG changes can indicate, for example, whether:

• there is left- or right-heart strain
• you have a rhythm disorder
• a myocardial infarction has occurred (in some cases there are no EKG changes after an infarction)
• the heart walls are thickened
• there is inflammation of the pericardium