Inherited cardiac conditions Flashcards
what causes an inherited cardiac condition (ICC)?
= misprints in blue print of the DNA that has been passed on from both parents to children
- DNA is ‘blue print’ used by body to build tissue & carry out living processes
- misprints in blue print are rare but can have big results in way body or organs work
what are the 3 main types of inherited cardiac conditions?
1) cardiomyopathy
2) channel-myopathy
3) aortopathy
what is cardiomyopathy?
- give examples.
= heart muscle abnormality
- ARVC (arrhythmogenic right ventricular cardiomyopathy)
- hypertrophic cardiomyopathy
what is channelopathy?
- give examples.
= heart rhythm abnormality
- Long QT syndrome
- brugada syndromeme
what is aortopathy?
- give examples?
= arterial blood vessel abnormality
- Marfan’s syndrome
- Loeys Dietz syndrome
how do inherited cardiac conditions present?
- normal appearances
- no features of the disease (reduced expressivity, carriers)
what symptoms would inherited cardiac conditions have?
Symptoms related to;
- arrhythmia: AF, ventricular ectopy, VT
- heart failure
- sudden death
name some channelopathies, a type of arrhythmogenic inherited cardiac conditions?
- congenital long QT syndrome
- brugada syndrome
- catecholaminergic polymorphic ventricular tachycardia (CPVT)
- short QT syndrome
- progressive familial conduction disease
= familial AF
= familial WPW
name some cardiomyopathies, a type of arrhythmogenic inherited cardiac conditions?
- hypertrophic cardiomyopathy
- arrhythmogenic right ventricular cardiomyopathy (ARVC)
- dilated cardiomyopathy
what causes channelopathies?
= mutations in genes that encode the cardiac ion channels.
- abnormal cardiac cellular electrophysiology
what do channelopathies mainly affect?
re-polarisation
Yes or No.
does channelopathies cause changes on the ECG?
= yes they cause abnormalities
Yes or No.
is the normal cardiac structure and function the same?
= yes its the same
in people with channelopathhies, what are people likely to develop?
- arrhythmias both atrial and ventricular
what is the cardiac action potential?
= summation of all ion currents across cell membrane
what does the surface ECG represent?
= summation of all APs
what does congenital long QT syndrome (cLQTS) do to an ECG?
= QTc interval prolongation
> 440ms in males
> 450ms in females
how many subtypes are there of cLQTS?
13 subtypes
describe the two autosomal types of congenital long QT syndrome?
1) autosmal dominant
= isolated LQT
- romano-ward syndrome
2) autosomal recessive
= associated with deafness
- Jervell & lange-neilsen syndrome
in cLQTS what is the hallmark arrhythmia?
i.e. what does excessive QT prolongation lead to?
= polymorphic VT - ventricular tachycardia (torsades de pointes VT)
how are TdP syncope triggered?
- exercise
- sudden auditory stimuli
- sleep
- QT prolongation states
= medication
= hypokalaemia
what is the primary presenting complaint in cLQTS?
- syncope
- Sudden Cardiac Death in children and young adults
what is the mechanism for QT prolongation?
1) Less re-polarising current prolongs APD
- e.g. K+ moving extracellular
2) more depolarisation prolonging APD
- e.g. Na+ & Ca+ moving intracellular
how would you manage cLQTS?
1) beta blockers
- nadolol (most effective at preventing arrhymias)
= BB’s they DONT SHORTEN QT
2) avoid QT prolonging drugs
3) correction of electrolyte abnormalities
4) avoidance of triggers
- strenuous swimming
- breath holding
- loud sudden noises
in brugada syndrome, what is there a risk of?
= risk of polymorphic VT or VF
what is common in brugada syndrome?
atrial fibrillation
what changes are seen on a ECG in brugada syndrome?
= ST elevation
= RBBB in V1-V3
- ECG findings may be intermittent and change over time
when might diagnostic ECG changes only be seen?
with provocative testing with felcainide or ajmaline (drugs that block the cardiac sodium channel)
describe the genes involved in brugada syndrome?
- 12 associated gened
= cardiac sodium channel
= calcium channel
is the brugada syndrome autosomal dominant or recessive?
dominant
= adults
8x males
in brugada syndrome, what are VF triggers?
- usually rest or sleep
- fever
- excessive alcohol, large meals
- genotypes & FH of SCD doesn’t indicate worse prognosis
how would you manage brugada syndrome?
- avoids drugs that may induce brugada changes on ECG
- avoid excessive alcohol and large meals
- prompt treatment of fever with anti-pyretic medications
- ICD only if ventricular arrhythmia (Secondary prevention) or spontaneous changes on ECG and syncope
what 4 drugs should you avoid in brugada syndrome?
- anti-arrhythmic drugs
- psychotropics
- analgesics
- anaesthetics
what are 3 most common cardiomyopathies?
1) hypertrophic cardiomyopathy
2) idiopathic dilated cardiomyopathy
3) arrhythmogenic right ventricular cardiomyopathy
in hypertrophic cardiomyopathy, where is the mutation?
= in sarcomeric genes
when does hypertrophic cardiomyopathy develop?
- at puberty
= sometimes with rapid acceleration of hypertrophy in adolescence and stabilisation in mild adulthood
= may be followed by progressive LV wall thinning in later
how would you treat hypertrophic cardiomyopathy?
1) beta blockers
2) if hypertrophy causes outflow tract obstruction, isotropic agents may be useful (e.g. verapamil or diltiazem) or septal ablation or surgery
3) treat heart failure if present and symptomatic
4) if AF develops, anti-coagulation is mandatory regardless of CHA2DS2 Vasc score
5) Implantable Cardioverter Defib for secondary prevention of SCD
what is the clinical presentation in hypertrophic cardiomyopathy?
- sudden death
- heart failure
- angina
- atrial fibrillation
- asymptomatic
who is most likely to develop dilated cardiomyopathy?
- males > females
what genes are mutated in dilated cardiomyopathy?
- sarcomere and desosmal genes, laminA/C and design if there is conduction disease, dystrophin if X-linked
what causes arrhythmogenic right ventricular cardiomyopathy?
= fibro-fatty replacement of cardiomyocytes in right ventricle
what part of the heart is involved in the majority of cases in arrhythmogenic right ventricular cardiomyopathy?
= left ventricle
what genes are mutated in
arrhythmogenic right ventricular cardiomyopathy?
- autosomal dominant mutations in genes for desmosomal proteins
- autosmal recessive mutations in non-desomsosomal genes
how would you manage inherited cardiac conditions?
1) DIAGNOSIS
- clinical and genetic testing
2) RISK MANAGEMENT
- lifestyle, pharmacological, non-pharmacological
3) FAMILY CASCADE SCREENING
name some lifestyle and triggers in inherited cardiac conditions?
- sports & physical exercise
- diet & alcohol
- medications
specifically, what lifestyle changes should be done in Long QT syndrome?
- Diet: potassium rich foods (bananas, beans, oranges, green leafy vegetables, nuts)
- Diarrhoea, vomiting
- Underwater breath holding.
- Avoiding sudden loud noises.
specifically, what lifestyle changes should be done in brugada syndrome?
- Excessive alcohol
- Prompt treatment of fevers
