A 26-Year-Old Woman with Recurrent Loss of Consciousness

Abstract

The case of a 26-year-old woman with congenital long QT syndrome and recurrent arrhythmic syncope which had been misdiagnosed as a seizure disorder is presented. Useful criteria for discriminating between loss of consciousness due to congenital long QT syndrome and loss of consciousness caused by seizure activity are discussed. The multiple potential causes and clinical implications of a prolonged QT interval, as well as the clinical features and management of congenital long QT syndrome are reviewed. CASEA 26-year-old woman presented to a general cardiology clinic with a chief complaint of palpitations. The palpitations had begun a few months prior and had been occurring with increased frequency in recent weeks. She characterized the episodes as a rapid heartbeat that alternated between a regular and irregular rhythm. She denied associated symptoms of chest discomfort or shortness of breath, but did experience lightheadedness. The palpitations lasted 30-60 seconds and occurred once or twice a week over the preceding two months. They seemed to occur at any time of day and without regard to physical activity, stress, or anything else she could identify. They had on occasion awakened her from sleep.Her past medical history was notable for dyslexia and a complex-partial seizure disorder. She had a history of five seizures: a first seizure at age 15, a second at age 18, and a third at age 20, at which point carbamazepine treatment was initiated. Computed tomography and magnetic resonance imaging of the head was normal. An electroencephalogram was normal as well. Ten months previously carbamazepine was discontinued because she had been free of seizures for several years. However, about two weeks prior to her cardiology appointment she had a fourth seizure, and treatment with topiramate was initiated. She had a fifth seizure a few days prior to her cardiology appointment.The seizures always occurred when she was in a state between sleeping and wakefulness and were always precipitated by a loud noise, such as a ringing telephone. She experienced a prodrome of anxiety, lightheadedness and tachycardia. She would hyperventilate prior to losing consciousness. These events were witnessed by her mother, a registered nurse, who noted tonic and focal twitching movements of her daughter. Her mother also reported that her daughter was sometimes incontinent of urine and generally unresponsive for a few minutes during these episodes. When her daughter awakened she was immediately alert and did not feel fatigued or confused.Family history was significant for premature coronary disease in her father, who had undergone coronary artery bypass grafting at 45 years of age. There was no family history of sudden death. Her only medication was topiramate 50 milligrams by mouth twice a day. She did not smoke tobacco, use any illicit drugs, or drink alcohol. She was an art student at a nearby university.Her heart rate was 94 beats per minute and her blood pressure was 118/64 mm Hg. She was a very pleasant, slender young woman. The physical ...