Ventricular fibrillation triggered by recurrent hypoglycemia in a patient with insulinoma associated with MEN1: case report and review of literature

Abstract

This report describes the case of a 44-year-old woman without structural heart disease who developed ventricular fibrillation (VF) during preoperative management of multiple pancreatic neuroendocrine tumors (NETs) associated with multiple endocrine neoplasia type 1. She had an insulinoma in the uncinate process and a non-functioning NET in the pancreatic tail. Immediately after intravenous glucose administration for recurrent hypoglycemia, VF occurred. An electrocardiogram obtained immediately before VF onset showed repolarization abnormalities with marked QTc prolongation, terminal T-wave bulging, and U waves. Laboratory testing revealed concomitant mild hypokalemia. No coronary artery disease was detected. The severe repolarization abnormalities improved after resection of the insulinoma. The presumed mechanism was that mild hypokalemia and recurrent hypoglycemia, together with hypoglycemia-induced epinephrine surge and extracellular-to-intracellular potassium shift, synergistically prolonged the action potential duration and induced early afterdepolarizations, which progressed from torsades de pointes to VF. This case highlights that unstable glycemic control in insulinoma can precipitate life-threatening arrhythmias, even in the absence of structural heart disease. Particularly when surgery is delayed, maintaining serum potassium as 4.5–5.0 mmol/L and preventing recurrent hypoglycemia are crucially important. Early recognition and intervention might help reduce arrhythmic risk in such patients.