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Cardiovascular > Arrhythmogenic inherited conditions > Flashcards

Arrhythmogenic inherited conditions Flashcards

1
Q

What are channelopathies?

A

Abnormal cardiac cellular electrophysiology which mainly effects the repolarisation phase.

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2
Q

If you have a channelopathy, if there a problem with the structure and function of the heart?

A

No its all normal but you have an abnormal ECG and a propensity to develop both atrial and ventricular arrhythymias

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3
Q

Who do channelopathies effect?

A

Young people. If you get a young person with AF think channelapathy

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4
Q

What does a surface ECG show?

A

The summation of all the ion currents across the cell membrane

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5
Q

What causes channelopathies?

A

Genetically inherited. Many genes and many different mutations but they lead to one phenotype

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6
Q

What is congenital long QT syndrome?

A

Where the QT segment >440milliseconds in men and >450 in women

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7
Q

What causes congenital long QT syndrome?

A

Mutation in many genes. Most common is the potassium voltage gated channel member 1 (KVLQT1). There are 13 subtypes.

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8
Q

What are the hallmark arrhythmias of congenital long QT syndrome?

A

Polymorphic VT and Torsades de Pointes.
Triggered by adrenergic stimulation.

Other associated arrhythmias are AF and heart block

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9
Q

How does congenital long QT syndrome present in children?

A

Syncope or sudden cardiac death

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10
Q

What is Romano Ward syndrome?

A

Isolated long QT syndrome. Autosomal dominant

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11
Q

What is Timothy syndrome/Anderson-Tawil syndrome?

A

Long QT syndrome with extracardiac features. Autosomal dominant

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12
Q

What is Jervell syndrome/Lange-Nielson syndrome?

A

Long QT syndrome associated with deafness. Autosoma recessive

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13
Q

What are the mechanisms of long QT syndrome?

A

Less repolarising current prolongs the action potential (decreased K+ currents)
More depolarising current prolongs the action potential (increased Na+ current)

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14
Q

What is the molecular basis for long QT syndrome?

Nature loads the gun but the environment pulls the trigger.

A

Gene mutations => faulty ion channel
Reduced or dysfunctional diastolic current that prolongs repolarisation.
QT interval extended which predisposes to polymorphic VT
An environmental trigger causes polymorphic VT => syncope/SCD

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15
Q

What is a class 1 diagnosis of congenital long QT syndrome?

A

QT >480ms in repeated 12 lead ECGs
or LQT risk score >3
or LQT syndrome mutation found irrespective of the QT duration

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16
Q

What is a class 2 diagnosis of congenital long QT syndrome?

A

QT >460ms with unexplained syncope in the absence of secondary causes of QT prolongation

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17
Q

What is the management of long QT syndrome?

A

Aviod QT prolonging drugs (www.crediblemed.org)
Correction of electrolyte abnormalities (high K+ diet, especially during diarrhoea, nausea and vomiting episodes)
Avoidance of swimming- strenuous swimming, breath holding and sudden loud noises

18
Q

What causes Brugada syndrome?

A

Many genes. Most common is Na+ voltage gated channel in the type Valpha subunit.
Autosomal dominant

19
Q

Brugada syndrome is autosomal recessive. T or F?

A

False. Its autosomal dominant

20
Q

What are the common arrythmias associated with Brugada syndrome?

A

AF, ST elevation (abnormal doming) and RBBB is V1-V3

Risk of polymorphic VT or VF

21
Q

What are the triggers for VF in Brugada syndrome?

A

Rest/sleep
Fever
Excessive alcohol/large meals
(More common in patients with previous MI or syncope)

22
Q

Does the genotype and family history of Brugada syndrome influence prognosis?

A

No

23
Q

How is Brugada syndrome managed?

A

1) Aviod drugs which may induce ST elevation (www.brugadadrugs.org) Antiarrythmic drugs, psychotrophics (antidepressants) Analgesics and anathetics
2) Aviod excessive alcohol/large meals
3) Prompt treatment of fever with antipyrexials
4) ICD implantation is recommended if patient have a cardiac arrest or documented spontaneous sustained VT and considered in ECG changes with syncope

24
Q

What causes cardiomyopathies?

A

Many genes and many mutations but only one phenotype.

25
Q

What is hypertrophic cardiomyopathy?

A

Very large muscular left ventricle. Blood supply insufficient to supply to cardiac muscle => Ischemia (arrhythmias) and infarction

26
Q

What causes hypertrophic cardiomyopathy?

A

Common gene mutations include beta myosin heavy chain or myosin binding protein C.
60% of mutations are is sarcomeric genes

27
Q

What are the ECG changes suggesting hypertrophic cardiomyopathy?

A

T inversions and repolarisation abnormalities

Large QRS complex suggestive of hypertrophy

28
Q

What is the clinical presentation of hypertrophic cardiomyopathy?

A 
Sudden cardiac death
Heart failure
Angina
AF
Assymptomatic
Use a risk score to predict SCD and whether to use and ICD
29
Q

What is dilated cardiomyopathy?

A

A condition in which the heart’s ability to pump blood is decreased because the heart’s main pumping chamber, the left ventricle, is enlarged and weakened. In some cases, it prevents the heart from relaxing and filling with blood as it should.

30
Q

In which populations is the incidence of dilated cardiomyopathy highest?

A

Males more than females and a lower incidence in childhood

31
Q

Where are gene mutations found in dilated cardiomyopathy?

A

Sarcomere desmosomal genes (lamin A/C gene) - only in 20% of cases

32
Q

What is a poor prognostic marker in dilated cardiomyopathy?

A

LV ejection fraction <35%

33
Q

Mutations in the lamin A/C gene in dilated cardiomyopathy are associated with wich arrythmias?

A

First degree heart block, Supra ventricular tachycardias and increased risk of SCD.
Some people have neuromuscular symptoms

34
Q

What is the management for dilated cardiomyopathy with a known genetic mutation?

A

Internal cardiac defib

35
Q

What is arrhythmogenic right ventricular cardiomyopathy?

A

Fibro fatty replacement of the cardiomyocytes in the right ventricle. Left ventricle is involved in >50% of cases

36
Q

What causes arrhythmogenic right ventricular cardiomyopathy?

A

Autosomal dominant mutations of genes for desmosomal proteins.
Autosomal recessive mutations in non desmosomal genes.

37
Q

What increases the risk of sudden cardiac death in arrhythmogenic right ventricular cardiomyopathy?

A 
Family history of premature SCD
Increasing severity of LV and RV dysfunction
Frequent, non sustain VT
Older age
Male gender
Long QRS  complex
38
Q

How is Arrhythmogenic right ventricular cardiomyopathy managed?

A

Aviod competitive sports
Beta blockers of amiodarone
ICD in patients with previous arrest
Catherter alblation of foci

39
Q

Subcutaineous ICDs look bette, have less risk and the patient has more movement flexibility but they cannot be used to treat some conditions. What are these?

A

Brady cardia support, cardiac resynchronisation or anti tachycardia pacing

40
Q

Generally how are inherited cardiac conditions managed?

A

Diagnosis: Clinical and genetic testing. (family members are also at risk
Risk management: Pharmacolocial interventions- beta blockers. Non pharmacological interventions- ICD. Lifestyle- aviod high dynamic, high static sport.
Cascade screening for families
MDT APPROACH

41
Q

Why is population testing not carried out for inherited cardiac conditions?

A

Increased false positive and anxieties.

Testing professional sports people is done in some countries

42
Q

What are the big impacts on young people with inherited cardiac conditions?

A

Psycho-social impact
Affects school, sports, pregnancy, employment and life insurance
ICD therapy for life

Cardiovascular (24 decks)

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