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MBBS IV - Junior Clerkship WCS > JC08 (Medicine) ** - Hereditary Cardiac Diseases > Flashcards

JC08 (Medicine) ** - Hereditary Cardiac Diseases Flashcards

1
Q

Types of hereditary cardiac diseases

A

Inherited cardiomyopathies

Inherited rhythm and conduction disorders

Familial hypercholesterolemia - CAD

Connective tissue diseases - Valvular heart diseases

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2
Q

List 4 major inherited cardiomyopathies**

A

Hypertrophic cardiomyopathy - HCM

Dilated cardiomyopathy - DCM

Arrhythmogenic Right Ventricular Cardiomyopathy - ARVC

Restrictive cardiomyopathy - RCM

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3
Q

List 4 major types of inherited cardiac rhythm/ conduction disorders **

A

Long QT syndrome - LQTS ***

Brugada Syndrome - BrS ***

Catecholaminergic polymorphic VT - CPVT

Primary ciliary dyskinesia - PCCD

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4
Q

Define cardiomyopathy

A

heterogeneous group of diseases of myocardium:
 Usually exhibit inappropriate ventricular hypertrophy/ dilatation
 Associated with mechanical and/or electrical dysfunction
 confined to the heart vs. part of generalized systemic disorders

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5
Q

Long QT syndrome

- Pathogenesis

A

Pathogenesis: Ion balance/ Ion channel dysfunction

Prolonged ventricular repolarization due to Decreased repolarized current (Blocked K channels) and Increased depolarization current (High Na)
Causing transmural re-entry and risk of torsade de pointes, polymorphic ventricular tachycardia

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6
Q

Long QT syndrome

  • Cut-off for Prolonged QT
  • Formula for corrected QT
A
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7
Q

Long QT syndrome

  • Presentation and symptoms
  • Triggers
A

 Syncope (usual)
 Sudden cardiac death (usual)
 Seizures

Triggers (like ACS): exercise, emotional stress, sleep (circadian), repose, etc.

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8
Q

Long QT Syndrome

Causes - Congenital and Acquired

A

Congenital:
- Ion Channelopathy (LQT1-10, JLN1, JLN2 mutations) due to Andersen syndrome, Timothy syndrome, Jervell and Lange-Nielson syndrome (AR) , Romano-Ward syndrome (AD)..etc

Acquired:

  • Drug-induced
  • Electrolyte imbalance: HypoK, HypoCa, HypoMg
  • ** Myocardium ischemia, myocarditis **
  • Metabolic/ endocrine: DM, Hypothyroidism, Pheochromocytoma…
  • Nutritional: Anorexia/ starvation, Bulimia, Alcoholism…
  • CNS: Trauma, SAH, CVA, Encephalitis
  • Cardiac: AV block, severe bradycardia, sick sinus syndrome
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9
Q

List classes of drugs that can cause LQTS

A
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10
Q

First-line investigations for LQTS

Relevant clinical history for Dx

A
  1. ECG: Long QT interval, Notched T wave/ T wave alternans, TdP
  2. Stress testing:
    a) Exercise testing (paradoxical QTc prolongation at faster HR)
    b) Adrenergic stimulation (Trigger polymorphic VT/ TdP)
  3. Exclude acuqired causes:
    - Electrolytes
    - Hormone tests
    - Head CT (for CNS causes)
  4. Genetic testing for ion channelopathies
    - LQTS gene mutation, JLN gene mutation (50% positive only due to limited penetrance)

___________________________________________________
Clinical History:
- Syncope with/without stress
- Arrhythmias
- Congenital deafness

Family History:
- Family members with confirmed LQTS
- Unexplained Sudden Cardiac Death in young

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11
Q

Name of clinical diagnostic criteria for LQTS

A

Schwartz score

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12
Q

Long QT syndrome

Treatment

A
  1. Resuscitate cardiac arrest
  2. Lifestyle advices: Low-intensity exercise only, Reduce startles/ emotional stresses, avoid heat stroke, avoid AED usage
  3. Beta-blockers (adrenergic blockade)***
  4. Cardiac implants and surgery:
    - Cardioverter-defibrillator (ICD)***,
    - Left cervicothoracic stellectomy (anti-adrenergic),
    - cardiac pacemakers (vs arrhythmogenic bradycardia),
    - Left cardiac sympathetic denervation
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13
Q

Brugada syndrome

- Pathogenesis

A

Defect in an ion channel gene - Mutation in SCN5A (cardiac Na+ channel gene) - Autosomal Dominant inheritance

> > Depolarization disorder in the RIGHT ventricle

> > ventricular tachyarrhythmias occurring at night/ at rest, causing sudden and unexpected death syndrome (SUDS) in males/ infants

SCN5A can also cause LQT3 - LQT/Brugada overlap syndrome
SCN5A also causes Arrhythmogenic right ventricular dysplasia (ARVD)

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14
Q

First-line investigations for Brugada syndrome

A
  1. ECG
    - ST elevation in right precordial leads (V1-V3), Inverted T wave
    - RV conduction block
    - Na channel blockers (ajmaline/ procainamide/flecainide) trigger/ unmask polymorphic VT
  2. ECHO
    - Usually normal
    - Septal hypertrophy, ARVC
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15
Q

Subtypes of Brugada syndrome

A

Type 1 ECG pattern (Diagnostic)

Latent/ Intermittent Brugada syndrome (need repeat ECG with Na channel blocker)

Brugada-like ECG (RBBB, Septal hypertrophy, ARVC)

Brugada ECG phenocopies (MI, PE, myocardial/ pericardial diseases)

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16
Q

Brugada syndrome

  • Presentation
A 
Malignant tachyarrhythmias at rest/ night (vagal influence) 
Sudden Cardiac death 
Persistent/ recurrent arrhythmias
Syncope, Seizures
Nocturnal agonal respiration
17
Q

Brugada syndrome

  • Treatment
A

Genetic counseling

Surgery: ICD, Catheter ablation

Recurrent ventricular arrhythmia: Adrenaline/ Isoproterenol (B-adrenergic agonist, analog of adrenaline)/ Quinidine (Class IA antiarrhythmic)

Life-style modification: Reduce fever, No alcohol, No cocaine

18
Q

Familial hypercholesterolemia

  • Pathogenesis
  • Demographics
A

Mutation in LDLR, APOB, PCSK9, LDLPAR (Autosomal Dominant)

> > Reduce LDL uptake from blood
Increase LDL deposition on vessel walls
Increase risk of premature, atherosclerotic Coronary heart disease

Homozygous mutation: Sudden cardiac death at 12.5 years
Heterozygous mutation: SCD at 35 years

19
Q

Familial hypercholesterolemia (FH)

  • Risk factors for SCD
  • Presentation
A

Same RFs as atherosclerotic CAD

  • Smoking, HTN, DM, Dyslipidemia…etc
  • Male sex

S/S:
 Xanthelasma
 Tendon xanthoma
 Sudden cardiac death

20
Q

Familial hypercholesterolemia

  • Diagnostic criteria name
  • Classification name
  • Treatment options
A

Diagnosis: Dutch Lipid Clinic Network criteria
Classification: Frederickson Classification

Treatment:
1. Lifestyle modification: smoking cessation, dietary advice

  1. Drugs:
    Statins (HMG-CoA reductase inhibitors, e.g. atorvastatin)*** +/- Bile acid- binding resin, Fibrates, Niacins, PCSK9 inhibitors
  2. Lipoprotein apheresis (refractory)
  3. Family member screening: FH, SCD, LDL cholesterol levels, Genetic tests for mutations…etc
21
Q

Hypertrophic cardiomyopathy (HCM)

  • Structural features
  • Epidemiology
A

Structural: Inappropriate LVH +/- LVOT obstruction

1) LVOT obstruction
2) Diastolic dysfunction
3) Myocardial ischemia
4) Mitral regurgitation

Epidemiology:
 1:500-1000 individuals
 Major cause of premature sudden cardiac death in young and apparently healthy athletes

22
Q

Hypertrophic cardiomyopathy (HCM)

  • Causes (genetic and non-genetic)
A

Genetic: Autosomal dominant genetic defects

  • Sarcomeric protein gene mutation: MYBPC3, MYH7, TNNT3, TNN13, TPM1, MYL3…etc
  • IEMs: Glycogen storage diseases
  • Lysosomal storage diseases, Neuromuscular diseases…etc
  • Mitochondrial diseases

Acquired:

  • Amyloidosis
  • Drug-induced (tacrolimus, hydroxychloroquine, steroids)
  • Diabetic mother
23
Q

Hypertrophic cardiomyopathy (HCM)

Clinical presentation

A

Variable presentations:

  • Incidental ECG/ ECHO
  • Dyspnea on exertion, orthopnea, PND
  • Angina
  • Pre-syncope/ syncope
  • Arrhythmias
  • Sudden Cardiac death
24
Q

Hypertrophic cardiomyopathy (HCM)

Risk factors for sudden cardiac death

A

Clinical risk factors:
Cardiac arrest by V-Fib, sustained V-tach
Family history of premature SCD
Unexplained syncope

Risk factors on investigations:
Massive LVH on ECHO
LV systolic dysfunction on Cardiac MRI (CMR)
LV apical aneurysm on cardiac imaging

25
Q

Hypertrophic cardiomyopathy (HCM)

Treatment options

A
  1. Exclude secondary causes (amyloidosis, metabolic disease, phaeochromocytoma)
  2. Genetic Counselling (genotyping, family screening)
  3. Symptomatic: ***
    - LVOTO: β blockers, disopyramide (verapamil), Myotomy-myectomy, septal alcohol ablation, dual chamber pacing
    - No LVOTO: β blockers, calcium antagonists
  4. High risk of SCD: implantable cardioverter defibrillator (ICD) ***
  5. High risk HF: ACE inhibitors, diuretics, β blockers
  6. High risk arrhythmia: antiarrhythmics
26
Q

Dilated cardiomyopathy (DCMP)

Causes
Presentation

A

Genetic: Familial DCMP

  • 90% AD Titin (TTN) and Lamin A/C (LMNA) gene mutations **
  • Neuromuscular disorders: DMD, BMD, Myotonic dystrophy
  • Mitochondrial diseases

Acquired:

  • Valvular heart disease
  • Viral myocarditis *
  • Myocardial ischemia
  • Toxins induced
  • Idiopathic

Presentation:
HF, SCD

27
Q

Dilated cardiomyopathy (DCMP)

Pathogenesis

A

Genetic mutations:
- DNA mutation altering gene product or MHC mutation altering immune system&raquo_space; T cell dysfunction&raquo_space; Generate autoantibodies against myocardium

Viral infection trigger:

  • Enteroviruses (esp. Coxsackie A/B), Herpesviruses, Adenovirus, Parcovirus..etc
  • Exacerbates immune response against myocardium
  • Myocardium damage
28
Q

Dilate Cardiomyopathy

Treatment options

A

Treat as Heart failure HFrEF:

  1. Drugs:
    - ACE-I/ ARNI
    - BB
    - MRA
    - Loop Diuretics
    - Dapagliflozin
  2. ICD, CRT
  3. Lifestyle modification:
    - Low-intensity exercise only
    - No exercise for 6 months after myocarditis
  4. Immunosuppressant vs autoantibodies
  5. Intractable ventricular arrhythmia: LVAD, Heart transplant
29
Q

Arrhythmogenic right ventricular dysplasia/ cardiomyopathy (ARVD)

Pathogenesis
Inheritance

A

Fibro-adipose infiltration into myocardium due to mutations: RyR2 gene, Desmoplakin, Plakoglobin…etc

Inheritance:
 Primarily autosomal dominant
 Variable penetrance and expressivity (1/3 familial)

30
Q

Arrhythmogenic right ventricular dysplasia/ cardiomyopathy (ARVD)

Presentation

A

 Ventricular arrhythmias/ SCD in young

□ Cardiac symptoms: palpitations, syncope, atypical chest pain

□ Right heart failure

 Naxos disease

  • Palmar-plantar keratoderma
  • Wooly hair
  • ARVD

(May overlap with Brugada syndrome)

31
Q

Arrhythmogenic right ventricular dysplasia/ cardiomyopathy (ARVD)

First-line investigations

A

ECHO, MRI, RV angiography - RV akinesia/ dyskinesia, RV dilatation, Poor RV function

ECG: Depolarization (Epsilon wave) or repolarization wave inversion in V1-V3

Arrhythmia: VT/ LBBB morphology

Family history: family members with ARVC

Tissue characterization (rarely done): Endomyocardial biopsy

32
Q

Arrhythmogenic right ventricular dysplasia/ cardiomyopathy (ARVD)

Risk factors for SCD

A 
History of VT
Poor LVEF (<35%)
NSVT/ Inducible VT in electrophysiology stufy 
Male sex 
Desmosomal variants 
RV dysfunction ...etc
33
Q

Treatment of ARVC

A

Genetic counseling

Arrhythmia: ICD, BB, Antiarrhythmics

RV dysfunction: Nitrates, ACEi/ ARB, BB, Diuretics

Thromboembolism: Antithrombotic therapy

HF: LVAD/ Heart transplant

Lifestyle: No competitive/ high intensity exercises

34
Q

Restrictive cardiomyopathy (RCM)

Pathogenesis, presentation

A

Stiff myocardial wall due to inherited or acquired causes

> > Normal systolic but abnormal diastolic dysfunction - rigid ventricular walls impeding LV filling (functionally resembles constrictive pericarditis)

S/S:
Symptoms:
□ Venous congestion → dyspnoea, systemic congestion
□ ↓CO → fatigue, weakness
Signs:
□ Congestive HF: pulmonary rales, distended veins, ascites, peripheral oedema
□ Kussmaul sign/hepatojugular reflux: positive (due to poor RV compliance)

35
Q

Restrictive cardiomyopathy (RCM)

Causes- genetic and acquired

A

Genetic:
AD mutation in sarcomere subunits, Myofibrillar myopathies…etc
Endocardial fibroelastosis

Acquired:

  • Idiopathic
  • Infiltrative diseases: Amyloidosis, Sarcoidosis
  • Storage diseases: Fabry disease, Gaucher disease, Hemochromatosis, MPS Type 1 and 2
  • Diabetic cardiomyopathy
  • Scleroderma
  • Carcinoid heart diseases
  • Endomyocardial fibrosis
  • chemo drugs, radiation induced
36
Q

Restrictive cardiomyopathy (RCM)

First-line investigations

A
  1. ECG
  2. Right heart catherization
  3. Cardiac MRI
  4. Nuclear scans for amyloidosis, sarcoidosis
  5. FDG- PET for sarcoidosis
  6. Endomyocardial biopsy
37
Q

Restrictive cardiomyopathy (RCM)

Treatment

A

no specific Tx (other than symptomatic) available
□ Treat underlying disease, eg. infiltrative disorders
□ Idiopathic RCMP: usually with relentless symptomatic progression and high mortality

MBBS IV - Junior Clerkship WCS (131 decks)

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