23-Year-Old Woman With Syncope

Resident in Internal Medicine, Mayo School of Graduate Medical Education, Mayo Clinic, Rochester, MN (C.A.B., L.T.H.); Advisor to residents and Consultant in Cardiovascular Diseases, Mayo Clinic, Rochester, MN (V.T.N.). A 23-year-old woman presented to the emergency department after an episode of syncope while at work. She had a medical history of depression and one episode of syncope several years earlier. Her most recent episode of syncope occurred earlier in the day while she was standing and assisting a student at school. There was no associated chest pain, diaphoresis, or sensation of warmth, but she experienced palpitations before the syncope. Immediately after the event, she had no postictal state and walked to the school nurse’s office, where her systolic blood pressure was found to be in the 80s mm Hg and an irregular heart rhythm was noted. Her family history was negative for heart disease. The patient worked at a local bar and consumed 6 alcoholic drinks per evening a few days per week. She noted that during the previousweek she experienced new-onset “heartburn” multiple times daily, which was partially relieved with omeprazole. On physical examination, the patient was afebrile. Her pulse rate was 92 beats/min and regular, blood pressure was 91/56 mm Hg, and respiratory rate was 16 breaths/min. She appeared fatigued but in no acute distress, and no rashes were evident. The lungs were clear to auscultation, and heart soundswere normalwithoutmurmurs. Results of the remainder of the complete multisystem examination were unremarkable. Laboratory studies yielded the following values (reference ranges shown parenthetically): hemoglobin, 15 g/dL (12.0-15.5 g/dL); leukocyte count, 9.1 10/L (3.5-10.5 10/L); sodium, 136 mmol/L (135-145 mmol/L), potassium, 4.1 mmol/L (3.6-5.2 mmol/L); and creatinine, 0.8 mg/dL (0.6-1.1 mg/dL). Results of a urine drug screen were negative. Electrocardiography (ECG) revealed normal voltage and normal sinus rhythm without remarkable ST changes. Chest radiography detected no abnormalities.