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Carotid sinus hypersensitivity and carotid sinus syndrome

Author
David Benditt, MD
Section Editor
Peter Kowey, MD, FACC, FAHA, FHRS
Deputy Editor
Brian C Downey, MD, FACC

INTRODUCTION

Carotid sinus hypersensitivity (CSH) consists of the observation that stimulation of the carotid artery baroreceptors in the neck results in a greater than expected fall in heart rate and drop in blood pressure. In such cases, carotid baroreceptor stimulation (eg, mechanical forces such as may occur with turning of the neck or looking upward) results in vagal activation and/or sympathetic inhibition. CSH is not a clinical diagnosis per se but is a potential cause for symptoms in some patients.

CSH tends to be observed mainly in older individuals (predominantly males) who have atherosclerotic vascular disease. However, CSH may also be observed in individuals who have acquired abnormalities of the structure of the neck (eg, prior neck surgery and/or irradiation) or tumors in the region of the carotid sinuses. CSH is a relatively common observation but only an infrequent cause of symptoms. Thus, CSH does not require treatment unless it is deemed to be causing symptoms, resulting in a condition termed carotid sinus syndrome (CSS).

CSH and CSS will be reviewed here. Other types of reflex syncope, including vasovagal syncope, as well as general discussions of the pathogenesis, etiology, and evaluation of syncope, are discussed separately. (See "Reflex syncope in adults: Clinical presentation and diagnostic evaluation" and "Syncope in adults: Epidemiology, pathogenesis, and etiologies" and "Syncope in adults: Clinical manifestations and diagnostic evaluation".)

DEFINITION

There is not a universally accepted definition of what constitutes an abnormal response to carotid baroreceptor stimulation, resulting in carotid sinus hypersensitivity (CSH). The most commonly accepted definition is presented in the 2017 American College of Cardiology/American Heart Association/Heart Rhythm Society (ACC/AHA/HRS) syncope guidelines, which consider an abnormal value to be heart rate (HR) pauses >3 seconds and a drop of systolic blood pressure (BP) >50 mmHg [1].

However, others believe that the scientific basis for these criteria is unclear and that the criteria are too sensitive and nonspecific. It has been therefore proposed that cerebral hypoperfusion for >5 seconds with the patient in an upright position be utilized [2]. Our experts agree that this is a more appropriate criterion, but regardless of the chosen definition, it is paramount to observe changes in HR and BP. (See 'Test results' below.)

                      
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Literature review current through: Nov 2017. | This topic last updated: Nov 13, 2017.
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References
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