A 72-year-old man comes to the emergency department after a syncopal episode. The patient briefly lost consciousness an hour ago while getting dressed. He remembers putting on a shirt and tie and the next thing he remembers is finding himself on the floor with his wife at his side. His wife reports that the patient had no abnormal extremity movements or involuntary micturition during the event. The patient has had several episodes of lightheadedness, especially in the morning while shaving, but has never lost consciousness or fallen. He has a history of poorly controlled hypertension and had a recent change in his medications. Other medical conditions include type 2 diabetes mellitus and hyperlipidemia. Blood pressure is 142/86 mm Hg while supine and 134/84 mm Hg while upright, and pulse is 72/min while supine and 80/min while upright. Physical examination shows no carotid bruit and normal jugular venous pressure. There is a grade 2/6 systolic murmur, best heard at the right second intercostal space, and both heart sounds are normal. There is loss of vibration sensation in the feet, and ankle reflexes are absent bilaterally. The remainder of the examination shows no abnormalities. ECG reveals normal sinus rhythm. Which of the following is the most likely cause of this patient's syncope?

Question

A 72-year-old man comes to the emergency department after a syncopal episode.  The patient briefly lost consciousness an hour ago while getting dressed.  He remembers putting on a shirt and tie and the next thing he remembers is finding himself on the floor with his wife at his side.  His wife reports that the patient had no abnormal extremity movements or involuntary micturition during the event.  The patient has had several episodes of lightheadedness, especially in the morning while shaving, but has never lost consciousness or fallen.  He has a history of poorly controlled hypertension and had a recent change in his medications.  Other medical conditions include type 2 diabetes mellitus and hyperlipidemia.  Blood pressure is 142/86 mm Hg while supine and 134/84 mm Hg while upright, and pulse is 72/min while supine and 80/min while upright.  Physical examination shows no carotid bruit and normal jugular venous pressure.  There is a grade 2/6 systolic murmur, best heard at the right second intercostal space, and both heart sounds are normal.  There is loss of vibration sensation in the feet, and ankle reflexes are absent bilaterally.  The remainder of the examination shows no abnormalities.  ECG reveals normal sinus rhythm.  Which of the following is the most likely cause of this patient's syncope?

Quizplus · Accepted Answer

11ec25c8_d13f_d0e7_bc81_b1ff1cc8e5c8_MD0003_00 This patient most likely has carotid sinus hypersensitivity (CSH). In the normal state, carotid sinus baroreceptors detect increases in blood pressure and respond by stimulating a relative increase in parasympathetic (vagal) tone that slows the heart rate and induces vasodilation to reduce and regulate blood pressure. In some individuals, especially elderly men with atherosclerotic disease, the carotid sinus baroreceptors become overly sensitive, triggering an exaggerated vagal response. This can cause a transient reduction in cerebral perfusion that manifests as syncope or presyncope (ie, lightheadedness). carotid sinus baroreceptors The exaggerated vagal response that characterizes CSH is often triggered by minimal tactile stimulus of the carotid sinus (eg, shaving, rubbing of a shirt collar while dressing or turning the head) and causes a >3 second ventricular pause and >50 mm Hg drop in systolic blood pressure. The diagnosis is made by carotid massage producing an exaggerated vagal response; this maneuver is often aided by a tilt table to ensure the patient is secured and does not fall. Treatment can involve placement of a permanent pacemaker. (Choice B) This patient's reduced vibratory sensation and ankle reflexes are consistent with diabetic peripheral neuropathy, which often involves damage to the autonomic nervous system. Although such damage can predispose to orthostasis and syncope, symptoms usually occur immediately after standing. (Choice C) Syncope due to intermittent cardiac arrhythmia (eg, paroxysmal ventricular tachycardia) usually occurs without warning symptoms and is a concern in older patients with cardiomyopathy or ischemic heart disease. The association of tactile stimulus of the carotid sinus with this patient's symptoms makes CSH more likely. (Choice D) Hypovolemia is a potential cause of syncope and presyncope; however, the symptoms are usually orthostatic and occur immediately after standing. (Choice E) Left ventricular outflow obstruction (eg, severe aortic stenosis) is a potential cause of syncope. Although this patient's systolic murmur could represent aortic stenosis, syncope or presyncope due to aortic stenosis is usually exertional. Educational objective: Carotid sinus hypersensitivity involves an exaggerated vagal response that is often triggered by tactile stimulation. The exaggerated response causes a >3 second ventricular pause and >50 mm Hg drop in systolic blood pressure, leading to a transient reduction in cerebral perfusion that manifests as syncope or presyncope. References: Diagnosis of carotid sinus hypersensitivity in older adults: carotid sinus massage in the upright position is essential. (http://www.ncbi.nlm.nih.gov/pubmed/10618329)

A 72-Year-Old Man Comes to the Emergency Department After a Syncopal