QRS complex

The QRS complex consists of the Q wave, the R wave and the S wave. The QRS complex comes after the P wave when the SA nodal action potential travels through the AV node to the ventricles to cause ventricular depolarization. The first downward deflection is called the Q wave. The first upward deflection is called the R wave. The second downward deflection after the R wave is called the S wave.

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