Histological findings of the atrioventricular conductive system in street heroin addicts, victims of sudden unexpected death.

A study of the atrioventricular (AV) conducting tissue was considered necessary for the examination of probable histologic changes that could justify the arrhythmias observed in street-heroin addicts. Postmortem coronary angiography and microscopic examination were performed in 50 heroin addicts (group A) and in 50 nonaddicts (group B), all male 16-40 years old. In group A, fatty and/or fibrous tissue replaced the AV node in 50% of cases while in group B in 14%. The main bundle was replaced by fatty and/or fibrous tissue in 44% in group A cases and 10% in group B. Intimal proliferation and fibromuscular dysplasia of the AV arteries in group A were correspondingly 26% and 14% and in group B 6% and 2%. Inflammation with focal and/or diffuse concentration of round cells of the AV node was detected in 54% in group A. These findings could explain a possible arrhythmia mechanism in this population.