Cardiac Arrhythmia and Sudden Cardiac Death

Question 1

what is a sudden cardiac death in a young person?

Answer 1

event that is non-traumatic , non violent, unexpected and resulting from sudden cardiac arrest within 6 hours of previously witnessed normal health

Question 2

causes of sudden cardiac death?

Answer 2

• Inherited arrhythmia syndromes
  
  • Inherited cardiomyopathies
  • Inherited multi-system disorder (complicated with CVS issues)

Question 3

examples of channelopathies?

Answer 3

• Congenital long QT syndrome
  
  • Brugada syndrome
  • Catecholaminergic polymorphic ventricular tachycardia
  • Short QT syndrome
  • Progressive familial conduction disease
  • Familial AF
    Familial WPW

Question 4

what is an after-depolarisation?

Answer 4

• 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

Question 5

main implication of long QT?

Answer 5

long time taken for repolarisation means ore time for potential extra depolarisation

Question 6

what are early after-depolarisations?

Answer 6

abnormal depolarisation during phase 2 or 3

caused by increase in frequency of abortive action potentials before normal repolarisation is complete

Question 7

what causes early after-depolarisation in phase 2 and 3?

Answer 7

phase 2 = augmented opening of calcium channels

phase 3 = sodium channels

Question 8

what can early after-depolarisations result in?

Answer 8

torsades de pointes

Question 9

what can potentiate early after-depolarisations?

Answer 9

hypokalaemia 
drugs that prolong the QT interval 
- including class Ia and III anti-arrhythmics

Question 10

risk of sudden death in congenital long QT?

Answer 10

0. 33-0.9% annually

- risk associated with severity of prolongation

Question 11

how is congenital long QT managed?

Answer 11

lifestyle (avoid strenuous exercise etc)
beta blockers
implanted defibrillator (only if risk of death >4%)

Question 12

describe AD congenital long QT?

Answer 12

divided into 2

• isolated long QT = romano ward syndrome
• extra cardiac features = anderson-tawil syndrome, timothy syndrome

Question 13

describe AR congenital long QT?

Answer 13

associated with deafness

AKA jervell and lange-nielsen syndrome

Question 14

how is long QT diagnosed?

Answer 14

QT > 480ms on repeated ECG

Question 15

describe LQT1?

Answer 15

most common type problem with potassium current

reduced function

Question 16

LQT1 ECG?

Answer 16

check notes

Question 17

describe LQT2?

Answer 17

2nd most common

also problem with potassium current

Question 18

LQT2 ECG?

Answer 18

check notes

Question 19

describe LQT3?

Answer 19

problem with sodium current
increased function (problem)

Question 20

LQT3 ECG?

Answer 20

check notes

Question 21

there is a very low risk of sudden cardiac death in LQT, however what should be done to minimise risk further?

Answer 21

avoid drugs which prolong QT (e.g clarithromycin)
correct any electrolyte abnormality quickly
avoid strenuous exercise and loud noise in LQT2

Question 22

what is short QT?

Answer 22

mutation in K+ channels
rare
usually dont live long

Question 23

what is brugada syndrome?

Answer 23

AD genetic disorder causing abnormal electrical activity in the heart
risk of polymorphic VT and VF
atrial fibrilation is common

Question 24

ECG changes in brugada syndrome?

Answer 24

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)

Question 25

genes associated with brugada syndrome?

Answer 25

12 associated | cardiac sodium channel (SCN5A) and calcium channel (CACN1Ac)

Question 26

how is brugada syndrome diagnosed?

Answer 26

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

Question 27

what can trigger VF in brugada syndrome?

Answer 27

rest or sleep fever excessive alcohol or large meals genotype and family history doesnt influence prognosis

Question 28

how is brugada managed?

Answer 28

avoid drugs causing ST elevation avoid excessive alcohol or food early paracetamol for fever (VERY IMPORTANT) can use implantable defibrillator (if previous cardiac arrest)

Question 29

what is catecholaminergic polymorphic ventricular tachycardia?

Answer 29

Adrenergic induced bidirectional and polymorphic VT, SVTs, triggered by emotional stress and physical activity

Question 30

ECG/ECHO features of catecholaminergic polymorphic ventricular tachycardia?

Answer 30

both are normal

Question 31

what causes AD catecholaminergic polymorphic ventricular tachycardia?

Answer 31

ryanodine receptor mutation (RyR2)

Question 32

what causes AR catecholaminergic polymorphic ventricular tachycardia?

Answer 32

cardiac calsequestrin gene (CASQ2)

Question 33

management of catecholaminergic polymorphic ventricular tachycardia?

Answer 33

avoid competitive sport/stress etc beta blockers ICD implantation + beta blockers +/- flecainide if previous cardiac arrest or recurrent syncope

Question 34

what is wolf parkinson white syndrome?

Answer 34

congenital extra electrical pathway in the heart

Question 35

ECG features in wolf parkinson white?

Answer 35

short PR interval delta wave ventricular pre-excitation via (accessory pathway)

Question 36

what can WPW cause?

Answer 36

AVRT AF can cause sudden death accessory pathway allows ventricles to fibrillate if atria fibrillate

Question 37

features of hypertrophic cardiomyopathy?

Answer 37

mutation in sarcomere genes most people present with late heart failure rather than sudden death 1% CV mortality per year

Question 38

management of hypertrophic cardiomyopathy?

Answer 38

avoid competitive sport | ICD if previous cardiac arrest

Question 39

what happens in dilated cardiomyopathy?

Answer 39

problem somewhere in proteins (sarcomeres) causing dilation of heart muscle over time

Question 40

what happens in arrhythmogenic right ventricular cardiomyopathy?

Answer 40

fibro-fatty replacement of cardiomyocytes | LV involvement in >50% of cases

Question 41

what causes arrhythmogenic right ventricular cardiomyopathy?

Answer 41

AD mutations in the genes for autosomal proteins | AR mutation in non-desmosomal genes

Question 42

what is associated with increased risk of sudden death in arrhythmogenic right ventricular cardiomyopathy?

Answer 42

``` family history of sudden death severe right/left ventricle dysfunction frequent non-sustained VT QRS prolongation VT induction on EPS male ```

Question 43

management of arrhythmogenic right ventricular cardiomyopathy?

Answer 43

``` avoid strenuous exercise beta blockers ICD implantation amiodarone considered in people who cant have beta blockers can have catheter ablation ```