ANATOMY

Detailed explanation-1: -Depolarization of the heart is the orderly passage of electrical current sequentially through the heart muscle, changing it, cell by cell, from the resting polarized state to the depolarized state until the entire heart is depolarized.

Detailed explanation-2: -Depolarization of the heart leads to the contraction of the heart muscles and therefore an EKG is an indirect indicator of heart muscle contraction. The cells of the heart will depolarize without an outside stimulus.

Detailed explanation-3: -The PQ interval is the time interval from the onset of atrial depolarization to the onset of ventricular depolarization. Accordingly, the PQ interval reflects the time required for the electrical impulse to propagate from the SA node to the ventricles. The length of the PQ interval is weakly dependent on heart rate.

Detailed explanation-4: -Ventricular depolarization occurs in part via an accessory pathway (AP) directly connecting the atrium and ventricle and thus capable of conducting electrical impulses into the ventricle bypassing the AV-His Purkinje conduction system.