QT prolongation and torsades de pointesDownloads

Two days after admission for myocardial infarction and subsequent coronary angioplasty, a 65-year-old man becomes distressed and diaphoretic in the cardiac intensive care unit. Suddenly he is no longer responsive. Pulse oximetry does not show a tracing. He has a history of hypertension and depression. Prior to his admission, his medication included ramipril and aripiprazole. Examination shows no carotid pulse. An ECG is shown. After beginning chest compressions, which of the following is the most appropriate step in management of the patient?

A 62-year-old man is brought to the emergency department because of syncope. He reports sudden onset of palpitations followed by loss of consciousness while carrying his groceries to his car. He is unable to recall any further details and does not have any chest pain or dizziness. He has a history of hypertension, type 2 diabetes mellitus, gastroparesis, and osteoarthritis of the knees. Medications include lisinopril, metformin, and ondansetron as needed for nausea. He also takes methadone daily for chronic pain. Apart from an abrasion on his forehead, he appears well. His temperature is 37.2 °C (98.9 F), heart rate is 104/min and regular, and blood pressure is 135/70 mm Hg. While he is in the emergency department, he loses consciousness again. Telemetry shows polymorphic ventricular tachycardia with cyclic alteration of the QRS axis that spontaneously resolves after 30 seconds. Results of a complete blood count, serum electrolyte concentrations, and serum thyroid studies show no abnormalities. Cardiac enzymes are within normal limits. Which of the following is the most likely underlying cause of this patient's syncope?