ECG interpretation and cardiac arrhythmias Flashcards
what is sudden cardiac death
non-traumatic, non-violent, unexpected sudden cardiac arrest within 6 hours of previously witnessed normal health
what is a common manifestation of many genetic conditions
give examples
arrhythmias
- inherited arrhythmia syndromes
- inherited cardiomyopathies
- inherited multi system disorder eg myotonic dystrophy
what are the 2 broad categorical causes of arrhythmias
channelopathies
cardiomyopathies
what is a channelopathy and give examples
rhythm problem
- LQTS
- Brugada
- Catecholaminergic polymorphic VT (CPVT)
- short QT syndrome
- familial Wolf Parkinson White WPW
- familial AF
what is a cardiomyopathy and give examples
structural disorder of the heart leading to abnormal rhythm formation
- hypertrophic
- restrictive
- dilated
- arrhythmogenic right ventricular cardiomyopathy ARVC
where is the normal pacemaker of the heart
SA node in the RA
what are ectopic pacemaker sites
sites outside the SA node that spontaneously depolarise
what are afterdepolarisations and when can they be seen
spontaneous depolarisations seen in a prolonged action potential
eg in LQTS
what are early afterdepolarisations
spontaneous depolarisation occurring in phase 2/3
what is a complications of early afterdepolarisations
Torsades de Pointes
hypo/hyperkalaemia can potentiate torsades de pointes
HYPOkalaemia
which drugs can potentiate torsades de pointes
any drug that increases QT interval - blocks K outflow in repolarisation: anti-arrhythmics - class I + III clarithromycin amiodarone fluoroquinolones tricyclic antidepressants
what does a surface ECG measure
summation of all ion currents across the cell membrane
what is the basic pathology in LQTS
long QT interval leads to an extradepolarisation in a vulnerable part of the heart leading to an arrhythmia
how many are carriers of Congenital LQTS
1 in 2000
what can trigger polymorphic VT/Torsades in congenital LQTS
adrenergic stimulation
what is the QT interval
ventricular depolarisation and repolarisation
start of the Q wave to the end of the T wave
how can LQTS present
seizures
syncope
life threatening arrhythmias
sudden death
management of congenital LQTS
B blockers
ICD
what is Jervell and Lang-Nielsen syndrome
AR inherited form of LQTS
associated with congenital deafness (bilateral SNHL) and ventricular tachyarrhythmias
what is Romano Ward syndrome
AD inherited form of LQTS with ventricular tachyarrhythmias and NO deafness
what is a prolonged QTc (QT interval corrected for heart rate) in males and females
males >440ms
females >460ms
what is Andersen Tawil syndrome
AD inherited form of LQTS with extra cardiac features eg developmental abnormalities, periodic muscles weakness
What scoring system is used for diagnosis of LQTS
Schwartz score