Blackout Flashcards
What are the divisions of syncopal causes of blackout
Reflex
Cardiac (reduced CO in arrhythmia, outlet obstruction)
Orthostatic
Cerebrovascular
What is reflex syncope
“primitive reflex”. HR and BP drops temporarily, reducing cerebral perfusion and leading to syncope. Some have a low threshold for activating this reflex in specific situations e.g. standing, being scared (blood, needles), straining (micturition, defacation)
What may cause orthostatic hypotension
Reduced intravascular volume (e.g. dehydration)
Normal autonomic response (transient tachycardia and peripheral vasoconstriction) or standing is blunted e.g. druggs or autonomic nueropathy
What are the reflex causes of blackouts
Vasovagal syncope
Carotid sinus hypersensitivity
Situational syncope e.g. micturition
What are the cardiac causes of blackout
Arrhythmias
Structural cardiac pathology causing outflow obstruction e.g. aortic stenosis, hypertrophic obstructive cardiomyopathy
What are the orthostatic causes of blackout
Drugs (anti-hypertensives, anti-sympathetics)
Dehydration
Autonomic instability
Baroreceptor dysfunction
What are the cerebrovascular causes of blackout
Vertebrobasilar insufficiency
Subclavian steal
Aortic dissection
What are the non-syncopal causes of blackout
Intoxication Head trauma Metabolic (hypoglycaemia) Psychogenic (non-epileptic_ seizures Narcolepsy
What is the main cause of loss of consciousness in a patient aged 25
Vasovagal syncope
Warning or presyncopal sensation (stomach, going pale, clammy)
What is the main cause of loss of consciousness in a patient aged 55
Vasovagal syncope and cardiac arrhythmias (usually secondary to IHD)
No warning, while playing sport or without trigger
What is the main cause of loss of consciousness in a patient aged 85
Orthostatic hypotension secondary to medications (diuretics, ACEi, beta blockers, CCBs)
Causes morbidity from broken bones, loss of consciousness and independence and mortality
What questions do you ask about before the loss of consciousness
Was there any warning
Were there any precipitating factors
Was there any recent head trauma
What does warning before the blackout tell you
no warning -> more likely cardiac cause e.g. arrhythmia, AS or cerebrovascular disease e.g. subclavian steal syndrome (although may be preceded by palpitations)
Most other blackout causes will have warning e.g. aura before epileptic seizure, dizziness before vasovagal
What does precipitating factors tell you about the loss of consciousness
Postural - orthostatic hypotension
Head turning - carotid sinus hypersensitivity
Sitting or lying down - arrhythmia
Exercise - primary cardiac pathology e.g. AS, cardiomyopathy
Vigorous arm activity - subclavian steal
What questions do you ask about during the loss of consciousness
How long were they unconscious for
Did they bite their tongue or move their limbs, or where they incontinent of urine or faeces
What does tongue biting or spasms during blackouts tell you
tongue-biting - epileptic seizure
twitching an incontinence - vasovagal or other
What questions do you ask about after the loss of consciousness
Did they recover spontaneously
How long did it take to recover if not
Were they confused
Summarise the before, during and after features of epilepsy
May have stereotyped aura before (partial) or none (general)
Can last minutes, same episodes every time, tongue biting
Slow recovery, confused for 5-30 minutes
Summarise the before, during and after features of Vasovagal attack
Vagal symptoms (sweating, pallor, nausea) may have precipitant
Last seconds, may twitch or be incontinent
Rapid recovery on sitting or lying
Summarise the before, during and after features of cardiac arrhythmias
No warning
Last seconds, may twitch or be incontinent
Rapid spontaneous recover
What is important to ask about in the past medical history for blackouts
Has it happened before Diabets Cardiac illness Peripheral vascular disease epilepsy Anaemia Psychiatric illness
What is important to ask about in the drug history for blackouts
insulin
Antihypertensives
Vasodilators
Antiarrhythmics
Antidepressants (SE of Tricyclic antidepressants)
Warfarin or anticoagulants (subdural haemorrhage>)
What is important to ask about in the social history for blackouts
Alcohol
Recreational drugs e.g. cocaine, amphetamines
What is important to ask about in the family history for blackouts
Sudden death in anyone <65 years of age
What signs do you look for on examination for blackout patients
Tongue bitting
Dehydration (tachycardia, dry tongue, hypotension)
head trauma
Heart rate and murmurs (slow, irregular pulse, AS murmur)
Carotid bruits (carotid artery stenosis)
Blood pressure (orthostatic)
Focal neurological signs (peripheral neuropathy or parkinsonism due to autonomic dysfunction)
What is orthostatic hypotension defined as
drop of 20 mmHg in systolic blood pressure or 10 mmHg diastolic on standing
What are the first line investigations for blackout
Bloods (capillary blood glucose, FBC, U&Es)
ECG
What are the investigations specific to suspicion of structural cardiac abnormality e.g. valve lesion
Echo
What are the investigations specific to suspicion of carotid sinus sensitivity
Carotid sinus massage
What are the investigations specific to suspicion of epilepsy
Brain scan (CT or MRI) to look for intracranial abnormality that can precipitate a seizure e.g. tumour + EEG
What is a Stokes Adams attack and what is the treatment
Sudden transient loss of consciousness induced by a slow or absent pulse -> loss of CO
Either due to third degree HB or sinoatrial disease
Lasts seconds, more than 15 -> twitching due to cerebral anoxia
After attack - patient is flushed
Treatment - pacemaker
What is epilepsy and what are seizures
Epilepsy is the tendency to have recurrent unprovoked seizures
Seizure - transient excessive electrical activity with motor, sensory or cognitive manifestations
What are the types of generalised seizure
Tonic clonic/grand mal: rigid -> convulse with rhythmic muscular contractions
Absence: loses consciousness -> vacant and unresponsive
Atonic: loss of tone
Tonic: rigid
Clonic: convulsion
Myoclonic: extremely brief muscle contraction(jerk)
What can partial seizures be split into
Simple - consciousness unimpaired
Complex - impaired
What is the tilt table test
Helps to determine whether there is a vasovagal cause
Patient placed on tilt table supine, and rotated upright. Test is positive if:
there is loss of consciousness, fall in HR or BP or symptoms develop
What are the main side effects of anticonvulsants in general
Teratogenic
valproate - weight gain, hair loss/curling, nausea, rash, tremor
Lamotrigine - Steven Johnson syndrome, headache, dizziness
Carbamazepine - rash, nausea, ataxia, diploplia, agranulocytosis, hypontraemia
Phenytoin - acne, rash, ataxia, sedation, ophthalmoparesis
What are the interactions of anticonvulsants
Carbamazepine and phenytoin interfere with Contraceptive pill -> double dose
Same interfere with warfarin
How do you test for carotid sinus hypersensitivity
Carotid sinus massage -> ECG and BP monitored for bradycardia/hypotension.
What is HOCM
Genetic mutation (inherited via dominant or sporadic)
Non-physiological left ventricular hypertrophy
Asymmetrical septal hypertrophy leads to left ventricular outflow obstruction
Exacerbated by systolic anterior movement of the mitral valve
Exacerbated by exercise
What is Long QT syndrome
Genetic mutation of cardiac channels (Na, K)
Prolonged repolarisation and a long QT interval on ECG, particularly on exertion
Associated with ventricular tachy
What is Brugada syndrome
Mutation of cardiac sodium channel gene
Autosomal dominant
RBBB + saddle shaped ST elevation V1-V3
What is arrhythmogenic right ventricular dysplasia
Myocardium is partially replaces by fatty tissue
ECG - T wave inversion V1-3, RBBB and epsilon wave
What is the treatment for rare cardiac causes of loss of consciousness
Implantable cardioverter defibrillator device
Beta blockers adjunct
