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Lect 10: Faints, falls and funny turns (Vasovagal Syncope In young ppl …
Lect 10: Faints, falls and funny turns
Syncope
Transient loss of consciousness due to global cerebral hypoperfusion (reduction in blood flow to brain)
Characterised by rapid onset, short duration & complete, spontaneous recovery
Vasovagal Syncope
In young ppl -> >90% of syncope cases --> VVS (faint)
Due to Bezold-Jarisch reflex
Vasodilated -> when standing -> BP falls -> Venous Return falls -> less blood returning to heart
Baroreceptors sense low BP -> Increased HR & Inotropy (contraction power)
Ventricles contract forcefully & quickly -> pumping against empty ventricle
Detected by vagus nerve -> medulla -> Vasovagal rxn
Reduce HR & BP -> paradoxical
If bleeding -> low HR & BP -> so less blood lost thru blood vessels (Ideal)
VVS -> body thinking that bleeding -> misinterpret -> suddenly shut down HR & BP -> protective reflex
But since moving arnd, muscle forcing some blood & baroreceptors x as sensitive
If enough exposure to cause BP to drop eventually VVS
Presyncope
Light headed
Blackout
Restless
Intense heat
Fatigue
Older ppl
Blood vessels stiff -> x prevent syncope from coming on
Symptoms unnoticed beforehand -> too quick to rmb
Syncope
Loss of consciousness
-Loss of postural tone
Injury
Transient
Incontinence
Myoclonic jerks -> in young healthy brains deprived of O2 & excitable nerves
Post Syncope
Spontaneous recovery
Fatigue -> clue for low BP
Coat hanger headache
Triggers
Soldiers
Standing, heat, dehydration, vasodilation (exercise, alcohol)
Situational syncope -> closely related to VVS
Pain
Cough
Nauseous
Tilt-table
Diagnostic tool for VVS
Record BP constantly
70 degrees -> allow gravity to pull blood down to legs -> if x reduce VV rxn -> GTN (nitrate spray) given to vasodilate -> cause VV rxn -> observe
VVS treatment
Water
Salt -> increase bp
Caffeine -> Increase bp & HR in short term
Compression stockings -> prevent blood to be pulled down to legs
Medication -> anti-angina medication
Pacemaker in aged
Carotid sinus syndrome -> only in aged
Maximal pulsation points in carotid artery -> baroreceptor which senses pressure in artery -> in elderly less sensitive/too sensitive -> detect small drop in BP -> x undergo entire Bezold-Jarisch reflex -> as vagus nerve is where abnormality is
Unexpected falls/syncope
Facial/head injuries
Types:
Vasodepressor (decreased bp)
Treat as VVS
Cardio-inhibitory (decreased HR)
Pacemaker
Either HR/BP or both
Orthostatic Hypotension
Low bp on standing straight
Get up from lying down -> head rush -> in elderly causes falls/blackouts
Lying down-> gravity has nowhere to pull blood -> central venous pressure in vena cava
But when stand up -> gravity pulls blood down -> central venous pressure in pelvis -> need mechanism to get blood back to heart
Seated to standing -> gravity pulling blood down to pelvis & legs -> BP dropped -> baro receptor respond -> activated sympathetic NS -> Parasympathetic NS withdraws -> increased HR & causes constriction in pelvis & legs -> forces blood back up to heart -> recover cardia output & BP
In OH -> those in red goes wrong
stiff blood vessels -> x constrict
HR much less responsive -> x go as high
Baroreceptor less sensitive
Vol of blood in ventricles less
Recognising OH -> low blood pressure -> similar to VVS but clues diff:
Symptoms after standing up
Worst in morning
Nocturnal diuresis -> less anti-diuretic hormone in aged ->
make more urine & dehydrated
Low cortisol levels
Dizziness -> because of drop in blood pressure
Falls
Aggravating factors
Meals rich in carbo -> cause low BP
Alcohols
Medications -> anti angina medication
Dehydration
Diagnosis -> lying & standing BP
Treatment -> same as VVS
Difference between VVS & OH
VVS -> A reflex; with specific triggers
OH -> Abnormal response -> disease; all the time
Recognising cardiac causes of syncope
Cause death
Look for:
History of heart disease:
Esp heart failure -> hv high risk of ventricular arrhythmia
Heart failure & syncope -> observe ventricular tachycardia/fibrillations -> high chances of death
Chest pain
Palpitations
Lil/x syncope
Abnormal ECG
Cardiac medications
Syncope while sitting/supine
VVS & OH -> tend to be while standing
1st degree heart block -> distance bet P wave & QRS complex -> higher -> delay at AV node -> x cause syncope
2nd degree heart block:
1) Mobitz 1 -> distance bet P wave & QRS varies throughout & dropped a beat -> could cause syncope -> further testing reqd
2) Mobitz 2 -> P-wave & QRS -> randomly non-conducted beats -> causes syncope -> consider pacemaker
3rd degree heart block -> No relationship bet P wave & Q waves -> atrium & ventricles work independently -> nothing passed thru AV node -> causes syncope -> need pacemaker
ECG -> impt to observe cardiogenic syncope
Brady-arrhythmias
Alternating left & right bundle branch block
Tachyarrthymias
Long/Short QT
Others (Rare)
Epsilon waves
Summary
Older ppl
Less pre-sycope/warning
Often present with falls x syncope
Carotid sinus syndrome common
Higher risk of cardiac causes