CAROTID SINUS SYNDROME

CAROTID SINUS SYNDROME - Jeremy Golding, MD
BASICS
DESCRIPTION
• In carotid sinus syndrome, stimulation of one or both of the hypersensitive carotid sinuses at the bifurcation of the common carotid arteries produces brief episodes of faintness or loss of consciousness. 4 types are described
- Cardioinhibitory: Vagally mediated, causing bradycardia, sinus arrest, or atrioventricular block for >3 seconds
- Vasodepressor: A sudden drop of peripheral vascular resistance leads to a >50 mm Hg decrease in systolic blood pressure (BP) without change in heart rate or to a >30 mm Hg symptomatic drop in systolic BP.
- Mixed: Combined cardioinhibitory and vasodepressor changes
- Cerebral: Extremely rare; carotid sinus hypersensitivity occurs without bradycardia or hypotension.
• System(s) Affected: Cardiovascular; Nervous
• Synonym(s): Hypersensitive carotid sinus syndrome; Carotid sinus syncope; Carotid sinus hypersensitivity
ALERT
Geriatric Considerations
• More likely to occur in elderly
• Associated with atheromata secondary to coronary artery disease. Should be considered in elderly patients with frequent falls.
GENERAL PREVENTION
• Avoidance of pressure on the neck
• Support hose may be helpful for some patients with vasodepressor type.
EPIDEMIOLOGY
• Predominant age: Elderly
• Predominant sex: Male > Female
Incidence
64 of 132 consecutive patients (48.5%) >65 evaluated for dizziness, falls, or syncope were found to have carotid sinus-type sensitivity.
RISK FACTORS
• Diffuse atherosclerosis
• Wearing tight collars
• Shaving over region of carotid sinus
• Emotional upheaval
• Head movement
ETIOLOGY
• Unknown etiology
• Stimulation of the hypersensitive baroreceptors in the carotid sinus affects vagus and sympathetic nerve outflow.
• Carotid body tumors
• Inflammatory and malignant lymph nodes in the neck
• Metastatic cancer
• Coronary artery disease
ASSOCIATED CONDITIONS
• Sick sinus syndrome
• Atrioventricular block
• Coronary artery disease


DIAGNOSIS
SIGNS AND SYMPTOMS
Paroxysmal
Dizziness
Syncope
Falls
Blurred vision
Vertigo
Tinnitus
Bradycardia
Hypotension
Pallor
Sweating
Tachypnea
No postictal symptoms
TESTS
Special tests
• With the patient in the supine position and while the ECG is monitored, manual pressure ("massage") of the carotid sinus causes asystole of >3 seconds (cardioinhibitory) and/or a drop in systolic BP as described in Description. Diagnostic yield may be increased by combining with tilt-table testing.
Diagnostic Procedures/Surgery
• Unilateral carotid sinus pressure ("massage") (check for potential contraindications before performing massage, including carotid bruits, known carotid hypersensitivity, and demonstrated carotid artery disease). Direct steady pressure is applied over the carotid sinus for 10 seconds.
• Orthostatic vital signs (exclude orthostatic hypotension)
• Electrophysiologic studies
• ECG
• Carotid duplex scan
DIFFERENTIAL DIAGNOSIS
• Vasovagal syncope
• Postural hypotension
• Primary autonomic insufficiency
• Hypovolemia
• Arrhythmias
• Sick sinus syndrome
• Syncope secondary to reduced cardiac output (e.g., aortic stenosis)
• Cerebrovascular insufficiency
• Emotional disturbances
• Other causes of syncope
TREATMENT
Outpatient. No treatment is required for asymptomatic individuals.
GENERAL MEASURES
Cardiac pacing (dual chamber) is the treatment of choice for recurrent episodes.
Diet
No special diet
Activity
No restrictions
MEDICATION (DRUGS)
First Line
• Anticholinergics: Atropine (acutely) for the cardioinhibitory type
• Sympathomimetics: Ephedrine
• Theophylline
• In one study, selective serotonin reuptake inhibitors were successful in controlling symptoms.
• Contraindications: Refer to manufacturer's instructions.
• Precautions: Concomitant usage of digitalis, -blockers, clonidine, and -methyldopa may accentuate response to carotid sinus massage.
• Significant possible interactions: Refer to manufacturer's instructions.
Second Line
Fludrocortisone has been used in clinical trials for patients with vasodepressor carotid sinus syndrome.
SURGERY
• Carotid sinus denervation by surgery or radiation therapy for selected patients
• Implantation of a permanent pacemaker helps prevent recurrent symptoms in patients with cardioinhibitory component.
• Surgery for selected patients with atheromata
FOLLOW-UP
DISPOSITION
Admission Criteria
Syncope of uncertain etiology
PROGNOSIS
May be serious if syncope is associated with atheromatous narrowing of sinus artery or basilar artery
COMPLICATIONS
• Prolonged confusion
• Frequent falls, leading to injuries and fractures
PATIENT MONITORING
Follow as an outpatient.
REFERENCES
1. ACC/AHA/NASPE 2002 Guideline update for implantation of cardiac pacemakers and antiarrhythmia devices: Summary article. A report of the American College of Cardiology/American Heart Association task force on practice guidelines (ACC/AHA/NASPE committee to update the 1998 pacemaker guidelines). Circulation. 2002;106:2145.
2. Braunwald E, ed. Heart Disease: A Textbook of Cardiovascular Medicine, 6th ed. Philadelphia: WB Saunders, 2001.
3. Isselbacher KJ, et al., eds. Harrison's Principles of Internal Medicine, 14th ed. New York: McGraw-Hill, 1998.
4. McIntoch SJ, Lawson J, Kenny RA. Clinical characteristics of vasopressor, cardioinhibitory, and mixed carotid sinus syndrome in the elderly. Am J Med. 1993;95:203-208.
MISCELLANEOUS
• See also: Atherosclerosis
• It is clinically important to distinguish carotid sinus syndrome from sick sinus syndrome.