Syncope

Anthony Ho, DO PGY4

Emergency Medicine

Introduction

• Symptom complex composed of brief loss of consciousness associated with inability to maintain postural tone that spontaneously resolves without medical intervention

• Epidemiology– 2% of ER visits– 1 out of 4 persons will have in lifetime– Elderly have the highest risk of morbidity– Near syncope is the same process– Differentiate from vertigo or dizziness

“Passed Out”

Pathophysiology

• Lack of blood flow to brainstem reticular activating system for 10-15 seconds

• Reduction of cerebral perfusion by 35% for 5-10 seconds

• Most common inciting event is drop in cardiac output

• Least common is vasospasms or other alterations in flow to CNS

Etiology• Causes of syncope

– Cardiac • Structural cardiopulmonary disease

– Valvular heart disease, aortic stenosis, tricuspid stenosis, cardiomyopathy, pulmonary HTN, Congenital Heart disease, Myxoma, pericardial disease, aortic dissection, PE, MI, ACS.

• Dysrhythmias– Bradydysrhythmias, Stokes-Adams attack, Sinus node disease, 2nd-3rd degree blocks,

pacemaker malfunction, tachydysrhythmias, Vtach, torsades de pointes, SVT, A Fib or Aflutter.

– Neural/Reflex mediated• Vasovagal• Situational

– Cough, micturition, defecation, swallow, neuralgia, • Carotid Sinus Syndrome

– Orthostatic– Psychiatric– Neurologic

• TIA, Subclavian Steal, Migraine– Medications

Cardiac Syncope

• 6 month mortality >10%• Underlying Structural Cardiopulmonary disease

– Think Aortic Stenosis in Elderly– Think Hypertrophic Cardiomyopathy in Young– PE can lead to Pulmonary outflow obstruction– AMI or ischemia can lead to decrease CO

• Dysrhythmias– Both tachy- and bradysrhythmias can lead to transient

hypoperfusion– Syncope is SUDDEN ONSET without prodromal

symptoms

Vasovagal or Neurally/Reflex-Mediated Syncope

• Syncope associated to inappropriate vasodilation, bradycardia, or both in response to inappropriate vagal or sympathetic tone

• SLOW PROGRESSIVE ONSET with associated prodrome

• Carotid Sinus Hypersensitivity, consider in elderly patients with recurrent syncope and negative cardiac evaluations

Orthostatic Syncope

• Occurs within 3 minutes of standing• Orthostatic tests positive if decrease in SBP by

>20mmHg or drop in pressure to <90• Non specific test: 40% of asymptomatic patients

>70 are positive• Many life threatening causes of syncope have

orthostatic symptoms, do not attribute as benign just because you have positive orthostatics

Psychiatric Illnesses

• Diagnosis of exclusion

• Associated with generalized anxiety and major depressive disorders

• i.e. Hyperventilation syndrome hypocarbia cerebral vasoconstriction

Neurologic Syncope

• Loss of consciousness with persistent neurologic deficits or AMS are not true syncope

• Stroke Syndromes with syncope– Brainstem ischemia– Posterior circulation ischemia (diplopia,

vertigo, nausea)– Subclavian steal syndrome

• Seizures often mimic syncope

Medication-Induced Syncope

• Usually contributes to orthostatic syncope

• Antihypertensive mediations (BB, CCB), diuretics, and proarrythmics

Elderly Population

• Cardiovascular risk is the best predictor of mortality with syncope

• Highest risk group– Calcified blood vessels are less compliant– LV becomes less compliant, increasing

dependence on atrial kick

• Incidence of vasovagal syncope decreases with age

• Increased orthostatic syncope

Evaluation

• ED goal – 1. Avoid litigation!– 2. Admit patients that will benefit (receive a diagnosis)

from admission.– 3. Discharge patients that won’t die (or have

complications) before their follow-up.– 4. Diagnose in the ED reversible or deadly causes

• RISK STRATIFICATION– Careful history– Thorough Physical Exam– EKG interpretation

History

• Symptoms of cardiopulmonary or neurological origin– Chest pain, palpitations, shortness of breath,

headache, abdomen or back pain, focal deficits.

• Family history of dysrhythmias, sudden cardiac death, prolonged QT

Physical Exam

• Focus on cardiovascular and neurological systems– Murmurs, rales (think HCM, AS)– Focal neurological exam– Rectal examination

EKG

• Cardiopulmonary disease– Acute ischemia– dysrhythmia (WPW, Brugada)– Heart block– Prolonged QT

Other test

• Carotid massage– Only small number of patients with

hypersensitivity with have true Carotid Sinus Syndrome

• Hyperventilation maneuver

• Neurologic Testing– CT/MRI not warranted for isolated syncope

Unexplained Syncope

• Unknown etiology in 40% of patients

• If diagnosis made, 80% of the time is in the emergency room!

Disposition

• SF Syncope Rules– CHF– Hematocrit <30– EKG changes– SBP<90– SOB

• Boston Syncope Criteria– 25 criteria

Practice Guideline

Post ED Evaluation

• Cardiac Syncope– Electrocardiographic monitoring– Echocardiography– Electrophysiology testing– Stress testing

• Neurologic Syncope– CT/MRA/Carotid Doppler– EEG

• Reflex-mediated syncope– Tilt-table testing

• Psychogenic– Psychiatric testing