Flashcards in Electrophysiology Deck (131)
What is the prevalence of congenital LQTS?
1 in 2000
Describe Jervell Lange Nielsen Syndrome.
Autosomal recessive congenital LQTS with associated sensorineural deafness. Associated with malignant course, cardiac events precipitated by emotional or physical stress.
What is the rate of SCD in those with Lange jervell Nielsen Syndrome?
In those with jervell Lange Nielsen Syndrome, what were the event rates for those aged 1, 3 and 18?
15, 50, 90%
How does pregnancy influence risk of events in those with LQTS (particularly LQTS2)
Higher risk of events 6-9 months post partum.
Describe pause dependence.
Duration of repolarisation is dependent on the duration of the preceding RR interval
What are the external triggers that classically exacerbate LQTS?
LQT1 - exercise, swimming, diving
LQT2 - noise, emotion
What preceding symptoms prior to syncope/seizure is highly suggestive of LQTS?
What types of LQTS have triggered events during sleep?
LQT2 and 3
Describe Andersen Tawil Syndrome.
Autosomal dominant condition characterised by episodes of potassium related paralysis, ventricular arrhythmia (LQT) and dysmorphic features.
What is the Schwartz score and what is it’s clinical use?
Estimate of the clinical likelihood of LQTS based on ECG, clinical and family history.
Used to guide investigation with genetic testing.
What is the role of ecg stress testing in those with suspected LQTS?
Exercise associated arrhythmias
Change in T wave morphology
Maladaptive QT response during recovery
What are the maladaptive T wave changes during recovery after ecg stress testing in a patient with LQTS?
QTc >470 at 2-4 mins - 70% PPV for LQT1
QTC >470 a 5 min - 70% PPV for LQT2
In what type of LQT is stress ecg not helpful and why?
LQT3 - QTc is short in exercise and recovery
What is the management of patients with symptomatic congenital LQTS?
1. General measures (avoid drugs, electrolyte optimisation, AED plan)
2. Lifelong beta blockade - propranolol (nadolol and metoprolol)
3. ICD as secondary prevention
4. ICD or sympathetic denervation if recurrent events despite maximum beta blockade
What is the rate of cardiac events in athletes with LQTS who chose to remain in competitive athletics?
Genotype pos/phenotype negative - 0% after 5 years (70 patients)
Genotype and phenotype pos - 1 in 60 after five years
How does type of LQTS inform on management?
LQT1 - better to avoid competitive athletics
LQT2 - avoid loud alarms, acute arousal events
LQT3 - less benefit with beta blockade. Consider adding mexilitine
When are ICDs recommended in Long QT?
1. Sudden cardiac arrest for secondary prevention
2. Recurrent cardiac syncope despite beta blockers and LCSD
3. Recurrent cardiac syncope despite beta blockers in those not a candidate for LCSD
4. Asymptomatic patient with LQT2/3 with resting QTc of 550
5. Post pubertal women LQT2 QTc>500
When is family history of LQTS associated SCD an indication for ICD?
What is the rate of major complications from ICD placement over 5 years?
31% (infection, lead fracture, dislodgement, inappropriate discharges, psychiatric)
What percentage of congenital LQTS will require ICD?
Describe Romano Ward Syndrome.
Autosomal dominant LQTS
Describe Brugada Syndrome.
Autosomal dominant disorder with variable expression characterised by characteristic ECG findings with risk of ventricular arrhythmias.
What percentage of patients with Brugada pattern ECGs will have an event in 2.5 years?
What mental health disease is associated with high rates of Brugada pattern on ECG?
Schizophrenia even after controlling for sodium channel blockers
What genes are causative of Brugada?
What channels are associated with Brugada?
Sodium channels 50%
Calcium channels 10%
What a drugs are associated with transient Brugada pattern?
Cocaine - sodium channel blockade
How does autonomic tone influence Brugada Syndrome?
increased arrhythmia at night suggests parasympathetic worsening of Brugada