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This ambulatory ECG was recorded from a 59 year old man who had been diagnosed as having nocturnal epilepsy at the age of 26 years.
The patient's initial presentation followed a motorbike accident, although he suffered no head injury. He has subsequently had multiple medical problems and saw an ear, nose, and throat surgeon at the age of 51 because of “sleep apnoea”. At that time he was noted to have neck swelling and a computed tomographic (CT) scan (bottom) showed bilateral carotid body tumours, although the diagnosis was not made.
He was referred to a cardiologist because of renewed diagnostic doubt regarding his nocturnal attacks which continued to occur, often in clusters, especially when he lay on his right side, despite anticonvulsant treatment. He gave a history of hypertension, renal dysfunction, and paroxysmal atrial fibrillation.
Following implantation of a permanent pacemaker four years ago he has had no further attacks. When light pressure is applied to the neck masses with the pacemaker's rate limit lowered, asystole is easily produced—carotid sinus hypersensitivity secondary to his carotid body tumours. In the absence of symptoms and because of his other medical problems, surgical removal has not been attempted. The tumours are very slow growing (comparing current CT scans to previous images) and must have produced carotid sinus hypersensitivity even when very small. The likely mechanism for this must be that the tumour changes the pressure transduction mechanisms within the carotid body, leading to hypersensitivity.