Sudden cardiac death Flashcards by Adele Atkins

Define sudden death

Not trauma, toxicity or poison (i.e. natural)
Not due to a chronic illness
“natural death within one hour of the onset of acute symptoms”

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List the causes of sudden cardiac death

Heart and/or its vessels
Noncardiac vessels (e.g. stroke or aneurysm)
Pulmonary system (pulmonary embolism)
Central nervous system (CNS) (rare seizures in epilepsy)

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Describe the 3 qualities of sudden death

Natural, rapid, unexpected

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Define sudden cardiac death

Sudden death due to cardiovascular/coronary vessel causes

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List some direct causes of sudden cardiac death

Coronary obstruction
infarct
embolism
Arrhythmia / Dysrhythmia

Disorders Leading to Risks for Sudden Cardiac Death
CHD / low LVEF
structural heart disease (e.g. cardiomyopathies)
Also developmental/genetic structural pathologies of the heart
primary arrhythmia

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List some disorders which lead to the risk of sudden cardiac death

Disorders Leading to Risks for Sudden Cardiac Death
CHD / low LVEF
structural heart disease (e.g. cardiomyopathies)
Also developmental/genetic structural pathologies of the heart
primary arrhythmia

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Describe cardiac arrest

A sudden stop in effective blood circulation due to the failure of the heart to contract effectively or at all

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Cardiac arrest is not the same as…

Myocardial infarction

Heart failure

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Describe arrhythmia and its causes

A variation in the normal beating pattern or rhythm of the heart
Arrhythmia is usually due to disorganisation of the electrical signals running through the heart

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List 3 causes of arrythmia

Electrical -ion channels and electrical issues at a cellular level
Structural- shape or size of cardiac tissue electrically unstable, causes signal delays
Ischaemic- low oxygen delivery causing electrical instability

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List the causes of primary arrythmia

Unstable myocardium - Often due to damaged or hypoxic tissue
Non-ischemic
Ion channel pathologies (channelopathies) - Long QT syndrome
Accessory conduction pathways

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What is a cardiomyopathy?

Pathology when heart size, shape or thickness is abnormal

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What can a cardiomyopathy cause?

Risk of pumping dysfunction or low output heart failure
conduction abnormalities (normal conduction pathways are altered)

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Lift the two types of cardiomyopathy

Dilated (eccentric)

Hypertrophic (concentric)

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Describe tetralogy of fallot

Associated with a higher risk of sudden cardiac death even after surgery

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To have arrythmia, you usually need both…

Substrate and trigger

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Describe a trigger

Brief event required to initiate a period of arrhythmia

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Describe a substrate

Ongoing underlying tissue instability that increases triggers or allows for maintenance and amplification or dysrhythmia

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What is R on T?

Early activity on the ECG that interferes with a T wave where the R wave is interfering with the next T wave and causing this new wave to come early. New beat starts even when the old beat has not yet finished

What is a pacemaker?

Implanted Electronic Device

Has electrodes that can stimulate the heart and consistently applies impulses for each heart beat

When are pacemakers used?

Mostly used for bradyarrhythmias and heart block

What is an implantable cardioverter defibrillator?

Implanted Electronic Device
Has electrodes that can stimulate the heart
Applies electrical impulses ONLY when ventricular dysrhythmias detected
Not at other times (cf pacemaker)
Protects from fast or uncontrolled rhythms for example ventricular fibrillation

When should an ICD be considered to be implanted?

Cardiac arrest due to ventricular fibrillation
Symptomatic heart failure with low LVEF
Low output heart failure after MI (40 days later)

What are antiarrhythmic drugs used for?

Mostly for supraventricular arrhythmias - Arrhythmias arising from atria or AV node

What do antiarrhythmic drugs do?

Usually affect ion channel activity or sympathetic drive

List some examples of antiarrhythmic drugs

Amiodarone Beta blocker Digoxin for AF (not really an antiarrhythmic drug)

What is reperfusion injury?

Tissue damage caused when blood supply returns to the tissue after a period of ischemia or hypoxia. Tissue damage and/or hypoxia lead to electrical irregularities & risk. The restoration of circulation results in inflammation and oxidative damage

How can you prevent reperfusion injury?

Cooling Immunosuppression Oxygen radical scavengers

What do syncope and seizures have in common?

Blackouts- unexplained losses of consciousness

What are seizures involved in?

Central nervous system problems

Describe vasovagal seizures

Vagal increase causes vasodilatation and low heart rate Triggered centrally not triggered at level of heart Most common form of syncope. Common in young adults Recurrent

Describe exertional seizures

Neurocardiogenic origin | Benign

What is the index case/probrand?

In medical genetics, the index case is the case of the original patient that stimulates investigation of other members of the family. The initial patient in the population of an epidemiological investigation- primary case

What is meant by the number needed to treat?

Statistical measurement of the impact of a medicine or therapy The average number of patients needed to be treated to prevent 1 additional bad outcome

What do most cases of sudden death relate to?

Arrhythmia

List the mechanisms of arrhythmia

Substrate for arrhythmia - Structural or electrical Ectopic activity - Early afterdepolarization, Short coupling interval and Delayed afterdepolarization Re-entry Wave break

Describe the process of ventricular remodelling

``` Ventricular remodelling Scar formation Myocardial fibrosis Coupling Dilatation Poor function ```

How does IHD provide substrate for arrhythmia?

Acute ischemia and ventricular remodelling

How does fibrosis cause arrythmia?

Barrier to electrical conductivity Patches of viable tissue however it is damaged Transmission of electrical impulses is very slow

List some causes of dilated cardiomyopathy

``` Idiopathic Viral Alcohol Drugs (chemotherapy) Autoimmune ```

What does dilated cardiomyopathy lead to?

Ectopy Re-entry VT/VF

Describe the pathophysiology of dilated cardiomyopathy

``` Trigger is inflammation of the heart Subendocardial myocardial fibrosis Neurohumoral activation Increased sympathetic tone Electrolyte disturbances ```

Describe hypertrophic cardiomyopathy

Most common cause of SCD in young athletes Autosomal dominant, incomplete penetrance Mutation of cardiac muscle sarcomere genes Asymmetrical septal hypertrophy Systolic anterior motion of mitral valve LV outflow tract obstruction

List the symptoms of hypertrophic cardiomyopathy

May be asymptomatic Exertional chest pain/dyspnoea Exertional syncope Palpitations

Describe Arrhythmogenic RV Cardiomyopathy

Genetic condition Multigenomic Replacement of the right ventricle myocardium with fibro-fatty tissue Hypertrophy and dilation of the right ventricle Ventricular tachycardia and ventricular fibrillation due to re-entry around interstitial fibrosis

Describe the symptoms of Arrhythmogenic RV cardiomyopathy

Often asymptomatic Exertional syncope and SCD Atrial arrhythmia common Epsilon wave on ECG

List some other structural heart diseases which increase the risk of sudden cardiac death

Aortic stenosis Mitral stenosis Mitral valve prolapse Congenital Heart Disease: