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)
- 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
- Treat as VVS
- Vasodepressor (decreased bp)
Cardio-inhibitory (decreased HR)
- Pacemaker
- Either HR/BP or both
- Either HR/BP or both
- Pacemaker
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
- Nocturnal diuresis -> less anti-diuretic hormone in aged ->
- Dizziness -> because of drop in blood pressure
- Falls
Aggravating factors
- Meals rich in carbo -> cause low BP
- Alcohols
- Medications -> anti angina medication
- Dehydration
Difference between VVS & OH
- VVS -> A reflex; with specific triggers
- OH -> Abnormal response -> disease; all the time
- Diagnosis -> lying & standing BP
- Treatment -> same as VVS
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
- History of heart disease:
- 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
- Epsilon waves
Summary
- Older ppl
- Less pre-sycope/warning
- Often present with falls x syncope
- Carotid sinus syndrome common
- Higher risk of cardiac causes