6: Cardiac conditions causing sudden death

Question 1

What is sudden cardiac death?

Answer 1

Sudden cardiac arrest and subsequent death

< 6h since seemingly normal health

Question 2

Is sudden cardiac death violent?

Answer 2

Non-violent

Non-traumatic

Question 3

Sudden cardiac death commonly occurs in which age group?

Answer 3

Young people

Who shouldn’t have heart disease

Question 4

Which genetic diseases can cause sudden cardiac death in young people?

Answer 4

Inherited arrhythmias

Imherited cardiomyopathies

Other inheritable diseases with cardiovascular involvement e.g myotonic dystrophy

Question 5

Name a channelopathy which can cause arrhythmias.

Answer 5

Long QT syndrome

Brugada syndrome

Catecholaminergic polymorphic ventricular tachycardia (CPVT)

lots more

Question 6

Name three cardiomyopathies which can be inherited through families.

Answer 6

Hypertrophic cardiomyopathy

Dilated cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC)

Question 7

What is automaticity?

Answer 7

SA node fires, generating heartbeat, without any external stimulus

Can be disordered (stupid fast) causing arrhythmia

Question 8

What are after depolarisations?

Answer 8

Abnormal depolarisations in cardiac myocytes

Interrupt normal conductions, causing arrhythmias (“triggered automaticity”)

Question 9

What specific type of abnormal electrical activity causes torsades de pointes?

What is torsades de pointes?

What condition is it associated with?

Answer 9

Early after depolarisations

Polymorphic VT with distinct appearance

Long QT syndrome

Question 10

What inherited channelopathy is associated with a bidirectional ventricular tachycardia?

Answer 10

Catecholaminergic polymorphic ventricular tachycardia (CPVT)

Question 11

Most inherited cardiac conditions are autosomal (dominant / recessive).

Answer 11

autosomal dominant

Question 12

What is the most common inherited cardiac condition?

Answer 12

Long QT syndrome

Question 13

What is an inherited cardiac condition seen in young children which has a poor prognosis?

Answer 13

Short QT syndrome

Question 14

brugada syndrome:

• polymorphic VT and VF, usually precipitated by illness
• distinct ecg appearance: V1 and V2, ST elevation; T wave inversion
• triggers: sleep, fever, alcohol excess and large meals
• Rx: avoid triggers, paracetamol for fever (antipyrexic and analgesic); ICD

Question 15

catecholaminergic polymorphic VT:

incidence = 1:10,000

adrenaline release causes a DISTINCT “bidirectional VT”

doesn’t show up on ECG until arrhythmia occurs

Question 16

Why isn’t defibrillation used in bidirectional polymorphic VT?

Answer 16

Releases adrenaline, which is a trigger of arrhythmia

i.e it makes it worse

Question 17

How is CPVT terminated?

Answer 17

Beta blockers and flecainide

Sedate and wait until the arrhythmia stops

Question 18

How is CPVT managed?

Answer 18

Avoid triggers (competitive sport, intensive exercise, stress)

Beta blockers

Flecainide

Question 19

What is Wolff-Parkinson White syndrome?

Answer 19

Accessory conduction pathway from left atrium to left ventricle

Bypassing AV node and allowing for arrhythmias

Question 20

What is the appearance of WPW on ECG?

Answer 20

Short PR interval

Delta wave (curved upstroke into QRS complex)

Question 21

Which arrhythmia can precipitate sudden cardiac death in people with WPW?

Answer 21

AF

because it carries through accessory pathway and causes VF

Question 22

What is the most common type of cardiomyopathy?

What heart conditions can it predispose you to?

Answer 22

Hypertrophic cardiomyopathy

Arrhythmias e.g AF –> Sudden cardiac death; Heart failure (because the walls are thickened and can’t pump as efficiently)

Question 23

What is the ECG finding of hypertrophic cardiomyopathy?

Answer 23

Elevated voltage criteria

Question 24

What can be fitted to reduce the risk of death in patients with hypertrophic cardiomyopathy?

Answer 24

ICD

Question 25

Apart from considering an ICD, how are patients with hypertrophic cardiomyopathy managed?

Answer 25

Avoid triggers (e.g avoid intensive exercise)

Question 26

icds in people with hypertrophic cardiomyopathy

risk > 6% indicated

4 -6 % consider

< 4% not indicated

Question 27

Which cardiomyopathy increases in prevalence in older patients?

Answer 27

Dilated cardiomyopathy

Question 28

Which investigation is used to diagnose dilated cardiomyopathy?

Answer 28

Echo

You can see dilated chambers and reduced LVEF

Question 29

What is the pathophysiology of ARVC?

Answer 29

Cardiac myocytes are replaced by fibro-fatty deposits

LV affected in majority of cases

Question 30

Is ARVC autosomal dominant or recessive?

Answer 30

Autosomal dominant

Question 31

How is ARVC managed?

Answer 31

Avoid triggers e.g intensive exercise

Beta blockers (especially sotalol - class III antiarrhythmic)

ICD in patients at high risk of sudden cardiac death

Question 32

Most inherited cardiac conditions are diagnosed (clinically / genetically).

Answer 32

Clinically

Because having a gene mutation doesn’t guarantee you’re going to have the phenotype

Question 33

What is meant by cascade screening for inherited diseases?

Answer 33

Start with patient and then branch out to siblings, children, parents etc.

Question 34

rx:

diagnose early

lifestyle changes (avoiding triggers e.g intensive exercise)

pharma - beta blockers usually

implantable defibrillators for young, fit patients

Question 35

Which abnormal heart rhythms are

a) shockable
b) not shockable?

Answer 35

a) VT, VF

b) PEA, aystole

Question 36

What are some complications of having an ICD fitted?

Answer 36

Foreign material - infection

Haemorrhage, rupture during lead fitting

Air injected during surgery - pneumothorax

Lead breaks

Question 37

How often do ICD leads need to be replaced surgically?

Answer 37

Every 20 years

Question 38

What is the risk that a patient will die during surgery to replace their ICD leads?

Answer 38

5%

e.g IVC tear