A 45-year-old woman was brought to the emergency department by ambulance due to a syncopal episode during the night. Her medical history was significant for node-positive breast cancer (in 2005), for which she received a lumpectomy. She declined further surgery, radiation and chemotherapy. Instead, she chose alternative therapy in Mexico. Her therapy in Mexico was a modified Gerson regimen, which consisted primarily of a diet of natural juices, herbal vitamins, coffee enemas and electrolyte supplementation. After several months, her cancer progressed, prompting her to seek further care in California (USA), where she began a cesium chloride protocol. This regimen consisted of 3 g oral cesium chloride daily. She also received small doses of molybdenum, indium, rubidium, selenium, germanium, vanadium and daily potassium chloride. She was not taking any other prescription or nonprescription medications.In the emergency department, her vital signs were stable. She was afebrile and her clinical examination was otherwise unremarkable. Her initial 12-lead electrocardiogram showed normal sinus rhythm with a prolonged corrected QT interval (QTc) of 516 ms (Figure 1). Her initial electrolyte panel was normal, with a potassium level of 3.9 mmol/L. Five hours later (09:55), she had a narrow complex tachycardia at a rate of 240 beats/min that responded to adenosine 6 mg intravenous push. At 13:13, her cardiac monitor revealed a pulseless torsades de pointes polymorphic ventricular tachycardia in the context of QT prolongation, which responded to 200 J of direct current cardioversion (Figure 2). At this time, amiodarone was initiated with 150 mg bolus, followed by a 1 mg/min infusion. Her postarrest 12-lead electrocardiogram showed normal sinus rhythm at 78 beats/min, with a QTc of 487 ms. At 16:26, she had another episode of torsades de pointes polymorphic ventricular tachycardia, which again responded to 200 J of direct current cardioversion. At 18:32, following another episode of successfully cardioverted pulseless polymorphic ventricular tachycardia, the amiodarone was discontinued due to potential further prolongation of QTc (Figure 3). A lidocaine 100 mg intravenous bolus was administered, followed by a continuous infusion of 2 mg/min, in addition to magnesium sulfate. The patient remained on lidocaine at a rate of 2 mg/min until 07:17 the following morning, when the dose was decreased to 1 mg/min. Within 2 h of this dose reduction, she began experiencing runs of premature ventricular contractions. The lidocaine was increased to 2 mg/min until the following day, when she was started on oral mexilitine therapy. She remained stable over the following six days and was discharged home. An echocardiogram during this admission revealed normal left atrial and left ventricular size, with normal biventricular systolic function. Over the course of the following six days, her potassium remained below 4.0 mmol/L (the lowest measurement was 3.0 mmol/L) despite aggressive potassium supplementation. During the course of her admission, ...