Intraventricular conduction disturbances in flying personnel: development and prognosis of bifascicular blocks

The evolutive characteristics as well as the qualification criteria applied in 21 cases of bifascicular blocks detected in a presumably healthy population consisting of 6,915 male individuals engaged in civilian flying activities (prevalence: 0.3%) were studied. The cases were divided in four groups according to the type and severity of the conduction disturbance. The sequence of conduction disturbances, ages and electrical axis rotation velocity are assessed. Bifascicular blocks may be complete or incomplete. The progression towards advanced conduction disturbances may affect the involved fascicles independently. Cases with incomplete bifascicular block have better prognosis, followed by those with primary conduction system disease. The mean time between the development of first and second conduction disturbance was 3.5 years. On an individual basis, once those etiologies which by themselves imply a future risk are ruled out, and provided they do not show evolutive features in frequent repeat evaluations, they may be waivered for flying activities, with a proposed maximum age of 60 years.