[Complete atrioventricular block during lithium therapy within therapeutic range].

A 69-year-old man came to the emergency unit because of vertigo and presyncope. A bipolar disorder - known since an age of 15 years - has been treated with 2 × 450 mg lithium and 100 mg perazine per day for several years (no other medications). With the exception of a low heart rate (36/min) clinical examination findings were unremarkable. Electrocardiography revealed a permanent complete atrioventricular block with a heart rate of 36/min. Echocardiography showed a normal left ejection fraction (EF 65 %). Laboratory tests were mainly unremarkable, particularly the lithium levels (0,7 mmol/l) were within the therapeutic range. Continuous treatment with orciprenaline stabilized the heart rate at an average of 52/min. After pacing with a provisional pacemaker a permanent pacemaker was implanted without complications, and the symptoms of vertigo and dizziness disappeared. Pacemaker checkup on the following day still showed a complete atrioventricular block with a heart rate of 28/min. Complete atrioventricular block secondary to chronic lithium therapy even in therapeutic levels is a rare complication with poor prognosis. Therefore it should be treated consequently.