Mobitz Type II atrioventricular block following tramadol and fentanyl in a patient with acute coronary syndrome and systolic heart failure

Serotonin syndrome is a potentially fatal condition allied with increased serotonergic activity in the central nervous system. There are published data reporting serotonin syndrome induced by either tramadol or fentanyl in combination with selective serotonin reuptake inhibitors in adult patients; however, there are no reports of serotonin syndrome resulting from the combination of tramadol and fentanyl. We report a case of a 52-year-old woman who was admitted to cardiology service and who developed Mobitz Type II atrioventricular (AV) block after administration of oral tramadol and intravenous fentanyl