Syncope resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Alejandro Lemor, M.D. [2]; Karol Gema Hernandez, M.D. [3]
Synonyms and keywords: Blacking out; collapse; faint; fainting; loss of consciousness; swoon; unconscious

Syncope Resident Survival Guide Microchapters
Overview
Causes
Classification
Diagnosis FIRE Complete Clues
Treatment
Do's
Don'ts

Overview

Syncope is the transient loss of consciousness (LOC) due to cerebral hypoperfusion and it is characterized by a rapid onset, a short duration and a spontaneous complete recovery. It is important to identify the cause of syncope and recognize high risk patients with structural heart disease or abnormal ECG findings. The initial management of syncope depends on the etiology of the syncope which can be either reflex, orthostatic hypotension or cardiovascular.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

• Hemorrhage
• Hypotension
• Hypoxia
• Ruptured abdominal aortic aneurysm
• Ventricular arrhythmia

Common Causes

• Aortic stenosis
• Arrhythmia
• Medications (vasodilators, diuretics, antiarrhythmics, antipsychotics)
• Orthostatic hypotension
• Vagal stimulation
• Vertebrobasilar insufficiency

Classification

Syncope is classified based on the pathophysiology of the etiology.

Cardiovascular Syncope

• Arrhythmias (bradycardia or tachycardia)
• Structural heart disease
• Drug-induced arrhythmia

Orthostatic Hypotension

• Primary autonomic failure (pure autonomic failure, Parkinson's disease)
• Secondary autonomic failure (diabetes, uremia)
• Drug-induced (alcohol, vasodilators, diuretics)
• Hypovolemia (hemorrhage, diarrhea)

Reflex Syncope

• Vasovagal
• Situational (cough, sneeze, postprandial, post-exercise)
• Carotid sinus hypersensitivity

Diagnosis

Focus Initial Rapid Evaluation of Suspected Syncope

Shown below is an algorithm depicting the Focus Initial Rapid Evaluation (FIRE) of suspected syncope.

Boxes in red signify that an urgent management is needed.

Identify cardinal signs and symptoms that increase the pretest probability of syncope ❑ Loss of consciousness (LOC) of: ❑ Short duration, AND ❑ Rapid onset, AND ❑ Complete spontaneous recovery

Identify alarming signs or symptoms ❑ Tachycardia ❑ Hypotension ❑ Severe dyspnea ❑ Hemorrhage ❑ Seizures

Unstable patient

Stable patient

❑ Immediately order an ECG

Continue with the diagnostic approach

ECG findings

Arrhythmia

Myocardial infarction

Normal EKG

Hemorrhage

Pulmonary embolism

Administer: ❑ Aspirin 162-325 mg ❑ Oxygen (2-4 L/min) if satO2 <90% ❑ Beta-blockers (unless contraindicated) ❑ Sublingual nitroglycerin 0.4 mg every 5 min for a total of 3 doses Do not delay primary angioplasty or fibrinolysis

❑ Manage the hypovolemic state ❑ Administer IV normal saline 2 L STAT ❑ Give vasopressors if needed ❑ Determine the location and etiology of the bleeding

Suggestive signs and symptoms: ❑ Sudden onset of dyspnea and tachypnea ❑ Tachycardia ❑ Pleuritic chest pain ❑ Symptoms suggestive of DVT ❑ Positive CT pulmonary angiography

Click here for arrhythmia resident survival guide

Click here for STEMI resident survival guide

Click here for shock resident survival guide

Click here for pulmonary embolism resident survival guide

Complete Diagnostic Approach to Suspected Syncope

Shown below is an algorithm summarizing the diagnostic approach to syncope based on the 2009 ESC Guidelines for the Diagnosis and Management of Syncope.

Abbreviations: TIA: transient ischemic attack; EEG: electroencephalography; HF: heart failure; AF: atrial fibrillation; SVT: supraventricular tachycardia; VT: ventricular tachycardia; MI: myocardial infarction; BBB: bundle branch block; SCD: sudden cardiac death; CAD: coronary artery disease; ARVC: arrhythmogenic right ventricular cardiomyopathy.

Characterize the symptoms: ❑ Loss of consciousness (LOC) ❑ Rapid or slow onset ❑ Short or long duration ❑ Spontaneous complete recovery or incomplete recovery ❑ Prodrome ❑ Diaphoresis ❑ Nausea ❑ Lightheadedness ❑ Pallor ❑ Warmth ❑ Blurry vision ❑ Chest pain (suggestive of cardiovascular syncope) ❑ Palpitations ❑ Position prior to LOC ❑ Supine (suggestive of cardiovascular syncope) ❑ Supine to erect posture (suggestive of orthostatic hypotension or reflex syncope) ❑ Prolonged standing (suggestive of reflex syncope) ❑ Activity prior to LOC (suggestive of cardiovascular or reflex syncope) ❑ Driving ❑ Machine operation ❑ Flying ❑ Competitive athletics ❑ Bowel or bladder incontinence (suggestive of reflex syncope)

Inquire about medications intake: ❑ Nitrates ❑ Diuretics ❑ Antiarrhythmic ❑ Alpha blocker ❑ Beta blocker ❑ ACE inhibitors ❑ ARB ❑ Hydralazine ❑ Ethanol ❑ Benzodiazepines ❑ Antipsychotics ❑ Tricyclic antidepressants ❑ Barbiturates

Obtain a detailed past medical history: ❑ Previous syncope episodes ❑ Time since previous episode ❑ Number of previous episodes ❑ Cardiovascular disease: ❑ Arrhythmia ❑ Heart block (LBBB, RBBB) ❑ Valvular heart disease ❑ Heart failure ❑ Hypertrophic cardiomyopathy ❑ Cardiac tumor ❑ Neurological diseases: ❑ Parkinson's disease ❑ Diabetic neuropathy ❑ Metabolic disorders (diabetes) ❑ Recent trauma

Identify possible triggers: Suggestive of reflex syncope ❑ Emotional stress ❑ Crowded places (agoraphobia) ❑ Warm weather ❑ Prolonged standing ❑ Cough ❑ Micturition ❑ Defecation ❑ Swallowing ❑ Head motion ❑ Arm motion ❑ Shaving Suggestive of cardiovascular or orthostatic hypotension ❑ Trauma ❑ Change in position ❑ Fatigue ❑ Exertion

Examine the patient: Vitals ❑ Heart rate ❑ Irregular rhythm (suggestive of AF) ❑ Tachycardia (suggestive of orthostatic hypotension, cardiovascular or reflex syncope) ❑ Bradycardia (suggestive of cardiovascular syncope) ❑ Blood pressure ❑ Measure in both arms, while standing and supine ❑ Orthostatic hypotension (Fall in systolic BP ≥ 20 mmHg and/or in diastolic BP of at least≥ 10 mmHg between the supine and sitting BP reading) ❑ Hypertension (suggestive of cardiovascular syncope) ❑ Respiratory rate ❑ Tachypnea (suggestive of reflex syncope) Respiratory ❑ Rales (suggestive of HF) Cardiovascular ❑ Palpitations (suggestive of arrhythmia) ❑ Carotid bruits (suggestive of cardiovascular syncope) ❑ Murmurs ❑ Aortic stenosis: crescendo-decrecendo systolic ejection murmur best heard at the upper right sternal border ❑ Pulmonary stenosis: systolic ejection murmur best heard at the left second intercostal space ❑ Heart sounds ❑ Loud P2 (suggestive of pulmonary hypertension) Neurologic ❑ Focal abnormalities (suggestive of stroke or cerebral mass) ❑ Hemiparesis ❑ Vision loss ❑ Aphasia ❑ Hypertonia ❑ Glasgow coma scale ❑ Signs suggestive of Parkinson's disease: ❑ Tremor ❑ Rigidity ❑ Bradykinesia/Akinesia ❑ Postural instability ❑ Shuffling gait

Order labs and tests: ❑ EKG (most important initial test) ❑ Myocardial infarction ❑ Tachyarrhythmia ❑ Heart block ❑ Bradyarrhythmia ❑ Long or short QT ❑ Bradyarrhythmia ❑ Electrolytes ❑ Hyponatremia ❑ Hypernatremia ❑ Hypokalemia ❑ Glucose (rule out hypoglycemia) ❑ ABG ❑ Hypoxia ❑ Hypocapnea (suggestive of tachypnea, rule out psychiatric disease)

Order imaging studies: ❑ Echocardiography in case of: ❑ Structural heart disease ❑ Myocardial infarction ❑ Cardiac valve disease ❑ Head CT in case of: ❑ Head trauma ❑ TIA

Confirm diagnosis of syncope Must have this 3 characteristics: ❑ Short duration, AND ❑ Rapid onset, AND ❑ Complete spontaneous recovery

Syncope

Non-syncopal LOC

Known etiology

Unknown etiology

Consider additional tests ❑ Stool guaiac test (rule out GI bleeding) ❑ Blood and urine toxicology tests (rule out intoxication)

Determine the etiology: ❑ Cardiovascular ❑ Arrhythmia ❑ Cardiac ischemia ❑ Structural heart disease ❑ Orthostatic hypotension ❑ Syncope after standing up and documentation of orthostatic hypotension (Class I; Level of Evidence: C) ❑ Reflex ❑ Vasovagal syncope precipitated by emotional distress and associated with typical prodome (Class I; Level of Evidence: C) ❑ Situational syncope during or after specific triggers (Class I; Level of Evidence: C)

Determine if there are any high risk criteria: ❑ Severe structural heart disease ❑ CAD ❑ Clinical or ECG features suggesting arrhythmic syncope ❑ Syncope during exertion or supine ❑ Palpitations at the time of syncope ❑ Family history of SCD ❑ Non-sustained VT ❑ Conduction abnormalities with QRS >120 ms ❑ Sinus bradycardia ❑ Pre-excited QRS complex ❑ Long or short QT ❑ Brugada pattern ❑ ARVC ❑ Important comorbidities ❑ Severe anemia ❑ Electrolyte disturbance

Consider alternative diagnoses: ❑ With loss of consciousness ❑ Epilepsy ❑ Inquire about suggestive signs include aura, prolonged confusion, muscle ache ❑ Inquire about past medical history ❑ Perform neurological evaluation (Class I; Level of Evidence: C) ❑ Perform tilt testing (Class IIb; Level of Evidence: C) , preferably with concurrent EEG and video monitoring if doubt of mimicking epilepsy ❑ Intoxication ❑ Vertebrobasilar TIA ❑ Without loss of consciousness ❑ Cataplexy ❑ Drop attacks ❑ Functional /psychogenic pseudosyncope ❑ Perform a psychiatric evaluation (Class I; Level of Evidence: C) ❑ TIA of carotid origin

High risk

Low risk

❑ Immediate in-hospital monitoring (in bed or telemetry) to look for abnormalities suggestive of arrhythmic syncope (Class I; Level of Evidence: B)

Recurrent episodes of syncope ❑ Order a Holter if > 1 episode/week (Class I; Level of Evidence: B) ❑ Order external loop recorder (ELR) if interval between episodes < 4 weeks (Class IIa; Level of Evidence: B) ❑ Perform carotid sinus massage in patients > 40 years with uncertain syncopal etiology (Class I; Level of Evidence: B) Contraindicated in patients with previous TIA or stroke in the past 3 months Contraindicated in patients with carotid bruits

Single episode of syncope

In case of suspicion of structural heart disease: ❑ Order an echocardiography (Class I; Level of Evidence: B)

Is any of the following high risk setting present? ❑ Potential risk of physical injury ❑ Occupational implications

Presence of structural heart disease

Absence of structural heart disease

Yes

No

❑ Treat accordingly

Perform a tilt test (Class I; Level of Evidence: B)

No further investigation

❑ No findings, OR ❑ Reflex syncope: induction of hypotension or bradycardia with reproduction of syncope (Class I; Level of Evidence: B), OR ❑ Orthostatic hypotension: induction of progressive orthostatic hypotension with or without symptoms (Class I; Level of Evidence: B)

Diagnostic Clues

Diagnostic clues for the etiologies of syncope Cardiovascular syncope Reflex syncope Orthostatic hypotension Diagnostic criteria ❑ Arrhythmia and cardiac ischemia-related syncope diagnosed by ECG specific findings (Class I; Level of Evidence: C) ❑ Cardiovascular syncope due structural heart disease (Class I; Level of Evidence: C) Additional findings ❑ Presence of definitive structural hearth disease ❑ Aortic stenosis ❑ Acute myocardial infarction ❑ Hypertrophic cardiomyopathy ❑ Pericardial disease ❑ Cardiac tumors ❑ Family history of unexplained sudden death ❑ Syncope during exertion or supine ❑ Abnormal ECG findings ❑ Sudden onset of palpitations before syncope Abnormal ECG findings ❑ Mobitz I second degree AV block ❑ Non-sustained VT ❑ Premature QRS complexes ❑ Wide QRS(≥ 0.12 s) ❑ Long or short QT intervals ❑ Early repolarization ❑ Q waves (myocardial infarction) ❑ Bifascicular block Diagnostic criteria ❑ Syncope after standing up and documentation of orthostatic hypotension (Class I; Level of Evidence: C) Additional findings ❑ Syncope after prolonged standing ❑ New antihypertensive drug or dosage change ❑ Presence of autonomic neuropathy ❑ Prolonged standing ❑ Associated with crowd or hot spaces Diagnostic criteria ❑ Vasovagal syncope precipitated by emotional distress and is associated with typical prodome (Class I; Level of Evidence: C) ❑ Situational syncope during or after specific triggers (Class I; Level of Evidence: C) ❑ Carotid sinus hypersensitivity if syncope is reproduced in the presence of asystole > 3 sec and/or fall in systolic blood pressure > 50 mmHg (Class I; Level of Evidence: B) Additional findings ❑ Absence of heart disease ❑ History of recurrent syncope ❑ After unpleasant sight, smell, sound or pain ❑ Associated to nausea or vomit ❑ Prolonged standing ❑ Associated with crowd or hot spaces ❑ Head rotation or pressure to carotid sinus ❑ After exertion ❑ Postprandial

Treatment

Shown below is an algorithm summarizing the therapeutic approach to syncope based on the 2009 ESC Guidelines for the Diagnosis and Management of Syncope.

Abbreviations: AF: Atrial fibrillation; SVT: Supraventricular tachycardia; VT: Ventricular tachycardia; MI: Myocardial infarction; BBB: Bundle branch block.

Determine the etiology

Cardiovascular syncope

Reflex Syncope

Orthostatic hypotension

❑ Treat the arrhythmia according to the type ❑ Schedule for cardiac pacing surgery in patients with: ❑ Sinus node disease (Class I; Level of Evidence: C) ❑ Mobitz II AV block or complete AV block (Class I; Level of Evidence: B) ❑ BBB with positive electrophysiological study (Class I; Level of Evidence: B) ❑ Schedule for catheter ablation in patients with: ❑ SVT (Class I; Level of Evidence: C) ❑ VT (Class I; Level of Evidence: C) In absence of structural hearth disease ❑ Administer antiarrhythmic drug therapy in patients with: ❑ AF (Class IIa; Level of Evidence: C) ❑ Failed catheter ablation (Class I; Level of Evidence: C) ❑ Schedule for implantable cardioverter defibrillator surgery in patients with: ❑ VT with heart disease (Class I; Level of Evidence: B) ❑ Electrophysiological study induced VT with previous MI (Class I; Level of Evidence: B) ❑ VT with inherited cardiomyopathy or channelopathy (Class IIa; Level of Evidence: B)

❑ Provide adequate hydration and salt intake (Class I; Level of Evidence: C) ❑ Provide additional therapy if needed: ❑ Administer midodrine 10 mg PO every 8 hours (Class IIa; Level of Evidence: B) Contraindicated in severe heart disease, acute renal failure, pheochromocytoma, severe hypertension or thyrotoxicosis OR ❑ Administer fludrocortisone 0.1 mg/day PO (Class IIa; Level of Evidence: C) ❑ Educate patients about isometric physical counterpressure maneuvers (PCM) (Class IIb; Level of Evidence: C) ❑ Position the patient in a head-up tilt sleeping position (>10°) to increase fluid volume (Class IIb; Level of Evidence: C)

❑ Explain the diagnosis and provide reassurance (Class I; Level of Evidence: C) ❑ Explain the risk of recurrence and educate regarding avoidance of triggers (Class I; Level of Evidence: C) ❑ Educate patients with prodrome about isometric physical counterpressure maneuvers (PCM) (Class I; Level of Evidence: B): ❑ Hand grip and arm tensing ❑ Leg crossing ❑ Consider cardiac pacing in: ❑ Dominant cardioinhibitory carotid sinus syndrome (Class IIa; Level of Evidence: B) ❑ Recurrent reflex syncope, age >40 years and spontaneous cardioinhibitory response during monitoring (Class IIa; Level of Evidence: B)

Do's

• Consider a tilt test:
  • To differentiate between reflex syncope and orthostatic hypotension (Class IIa; Level of Evidence: C)
  • If syncope is due to a psychiatric disease (Class IIb; Level of Evidence: C)
  • To differenciate syncope with jerking movements from epilepsy (Class IIb; Level of Evidence: C)
  • If syncope happened after standing up from a seated position due to possible orthostatic hypotension(Class IIb; Level of Evidence: C)
• Consider implantable loop recorder before cardiac pacing in patients with suspected or confirmed reflex syncope presenting with frequent or traumatic syncopal episodes.
• Perform exercise testing in patients who experience syncope during or after exertion (Class I; Level of Evidence: C).

Don'ts

• Don't perform carotid sinus massage in patients with previous TIA or stroke within the past 3 months and in patients with carotid sinus bruits unless carotid sinus doppler studies excluded significant stenosis (Class III; Level of Evidence: C).
• Don't perform tilt testing for the assessment of response to treatment. (Class III; Level of Evidence: B).
• Don't perform isoproterenol tilt test in patients with ischemic heart disease (Class III; Level of Evidence: C).
• Don't use adenosine stress test as a diagnostic test to select patients for cardiac pacing due to the lack of correlation with spontaneous syncope (Class III; Level of Evidence: B).
• Don't perform electrophysiologic study if there is already indication for implantable cardioverter defibrillator in patients with ischemic heart with suspected arrhythmic cause.
• Don't perform electrophysiologic study in patients with normal ECG, no heart disease and no palpitations unless non-syncopal LOC is suspected (Class III; Level of Evidence: B).
• Don't give beta blockers for patients with reflex syncope (Class III; Level of Evidence: A).

References

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