Osmosis video - ECG QRS transition

The QRS transition in an ECG is the point at which the QRS complex changes from positive to negative or vice versa. This change reflects the depolarization of the ventricles, and is caused by the flow of current from the atria through to the ventricles. The QRS transition occurs when the ventricles reach their depolarization peak and is therefore a good measure of how well-paced the heartbeat is.