title: Second degree atrioventricular block.
abstract: 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.
mesh_terms: D000337:Aerospace Medicine; D001283:Atrioventricular Node / Q000503:physiopathology; D002036:Bundle of His / Q000503:physiopathology; D002037:Bundle-Branch Block / Q000150:complications; D002568:Certification; D002908:Chronic Disease; D005500:Follow-Up Studies; D006327:Heart Block / Q000145:classification* / Q000150:complications / Q000175:diagnosis; D006801:Humans; D008297:Male; D011379:Prognosis; D011690:Purkinje Fibers / Q000503:physiopathology