4- inherited cardiac conditions Flashcards
what are the types of inherited conditions?
- cardiomyopathy = something wrong with heart muscle
- channelopathy = relate mostly to ion channels and give rise to arrhythmia - not HF
- aortopathies
what are types of cardiomyopathy?
- hypertrophic cardiomyopathy (thickened muscle)
- dilated cardiomyopathy (large & weakened muscle)
- arrhythmogenic RV cardiomyopathy (specific arrhythmia that largely affects right side)
what are types of channelopathy?
- congenital long QT syndrome (delay in cardiac repolarisation, phase3)
- Brugada syndrome = abnormalities in ventricular electrical activity (coved type ST ecg)
- catecholaminergic polymorphic VT (episodes of Vtach triggered by exercise & emotional stress,high catecholamine levels when children exercise)
- Short QT syndrome (mutated K+ channels = accelerated repolarisation = risk of vfib
- Progressive familial conduction disease
- Familial AF
- Familial Wolff-Parkinson-White (WPW) syndrome = accessory pathway between atria & ventricles
how do cardiac conditions present?
- can be variable (some have normal appearance and no symptoms)
- symptoms usually relate to underlying condition e.g. arrhythmia or heart failure
what are heart rhythm related symptoms for inherited cardiac conditions?
- palpitations, presyncope, syncope, breathlessness, chest pain, sudden death
- may be sinus bradycardia or heart block eg in cLQTS; or tachyarrhythmia eg AF in Brugada syndrome or cLQTS, or ventricular arrhythmia (ventricular ectopy, VT, VF)
what are cardiomyopathy related symptoms for inherited cardiac conditions?
congestive heart failure: breathlessness, peripheral oedema, orthopnoea weakness, may be systolic HF (dilated CMPY) or diastolic heart failure (hypertrophic CMPY)
what are channelopathies?
- Mutation in genes that encode the cardiac ion channels.
- Abnormal cardiac cellular electrophysiology
- Mainly affecting repolarization
(normal cardiac structure & function)
= means develops arrhythmia both atria & ventricles
what is normal length of QT in males & females?
440 ms in males
460 ms in females (longer due to hormones)
what is congenital long QT syndrome?
when you inherit condition meaning long QT interval which is ventricular depolarisation & repolarisation
how can you inherit congenital long QT syndrome?
- 13 subtypes of LQTS each associated with different genetic mutations
- it can be inherited as autosomal dominant resulting in isolated LQT known as romano-ward syndrome
- it can be inherited as autosomal recessive - associated with deafness; jervell & lange-neilson syndrome
what is the hallmark of arrhythmia that prolongation of QT can lead to?
polymorphic VT (Torsades de Pointes VT = twisting of points)
what are associated arrhythmias observed with congenital long QT syndrome?
lone’ AF’ and heart block
what is the common primary presenting complaint with long QT syndrome?
Syncope, sudden cardiac death in children and young adults
what are triggers of torsades de pointes & syncope?
- Exercise
- Sudden auditory stimuli
- Sleep
- QT prolonging states
- Medication
- hypokalaemia
what is molecular basis of LQTS?
gene altered that affects ion channel that results in reduced or dysfunctional ionic current which means prolonged cardiac repolarisation which means QT interval prolongation and then with triggers leads to polymorphic ventricular tachycardia (changing all the time - torsades de pointes)