Definition of syncope
- Transient, self-limited LOC
- Onset rapid
- Recovery spontaneous, complete, and usually prompt
- Transient global cerebral hypo-perfusion (brain not getting enough oxygen)
Explain cerebral auto-regulation & syncope
Classification of syncopal disorders
Real or apparent loss of consciousness
Syncope
- Neurally-mediated reflex syncopal syndromes
- Orthostatic
- Cardiac arrhythmias
- Structural cardiac or cardiopulmonary disease
- Cerebrovascular – steal syndromes
Non-syncopal
- Disorders resembling syncope with impairment or loss of consciousness (e.g. seizures)
- Disorders resembling syncope without impairment or loss of consciousness (e.g. psychogenic syncope)
Epidemiology of syncope
- Prevalence adults >17yrs old approx 10%
- Lifetime risk up to 70 years approx 42%
- 3-5% ED attendances
- 1-3% hospital admissions
Mortality link with syncope
- Excessive mortality
- Left ventricular failure
- Hypertrophic cardiomyopathy
- Aortic stenosis
- Previous ventricular arrhythmia
- No increased mortality
- Young patients without heart disease & normal ECG
- Neurally mediated syndromes
Explain reflex mediated syncope
- Mostly vasovagal syncope
- Carotid sinus syndrome (pressure on carotid sinus cause syncope)
- Situational syncope - cough (excess cough too high inter-thoracic pressure = syncope), micturition (bladder contracts = syncope), defaecation, brass instrument players, adolescent stretch (stretch arms = syncope)
- Any age
- Mostly in younger people and grow out
Explain orthostatic hypotension
- Fall of SBP>20mmHg or DBP>10mmHg within 3 minutes of standing
- Cause:
- Drugs (medication e.g. anti-hypertensives, anti-depressants, anti-psychotics)
- Autonomic failure (e.g. diabetic neuropathy)
Cardiac causes of syncope
- Arrhythmia – CHB, VT.
- Structural cardiac disease
- Aortic stenosis
- Cardiomyopathy
When is misdiagnosis of syncope?
- Community and secondary care epilepsy patients
- 30% misdiagnosis
- “Receiving treatment that doesn’t work and which fails to control a condition they don’t have”
Initial evaluation of syncope & questions
- Is loss of consciousness attributable to syncope or not?
- Is heart disease present or absent?
- Are there important clinical features in the history that suggest the diagnosis?
Questions about circumstances just prior to attack
- Position - supine, sitting, standing
- Activity - rest, change in posture, during or after exercise, during or immediately after urination, defaecation, cough or swallowing
- Predisposing factors - crowded or warm places, prolonged standing, post-prandial
- Precipitating events - fear, intense pain, neck movements
Questions about onset of attack
- Nausea, vomiting, abdominal discomfort
- Feeling of cold, sweating, aura, pain in neck or shoulders, blurred vision
Questions about attack (eyewitness)
- Skin colour - pallor, cyanosis
- Duration of loss of consciousness
- Movements and their duration
- Tongue biting
- Urine incontinence (can happen in syncope and epilepsy)
Questions about end of attack
- Sweating, feeling of cold, nausea
- Confusion, focal neurology
- Skin colour
- Injury
- Chest pain, palpitations
Questions about background
- Family history of sudden death (especially under 40), congenital arrhythmogenic heart disease or fainting
- Previous cardiac disease
- Neurological history
- Metabolic disorders
- Medication (hypotensive, antiarrhythmic, and QT prolonging agents → longer than 500ms = ventricular arrhythmias)
What looking for in examination of syncope?
- Signs of cardiac failure/murmurs
- Neurological evaluation
Investigations in syncope
The most important investigation is a 12 lead ECG
Telling the difference between right and left bundle branch block
Right bundle = V6 has S wave
Left bundle = V1 has S wave
Left vs right axis deviation
Left axis deviation = Lead 1 and 2 away from each other
Right axis deviation = Lead 1 and 2 towards each other
What is wrong?
QT prolongation (cause by hypomagnesium, hypocalcaemia, hypokalaemia)
What is wrong with ECG?
Shortened PR interval and axis deviation
Wolf-Parkinson White syndrome
What is wrong with this ECG?
ST elevation
When to hospitalise a patient with syncope?
- Significant heart disease
- ECG abnormalities
- Syncope during exercise
- Severe injury
- Family history of sudden death
- Syncope in supine position
- Frequent recurrent episodes
- High suspicion of cardiac arrhythmia
- Stroke/focal neurology
