Asystole-induced Bradycardia by Dexmedetomidine during Endoscopic Submucosal Dissection.

Although dexmedetomidine (DEX) is a widely used analgesic and sedative agent for endoscopic procedures, cardiovascular complications, such as bradycardia and hypotension, are frequently experienced. We herein report the first case of asystole-induced bradycardia due to DEX during endoscopic submucosal dissection (ESD). An 81-year-old man without cardiovascular diseases was referred for gastric carcinoma. ESD was started after administering a loading dose of DEX followed by a continuous maintenance infusion of DEX. The patient's heart rate gradually decreased, and then cardiac arrest occurred. DEX has a risk of cardiac arrest, so bradycardia should not be underestimated during sedation with DEX.