ECG Interpretation and Cardiac Arrhythmias Flashcards
What inherited cardiac conditions are most likely to cause sudden death?
Inherited channelopathies/ arrhythmias Inherited cardiomyopathies (structural problem) Inherited Multi-System Disease causing cardiac involvement (e.g. Myotonic dystrophy)
Most patients are entirely fit and healthy until an event which causes sudden death. TRUE/FALSE?
TRUE
- many patients never become symptomatic
Why does Long QT syndrome (and otherr channelopathies) put patients at a higher risk of sudden death?
- Ventricular repolarisation takes longer than normal
- Early after-depolarisations or ectopic beats at vulnerable points of the cardiac cycle can cause Torsades de Pointes
- This cardiac rhythm is very inefficient and cannot be sustained, resulting in sudden death
Give an example of a QT prolonging drug and why these can potentially cause harm?
- Clarithromycin
- If given to patient with an ALREADY undiagnosed prolonged QT syndrome, this drug puts them at a much higher risk of sudden death
What other channelopathies can put patients at a higher risk of sudden death and how are these identified?
Brugada syndrome - ST elevation and RBBB in V1-3
Short QT - usually diagnosed in young children who often experience sudden death in childhood
Catecholamine Polymorphic Ventricular Tachycradia (CPVT) - arrhythmias triggered by adrenergic stimulation => patient goes into VT
What triggers patients with congenital long QT syndrome to go into Torsades de Pointes?
- Adrenergic stimulation
What is the mainstay of treatment for most patients with prolonged QT syndrome?
Beta blockers
- some may have an ICD but this is more common in other conditions as risk of sudden death is lower in Long QT
Is Prolonged QT syndrome autosomal dominant or recessive?
Isolated Long QT = Dominant
Long QT and Deafness = Recessive
How is a diagnosis of Long QT made?
- usually by specialists in an MDT meeting
- QT interval of >480ms on repeated ECGs = suggestive
- If risk score calculated and >3, this is also suggestive
What ECG differences are present in the different variations of Prolonged QT syndrome?
LQTS1 - Large and wide T wave
LQTS2 - Notch in middle of T wave
LQTS 3 - Very delayed T wave
What advice should be given to both doctors and patients when managing those who have been diagnosed with prolonged QT syndrome?
- Avoid QT prolonging drugs
- Correct electrolyte disturbances (e.g. during vomiting/diarrhoea)
- Avoid strenuous exertion in LQTS1 - e.g. swimming
- Avoid very loud noises in LQTS2
What ECG changes occur in Brugada Syndrome, and when are these more likely to appear?
- ST elevation and Right Bundle Branch Block in leads V1-3
- These signs are intermittent on ECGs
- Occurs more frequently when patient is feverish
Other factors which may increase risk are:
=> when resting/sleeping
=> Alcohol/large meals
Patients with family members who have experienced sudden death due to brugada syndrome are therefore at increased risk of sudden death themselves. TRUE/FALSE?
FALSE
- this does NOT increase a patients risk
What treatment could potentially be lifesaving in Brugada syndrome?
paracetamol - to reduce fever
What drugs should be avoided in Brugada syndrome?
- antiarrhythmics
- analgesics
- psychotropics
What triggers Catecholamine Polymorphic Ventricular Tachycardia syndrome (CPVT)?
- emotional tress
- physical activity
What is the characteristic ECG finding in CPVT?
Bidirectional VT => some QRS complexes go upwards and some go downwards
How is CPVT treated?
- controlled by Beta Blockers
- ICDs usually also in place
- rarely treated with flecainide
Describe how unwanted arrhythmias can be produced in Wolff-Parkinson White syndrome?
- accessory pathway stops conduction delay in AV node
=> arrhythmias in the atria (Which would usually cease at the AV Node) can be passed to the ventricles
What abnormal finding is found on an ECG of Wolff-Parkinson White?
Delta Wave
How is Wolff-Parkinson White Syndrome treated?
Cardiac ablation
What problems does hypertrophic cardiomyopathy cause?
- rhythm problems related to large muscle bulk
- Also obstruction may occur
HOw does hypertrophic cardiomyopathy usually present?
- sudden death
- heart failure (this may be end stage)
What should patients with hypertrophic cardiomyopathy avoid?
- competitive sport
- ICD implantation may be required depending on risk
Describe the problem in dilated cardiomyopathy
Problem within the proteins holding the cardiac myocytes together
=> the heart dilates and pulls apart
=> heart muscle cant pump well
=> this leads to rhythm problems
Describe what rhythm problem occurs in Arrhythmogenic RV Cardiomyopathy
Ventricular tachycardia which goes continually around the right ventricle
How is ARVC managed?
- ICD given to high risk patients
- Avoidance of competitive sport recommended
Where in the heart are ICDs placed?
- 1 wire in the RA
- 1 wire in the RV
(device usually sits under left clavicle)
NEW devices can be inserted s/c on the breast bone
What complications can arise from an ICD placement?
- infection
- clots (can break off and cause stroke or PE)
- haemothorax
- Pneumothorax
ALSO high risk of death during ICD extraction
HOw long should the QT interval roughly be on an ECG?
QT interval should complete before the halfway point between two QRS complexes
What condition can cause inverted T waves?
hypertrophic cardiomyopathy OR other structural abnormalities
What Extra wave is seen on the ECG of Arrhythmogenic RV cardiomyopathy?
Epsilon wave
- “blip” straight after QRS complex
