Cardiac Arrhythmia and Sudden Cardiac Death Flashcards
what is a sudden cardiac death in a young person?
event that is non-traumatic , non violent, unexpected and resulting from sudden cardiac arrest within 6 hours of previously witnessed normal health
causes of sudden cardiac death?
- Inherited arrhythmia syndromes
- Inherited cardiomyopathies
- Inherited multi-system disorder (complicated with CVS issues)
examples of channelopathies?
- Congenital long QT syndrome
- Brugada syndrome
- Catecholaminergic polymorphic ventricular tachycardia
- Short QT syndrome
- Progressive familial conduction disease
- Familial AF
Familial WPW
what is an after-depolarisation?
- Abnormal depolarisations of cardiac myocytes that interrupt phase 2, 3 or 4 of the cardiac AP in the cardiac conduction system of the heart
- Can lead to triggered activity seen as sustained cardiac arrhythmia
main implication of long QT?
long time taken for repolarisation means ore time for potential extra depolarisation
what are early after-depolarisations?
abnormal depolarisation during phase 2 or 3
caused by increase in frequency of abortive action potentials before normal repolarisation is complete
what causes early after-depolarisation in phase 2 and 3?
phase 2 = augmented opening of calcium channels
phase 3 = sodium channels
what can early after-depolarisations result in?
torsades de pointes
what can potentiate early after-depolarisations?
hypokalaemia drugs that prolong the QT interval - including class Ia and III anti-arrhythmics
risk of sudden death in congenital long QT?
- 33-0.9% annually
- risk associated with severity of prolongation
how is congenital long QT managed?
lifestyle (avoid strenuous exercise etc) beta blockers implanted defibrillator (only if risk of death >4%)
describe AD congenital long QT?
divided into 2
- isolated long QT = romano ward syndrome
- extra cardiac features = anderson-tawil syndrome, timothy syndrome
describe AR congenital long QT?
associated with deafness
AKA jervell and lange-nielsen syndrome
how is long QT diagnosed?
QT > 480ms on repeated ECG
describe LQT1?
most common type problem with potassium current
reduced function
LQT1 ECG?
check notes
describe LQT2?
2nd most common
also problem with potassium current
LQT2 ECG?
check notes
describe LQT3?
problem with sodium current increased function (problem)
LQT3 ECG?
check notes
there is a very low risk of sudden cardiac death in LQT, however what should be done to minimise risk further?
avoid drugs which prolong QT (e.g clarithromycin)
correct any electrolyte abnormality quickly
avoid strenuous exercise and loud noise in LQT2
what is short QT?
mutation in K+ channels
rare
usually dont live long
what is brugada syndrome?
AD genetic disorder causing abnormal electrical activity in the heart
risk of polymorphic VT and VF
atrial fibrilation is common
ECG changes in brugada syndrome?
ST elevation and RBBB in V1-V3
- diagnostic ECG changes may only be seen with provocative testing with flecainide or ajmaline (drugs blocking sodium channels)
genes associated with brugada syndrome?
12 associated
cardiac sodium channel (SCN5A) and calcium channel (CACN1Ac)
how is brugada syndrome diagnosed?
ST elevation with type 1 morphology >2mm in one or more leads among the right precordial leads V1 and/or V2
can do after provocative drug test with sodium channel blockers
what can trigger VF in brugada syndrome?
rest or sleep
fever
excessive alcohol or large meals
genotype and family history doesnt influence prognosis
how is brugada managed?
avoid drugs causing ST elevation
avoid excessive alcohol or food
early paracetamol for fever (VERY IMPORTANT)
can use implantable defibrillator (if previous cardiac arrest)
what is catecholaminergic polymorphic ventricular tachycardia?
Adrenergic induced bidirectional and polymorphic VT, SVTs, triggered by emotional stress and physical activity
ECG/ECHO features of catecholaminergic polymorphic ventricular tachycardia?
both are normal
what causes AD catecholaminergic polymorphic ventricular tachycardia?
ryanodine receptor mutation (RyR2)
what causes AR catecholaminergic polymorphic ventricular tachycardia?
cardiac calsequestrin gene (CASQ2)
management of catecholaminergic polymorphic ventricular tachycardia?
avoid competitive sport/stress etc
beta blockers
ICD implantation + beta blockers +/- flecainide if previous cardiac arrest or recurrent syncope
what is wolf parkinson white syndrome?
congenital extra electrical pathway in the heart
ECG features in wolf parkinson white?
short PR interval
delta wave
ventricular pre-excitation via (accessory pathway)
what can WPW cause?
AVRT
AF
can cause sudden death
accessory pathway allows ventricles to fibrillate if atria fibrillate
features of hypertrophic cardiomyopathy?
mutation in sarcomere genes
most people present with late heart failure rather than sudden death
1% CV mortality per year
management of hypertrophic cardiomyopathy?
avoid competitive sport
ICD if previous cardiac arrest
what happens in dilated cardiomyopathy?
problem somewhere in proteins (sarcomeres) causing dilation of heart muscle over time
what happens in arrhythmogenic right ventricular cardiomyopathy?
fibro-fatty replacement of cardiomyocytes
LV involvement in >50% of cases
what causes arrhythmogenic right ventricular cardiomyopathy?
AD mutations in the genes for autosomal proteins
AR mutation in non-desmosomal genes
what is associated with increased risk of sudden death in arrhythmogenic right ventricular cardiomyopathy?
family history of sudden death severe right/left ventricle dysfunction frequent non-sustained VT QRS prolongation VT induction on EPS male
management of arrhythmogenic right ventricular cardiomyopathy?
avoid strenuous exercise beta blockers ICD implantation amiodarone considered in people who cant have beta blockers can have catheter ablation
