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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 required

  • Stable patient may be returned to primary care physician

COMPLICATIONS

  • Trauma associated with syncope

  • Accidents ...

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