cardiac conditions that cause sudden death Flashcards
what is considered a long QT interval usually
>450ms
what happens in long QT syndrome
the ventricular repolarizationis prolonged - long QT interval
romano ward syndrome
autosomal dominant cuase of long QT syndrome - causes isolated long QT
JLN syndrome
autosomal recessive cause of congenital long QT - associated with congenital deafness
why does hypokalaemia cause acquired long QT
K leaving the cell si responsible for stages 2 3 and 4 of the AP
if there is less K, prolongs the plateau phase
what 2 other electrolyte abnormalities cause acquried long QT
hypoMg
hypoCa
which ABx cause long QT
macrolides eg azithromycin
what other drugs cause long QT
antidepressants, TCA and citalopram
antipsychotics
which class of anti arrhythmic drugs prolonged the plateau phase of the cardiac AP
3 - amiodarone and sotalol
what do the LGT genes encode
cardiac potassium and sodium channels
what is the genetics cause of long qt
heterogenous - caused by lots of different genes
each different gene causes a disease with a different phenotype
what are the particular provocations for LGT 1 2 and 3
1 - strenuous exericse, especially swimming
2 - emotion and loud noises
3 - rest or sleep
what can long at lead to and what are the symptoms
torsade de pointes - a polymorphic ventricular tachycardia
syncope and palpitations
what is the danger of TdP
it can degenerate into ventricular fibrillation
can terminate spontaneously
what is assoicated with increased risk in long qt syndrome
the length of the qt interval
what treatment is advised for congenital long qt syndrome
- avoid triggers
- beta blockers (not sotalol)
- permanent pacing
- ICD
who is eligible for an ICD with congenital long qt
those resuscitated from cardiac arrest or those with syncope despite beta blocker treatment
genes encoding which channels are mutated in short QT syndrome
K channels
short QT syndrome presentation
usually seen in young children adn they often dont survive, it is a cause of SIDS
assoicated with AF, ventricular arhythmias and suden death
management of short QT syndrome
ICD
what is the classical ECG of brugada syndrome
ST elevation, inverted T wave, RBBB in V1-3
does someone with brugada syndrome have ecg changes all the time?
no, may be intermittent and change over time
often seen with fever
what drugs can be used to provoke ecg changes in brugada syndrome
class 1 anti arrhythmics - flecainide or ajmoline
what are some triggers for VF in brugada syndrome
rest, sleep, fever, aalcohol, large meals
what drug should be avoided in brugada syndrome
beta blockers
what is the management of brugada syndrome
ICD - advised in those who have a cardiac arrest, abnormal ecg or collapse
what is the inheritance of CPVT
au dominant
what happens in CPVT
catecholamine release in response to activity or stress causes sympathetic stimulation of the heart - leads to an increase in IC calcium ion concentration and results in an arrhythmia cascade
mutations in which genes are associated with CPVT
RYR2 or CASQ2
what arrhythmia does CPVT cause
bidirectional ventricular tachycardia
how does CPVT present
with syncope or sudden death on activity/stress
what are the investigations of CPVT like when it is not being provoked
normal at baseline
why is management of CPVT hard
a cardiac event or defibrillation cause catecholamine release which trigger the arrhythmia. so does hospital environemnet and stress
management of CPVT
beta blockers
fleicainide
ICD
what happens in WPW syndrome
there is a congneital anatomical re entrant circuit between the atria and ventricles called the bundle of Kent - this doesnt have a refractory period so allows electrical signals to go back from ventricles to atria really fast
what is the risk in WPW linked to
how fast the bundle of kent can transmit signals
ecg changes in WPW
delta wave on ecg - slurred upstroke on QRS complex
short PR interval
