Third-Degree Block

Third-Degree Block

Atrial rate Regular; P to P is regular (if underlying rhythm sinus), 60 to 100 bpm, can be variable (eg atrial fibrillation)

Ventricular rate Regular; R to R is regular, ≤60 bpm (40 to 60 bpm fi junctional, 15 to 40 bpm if ventricular)

More P waves than QRS complexes (Complete A-V dissociation)

Unchanged unless aberrant conduction due to premature beat or increased rate