First-degree atrioventricular block in 14-year-old child due to Lyme disease.

Lyme disease is an infectious disease caused by bacteria of the Borrelia burgdorferi sensu lato (Bbsl) complex and is characterized by predominant lesions of the skin, cardiovascular system, nervous system and musculoskeletal system. We have described a clinical case of first-degree atrioventricular block in a 14-year-old boy caused by Lyme borreliosis. The disease started with the manifestations of cardiovascular system involvement. The patient and his parents did not recall observing a tick bite or manifestation of erythema migrans (EM). The boy was prescribed doxycycline. Three weeks after antibiotic therapy a second ECG examination was performed and showed no abnormalities.