Table 2: Indications for Electrophysiology Study of Atrioventricular Block.

Suspicion of concealed AV junctional extrasystoles Asymptomatic type I second degree AV block with bundle branch block Asymptomatic second degree AV block with bundle branch block Questionable diagnosis of type II block with a narrow QRS complex Suspicion of bradycardia-dependent (phase 4) infranodal block Transient second degree AV block with bundle branch block in patients with inferior myocardial infarction where the site of block is suspected to be in the His-Purkinje system rather than the AV node Third degree AV block with a fast ventricular rate Progressive conduction disease due to neuromuscular disorders or suspected SCN5A mutations