Picture 1. □ PICTURES IN CLINICAL MEDICINE □ Ventricular Fibrillation Following Bidirectional Tachycardia due to Digitalis Toxicity

(DOI: 10.2169/internalmedicine.50.6092) A 79-year-old woman with a previous history of hyper-tension, congestive heart failure and persistent atrial fibrilla-tion was admitted to our hospital with a diagnosis of retro-peritoneal abscess. Transthoracic echocardiography revealed a left ventricular ejection fraction of 55%. She received an intravenous administration of digoxin (0.125 mg daily) for rate control of atrial fibrillation from hospital day 9 and hemodialysis for acute renal failure from hospital day 15. On hospital day 29, bidirectional tachycardia characterized by QRS complexes with an alternating shift in the morphol-ogy on ECG monitoring, spontaneously developed (Pic-ture 1A and B), followed by ventricular fibrillation (VF) (Picture 1C), which was successfully defibrillated by DC-shock (Picture 1D). The serum level of digoxin was 2.4 ng/ mL, which was just above the upper limit of the therapeutic range. Serum potassium and magnesium were 2.7 mEq/L and 2.3 mEq/L, respectively. There may be an increased risk of an event of VF with digitalis therapy accompanied by left ventricular dysfunction and hypopotassemia (1). Digitalis toxicity causes bidirec-tional tachycardia (2). This case clearly exhibited the ar-rhythmic cascade which leads to the development of VF due to digital toxicity