6: Cardiac conditions causing sudden death Flashcards
What is sudden cardiac death?
Sudden cardiac arrest and subsequent death
< 6h since seemingly normal health
Is sudden cardiac death violent?
Non-violent
Non-traumatic
Sudden cardiac death commonly occurs in which age group?
Young people
Who shouldn’t have heart disease
Which genetic diseases can cause sudden cardiac death in young people?
Inherited arrhythmias
Imherited cardiomyopathies
Other inheritable diseases with cardiovascular involvement e.g myotonic dystrophy
Name a channelopathy which can cause arrhythmias.
Long QT syndrome
Brugada syndrome
Catecholaminergic polymorphic ventricular tachycardia (CPVT)
lots more
Name three cardiomyopathies which can be inherited through families.
Hypertrophic cardiomyopathy
Dilated cardiomyopathy
Arrhythmogenic right ventricular cardiomyopathy (ARVC)
What is automaticity?
SA node fires, generating heartbeat, without any external stimulus
Can be disordered (stupid fast) causing arrhythmia
What are after depolarisations?
Abnormal depolarisations in cardiac myocytes
Interrupt normal conductions, causing arrhythmias (“triggered automaticity”)
What specific type of abnormal electrical activity causes torsades de pointes?
What is torsades de pointes?
What condition is it associated with?
Early after depolarisations
Polymorphic VT with distinct appearance
Long QT syndrome
What inherited channelopathy is associated with a bidirectional ventricular tachycardia?
Catecholaminergic polymorphic ventricular tachycardia (CPVT)
Most inherited cardiac conditions are autosomal (dominant / recessive).
autosomal dominant
What is the most common inherited cardiac condition?
Long QT syndrome
What is an inherited cardiac condition seen in young children which has a poor prognosis?
Short QT syndrome
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
catecholaminergic polymorphic VT:
incidence = 1:10,000
adrenaline release causes a DISTINCT “bidirectional VT”
doesn’t show up on ECG until arrhythmia occurs
Why isn’t defibrillation used in bidirectional polymorphic VT?
Releases adrenaline, which is a trigger of arrhythmia
i.e it makes it worse
How is CPVT terminated?
Beta blockers and flecainide
Sedate and wait until the arrhythmia stops
How is CPVT managed?
Avoid triggers (competitive sport, intensive exercise, stress)
Beta blockers
Flecainide
What is Wolff-Parkinson White syndrome?
Accessory conduction pathway from left atrium to left ventricle
Bypassing AV node and allowing for arrhythmias
What is the appearance of WPW on ECG?
Short PR interval
Delta wave (curved upstroke into QRS complex)
Which arrhythmia can precipitate sudden cardiac death in people with WPW?
AF
because it carries through accessory pathway and causes VF
What is the most common type of cardiomyopathy?
What heart conditions can it predispose you to?
Hypertrophic cardiomyopathy
Arrhythmias e.g AF –> Sudden cardiac death; Heart failure (because the walls are thickened and can’t pump as efficiently)
What is the ECG finding of hypertrophic cardiomyopathy?
Elevated voltage criteria
What can be fitted to reduce the risk of death in patients with hypertrophic cardiomyopathy?
ICD
Apart from considering an ICD, how are patients with hypertrophic cardiomyopathy managed?
Avoid triggers (e.g avoid intensive exercise)
icds in people with hypertrophic cardiomyopathy
risk > 6% indicated
4 -6 % consider
< 4% not indicated
Which cardiomyopathy increases in prevalence in older patients?
Dilated cardiomyopathy
Which investigation is used to diagnose dilated cardiomyopathy?
Echo
You can see dilated chambers and reduced LVEF
What is the pathophysiology of ARVC?
Cardiac myocytes are replaced by fibro-fatty deposits
LV affected in majority of cases
Is ARVC autosomal dominant or recessive?
Autosomal dominant
How is ARVC managed?
Avoid triggers e.g intensive exercise
Beta blockers (especially sotalol - class III antiarrhythmic)
ICD in patients at high risk of sudden cardiac death
Most inherited cardiac conditions are diagnosed (clinically / genetically).
Clinically
Because having a gene mutation doesn’t guarantee you’re going to have the phenotype
What is meant by cascade screening for inherited diseases?
Start with patient and then branch out to siblings, children, parents etc.
rx:
diagnose early
lifestyle changes (avoiding triggers e.g intensive exercise)
pharma - beta blockers usually
implantable defibrillators for young, fit patients
Which abnormal heart rhythms are
a) shockable
b) not shockable?
a) VT, VF
b) PEA, aystole
What are some complications of having an ICD fitted?
Foreign material - infection
Haemorrhage, rupture during lead fitting
Air injected during surgery - pneumothorax
Lead breaks
How often do ICD leads need to be replaced surgically?
Every 20 years
What is the risk that a patient will die during surgery to replace their ICD leads?
5%
e.g IVC tear
