A form of ventricular pre-excitation characterized by a normal PR interval and a long QRS interval with an initial slow deflection (delta wave). In this syndrome, the atrial impulse travel to the ventricle via the MAHAIM FIBERS which connect atrioventricular node directly to the right ventricle wall (NODOVENTRICULAR ACCESSORY PATHWAY) or to the RIGHT BUNDLE BRANCH OF HIS (nodofascicular accessory pathway).