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
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

Cardiovascular syncope	Orthostatic hypotension	Reflex syncope
Arrhythmias (bradycardia or tachycardia) *Structural heart disease *Drug-induced arrhythmyas	*Primary autonomic failure *Secondary autonomic failure *Drug-induced *Hypovolemia	*Vasovagal *Situational *Carotid sinus syncope

Diagnosis

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

Characterize symptoms ❑ Loss of consciousness (LOC) ❑ Rapid onset ❑ Short duration ❑ Spontaneous complete recovery ❑ Prodrome: ❑ Diaphoresis ❑ Nausea ❑ Blurry vision ❑ Chest pain (suggestive of cardiovascular syncope) ❑ Palpitations ❑ Bowel or bladder incontinence (suggestive of reflex syncope) ❑ Activity prior to LOC: ❑ Driving ❑ Machine operation ❑ Flying ❑ Competitive athletics (suggestive of cardiovascular or reflex syncope) ❑ Position prior to LOC: ❑ Supine (suggestive of cardiovascular syncope) ❑ Sitting (suggestive of orthostatic hypotension or reflex syncope) ❑ Standing (suggestive of orthostatic hypotension or 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 vasovagal syncope) ❑ Emotional stress ❑ Crowded places (agoraphobia) ❑ Change in position ❑ Fatigue ❑ Exertion ❑ Warm weather ❑ Prolonged standing ❑ Cough ❑ Micturition ❑ Defecation ❑ Swallowing ❑ Head motion ❑ Arm motion ❑ Shaving ❑ Trauma

Examine the patient ❑ Vitals ❑ Heart rate ❑ Tachycardia (suggestive of orthostatic hypotension, cardiovascular or vasovagal syncope) ❑ Bradycardia (suggestive of cardiovascular syncope) ❑ Blood pressure: ❑ Hypotension (suggestive of orthostatic hypotension) ❑ 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 ❑ 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

Order imaging studies To rule out structural heart disease or valvular disease: ❑ Echocardiography To rule out TIA: ❑ Head CT

Abnormal EKG ❑ 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

Normal EKG Consider additional tests ❑ Stool guaiac test (rule out GI bleeding) ❑ Blood and urine toxicology tests (rule out intoxication) Rule out other possible diagnoses: ❑ With loss of consciousness: ❑ Coma (Glasgow coma scale < 8, profound state of unconsciousness) ❑ Sudden cardiac arrest (absence of pulse) ❑ Epilepsy (inquire past medical history) ❑ Perform neurological evaluation ❑ Perform tilt testing, 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 (patients with conversion disorder) ❑ TIA

Cardiovascular syncope Additional findings: ❑ Heart rate: ❑ Tachycardia (in patients with arrhythmia) ❑ Normal ❑ Bradycardia (in patients with heart block) ❑ Cardiac evaluation: ❑ Palpitations (suggestive of arrhythmia ❑ Carotid bruits (suggestive of carotid stenosis) ❑ 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 ❑ Presence of structural hearth disease ❑ Aortic stenosis ❑ Acute myocardial infarction ❑ Hypertrophic cardiomyopathy ❑ Pericardial disease ❑ Cardiac tumors ❑ Occurred during exertion

Orthostatic hypotension Additional findings: ❑ Blood pressure (BP): ❑ Measure in both arms, while standing and supine ❑ Fall in systolic BP ≥ 20 mmHg and/or in diastolic BP of at least≥ 10 mmHg between the supine and sitting BP reading ❑ Heart rate: tachycardia ❑ Cardiac evaluation: palpitations ❑ After standing up or prolonged standing ❑ Start of new antihypertensive drug ❑ Presence of autonomic neuropathy

Reflex Syncope Additional findings: ❑ Heart rate: tachycardia or normal ❑ Absence of heart disease ❑ History of recurrent syncope ❑ After unpleasant sight or odor ❑ Associated to nausea ❑ Head rotation or pressure to carotid sinus ❑ Neurological system: look for focal neurologic signs: ❑ Hemiparesis ❑ Vision loss ❑ Aphasia ❑ Hypertonia ❑ If present, order a head CT or MRI ❑ EKG findings: tachycardia, normal or bradycardia

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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