ECG (electrocardiogram) is a recorder of the electrical activity of the heart at rest.
Provides info about the heart rate and rhythm.
The ECG wave consists of 3 parts: P-wave, QRS complex, and T-wave.
P-wave: it is associated with right and left atrial depolarization.
QRS-complex: ventricular depolarization. Very rapid. Largest wave.
S-T-interval: after QRS in the time when the ventricle is depolarized. Can be used to diagnose ischemia or hypoxia.
T-wave: ventricular repolarization. Relaxation of the ventricular wall.