Image IQ: 43-Year-Old Woman with Episodes of Fainting

Case: A 43-year-old woman went to the ED after several episodes of fainting over the past two days. She had recently had pneumonia and was just finishing up a prescription for erythromycin, so she worried that maybe she was still sick even though her pneumonia symptoms had been clearing up. Over the last two days, she had been feeling light-headed, dizzy, and had heart palpitations. During the exam, her doctor noted tachycardia and ordered an ECG. A blood test showed hypokalemia.