What does the P-wave represent in an ECG?

Step-by-step solution

The P-wave represents the electrical excitation (or depolarisation) of the atria, which leads to the contraction of both the atria . The QRS complex represents the depolarisation of the ventricles, which initiates the ventricular contraction. The contraction starts shortly after Q and marks the beginning of the systole. The T-wave represents the return of the ventricles from excited to normal state (repolarisation). The end of the T-wave marks the end of systole. Obviously, by counting the number of QRS complexes t