We report a case of gastric dilatation in a ventilated 18-year-old woman, which was revealed by the acute onset of hypotension, sinus bradycardia, and complete atrioventricular block. Hypotension and cardiac rhythm disturbances resolved with intravenous injection of atropine, but recurred a few minutes later and required a second bolus of atropine, which had a transient beneficial effect. Only gastric decompression, as soon as gastric distention was recognized, was able to restore normal cardiac rhythm and adequate blood pressure. This case highlights the seriousness of gastric dilatation and argues for the vagal mechanism of cardiac rhythm and conduction troubles complicating gastric dilatation.