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

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
  • 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