Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ KEY FEATURES +++ ESSENTIALS OF DIAGNOSIS ++ Most common mechanism of syncope in the young Bradycardia (vagal) and profound hypotension (vasodepressor) may occur either alone or in varying proportions Pain, fear, or emotion may precipitate syncope Many spells over several years are suggestive of this disorder Tilt testing is useful in the diagnosis +++ GENERAL CONSIDERATIONS ++ Generally occurs with no structural heart disease Prolonged standing may precipitate this disorder Usually associated with prodrome such as nausea and diaphoresis Bezold-Jarisch reflex triggered by mechanoreceptors of the inferoposterior myocardium leads to sympathetic withdrawal and unopposed vagal input This reflex may be a contributor to syncope due to aortic stenosis and hypertrophic cardiomyopathy Fatigue, pallor, and diaphoresis after syncope are common +++ CLINICAL PRESENTATION +++ SYMPTOMS AND SIGNS ++ Recurrent syncope with prodromal symptoms +++ PHYSICAL EXAM FINDINGS ++ Generally normal in between syncopal episodes +++ DIFFERENTIAL DIAGNOSIS ++ Sick sinus syndrome Orthostatic hypotension Iatrogenic syncope caused by antihypertensive medications +++ DIAGNOSTIC EVALUATION +++ LABORATORY TESTS ++ CBC, basic metabolic panel +++ ELECTROCARDIOGRAPHY ++ ECG to evaluate baseline intervals +++ IMAGING STUDIES ++ Echocardiogram to exclude structural heart disease +++ DIAGNOSTIC PROCEDURES ++ Head-up tilt-table testing If regular tilt testing is negative, consider provocative tilt testing with isoproterenol or carotid sinus massage Rare patient benefits from implantable loop recorder +++ TREATMENT +++ CARDIOLOGY REFERRAL ++ Patient with frequent syncope should be referred to a cardiologist +++ HOSPITALIZATION CRITERIA ++ Hospitalization seldom required Recurrent syncope especially with injuries +++ MEDICATIONS ++ Salt and fluid loading; avoidance of dehydration Fludrocortisone 0.2 mg PO daily Beta blockers, such as metoprolol 50 mg/day Adrenergic agonist midodrine 10 mg 3 times daily Serotonin reuptake inhibitors, such as paroxetine 20 mg/day Disopyramide 600 mg/day in divided doses +++ THERAPEUTIC PROCEDURES ++ Dual-chamber pacemaker with rate-drop feature is rarely performed as it only addresses bradycardia (vagal) and not the profound hypotension (vasodepressor) +++ SURGERY ++ None required +++ MONITORING ++ After initiation of therapy, tilt test may be repeated to document efficacy +++ DIET AND ACTIVITY ++ Additional salt intake Avoid dehydration +++ ONGOING MANAGEMENT +++ HOSPITAL DISCHARGE CRITERIA ++ After therapy is started +++ FOLLOW-UP ++ Three months after initial assessment If symptoms are frequent, earlier follow-up may be ... 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 Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth