ECG interpretation Flashcards
What categories can arrhythmogenic inherited cardiac conditions be grouped into?
Channelopathies and cardiomyopathies
What does a channelopathy result in
Arrhythmogenesis related to ion current imbalance and development of early and late depolarisations
What does cardiomyopathy result in?
Arrhythmogenesis related to scar/electrical barrier formation and subsequent entry
List some channelopathies
- congenital long QT syndrome
- brugada syndrome
- catecholaminergic polymorphic ventricular tacycardia (CPVT)
- Short QT syndrome
- Progressive familial conduction disease
- Familial AF
- Familial WPW
List some cardiomyopathies
- Hypertrophic cardiomyopathy
- Arrhythmogenic right ventricular cardiomyopathy (ARVC)
- Dilated cardiomyopathy
What are after depolarisations?
Abnormal depolarisations of cardiac myocytes that interrupt phase 2, 3 or 4 of the cardiac AP
When do early afterdepolarisations occur?
What causes them?
Occur with abnormal depolarisation during phase 2 or phase 3, and are caused by an increase in the frequency of abortive action potentials before normal repolarisation is completed
Phase 2 may be interrupted due to augmented opening of _______ channels, while phase 3 interruptions are due to the opening of _______ channels
Phase 2 may be interrupted due to augmented opening of calcium channels, while phase 3 interruptions are due to the opening of sodium channels
Early afterdepolarisations can result in…
Torsades des pointes
Early after depolarisations can be potentiated by ____________ and drugs that prolong the QT interval including class __ and ___ antiarrhythmic
Early after depolarisations can be potentiated by hypokalaemia and drugs that prolong the QT interval including class Ia and III antiarrhythmic
What is a side effect of clarithromycin?
Prolongation of the QT interval
What is the treatment for long QT syndrome?
Beta blocker is protective in some
Others need a ICD
Which LQTS is shown here?
What is the commonest trigger?
What is its penetrance?
LQTS1
Exercise
62%
Which LQTS is shown here?
What is the commonest trigger?
What is its penetrance?
LQTS2
Emotional stress
75%
Which LQTS is shown here?
What is the commonest trigger?
What is its penetrance?
LQTS3
Sleep
90%
Which current is involved in each LQTS?
LQTS 1= K current (Iks)
LQTS 2= K current (Ikr)
LQTS 3= Na current
What is the inheritance pattern of LQTS?
Autosomal dominant
- Isolated LQT= Romano Ward
- Extra-cardiac symptoms= Andersen and Timothy syndrome
Autosomal Recessive
- Jervell and Lange-Nielsen Syndrome= associated deafness
What score is used to diagnose LQTS?
Schwartz score
What should be avoided in LQTS1 and LQTS2?
LQTS1 = strenuous swimming
LQTS2= loud noises
What is the risk of brugada syndrome?
Polymorphic VT, VF
What is common in brugada syndrome?
Atrial fibrillation
What ECG findings are common in brugada syndrome?
ST elevation and RBBB in V1-V3
What may be needed to see brugada syndrome on ECG?
provocation with flecainide or ajmaline - block the cardiac sodium channel
Which genes are associated with brugada syndrome?
- cardiac sodium challen (SCN5A)
- Calcium channel (CACN1Ac)
Who is brugada syndrome common in?
Adults, 8 x commoner in males
