Electrocardiographic QT prolongation and sudden death in renal hypokalemic alkalosis

Abstract

A 3-year-old boy was found to have a mixed tubulopathy with hypokalemia (1.9 mmol/l), alkalosis (blood pH 7.51, plasma carbon dioxide pressure 46 mm Hg, plasma bicarbonate 35.7 mmol/l) and hypophosphatemia (1.21 mmol/l). An electrocardiogram disclosed a prolonged heart rate corrected QT interval of 490 ms. The boy was put on potassium chloride, phosphate and nonsteroidal anti-inflammatory agents. With this treatment plasma phosphate normalized and plasma potassium increased up to 3.0-3.3 mmol/l. Three years later the child, who did not have history of gastroesophageal reflux or epileptic convulsions, suddenly died during sleep. The cause of death could not be determined through gross examination of the body. The history of hypokalemia, the QT-prolongation, the sudden death and the failure to assess the cause of death through gross examination of the body suggest that death was caused by an arrhythmia secondary to hypokalemia.