Syncope resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Karol Gema Hernandez, M.D. [2]; Alejandro Lemor, M.D. [3]

Syncope Resident Survival Guide Microchapters
Overview
Causes
Classification
Diagnosis Suspected syncope Confirmed syncope
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 the syncope and recognize high risk patients (those with structural heart disease or abnormal EKG). The initial management depends on the etiology of the syncope (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 arrhythmyas

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 syncope

Diagnosis

Diagnostic Algorithm in Patients with 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 symptoms ❑ Loss of consciousness (LOC) ❑ Rapid or short 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: ❑ Driving ❑ Machine operation ❑ Flying ❑ Competitive athletics (suggestive of cardiovascular or reflex syncope) ❑ Bowel or bladder incontinence (suggestive of reflex syncope) Inquire about medications intake: ❑ Nitrates ❑ Diuretics ❑ Antiarrhythmic ❑ Alpha blocker ❑ Beta blocker ❑ ACE inhibitors or ARB ❑ Hydralazine ❑ Ethanol ❑ Benzodiazepines ❑ Antipsychotics ❑ Tricyclic antidepressants ❑ Barbiturates Obtain a detailed past medical history: ❑ Previously healthy ❑ Previous syncope episodes ❑ Cardiovascular disease: ❑ Arrhythmia ❑ Heart block (LBBB, RBBB) ❑ Valvular heart disease ❑ Heart failure ❑ Hypertrophic cardiomyopathy ❑ Cardiac tumor ❑ Neurological diseases: ❑ Parkinson's disease ❑ Diabetic neuropathy ❑ 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) ❑ Lungs ❑ Rales (suggestive of HF) ❑ Heart ❑ 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)

Order labs and tests ❑ EKG (most important initial test) ❑ Myocardial infarction ❑ Tachyarrhythmia ❑ Heart block ❑ 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 ❑ Short duration ❑ Rapid onset ❑ Complete spontaneous recovery Must have this 3 characteristics

Syncope

Non-syncopal LOC

Certain etiology: ❑ Cardiovascular ❑ Orthostatic hypotension ❑ Reflex

Uncertain etiology

❑ Confirm with specific test: - EEG - US of neck arteries - Brain CT - Brain MRI OR ❑ Consult with specialist

Risk stratification

Determine if there are any high risk criteria: ❑ Severe structural or 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-exited QRS complex ❑ Prolonged or short QR interval ❑ Brugada pattern ❑ ARVC ❑ Important comorbidities: ❑ Severe anemia ❑ Electrolyte intolerance

❑ If yes: High risk

❑ If no: Low risk

Immediate in-hospital monitoring: In bed or telemetry

Low risk, recurrent syncopes: ❑ Cardiac or neurally mediated tests as appropriate: -Holter if >1 episode/week -ELR if interval between episodes <4 weeks Delayed treatment guided by ECK documentation

Low risk, single syncope

❑ If suspicion of structural heart disease: Echocardiography

Was it in high risk setting?

If yes: Treat as according

No structural heart disease

Yes

No: No further evaluation

Tilt testing

Diagnostic Algorithm in Patients with Confirmed Syncope

Determine the etiology

Cardiovascular syncope ❑ Presence of definitive structural hearth disease ❑ Aortic stenosis ❑ Acute myocardial infarction ❑ Hypertrophic cardiomyopathy ❑ Pericardial disease ❑ Cardiac tumors ❑ Family history of unexplained sudden death ❑ Occurred during exertion or supine ❑ Abnormal EKG ❑ Sudden onset of palpitations before syncope Abnormal EKG 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

Orthostatic hypotension ❑ After standing up or prolonged standing ❑ Start of new antihypertensive drug or dosage change ❑ Presence of autonomic neuropathy ❑ Prolonged standing ❑ Associated with crowd or hot spaces

Reflex Syncope ❑ 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 of the syncope

Cardiovascular

Orthostatic hypotension

Reflex

Depends on the cause of the arrhythmia: ❑ Schedule for cardiac pacing surgery in patients with sinus node disease, Mobitz II AV block, BBB with positive electrophysiological study ❑ Schedule for catheter ablation in patients with SVT and VT in absence of structural hearth disease ❑ Administer antiarrhythmic drug therapy in patients with AF, failed catheter ablation ❑ Schedule for implantable cardioverter defibrillator surgery in patients with VT with heart disease, electrophysiological study induced VT in patients with previous MI, VT and inherited cardiomyopathy

❑ Adequate hydration and salt intake ❑ Adjunctive therapy if needed: ❑ Administer midodrine 10 mg PO q8hr Contraindicated in severe heart disease, acute renal failure, pheochromocytoma, severe hypertension or thyrotoxicosis ❑ or fludrocortisone 0.1 mg/day PO

❑ Explain diagnosis, provide reassurance ❑ Explain risk of recurrence and avoidance of triggers ❑ Isometric physical counterpressure maneuvers (PCM) in patients with prodrome: ❑ Hand grip and arm tensing ❑ Leg crossing

Do's

• Tilt testing is indicated to demonstrate susceptibility to reflex syncope.
• Tilt testing should be considered to discriminate between reflex and OH syncope.
• Perform tilt testing if the cause of syncope is a psychiatric disease.
• Tilt testing may be considered for differentiating syncope with jerking movements from epilepsy.
• If syncope happened after standing up position, there should be documentation with active standing or tilt testing in order to diagnose orthostatic hypotension.
• Perform carotid sinus massage if patient >40 years with syncope of unknown etiology after initial evaluation.
• If multiple unexplained falls; perform tilt testing.
• Consider implantable loop recorder before embarking on cardiac pacing in patients with suspected or confirmed reflex syncope presenting with frequent or traumatic syncopal episodes.
• Evaluate neurologically if syncope is due to autonomic failure, to evaluate underlying disease.

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 (except if carotid sinus Doppler studies excluded significant stenosis).
• Don't use tilt testing for assessment of treatment.
• Don't perform isoproterenol tilt test in patients with ischemic heart disease.
• Don't use adenosine stress test as a diagnostic test to select patients for cardiac pacing, owing to lack of correlation with spontaneous syncope.
• 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 EKG, no heart disease, and no palpitations.

References

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