genetics of arrythmia

Question 1

What are the two types of inherited cardiac conditions ?

Answer 1

• channelopathies

- cardiomyopathies

Question 2

What are the relevant channelopathies?

Answer 2

• congenital long QT syndrome

- Brugada Syndrome

Question 3

What are the relevant cardiomyopathies?

Answer 3

• Hypertrophic cardiomyopathies

- Arrythmatic right ventricular cardiomyopathy

Question 4

What are channelopathies?

Answer 4

mutation in genes that encode the cardiac ion channels.

Question 5

What are the characteristics of channelopathies?

Answer 5

• abnormal cellular electrophysiology
• mainly affecting repolarisation
• abnormalities on ECG
• normal cardiac structure and function
• propensity to develop arrhythmia both atrial and ventricular
• what out if they are young and have AF

Question 6

What causes congenital long QT syndrome?

Answer 6

• mutations in may genes that cause one phenotype

- potassium current is the most common gene involved

Question 7

What are the lengths of the QT interval in congenital long QT syndrome?

Answer 7

• anything longer than 440ms in males

- anything longer than 450ms in females

Question 8

What is the most common type of congenital long QT syndrome?

Answer 8

autosomal dominant

-isolated Long QTS

Question 9

What is the other type of congenital long QT syndrome?

Answer 9

autosomal recessive

-malignant

Question 10

What is the hallmark arrhythmia in congenital LQTS?

Answer 10

polymorphic VT

Question 11

What are the primary complaints in congenital LQTS?

Answer 11

• syncope

- Sudden Cardiac Death in children and young adults

Question 12

What are the triggers for congenital LQTS?

Answer 12

• exercise
• sudden auditory stimulus
• prolonged QT (meds or hypokalaemia)
• sleep

Question 13

What are the mechanisms of QT prolongation?

Answer 13

• For potassium channel mutations it causes increased repolarising current to prolong QT
• For sodium channel mutations it causes increased depolarisation that prolongs QT

Question 14

What is the molecular basis of LQTS?

Answer 14

• mutation of ion channel
• reduced or dysfunctional ionic current
• prolonged cardiac repolarisation
• QT interval prolongation
• triggers polymorphic ventricular tachycardia

Question 15

What are the risk factors of SCD in LQTS?

Answer 15

• age dependant
• gender (pre-adolescent males or adult females)
• increasing QT duration
• prior syncope and response to beta blockers

Question 16

What are the potential arrhythmias from Brugada syndrome?

Answer 16

• polymorphic VT and VF

- atrial fibrillation

Question 17

What are the ECG findings in Brugada’s syndrome?

Answer 17

• ST elevation
• RBBB in V1-V3
• ECG findings may be intermittent
• diagnostic ECG changes may be seen only with provocative testing with drugs

Question 18

How many genes are associated with brugada’s syndrome?

Answer 18

• 12 associated genes

- cardiac sodium channel and calcium channel

Question 19

Is Brugada syndrome dominant or recessive?

Answer 19

-dominant

Question 20

What are the VF triggers in Brugada syndrome?

Answer 20

• usually rest or sleep
• fever
• excessive alcohol
• large meals
• genotype and family history

Question 21

What drugs to avoid in Brugada syndrome?

Answer 21

• anti-arrythmatic drugs
• psychotropic
• analgesics
• anaesthetics