Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ KEY FEATURES +++ ESSENTIALS OF DIAGNOSIS ++ Syncope or near syncope occurring during carotid sinus stimulation Precipitating events such as shaving or looking up may be reported Syncope tends to be abrupt, and the patient may not recall a specific maneuver Occurs in older patients Bradycardia and vasodepressor element may both play a role +++ GENERAL CONSIDERATIONS ++ Pure cardioinhibitory response is most common (60–80%) Pure vasodepressor response is rare (5–10%) The remainder is of a mixed variety Syncope or near syncope may occur during carotid sinus stimulation or fortuitous Holter monitoring showing asystole during maneuvers of carotid sinus stimulation Increased vagal activity and inhibition of peripheral sympathetic activity occur as part of carotid sinus reflex Heightened response to carotid sinus pressure Frequently associated with coronary artery disease Tendency to occur in older patients Maneuvers that precipitate syncope may include: – Tight collars – Heavy lifting – Trumpet playing – Sometimes the pressure of a seatbelt May be a cause of symptoms such as shortness of breath, angina, and syncope in patients with atrial fibrillation Carotid aneurysm and head-neck tumors can predispose to CSH +++ CLINICAL PRESENTATION +++ SYMPTOMS AND SIGNS ++ Dizziness Presyncope Syncope May present as unexplained falls +++ PHYSICAL EXAM FINDINGS ++ No specific features other than reproduction of symptoms on carotid sinus pressure May have features of coexistent coronary heart disease or carotid bruit +++ DIFFERENTIAL DIAGNOSIS ++ Neurocardiogenic syncope Ventricular tachycardia may coexist with carotid sinus hypersensitivity, particularly in patients with previous myocardial infarction or systolic dysfunction +++ DIAGNOSTIC EVALUATION +++ LABORATORY TESTS ++ CBC, basic metabolic panel +++ ELECTROCARDIOGRAPHY ++ ECG to identify previous myocardial infarction and arrhythmic disorders Ambulatory cardiac monitoring to document episodes and detect rhythm disturbances +++ IMAGING STUDIES ++ Generally not required unless there is evidence of underlying structural heart disease +++ DIAGNOSTIC PROCEDURES ++ Carotid sinus massage (contraindicated if there is a bruit, history of stroke, or carotid surgery) The carotid sinus massage should be done with ECG and hemodynamic monitoring The duration of the massage should not exceed 5–10 seconds Comprehensive evaluation includes both supine and upright carotid sinus massage Cardioinhibitory response is defined as ≥ 3 seconds of ventricular standstill (terminate carotid pressure at the onset of asystole) Vasodepressor response is defined as a drop in systolic blood pressure of ≥ 50 mm Hg +++ TREATMENT +++ CARDIOLOGY REFERRAL ++ All patients with a clinical suspicion of carotid sinus hypersensitivity should be evaluated by a cardiac electrophysiologist +++ HOSPITALIZATION CRITERIA ++ If marked asystole ... Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free a profile for additional features.