6: Inherited cardiac conditions Flashcards
What are the two main types of inherited heart disease?
Channelopathies (leading to arrythmia)
Cardiomyopathies
What is a common sign of inherited heart disease?
Arrythmias
People with inherited heart disease often present with what type of arrythmia?
Sinus bradycardia
You may fit a pacemaker and never know that the disease has a genetic basis
Name three common channelopathies.
Long QT syndrome
Brugada syndrome
Catecholaminergic polymorphic ventricular tachycardia (CPVT)
Name three common cardiomyopathies.
Hypertrophic cardiomyopathy
Arrythmogenic right ventricular cardiomyopathy (ARVC)
Dilated cardiomyopathy
Inherited cardiac conditions tend to be diagnosed using which kind of test?
Genetic testing
Inherited cardiac condition patients need to be advised on how they can manage their ___ factors.
risk
If a patient is diagnosed with inherited cardiac disease, who else may be screened?
The patient’s family
How does channelopathy cause arrythmia?
Movement of ions into/out of cardiac cells becomes dysfunctional, depolarisation doesn’t occur properly and therefore contraction of muscle doesn’t either
The most common mutation causing channelopathy is that of ___ channels, which causes ___ __ ___.
K+ channels
Long QT syndrome
Mutations in which channel’s genes causes Brugada syndrome?
Na+ channels
Mutations in Ryanodine channel genes causes which type of arrythmia?
Cathecolaminergic polymorphic ventricular tachycardia (CPVT)
What causes Long QT syndrome?
Mutations in K+ channels
Reduction in repolarising currents
Resulting in longer action potentials
What arrythmia can occur as a result of QT interval prolongation?
Ventricular tachycardia (to compensate for reduced heart rate)
What symptom can occur in people with long QT syndrome?
Syncope
What channelopathy do you (probably) have if your QT interval is >= 0.48s?
Long QT syndrome
How long must your QT interval be to be diagnosed with long QT syndrome?
>= 0.48s
There are ___ variations of long QT syndrome with different ___ of lethal cardiac events.
three
triggers
In patients with long QT syndrome - you need to avoid specific ___ - why?
drugs
Some drugs further prolong the QT interval, which puts patients at risk of arrythmia and sudden death
Patients with long QT syndrome should avoid ___ which may cause arrythmia.
triggers
What is an example of a trigger for LQTS1?
Breath holding → avoid strenuous swimming
What is an example of a trigger for LQTS2?
Loud noises (alarm clocks, guns, gaffs)
What arrythmia is common in Brugada syndrome?
Atrial fibrillation
What channels are affected in Brugada syndrome?
Sodium channels
Calcium channels
(slows upstroke and prolongs action potential)
What are some ECG indicators of Brugada syndrome?
ST elevation in chest leads
Which drugs may you need to give a patient to bring out ECG changes characteristic of Brugada syndrome?
Sodium channel blockers
e.g Flecainide, ?ajmaline
What drug treatments should be avoided in patients with Brugada syndrome?
Anti-arrhythmic drugs (e.g Na+ channel blockers - flecainide, ajmaline)
Psychotropic drugs
Analgesics
Anaesthetics
Which inherited cardiac disease is induced by adrenergics?
Catecholaminergic polymorphic VENTRICULAR TACHYCARDIA
What is CPVT triggered by?
Emotional stress
Physical activity
(anything that releases catecholamines like adrenaline)
What kind of VT will be seen in the ECG of someone with CPVT?
Bi-directional ventricular tachycardia
Why are CPVT patients advised to avoid strenuous exercise and stress?
Releases adrenaline, which is a trigger for the VT
Use of ___ - which give out adrenaline-producing, stressful shocks, should be considered carefully in those with CPVT.
Pacemakers
Which sodium channel blocker improves the outcome of those with CPVT?
Flecainide
(remember that it’s strongly contraindicated in Brugada syndrome)
Which class of drugs is used to calm VT in CPVT?
Beta blockers (beta adrenoceptor antagonists)
Which kind of cardiomyopathy is most common?
Hypertrophic cardiomyopathy
Name three types of inherited cardiomyopathy.
Hypertrophic cardiomyopathy
Dilated cardiomyopathy
and
Cardiomyopathy which selectively targets the right ventricle:
Arrhytmogenic right ventricular cardiomyopathy (ARVC)
Hypertrophic cardiomyopathy ___ the myocardium and causes stiffening, reducing the ___ ___.
thickens
cardiac output
What arrythmia can occur as a result of hypertrophic cardiomyopathy?
Blood doesn’t pump so back pressure causes atrial hypertrophy / dilatation
⇒ atrial fibrillation
If a patient’s presentation, ECG etc. suggest cardiac hypertrophy but you can’t pin down a specific disease, what should be tested?
Genetics
When should the use of nitrates be avoided?
Significant outflow tract obstruction
because it reduces coronary filling in patients already prone to ischaemia, syncope
What does ICD stand for?
Implantible cardioverter defibrillator
What is an ICD used for?
Restores normal sinus rhythm by shocking an arrythmia
What is dilated cardiomyopathy?
Dilatation of the left ventricle, reducing cardiac output due to poorer pumping capability
What is arrhythmogenic right ventricular cardiomyopathy?
Fibro-fatty replacement of cardiac myocytes in the RIGHT VENTRICLE, which causes arrythmia (e.g VT)
Why should patients with ARVC avoid competitive sports?
Associated with increased right ventricle pressure which worsens the conditions
What drugs and mechanical interventions are recommended in patients with ARVC?
Beta blockers or amiodarine
ICD implantation or catheter ablation of affected nerves
What may the only presentation be for someone with an undiagnosed, inherited cardiac condition?
Sudden death
you want to avoid this
ICDs have a variety of possible ___.
complications
What are some complications associated with ICDs?
Endocarditis
Perforation
Thromboembolic events
What kind of screening involves investigating people more at risk of ICD, e.g family, rather than random individuals?
Cascade screening
On an ECG, what is torsades de pointes?
Which type of arrythmia is it?
What inherited cardiac condition is it an indicator of?
What arrythmia can it degenerate into?
Irregular QRS complexes which seem to twist around the ECG baseline
Polymorphic VT
Long QT syndrome
Ventricular tachycardia
Which arrythmia can be triggered in people with Brugada syndrome?
Ventricular fibrillation
What can trigger ventricular fibrillation in people with Brugada syndrome?
Rest / sleep
What kind of polymorphic arrythmia is seen in catecholaminergenic polymorphic ventricular tachycardia (CPVT)?
Bi-directional ventricular tachycardia
