eMedicine Specialties > Cardiology > Arrhythmias

Carotid Sinus Hypersensitivity

Author: Mevan N Wijetunga, MD, FACC, Cardiac Electrophysiologist, Central Minnesota Heart Center at St Cloud Hospital
Coauthor(s): Irwin J Schatz, MD, Professor, Department of Internal Medicine, University of Hawaii
Contributor Information and Disclosures

Updated: May 12, 2009

Introduction

Background

Carotid sinus hypersensitivity (CSH) is an exaggerated response to carotid sinus baroreceptor stimulation. It results in dizziness or syncope from transient diminished cerebral perfusion.

Although baroreceptor function usually diminishes with age, some people experience hypersensitive carotid baroreflexes. For these individuals, even mild stimulation to the neck results in marked bradycardia and a drop in blood pressure.

CSH predominantly affects older males. It is a potent contributory factor and a potentially treatable cause of unexplained falls and neurocardiogenic syncopal episodes in elderly people.1,2 Yet, CSH is often overlooked in the differential diagnosis of syncope.

CSH, orthostatic hypotension, and vasovagal syncope are common conditions that are likely to coexist in patients with syncope and falls.3

Pathophysiology

The carotid sinus reflex plays a central role in blood pressure homeostasis. Changes in stretch and transmural pressure are detected by baroreceptors in the heart, carotid sinus, aortic arch, and other large vessels. Afferent impulses are transmitted by the carotid sinus, glossopharyngeal, and vagus nerves to the nuclei tractus solitarius and the para median nucleus in the brain stem. Efferent limbs are carried through sympathetic and vagus nerves to the heart and blood vessels, controlling heart rate and vasomotor tone.

In CSH, mechanical deformation of the carotid sinus (located at the bifurcation of the common carotid artery) leads to an exaggerated response with bradycardia or vasodilatation, resulting in hypotension, presyncope, or syncope.

Studies in humans have suggested that autonomic degeneration with accumulation of hyperphosphorylated tau or alpha-synuclein in neurones in medulla may impair central regulation of baroreflex responses and predispose elderly patients to CSH.4

However, the exact mechanism and site of abnormal sensitivity is unknown. The exaggerated response may be due to changes in any part of the reflex arc or the target organs.

Clinically, 3 types of CSH have been described.

  1. The cardioinhibitory type comprises 70-75% of cases. The predominant manifestation is a decreased heart rate, which results in sinus bradycardia, atrioventricular block, or asystole due to vagal action on sinus and atrioventricular nodes. This response can be abolished with atropine.5
  2. The vasodepressor type comprises 5-10% of cases. The predominant manifestation is a vasomotor tone decrease without a change in heart rate. The significant resulting drop in blood pressure is due to a change in the balance of parasympathetic and sympathetic effects on peripheral blood vessels. This response is not abolished with atropine.
  3. The mixed type comprises 20-25% of cases. A decrease in heart rate and vasomotor tone occurs.

The terms spontaneous carotid sinus syndrome and induced carotid sinus syndrome have been introduced to categorize patients who are presumed to have CSH.

  • The term spontaneous carotid sinus syndrome refers to a clinical situation in which the symptoms can be clearly attributed to a history of accidental mechanical manipulation of the carotid sinuses (eg, taking pulses in the neck, shaving) and CSH is reproduced by carotid sinus massage. Spontaneous carotid sinus syndrome is rare and accounts for about 1% of causes of syncope.
  • The term induced carotid sinus syndrome refers to a clinical situation in which a patient has no clear history of accidental mechanical manipulation of the carotid sinuses and has a negative result from workup for syncope, except for a hypersensitive response to carotid sinus massage, which can be attributed to the patient's symptoms. Induced carotid sinus syndrome is more prevalent than spontaneous carotid sinus syndrome and accounts for the bulk of patients with an abnormal response to carotid sinus massage observed in the clinical setting.

Frequency

United States

CSH is found in 0.5-9.0% of patients with recurrent syncope.

International

CSH is observed in up to 14% of elderly nursing home patients and 30% of elderly patients with unexplained syncope and drop attacks.

Mortality/Morbidity

  • CSH is associated with an increased risk of falls, drop attacks, bodily injuries, and fractures in elderly patients.
  • Rates of total mortality, sudden death, myocardial infarction, or stroke are unaffected by the presence of CSH.

Sex

CSH is more common in males than in females.

Age

CSH is predominantly a disease of elderly people; it is virtually unknown in people younger than 50 years.

Clinical

History

Although many patients remain asymptomatic, the following are symptoms of CSH:

  • Recurrent dizziness, near-syncope
  • Recurrent syncope6
  • Nonaccidental, unexplained falls1
  • Symptoms produced by head turning or wearing garments with tight-fitting collars
  • Neck tumors, extensive neck scarring secondary to radical dissection or radiation fibrosis or neck trauma
  • Possible prodrome or retrograde amnesia for the syncopal event

Physical

Signs of CSH found upon examination include the following:

  • Hypotension
  • Bradycardia
  • Asystole
  • Auscultation for carotid artery bruit prior to consideration of carotid sinus massage

Causes

CSH is associated with the following:

More on Carotid Sinus Hypersensitivity

Overview: Carotid Sinus Hypersensitivity
Differential Diagnoses & Workup: Carotid Sinus Hypersensitivity
Treatment & Medication: Carotid Sinus Hypersensitivity
Follow-up: Carotid Sinus Hypersensitivity
References
Further Reading
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References

  1. Parry SW, Steen N, Bexton RS, Tynan M, Kenny RA. Pacing in elderly recurrent fallers with carotid sinus hypersensitivity: a randomised, double-blind, placebo controlled crossover trial. Heart. May 2009;95(5):405-9. [Medline].

  2. Gillespie LD, Robertson MC, Gillespie WJ, Lamb SE, Gates S, Cumming RG, et al. Interventions for preventing falls in older people living in the community. Cochrane Database Syst Rev. Apr 15 2009;CD007146. [Medline].

  3. Tan MP, Newton JL, Chadwick TJ, Parry SW. The relationship between carotid sinus hypersensitivity, orthostatic hypotension, and vasovagal syncope: a case-control study. Europace. Dec 2008;10(12):1400-5. [Medline].

  4. Miller VM, Kenny RA, Slade JY, Oakley AE, Kalaria RN. Medullary autonomic pathology in carotid sinus hypersensitivity. Neuropathol Appl Neurobiol. Aug 2008;34(4):403-11. [Medline].

  5. Lacerda Gde C, Pedrosa RC, Lacerda RC, Santos MC, Perez Mde A, Teixeira AB, et al. Cardioinhibitory carotid sinus hypersensitivity: prevalence and predictors in 502 outpatients. Arq Bras Cardiol. Mar 2008;90(3):148-55. [Medline].

  6. Kuo FY, Hsiao HC, Chiou CW, Liu CP. Recurrent syncope due to carotid sinus hypersensitivity and sick sinus syndrome. J Chin Med Assoc. Oct 2008;71(10):532-5. [Medline].

  7. Ballard C, Shaw F, McKeith I, Kenny R. High prevalence of neurovascular instability in neurodegenerative dementias. Neurology. Dec 1998;51(6):1760-2. [Medline].

  8. Kenny RA, Shaw FE, O'Brien JT, Scheltens PH, Kalaria R, Ballard C. Carotid sinus syndrome is common in dementia with Lewy bodies and correlates with deep white matter lesions. J Neurol Neurosurg Psychiatry. Jul 2004;75(7):966-71. [Medline].

  9. Epstein AE, DiMarco JP, Ellenbogen KA, Estes NA 3rd, Freedman RA, Gettes LS, et al. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices) developed in collaboration with the American Association for Thoracic Surgery and Society of Thoracic Surgeons. J Am Coll Cardiol. May 27 2008;51(21):e1-62. [Medline].

  10. Moore A, Watts M, Sheehy T, et al. Treatment of vasodepressor carotid sinus syndrome with midodrine: a randomized, controlled pilot study. J Am Geriatr Soc. Jan 2005;53(1):114-8. [Medline].

  11. Benditt DG, Fahy GJ, Lurie KG, et al. Pharmacotherapy of neurally mediated syncope. Circulation. Sep 14 1999;100(11):1242-8. [Medline].

  12. Brignole M. Randomized clinical trials of neurally mediated syncope. J Cardiovasc Electrophysiol. Sep 2003;14(9 Suppl):S64-9. [Medline].

  13. Brignole M, Menozzi C, Lolli G, et al. Long-term outcome of paced and nonpaced patients with severe carotid sinus syndrome. Am J Cardiol. Apr 15 1992;69(12):1039-43. [Medline].

  14. Kenny RA, O'Shea D, Parry SW. The Newcastle protocols for head-up tilt table testing in the diagnosis of vasovagal syncope, carotid sinus hypersensitivity, and related disorders. Heart. May 2000;83(5):564-9. [Medline].

  15. Kenny RA, Richardson DA, Steen N, et al. Carotid sinus syndrome: a modifiable risk factor for nonaccidental falls in older adults (SAFE PACE). J Am Coll Cardiol. Nov 1 2001;38(5):1491-6. [Medline].

  16. McIntosh SJ, Lawson J, Kenny RA. Clinical characteristics of vasodepressor, cardioinhibitory, and mixed carotid sinus syndrome in the elderly. Am J Med. Aug 1993;95(2):203-8. [Medline].

  17. Morillo CA, Camacho ME, Wood MA, et al. Diagnostic utility of mechanical, pharmacological and orthostatic stimulation of the carotid sinus in patients with unexplained syncope. J Am Coll Cardiol. Nov 1 1999;34(5):1587-94. [Medline].

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Further Reading

Clinical guidelines

 Clinical practice guideline for the assessment and prevention of falls in older people.
National Collaborating Centre for Nursing and Supportive Care - National Government Agency [Non-U.S.].  2004 Jun.  185 pages.  NGC:003968

(1) ACC/AHA guidelines for the management of patients with ST-elevation myocardial infarction. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to revise the 1999 guidelines for the Management of Acute Myocardial Infarction). (2) 2007 focused update of the ACC/AHA 2004 guidelines for the management of patients with ST-elevation myocardial infarction. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.
American College of Cardiology Foundation - Medical Specialty Society
American Heart Association - Professional Association.  1996 Nov 1 (revised 2004 Jul; addendum released 2008 Jan).  Original guideline: 211 pages; Focused update: 38.  NGC:006289

Preventing falls in acute care. In: Evidence-based geriatric nursing protocols for best practice.
Hartford Institute for Geriatric Nursing - Academic Institution.  2003 (revised 2008 Jan).  38 pages.  NGC:006349

ACC/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices). 9
American College of Cardiology Foundation - Medical Specialty Society
American Heart Association - Professional Association
Heart Rhythm Society - Professional Association.  1998 Apr (revised 2008 May 27).  62 pages.  NGC:006498

Clinical trials

Vestibular Rehabilitation and Dizziness in Geriatric Patients

Evaluation of Syncope, Its Diagnosis, Treatment, Outcome and Prognosis


Related eMedicine topics


Sinus Bradycardia

Syncope

Syncope

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Keywords

carotid sinus, CSH, hypersensitive carotid reflex, Weiss-Baker syndrome, dizziness, syncope, baroreceptors, cardioinhibitory type of carotid sinus hypersensitivity, vasodepressor type of carotid sinus hypersensitivity, mixed type of carotid sinus hypersensitivity, carotid sinus baroreceptor stimulation, carotid sinus reflex, spontaneous carotid sinus syndrome, induced carotid sinus syndrome, hypertension, coronary artery disease, neurocardiogenic syncope, dementia with Lewy body disease, carotid sinus massage, accidental mechanical manipulation of the carotid sinuses, carotid sinus stimulation

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Contributor Information and Disclosures

Author

Mevan N Wijetunga, MD, FACC, Cardiac Electrophysiologist, Central Minnesota Heart Center at St Cloud Hospital
Mevan N Wijetunga, MD, FACC is a member of the following medical societies: American College of Cardiology and Heart Rhythm Society
Disclosure: Nothing to disclose.

Coauthor(s)

Irwin J Schatz, MD, Professor, Department of Internal Medicine, University of Hawaii
Irwin J Schatz, MD is a member of the following medical societies: Alpha Omega Alpha, American Autonomic Society, American College of Cardiology, American College of Physicians, American Federation for Medical Research, and American Heart Association
Disclosure: Nothing to disclose.

Medical Editor

Hanumant Deshmukh, MD †, Former Chief of Cardiology, Veterans Affairs Medical Center; Former Associate Professor, Department of Medicine, Rosalind Franklin University of Medicine and Science
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Steven J Compton, MD, FACC, FACP, Director of Cardiac Electrophysiology, Alaska Heart Institute, Providence and Alaska Regional Hospitals
Steven J Compton, MD, FACC, FACP is a member of the following medical societies: Alaska State Medical Association, American College of Cardiology, American College of Physicians, and Heart Rhythm Society
Disclosure: Nothing to disclose.

CME Editor

Amer Suleman, MD, Consultant in Electrophysiology and Cardiovascular Medicine, Department of Internal Medicine, Division of Cardiology, Medical City Dallas Hospital
Amer Suleman, MD is a member of the following medical societies: American College of Physicians, American Heart Association, American Institute of Stress, American Society of Hypertension, Federation of American Societies for Experimental Biology, Royal Society of Medicine, and Society of Cardiac Angiography and Interventions
Disclosure: Nothing to disclose.

Chief Editor

Jeffrey N Rottman, MD, Professor of Medicine and Pharmacology, Director, Clinical Cardiac Electrophysiology Fellowship Program, Vanderbilt University School of Medicine; Chief, Department of Cardiology, Nashville Veterans Affairs Medical Center
Jeffrey N Rottman, MD is a member of the following medical societies: American Heart Association and North American Society of Pacing and Electrophysiology (NASPE)
Disclosure: Nothing to disclose.

 
 
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