A case of cardiomegaly with unilateral pulmonary edema is presented. The predisposing etiologies were severe hypoglycemia and a hypertonic glucose infusion into a branch of the left lower lobe pulmonary vein. Resolution resulted following maintenance of adequate glucose levels, vigorous cardiopulmonary support, and repositioning of the catheter tip in the inferior vena cava. The pathophysiologic mechanism was direct endothelial injury with an osmotic diuresis. The role of the release of a vasoactive substance was postulated.