Sudden Death Flashcards
what are the four H’s that can cause cardiac arrest?
hypoxia
hypovolaemia
hyperkalaemia + other metabolic
hypothermia
what are the four T’s that can cause cardiac arrest?
thrombosis
tamponade
toxins
tension pneumothorax
what is the definition of shock?
a condition of inadequate perfusion to sustain normal organ function
what are the four main classes of shock?
hypovolaemic
cardiogenic
obstructive
distributive
what is hypovolaemic shock?
a state of shock due to insufficient circulating volume
what can cause hypovolaemic shock?
any loss of fluids
what does the clinical presentation of hypovolaemic shock depend on?
the degree of hypovolaemia
how the body is compensating
describe how young people with hypovolaemic shock compensate
initially very well
decompensate rapidly if fluid loss continues
what is cardiogenic shock?
a state of shock due to the heart being unable to pump to meet circulatory demands
what is the most common cause of cardiogenic shock?
acute MI
what is another possible cause of cardiogenic shock?
acute valve dysfunction e.g. acute mitral valve prolapse
clinical signs in cardiogenic shock are caused by what two things?
poor flow
backpressure
what clinical signs are present in cardiogenic shock due to poor flow?
hypotension
fatigue
syncope
what clinical signs are present in cardiogenic shock due to back pressure?
pulmonary oedema
elevated JVP
hepatic congestion
what is obstructive shock?
shock due to a physical obstruction to the heart or great vessels
what is the mechanism of shock in obstructive shock?
blockage affects cardiac filling and reduces the blood volume available
what are three possible causes of obstructive shock?
PE
cardiac tamponade
tension pneumothorax
what are other names for distributive shock?
vasodilatory shock
warm shock
what happens in distributive shock?
vessels dilate so there is not enough blood to maintain pressure and perfusion
what are the three subtypes of distributive shock?
septic
anaphylactic
neurogenic
what causes septic shock?
microbes release toxins that cause impaired vasoconstriction
what can be used to detect hypoperfusion in septic shock?
rising lactate levels
what drugs need to be given ASAP in septic shock?
antibiotics
vasopressors
what causes anaphylactic shock?
mast cells release vasodilators
what drug should be given in anaphylactic shock?
adrenaline
what can be measured to confirm diagnosis of anaphylactic shock?
serum try-tase
what causes neurogenic shock?
loss of sympathetic outflow due to a spinal injury
what is the mechanism of shock in neurogenic shock?
loss of sympathetics = vasodilation, hypotension and bradycardia
what drugs are given for neurogenic shock?
dopamine
vasopressors
what is clinical death?
the period of respiratory, cardiac and nervous system arrest when resuscitation can restore life
what does the duration of clinical death depend on?
how long the cerebral cortex survives
what is the normal duration of clinical death?
3-6 minutes
what is penetrance?
the likelihood of getting a disease if you have the mutation
what does it mean if a disease has 100% penetrance?
you will always get the disease if you have the mutation
name one way of analysing genes
next generation sequencing
what is a variant?
any change in DNA sequence
what is a mutation?
a pathogenic variant
what is a polymorphism?
a variant that is prevalent in the general population that is often benign
what does it mean if a variant is class 1?
it is benign
what does it mean if a variant is class 3?
it is a variant of uncertain significance
what does it mean if a variant is class 5?
it is pathogenic
mutations in what gene causes Marfan syndrome?
fibrillar
mutations in what genes can cause Loeys Dietz syndrome?
TBR1
TBR2
what is the definition of sudden cardiac death?
non-traumatic unexpected death due to sudden cardiac arrest within six hours of normal health
what are the two categories of arrhythmogenic inherited cardiac conditions?
channelopathies
cardiomyopathies
name a channelopathy
congenital long QT
what causes an arrhythmia in a channelopathy?
ion current imbalance
what causes an arrhythmia in a cardiomyopathy?
physical barrier to electrical current
what arrhythmia can occur in patients with congenital LQTS?
polymorphic VT (torsades de pointes)
what triggers torsades de pointes in congenital LQTS?
adrenergic stimulation
what is the risk of death from congenital LQTS associated with?
the severity of the QT prolongation
how many types of congenital LQTS are there?
thirteen
what is the name of the syndrome in which patients have isolated congenital LQTS?
romano ward syndrome
what two syndromes exist where patients have congenital LQTS and extra cardiac features?
Anderson tawil
Timothy
what autosomal recessive form of congenital LQTS is associated with deafness?
jervell and lange nielsen syndrome
what are the three criteria that can be used to diagnose congenital LQTS?
QT interval >480ms
LQTS risk score >3
presence of pathogenic mutation
what causes congenital short QT syndrome?
a mutation in cardiac K+ channels
what is the criteria for congenital short QT syndrome?
QT <300ms at a heart rate <80bpm
what arrhythmia can congenital short QT syndrome be associated with?
AF
who may present with congenital short QT syndrome?
young children
what is the mortality like in congenital short QT syndrome?
most patients die
what arrhythmias are possible complications of brugada syndrome?
VT
VF
AF
what is seen on ECG in brugada syndrome?
ST elevation and RBBB in V1-V3
what type of drugs can be given to illicit the ECG changes in brugada syndrome?
cardiac sodium channel blockers
name two cardiac sodium channel blockers
flecainide
ajmaline
how many genes are associated with brugada syndrome and what do they code for?
12
cardiac sodium and calcium channels
what is the inheritance pattern for brugada syndrome?
autosomal dominant
name four triggers for VF in brugada syndrome?
sleep
fever
alcohol
large meals
what four classes of drugs should be avoided in brugada syndrome?
anti arrhythmias
psychotropics
analgesics
anaesthetics
what triggers VT in catecholaminnergic polymorphic VT?
emotional stress
physical activity
what does an ECG and ECHO look like in catecholaminnergic polymorphic VT?
normal
what gene causes autosomal dominant catecholaminnergic polymorphic VT?
RyR2
what gene causes autosomal recessive catecholaminnergic polymorphic VT?
CASQ2
mutations in which genes cause hypertrophic cardiomyopathy?
sarcomeric genes
what three ways can patients with hypertrophic cardiomyopathy present?
sudden death
heart failure
AF
