Sudden Cardiac Death And Catecholaminergic Arrest Flashcards
What is sudden cardiac death
Death within 6 hours of witnessed normal heath due to SCA
What is sudden arrhythmic death syndrome
Death from SCA with no cause on PM
Name some causes of SCD
Coronary artery disease
Structural - LV hypertrophy, HF, myocarditis
Arrhythmias
Noncardiac -drug OD, PE
Describe hypertrophic cardiomyopathy
Asymetrical thickening of the myocardium (particularly AV septum) which can lead to LV outflow obstruction. The myocytes are chaotic and there can be an element of fibrosis
What are the results of the hypertrophy seen in HCM
LV outflow obstruction
Risk of VT and VF
Reduced pumping efficiency
Mitral valve abnormalities
What are the genetics of HCM
AD mutation in genes encoding sarcomeric proteins eg B-myosin heavy chain and troponin
what is your typical HCM patient
Black, male, 20-30 y/o
Syncope, chest pain SOB etc on physical exertion
What does an ECG of a HCM patient look like
Non-specific changes
Dagger Q waves (more activity but more muscle to pass through)
ST segment often goes in the opposite direction to QRS
T wave inversion
AF and SVT
How is HCM managed
Amiodarone B blockers Verapamil Anticoagulant and catheter ablation for AF ICD
What is ARVC
Arrhythmogenic RV cardiomyopathy
Fibro-fatty replacement of RV myocytes meaning RV free wall is thin
What are the genetics of ARVC
AD mutations in desmosomal genes
What is the typical ARVC patient
Northern Italy/Greece, teens/20’s, males, during competitive sport
Palpitations and syncope
Eventually get HF
What does the ECG of ARVC show
Epsilon waves (blip at the end of QRS) VT with LBBB or ectopics cause the symptoms V1-V3 show T inversion, prolonged S wave upstroke, wide QRS
How is ARVC managed
Amiodarone and b-blockers
ICD
Radio frequency ablation
What is dilated cardiomyopathy
LV enlarges and has contractile dysfunction (reducing ejection fraction) but LV wall thickness is normal
RV may also be involved
What are the genetics of dilated cardiomyopathy
AD
Genes encoding sarcomeric or lamin A or C
(Only 30% of cases are genetic - lots of other things cause it)
What is a typical dilated cardiomyopathy patient
Black,male, 20-60 y/o
How would dilated cardiomyopathy present
Often as congestive HF
AF or stroke as a result
What would investigations for dilated cardiomyopathy show
CXR: cardiomegaly and pulmonary oedema
ECG: very non specific sinus tachy, LBBB
Echo: LV dilation, reduced systolic and diastolic function, mitral/tricuspid regurg
How is dilated cardiomyopathy managed?
As HF so ACEi, b-blockers, digoxin
What is brugada syndrome
Arrythmias (VF or pVT) leading to SCD in the presence of a structurally normal heart
What are the genetics of brugada syndrome
AD mutation affecting sodium ion channels
What is the typical brugada syndrome presentation
East Asian
Syncopal episodes when high vagal tone, fever or alcohol
What are the ECG features of brugada syndrome
Coved ST + inverted T + J point elevation in V1-3
May have prolonged PR
How can the ecg changes of brugada be induced
Ajmaline
How is brugada syndrome diagnosed?
ECG changes + one of: Documented pVT or VF Family history of SCD <45 Family members with coved ST syncope Nocturnal agonal respiration
How is brugada syndrome managed
ICD + avoidance of flecainide, verapamil, amytiptiline, propranolol, hypokalaemia, fever
What is the normal QT interval
<440 males
<460 females
What causes the SCD in long QT
Ventricular tachyarrhythmia
What is LQTS
Encompasses a range of syndromes all leading to prolonged myocardial repolarisation
Also encompasses acquired LQTS
What can cause acquired LQTS
Drugs, hypokalaemia/magnasaemia/calcaemia, hypothermia, MI, SAH
What are the genetics of LQTS 1-3 and the affect on the ion channels
LQT1 and LQT2: KCNQ1 and KCNH2 (K leaves cell too slowly)
LQT3: SCN5a (Na enters cell too quickly)
In which situations would LQT1-3 present themselves
1 - increased adrenergic tone (particular swimming)
2 - startling
3 - resting and bradycardia
Describe the T wave ECG features of LQTS 1-3
1 - broad based T
2 - notched T
3 - prolonged ST
Describe the generic ECG changes for all LQTS
Prolonged QTc
T wave abnormalities (specific to each type)
TdP
T wave alternans
How is the QTc interval calculated?
Bazetts formulae
QT/ square root of RR interval
(QT is measured from initial wave of QRS to T wave return to baseline
How does LQTS present
Young people with syncope
Often have prodrome of palpitations, chest pain and SOB
How is LQTS managed?
B blocker
ICD
Lifestyle changes
What is romana ward
The phenotypic classification of LQTS 1-6, 9-12
What is Jervell and Lange Nielsen
AR mutation. 2 inherited copies of KCNQ1 (whereas 1 copy = Romano ward)
Aside from cardiac features, what else do jervell and Lange Nielsen patients have
Bilateral sensorineural deafness
What is Anderson Tawil syndrome
Phenotypic name for LQTS 7
Which gene is effected in LQT7 (Anderson Tawil)
KCNJ2
How does Anderson Tawil present (ecg and features)
Bidirectional VT Low set ears and wide spaced eyes Clinodactyly Syndactyly Short Scoliosis Hypokalaemic periodic paralysis
What is Timothy syndrome and it’s genetics
Phenotypic name for LQTS8
CACNA1C
What ion channel is affected and what is the implication in Timothy syndrome
Delayed calcium channel closing (so more calcium in) leading to increased intracellular exciteability
How does Timothy syndrome present
Syndactyly, congenital heart malformation, autism
In atypical they also have joint issues and AF
What is CPVT
Catecholaminergic polymorphic ventricular tachycardia
Talk through the genetic mutation and resulting ion channel abnormality that leads to biderectional VT in CPVT
AD mutation of RyR2 = leaky ryandadine receptor channel = Ca leaks out of SR in diastole = afterdepolarisation = bidirectional VT
How do adrenergics worsen the situation in CPVT
More Ca in the SR so more to leak out + adrenergics increase the sensitivity of the ryanadine receptor channel
What is your typical CPVT patient
Child/adolescent with FH of SCD and person history of “seizures”
What ECG features are seen in CPVT
Normal at rest!
Bidirectional VT or VF on exercise or emotional stress
What is the immediate management of CPVT
Adrenaline will worsen the VT
Give B blockers
What is the long term management of CPVT
ICD
B-Blocker
Fleccainide, verapamil
What is Lev-Lenegres/PCCD, it’s genetic mutation and ion channel involved
Progressive cardiac conduction defect
SCN5A
Sodium channel affected
What are the ECG features of PCCD
Over time they progress to a complete heart block with resulting arrythmias
How is PCCD managed
Pacemaker for bradycardia
Anti arrhythmics
What is adrenalines affect on a1 receptors
Vasoconstriction
Increased aortic diastolic pressure to increase coronary blood flow
BUT decreased cerebral perfusion pressure
What does adrenaline acting on A2 result in
Platelet activation = damage to cerebral vasculature
What does adrenaline acting on B1 result in
Increased inotropy and chonotropy which increases myocardial metabolic demand
What were the results of paramedic 2 trial
Adrenaline increased 30 day survival but decreases neurological outcome
