Cardiac Causes and ECG Flashcards
what is sudden cardiac death
an event that is non traumatic, non violent, unexpected and resulting from sudden cardiac arrest within 6 hours of previously witnessed normal health
what types of genetic conditions can cause arrythmias
inherited arrhythmia syndromes
inherited cardiomyopathies
inherited multisystem diseases with CVS involvement (e.g. myotonic dystrophy, collagen problems)
what are the types of channelopathies
congenital long QT syndrome brugada syndrome catecholamigeric polymorphic ventricular tachycardia (CPVT) short QT syndrome progressive familial conduction disease familial AF familial WPW
what are the types of cardiomyopathies
hypertrophic cardiomyopathy
arrhythmogenic right ventricular cardiomyopathy (ARVC)
dilated cardiomyopathy
what is a channelopathy
arrhythmogenesis related to ion current imbalance and development of early and late depolarisation
how do cardiomyopathies cause arrhythmias
due to scar/ electrical barrier formation
what are after depolarisations
abnormal depolarisations of cardiac myocytes that interrupt phase 2,3 or 4 of the cardiac AP in the conduction system of the heart
(extra electrical activities that cause problems)
what can after depolarisations cause
can lead to triggered activity seen as sustained cardiac arrhythmia
what is an early afterdepolarisation (EAD)
abnormal depolarisation during phase 2 or 3
caused by an increase in the frequency of abortive action potentials before normal repolarisation is completed
phase 2 interrupted by increased Ca channels opening
phase 3 interrupted by opening of Na channels
what can early afterdepolarisation cause
torsades de pointes
what is torsades de pointes
polymorphic ventricular tachycardia
associated with a prolonged QT
can be congenital or acquired
caused by ectopic beat landing on the abnormal T wave in prolonged QT syndrome
what can cause early after depolarisations
hypokalaemia drugs that prolong QT interval- clarithromycin, class Ia and III antiarrhythmic agents
what gene causes long QT syndrome
potassium voltage gate channel - KCNQ1 gene
what gene causes brugada syndrome
sodium channel voltage gated alpha subunit - SCN5A
calcium channel CACN1Ac
what receptor is affected in catecholamingeric polymorphic VT
ryanodine
is short QT syndrome common
very rare
what are the risk of congenital long QT syndrome
polymorphic VT (torsades de pointes) triggered by adrenergic stimulation
syncope- 5%
SCD 0.33-0.9%
(risk associated with severity of QT prolongation)
how common is congenital LQTS
1 in 2000 are carriers
what are the types of congenital LQTS
autosomal dominant:
-isolated LQT-
romano-ward syndrome
-extra cardiac features- anderson- tawil syndrome, timothy syndrome
autosomal dominant:
-associated with deafness- jervell and lange nielsen syndrome
what are the features of LQTS on ECG
QTc (corrected QT) >/= 480 ms in the absence of secondary causes in repeated ECG
abnormal T waves- bifid
AF (irregularly irregular) + abnormal T waves= LQTS
what can trigger LQTS
exercise - LQTS1
emotional stress
sleep
loud noises - LQTS2
what is the management for congenital long QT syndrome
avoid QT prolonging drugs- clarithromycin
correct electrolyte abnormalities (hypokalaemia/ magnesaemia/ calcaemia)
avoid swimming - dangerous
environment
beta blockers
ICD (high morbility)
loud noises - alarm clock in morning
what score to calculate long QT risk
scwartz score
what gene causes congenital short QT syndrome
mutation in cardiac K+ channels
what are features of congenital short QT syndrome
QT <300ms at a heart rate <80bpm
may be associated with AF
may present in young children
VERY MALIGNANT
what is the management for congenital short QT syndrome
hard to manage
?anti-arrhythmic drugs : quinidine, flecainide
ICD hard with children as increased body use, pyschological issues and inappropriate discharges due to T wave oversensing
what are the risks in brugada syndrome
polymorphic VT, VF
AF
arrhythmia incdence 1% if asymptomatic, 3.2% in patients with syncope, 13.5 if previous cardiac arrest
what inheritance does brugada syndrome follow
autosomal dominant
men 8x more likely to get it
(genotype and family history of SCD does not influence progosis)
what are the features of brugada syndrome on ECG
ST elevation in V1 and 2
RBBB in V1-3
two R waves in V1= RSR
may be intermittent and change over time
how can a diagnosis of brugada be made
only with provocative testing with flecainide or ajmaline (drugs that block the cardiac sodium channel)
What triggers VF In brugada syndrome
abnormal rest or sleep
fever
excessive alcohol
large meals
what is the management of brugada syndrome
avoid drugs that indice ST elevatio in right precordial leads
avoid excess alcohol and large meals
prompt treatment of fever with antipyrexials- paracetamol
if had previous cardiac arrest /sustained spontaneous SVT then ICD
consider ICD if history of syncope
what drugs should you avoid in brugada syndrome
antiarrhythmics
psychotrophics
analgesics
anaesthetics
what is catecholaminergic polymorphic ventricular tachycardia
adrenergic induced bidirectional and polymorphic VT and SVTz
what triggers CPVT
emotional stress, physical activity
what are the types of CPVT
Autosomal dominant- ryanodine receptor mutation
recessive- cardiac calsequestrin gene (CASQ2)
what are the features of CPVT on IX
normal ECG and echo
what is the management for CPVT
avoid competitive sports, strenuous exercise, stressful environments
beta blockers +/- flecainide if spontaneous/ stress induced VAs
if previous arrest, recurrent syncope or polymorphicbidirectional CT despite therapy then ICD
beta blockers for genetically +ve family members, even with negative exercise test
what are the features of wolffparkinson white syndrome on ECG
short PR wave
delta wave slurring into QRS complex
ventricular preexcitation
what are the risks in WPW
AV reentrant tachycardia most common arrhythmia
AF
small risk of SCD
what causes WPW
extra bit of conducting tissue, accessory pathway. AV node has build in delay normally but in accessory pathway no conduction delay= ventricles fibrillate at the same rate as artia fibrillating
what test to assess the risk in WPW
exercise ECG- see if able to maintain normal conduction in exertion
if risk then ablate pathway
what mutation causes hypertrophic cardiomyopathy
mutation in sarcomeric genes
what are the problems in hypertrophic cardiomyopathy
rhythm problems and obstruction to outflow of blood
how might hypertrophic cardiomyopathy present
sudden death
HF/ end stage HF
AF
what management for hypertrophic cardiomyopathy if risk of SCD (age, FHx, unexplained syncope, previous arrest due to VT/VF, spontaneous sustained VT causing syncope or haemodynamic compromise)
implant cardiac device
what should you avoid in hypertrophic cardiomyopathy
competitive sport
who gets dilated cardiomyopathy
1 in 2500
low in childhood
more common in males
what genes cause dilated cardiomyopathy
sarcomere and desomal genes,
laminA/C and desmin if conduction disease,
dystophin if x linked
what is the risk on dilated cardiomyopathy
LVEF = 35%
what is arrhythmogenic right ventricular cardiomyopathy (ARVC)
fatty infiltrations in right ventricle causing fibrofatty replacement of cardiomyocytes
half have LV involvement
causes rhythm problems as signals go round the fat cells- VT
(1 in 1000-5000 prevalence, mortality 0.9%/year)
what mutations in ARVC
AD mutations in genes for desmosomal proteins
AR mutations in nondesmosomal genes
what increases risk of SCD in ARVC
FHx of premature SCD
severity of R and LV function
frequent non-sustained VT
what are the features of ARVC
on ecg QRS prolongation with late blip in it = epsilon waves
VT induction on electrophysiology studies
affects males more
what is the treatment for ARVC
usually get ICD avoid competitive sports beta blockers amiodarone if symptomatic/ CI to BB catheter alblation if symptomatic
how does an ICD work - what are the complications
leads (2) go into right ventricle and artia, monitors rhythm and delivers shock if needed
- endocarditis
- perforation
- hemothorax
- pneumothorax
- thromboembolic events
- vascular complications
- lead fractures/ extraction complications dislodgements
why is it important to identify pre symptomatic patients at risk of SCD
SCD may be only presentation
young age group at risk
effective therapies available- lifestyle, BBs, ICD
to find other family members at risk
when should a QT interval usually finish
before halfway point of RR interval
what is seen on ECG in hypertrophic cardiomyopathy
inverted T waves
