The anatomy of the intrinsic conduction system causes contraction of the ventricles to begin at the apex and move superiorly. Why is this important? The anatomy of the intrinsic conduction system causes contraction of the ventricles to begin at the apex and move superiorly. Why is this important? because the Purkinje fibers conduct action potentials away from the heart apex because the AV bundle is the only electrical connection between the atria and the ventricles