Complete heart block: Sinus rhythm with slow junctional or idioventricular escape rhythym

Multiple successive QRS complexes appear that are of ventricular origin and occur at a rate which is slower than the underlying sinus rhythm. The presence of P waves that occur independent of the QRS complexes is evidence of atrioventricular dissociation.

The normal P wave in sinus rhythm is slightly notched since activation of the right atrium precedes that of the left atrium. The P wave is upright in a positive direction in leads I and II. A P wave with a uniform morphology precedes each QRS complex. The rate is between 60 and 100 beats per minute and the cycle length is uniform between sequential P waves and QRS complexes. In addition, the P wave morphology and PR intervals are identical from beat to beat.