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CLASP - Sudden death > Cardiac conditions that cause sudden death > Flashcards

Cardiac conditions that cause sudden death Flashcards

1
Q

What is sudden cardiac death?

A

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

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2
Q

What are the 2 types of arrythmogenic inherited cardiac conditions?

A

Channelopathies and cardiomyopathies

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3
Q

Name some inherited channelopathies

A

Congenital long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia (CPVT), short QT syndrome

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4
Q

Name some inherited cardiomyopathies

A

Hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy (ARVC)

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5
Q

In channelopathies what is the arrythmogenesis related to?

A

Ion current imbalance and development of early and late depolarisations

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6
Q

In cardiomyopathies what is the arrhythmogenesis related to?

A

Scar/electrical barrier formation and subsequent re-entry

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7
Q

What is an afterdepolarisation?

A

After depolarisations are abnormal depolarisations of cardiac myocytes that interrupt phsae 2,3 or 4 of the cardiac AP in the cardiac conduction system of the heart. After depolarisations can lead to triggered activity seen as sustained cardiac arrythmia

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8
Q

When do early after depolarisations occur?

A

During phase 2 or 3

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9
Q

What causes early after depolarisations (EADs)?

A

An increase in the frequency of abortive action potentials before normal repolarisation is completed. Phase 2 may be interrupted due to augmented opening of calcium channels, while phase 3 interruptions are due to the opening of calcium channels

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10
Q

What can occur as a result of EADs?

A

Torsades de Pointes

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11
Q

What can potentiate and EAD?

A

Hypokalaemia and drugs that prolong the QT interval, including class Ia and III anti-arrhythmic agents

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12
Q

When do delayed after depolarisations (DADs) occur?

A

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

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13
Q

What causes DADs?

A

Elevated cytosolic calcium concentrations, classically seen with digoxin toxicity

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14
Q

What is the classical feature associated with DADs?

A

Bidirectional ventricular tachycardia (also seen in CPVT)

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15
Q

How do DADs occur?

A

The overload of the sarcoplasmic reticulum may cause spontaneous Ca release after repolarisation, causing released Ca to exit the cell through the 3Na/Ca exchanger which results in a net depolarizing current

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16
Q

What mode of inheritance are most cardiac conditions inherited by?

A

Autosomal dominant inheritance

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17
Q

What occurs as a result of congenital LQTS?

A

Polymorphic VT (Torsades de Pointes) triggered by adrenergic stimulation

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18
Q

What is the risk of sudden cardiac death in congenital long QT syndrome?

A

In untreated LQTS risk = 0.33-0.9% and this risk increases with increasing QT duration. Risk also depends on gender (pre-adolescent males and adult females), age, prior syncope and response to beta-blockers

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19
Q

What is the mode of inheritance for congenital LQTS?

A

Mainly autosomal dominant - isolated LQT = Romano-Ward syndrome. Autosomal recessive is associated with deafness and is called Jervell and Lange-Nielsen syndrome

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20
Q

How many subtypes of congenital LQTS are there?

A

13 subtypes i.e. 13 genes

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21
Q

What are the diagnostic criteria for LQTS?

A

Class I = QT interval >/=480ms in repeated 12-lead ECGs or LQTS risk score >3 or the presence of a confirmed pathogenic LQTS mutation irrespective of the QT duration Class IIa - QT interval >/=460ms in repeated 12-lead ECGs in patients with an unexplained syncopal episode in the absence of secondary causes for QT prolongation

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22
Q

What lifestyle changes are recommended in all patients with LQTS?

A

Avoidance of QT prolonging drugs, correction of electrolyte abnormalities that may occur during diarrhoea, vomiting or metabolic conditions, avoidance of genotype-specific triggers for arrhythmias e.g. strenuous swimming in LQTS1 and loud noises in LQTS2

23
Q

What causes short QT syndrome?

A

A mutation in the cardiac K channels

24
Q

How may short QT syndrome present?

A

May present in children, may be associated with AF, QT interval <300ms at heart rate of <80bpm

25
Q

What is the general prognosis for short QT syndrome?

A

VERY malignant so bad prognosis

26
Q

What drugs can be used to treat short QT syndrome?

A

Anti-arrhythmic drugs - quinidine, flecainide

27
Q

What are the typical ECG findings for Brugada syndrome?

A

ECG findings may be intermittent, change over time. Can usually see ST elevation and RBBB in V1-3. Diagnostic ECG changes may only be seen with provocative testing with flecainide or ajmaline (drugs that block the cardiac Na channel)

28
Q

How is Brugada syndrome inherited?

A

Autosomal dominant, 8x more common in males, 12 associated genes (SCN5A and CACN1Ac)

29
Q

Ventricular fibrillation can occur in Brugada syndrome, name some of the triggers for this

A

Rest/sleep, fever, excessive alcohol, large meals

30
Q

What lifestyle changes are recommended in all patients with Brugada syndrome?

A

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

31
Q

When is ICD recommended for patients with Brugada syndrome?

A

Those who are survivors of an aborted cardiac arrest and/or have documented spontaneous sustained VT. ICD implantation should be considered in patients with a spontaneous diagnostic type I ECG pattern and history of syncope

32
Q

What drugs should be avoided in Brugada syndrome?

A

Anti-arrhythmic drugs, psychotropics, analgesics and anaesthetics

33
Q

What is catecholaminergic polymorphic ventricular tachycardia (CPVT)?

A

Adrenergic induced bidirectional and polymorphic VT, SVTs, triggered by emotional stress and/or physical activty

34
Q

What would appear on ECG and ECHO in CPVT?

A

Normal findings

35
Q

How is CPVT inherited?

A

Autsomal dominant - ryanodine receptor mutation Autosomal recessive - cardiac calsequestrin gene

36
Q

What lifestyle changes are recommended in all patients with CPVT?

A

Avoidance of competitive sports, strenuous exercise and stressful environments

37
Q

What treatment is available for patients with CPVT?

A

Beta-blockers are recommended for all patients, ICD implantation with or without flecainide is recommended in patients who experience cardiac arrest, recurrent syncope or polymorphic/bidirectional VT despite optimal therapy

38
Q

What features would be seen on an ECG in Wolff-Parkinson-White syndrome?

A

Short PR interval and delta waves

39
Q

What is the most common arrhythmia associated with WPWS?

A

Atrioventricular re-entrant tachycardia

40
Q

What is the cause of WPWS?

A

Ventricular pre-excitation

41
Q

What causes hypertrophic cardiomyopathy?

A

Mutation in sarcomeric genes in 60% of cases, 5-10% due to MYBPC3 gene mutation

42
Q

What is the associated mortality with HOCM?

A

1% cardiovascular mortality/year in unselected patients

43
Q

What is recommended in HOCM patients to prevent sudden cardiac death?

A

Avoidance of competitive sports, ICD implantation in patients who have survived cardiac arrest due to VT or VF or who have spontaneous sustained VT causing syncope or haemodynamic compromise and have a life expectancy of >1 year

44
Q

Describe the prevalence of dilated cardiomyopathy

A

1 in 2500, low in childhood, males > females

45
Q

What causes dilated cardiomyopathy?

A

Sarcomere and desmosomal genes, laminA/C and desmin if there is conduction disease, dystrophin if X-linked. Mutations are found in 20% of cases

46
Q

What causes arrhythmogenic right ventricular cardiomyopathy (ARVC)?

A

Fibro-fatty replacement of cardiomyocytes. Autosomal dominant mutations in the genes for desmosomal proteins; autosomal recessive mutations in non-desmosomal genes

47
Q

How many patients get LV involvement with ARVC?

A

>50% of cases get left ventricular involvement

48
Q

What are the risk factors associated with sudden cardiac death in ARVC?

A

Family history of premature SCD, severity of RV and LV function, frequent non-sustained VT, QRS prolongation on EG, VT induction on electrophysiology study (EPS), male gender and age at presentation

49
Q

What are the recommended treatments for ARVC?

A

Avoidance of competitive sports, beta-blockers to the maximum tolerated dose, ICD implantation in patients with a history of aborted SCD and haemodynamically poorly tolerated VT, amiodarone in patients with frequent PVC or NSVT who have contraindications to beta-blockers. If unresponsive to this, catheter ablation should be considered

50
Q

What is the only known treatment for ventricular fibrillation?

A

Defibrillation

51
Q

What does defibrillation do?

A

Delivers high amounts of energy to cause all cardiac myocytes to fully depolarise. This resets all cardiac myocytes to enable normal electrical activation to recommence. Defibrillation is most successful the quicker it is delivered

52
Q

Name some complications associated with transvenous leads (ICD)

A

Endocarditis, perforation, haemothorax, pneuomthorax, thromboembolic events, lead fractures, vascular complications, lead extraction complications, lead dislodgement

53
Q

When would a subcutaneous ICD (S-ICD) be considered over a transvenous ICD?

A

In patients with an indication for an ICD when pacing therapy for bradycardia support, cardiac resynchronisation or anti-tachycardia pacing is not needed. It is also useful when venous access is difficult, after the removal of a transvenous ICD for infections or in young patients with a long-term need for ICD therapy

CLASP - Sudden death (4 decks)

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