Relationship between clinical presentation of atrioventricular block and its localization defined by His bundle electrogram.

The frequency of clinical and electrocardiographic symptoms in dependence on the localization of the atrioventricular (AV) block, defined with the aid of His bundle electrogram, was investigated in 49 patients with 2nd-or 3rd-degree AV block. The Adams-Stokes syndrome, broad ventricular complex, and Mobitz II-type AV block were most frequently encountered in patients with infrahisian block, whereas Mobitz I type block was most frequently found in patients with suprahisian block. A chronic course of AV block was most frequent in patients with intrahisian block. The mean ventricular frequency of complete blockade was highest in suprahisian block, and lowest in infrahisian block. The localization of the block is a decisive factor for estimation of the prognosis and for indication of pacemaker implantation.