Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ KEY FEATURES +++ ESSENTIALS OF DIAGNOSIS ++ Sudden, unexpected, and transient loss of consciousness and postural tone Spontaneous and full recovery +++ GENERAL CONSIDERATIONS ++ The loss of consciousness resolves spontaneously without intervention Common pathophysiologic mechanism is secondary to reduction in cerebral blood flow and cerebral hypoperfusion Common condition experienced by 5–20% of adults by age 75 Responsible for 3% of hospital admissions and 6% of emergency room visits In general, syncope carries a benign prognosis Important causes include: – Valvular stenosis – Hypertrophic cardiomyopathy – Pulmonary emboli – Bradyarrhythmias such as complete heart block – Tachyarrhythmias such as ventricular tachycardia – Neurocardiogenic syncope – Situational syncope such as cough or micturition syncope Iatrogenic causes include: – Medications with negative chronotropic activity such as beta blockers – Orthostatic hypotension secondary to vasodilators or aggressive diuresis – Pacemaker malfunction in a pacemaker-dependent patient A thorough history establishes the cause of syncope or suggests the necessary diagnostic test in up to 85% of patients +++ CLINICAL PRESENTATION +++ SYMPTOMS AND SIGNS ++ History and symptoms depend on precipitating causes Relevant information includes: – Details of precipitating factors (micturition, cough, exertion) – Associated symptoms (palpitations, chest pain) – Position (standing, sitting, changing position) – Details about the episode (injury, incontinence, rapid recovery versus postictal state) +++ PHYSICAL EXAM FINDINGS ++ Orthostatic blood pressure must be assessed (orthostatic hypotension within 3 minutes on standing) Carotid sinus massage may be useful to elicit carotid hypersensitivity with a marked fall in heart rate Evaluate for the presence of murmurs on cardiac auscultation Other findings depend on the cause of syncope +++ DIFFERENTIAL DIAGNOSIS ++ Seizures Glossopharyngeal neuralgia Metabolic states such as hypoglycemia Cerebrovascular disease such as vertebrobasilar insufficiency Psychiatric disorder with hyperventilation Akinetic falling spells of the elderly +++ DIAGNOSTIC EVALUATION +++ LABORATORY TESTS ++ CBC Basic metabolic panel +++ ELECTROCARDIOGRAPHY ++ ECG to detect conduction abnormality Ambulatory ECG, event recorder, or implantable ECG loop recorder to diagnose either marked bradycardia or tachycardia +++ IMAGING STUDIES ++ Echocardiography is done to exclude valvular heart disease, hypertrophic cardiomyopathy, and other hemodynamically significant changes (should be done only if clinical examination is suggestive) Spiral CT or pulmonary angiogram may be done to diagnose pulmonary embolism or dissection of the aorta +++ DIAGNOSTIC PROCEDURES ++ Head-up tilt testing to evaluate neurocardiogenic syncope Electrophysiologic studies may be considered to evaluate malignant syncope for life-threatening ventricular arrhythmia +++ TREATMENT +++ CARDIOLOGY REFERRAL ++ If a cardiac cause is likely or suggested by initial evaluation, then referral is recommended +++ HOSPITALIZATION CRITERIA... Your Access profile is currently affiliated with [InstitutionA] and is in the process of switching affiliations to [InstitutionB]. Please select how you would like to proceed. Keep the current affiliation with [InstitutionA] and continue with the Access profile sign in process Switch affiliation to [InstitutionB] and continue with the Access profile sign in process 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 Error: Incorrect UserName or Password Username Error: Please enter User Name Password Error: Please enter Password Sign in Forgot Password? Forgot Username? Download the Access App: iOS | Android Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free profile for additional features.