Isorhythmic AV dissociation

Rhythm strip showing sinus rhythm with isorhythmic atrioventricular dissociation. The sinus P waves and QRS complex have a similar rate, but the P waves are not conducted as ventricular depolarization is initiated by a junctional focus. Note that the P waves appear to move into, fuse with (beats 2 and 3), and then move out of (beats 4 through 7) the QRS complex.