Inherited Cardiac Conditions

Question 1

what can an arrhythmia be?

Answer 1

a common manifestation of many genetic conditions
inherited arrhythmia syndromes
inherited cardiomyopathies
inherited multi-system diseases with CVS involvement
myotonic dystrophy

Question 2

2 types of arrhythmogenic inherited cardiac conditions

Answer 2

channelopathies

cardiomyopathies

Question 3

channelopathies examples

Answer 3

congenital long QT syndrome 
brugada syndrome 
catecholaminergic polymorphic ventricular tachycardia (CPVT)
short QT syndrome 
progressive familial conduction disease
familial AF 
familial WPW

Question 4

cardiomyopathies examples

Answer 4

hypertrophic cardiomyopathy
arrhythmogenic right ventricular cardiomyopathy
dilated cardiomyopathy

Question 5

channelopathies

Answer 5

arrhythmogenesis is related to ion current imbalance and development of early and late depolarisations
transmural ADP dispersion

Question 6

cardiomyopathies

Answer 6

arrhymogenesis related to scar/electrical barrier formation and subsequent re-entry

Question 7

summation of all ion currents across the cell membrane

Answer 7

the surface ECG

Question 8

after depolarisations

Answer 8

abnormal depolarisations of cardiac myocytes that interrupt phase 2,3 or 4 of the cardiac AP
can lead to triggered activity seen as sustained cardiac arrhythmia

Question 9

when are early afterdepolarisations?

Answer 9

during phase 2 or 3

Question 10

what causes early afterdepolarisations

Answer 10

an increase in frequency of abortive APs before normal repolarisation is completed

Question 11

what can EADs lead to?

Answer 11

torsades de pointes

Question 12

why would phase 2 be interrupted by an EAD?

Answer 12

augmented opening of calcium channels

Question 13

why would phase 3 be interrupted by an EAD?

Answer 13

opening of sodium channels

Question 14

when do delayed afterdepolarisations occur?

Answer 14

during phase 4, after repolarisation is completed but before another action potential would normally occur via the normal conduction system of the heart

Question 15

why do DADs occur?

Answer 15

due to elevated cystolic calcium concentrations
the overload of the SR may cause spontaneous Ca2+ release after repolarisation, causing the released Ca2+ to exit the cell through the 3Na+/Ca2+ exchanger
this results in a net depolarising current

Question 16

when are DADs seen?

Answer 16

digoxin toxicity
bidirectional ventricular tachycardia
catecholaminergic polymorphic ventricular tachycardia (CPVT)

Question 17

what is the mechanism of QT prolongation?

Answer 17

less repolarising current prolongs ADP
-or-
more depolarising current prolongs ADP

Question 18

congenital LQTS

Answer 18

polymorphic VT (torasades de pointes) triggered by adrenergic stimulation
syncope
risk associated with severity of QT prolongation

Question 19

autosomal dominant LQTS

Answer 19

isolated LQT- romano-ward syndrome

extra cardiac features- anderson-tawil syndrome, timothy syndrome

Question 20

autosomal recessive LQTS

Answer 20

associated with deafness; jervell and lange-neilsen syndrome

Question 21

LQTS diagnosis

Answer 21

QTc >480 ms in repeated 12-lead ECGs or LQTS risk score >3

confirmed pathogenic LQTS mutation irrespective of the duration

QTc >460 ms in repeated 12-lead ECGs in patients with an unexplained syncopal episode in the absence of secondary causes for QT prolongation

Question 22

risk of sudden cardiac death in LQTS

Answer 22

age dependant 
gender 
- pre-adolescent males
- adult females
increasing QT duration 
prior syncope 
response to beta blockers

Question 23

risk management in LQTS

Answer 23

avoidance of QT prolonging drugs
correction of electrolyte abnormalities
avoidance of genotype-specific triggers eg strenuous swimming and exposure to loud nosies

Question 24

brugada syndrome

Answer 24

risk of polymorphic VT, VF
atrial fibrillation common
ST elevation and RBBB in V1-V3
ECG findings may be intermittent and change over time
diagnostic ECG changes may seen only with provocative testing with flecainide or ajmaline
autosomal dominant
usually adult males

Question 25

VF triggers in brugada syndrome

Answer 25

rest or sleep fever excessive alcohol, large meals

Question 26

risk management in brugada syndrome

Answer 26

avoidance of drugs that may induce ST segement elevation in right precordial leads avoidance of excessive alcohol intake and large meals prompt treatment of any fever with antipyretic drugs

Question 27

ICD implantation in brugada syndrome

Answer 27

survivors of cardiac arrest or have documented sustained VT | spontaneous diagnostic type I ECG pattern and history of syncope

Question 28

drugs to avoid in brugada syndrome

Answer 28

anti-arrhythmic drugs psychotropics analgesics anaesthetics

Question 29

catecholaminergic polymorphic ventricular tachycardia

Answer 29

adrenergic induced bidirectional and polymorphic VT, SVTs, triggered by emotional stress, physical activity normal ECG and ECHO

Question 30

autosomal dominant catecholaminergic polymorphic ventricular tachycardia

Answer 30

ryanodine receptor mutation

Question 31

recessive catecholaminergic polymorphic ventricular tachycardia

Answer 31

cardiac calsequestrin gene

Question 32

CPVT risk management

Answer 32

avoidance of competitive sports, strenuous exercise and stressful environments B blockers

Question 33

ICD implantation in CPVT

Answer 33

cardiac arrest recurrent syncope polymorphic/ bidirectional VT despite optimal therapy

Question 34

flecainide

Answer 34

patients with CPVT where there are risks/contraindications for an ICD

Question 35

complications associated with transvenous leads

Answer 35

``` endocarditis perforation haemothorax pnemothorax thromboembolic events vascular complications lead fractures lead extraction complications lead dislodgement ```

Question 36

S-ICD

Answer 36

an alternative to transvenous defibs in patients with an indication for an ICD when pacing therapy for bradycardia, cardiac resynch or antitachycardia pacing is not needed

Question 37

hypertrophic cardiomyopathy

Answer 37

mutation in sarcomeric genes

Question 38

HOCM clinical presentations

Answer 38

sudden death heart failure end stage HF atrial fibrillation

Question 39

dilated cardiomyopathy

Answer 39

more males than females | sarcomere and desosomal genes/ laminA/C and desmin if there is conduction disease, dystophin if X linked

Question 40

lamin A/C

Answer 40

``` progressive dilated cardiomyopathy atrioventricular block (first degree heart block) SVT and VA high risk of sudden death sometimes neuromuscular symptoms ```

Question 41

arrhythmogenic right ventricular cardiomyopathy

Answer 41

fibro-fatty replacement of cardiomyocytes | LV involvement

Question 42

mutations in arrhythmogenic right ventricular cardiomyopathy

Answer 42

autosomal dominant in the genes for desmosomal proteins | autosomal recessive mutations in nondesmosomal genes

Question 43

risk of sudden death in ARVC

Answer 43

``` family history severity of RV and LV function frequent non-sustained VT QRS prolongation VT induction on EPS male age ```

Question 44

risk management in ARVC

Answer 44

``` avoidance of competitive sports B blcokers ICD implantation amiodarone catheter ablation ```

Question 45

cascade screening

Answer 45

Produces a greater rate of case identification than general population screening. Once a diagnosis is confirmed in an individual, testing is extended to first degree and second degree relatives. If relatives test positive, their first and second degree relatives are approached and offered testing, and so on