An ECG shows the waveform of your heart.
Recording your cardiac waveform with a surface ECG can tell us about your heart's rhythm, its position in the ribcage, and the process of electrical excitement in its cardiac muscle. Biological heart diseases are often connected with serious changes in the heart's waveform. Examples include an increase in the so-called ST segment in an acute heart attack, a decoupling of the actions of the heart's atriums and chambers during an AV block of the third degree, or a so-called left bundle branch block in advanced cardiac insufficiency. A resting ECG always has to be considered in combination with further imaging results of the heart.