Inherited cardiac conditions Flashcards
(40 cards)
What are the 3 main inherited heart muscle abnormalities ?
Cardiomyopathies:
- Hypertrophic cardiomyopathy
- Dilated cardiomyopathy
- Arrhythmogenic Right Ventricular cardiomyopathy (ARVC)
What are the 3 main inherited heart rhythm abnormalities ?
Channelopathies:
- Congenital Long QT syndrome
- Brugada Syndrome
- Catecholaminergic Polymorphic Ventricular tachycardia (CPVT)
What is long QT syndrome and why is it important to recognise ?
- It is an inherited condition associated with delayed repolarization of the ventricles.
- It is important to recognise as it may lead to ventricular tachycardia/torsade de pointes and can therefore cause collapse/sudden death.
On ECG what is defined as a prolonged QT interval ?
QTc interval prolongation:
- >440 ms in males
- >450 ms in females
What is the main mutation associated with long QT syndrome ?
KCNQ1
What are the 2 congenital causes of long QT syndrome and how do you differentiate between the two ?
- Autosomal dominant - Romano-Ward syndrome (no deafness)
- Autosomal recessive - Jervell-Lange-Nielsen syndrome (includes deafness and is due to an abnormal potassium channel)
What is the main presenting complaint of long QT sydrome ?
Syncope, SCD in children and young adults
What are the potential triggers of torsades de pointes & syncope in patients with long QT syndrome ?
- Exercise
- Sudden auditory stimuli
- Sleep
- QT prolonging states - Medication, hypokalaemia
What drugs can cause or worsen long QT syndrome ?
- Amiodarone, sotalol, class 1a antiarrhythmic drugs
- Tricyclic antidepressants, SSRI’s (especially citalopram)
- Methadone
- Chloroquine
- Terfenadine
- Erythromycin
- Haloperidol
- Ondanestron
List the other causes of long QT syndrome
- Electrolyte: hypocalcaemia, hypokalaemia, hypomagnesaemia
- Acute myocardial infarction
- Myocarditis
- Hypothermia
- Subarachnoid haemorrhage
What is the management of long QT syndrome ?
- 1st line = Beta blockers + Avoidance (of QT prolonging drugs triggers e.g. strenuous swimming, Breath holding, Loud sudden noises)
- Also correction of electrolyte abnormalities, maintenance of serum K at upper limit of normal range.
What is brugada syndrome ?
It is an autosomal dominant inherited cardiovascular disease with may present with sudden cardiac death
Who is burgada syndrome most common in ?
Asians
What is the main mutation associated with causing brugada syndrome ?
SCN5A mutation
What arrhythmias can burgada syndrome result in (& hence SCD)?
- Risk of polymorphic VT, VF
- AF common
How is brugada syndrome diagnosed ?
1st line for diagnosis = ECG (after administration of flecainide or ajmaline)
What are the characteristic ECG changes of brugada syndrome ?
- convex ST segment elevation > 2mm in > 1 of V1-V3 followed by a negative T wave
- partial RBBB
What are the triggers of arrhythmias in people with brugada syndrome ?
- Usually rest or sleep
- Fever
- Excessive alcohol, large meals
What is the treatment of brugada syndrome ?
- ICD if ventricular arrhythmia
- Avoidance of drugs that may induce Brugada changes, excessive alcohol and large meals & prompt treatment of fever with anti pyretic medications
What drugs should be avoided in patients with brugada syndrome ?
- Anti-arrhythmic drugs (beta blockers may aggravate ECG changes, therefore only under supervision).
- Psychotropics
- Analgesics
- Anaesthetics
Define what cardiomyopathy is
- Any disease of the cardiac muscle
- Often result in changes in the size of the heart chambers and thickness of the heart
Describe what hypertrophic obstructive cardiomyopathy (HOCM) is
It is an autosomal dominant disorder of muscle tissue caused by defects in the genes encoding contractile proteins.
What are the main mutations which cause HOCM?
Mutation in sarcomeric genes (2 main ones are MYBPC3 or MYH7)
Describe the pathophysiology of HOCM
Mutations result in diastolic dysfunction → left ventricle hypertrophy → decreased compliance → decreased CO
