A 50-year-old woman with a history of essential hypertension and depression was admitted to a telemetry unit because of 2 episodes of syncope within a 48-hour period. There were no other symptoms. Her blood pressure was 130/78 mm Hg, and findings on chest radiographs were normal. The serum potassium level was 3.3 mmol/L. The patient was being treated with clarithromycin for an upper respiratory tract infection. Her other medications were hydrochlorothiazide, fluoxetine, and a potassium supplement. A rhythm trace was recorded (Figure 1).
Which of the following apply to the arrhythmia in Figure 1?
sinus with paroxysmal ventricular tachycardia
torsades de pointes
prefibrillatory ventricular arrhythmia
Transient episodes of the arrhythmia recurred: 2 episodes deteriorated to ventricular fibrillation and required defibrillation. A 12-lead electrocardiogram during regular sinus rhythm was obtained (Figure 2).
The trace in...