Second degree atrioventricular block

Type II block, or type I block when associated with bundle branch block, carry a relatively high risk in terms of progression to higher degrees of A-V block. Long-term follow-up studies of subjects with type I block and narrow QRS complexes have however produced rather conflicting results. Some studies have indicated that the condition is benign whilst others have reported a high incidence of progression to symptomatic complete heart block requiring permanent pacemaker implantation. Aircrew with type I second degree A-V block and narrow QRS complexes should undergo extensive evaluation but may be fit for multi-crew operations. The diagnosis of type II A-V block or type I block with wide QRS complexes should disbar from medical certification to fly.