Conductivity - Long QT Syndrome

Question 1

What is a Long QT syndrome?

Answer 1

Long QT syndrome (LQTS) is an inherited condition associated with delayed repolarization of the ventricles.

Question 2

Why is Long QT very dangerous?

Answer 2

It is important to recognise as it may lead to ventricular tachycardia/torsade de pointes and can therefore cause collapse/sudden death.

Question 3

What is considered a long QT interval?

Answer 3

2 large squares

Question 4

What are the symptoms of long QT syndrome?

Answer 4

Blackout, seizures, heart palpitations

Question 5

2 congenital syndromes which may cause a prolonged QT interval

Answer 5

Jervell-Lange-Nielsen syndrome (includes deafness and is due to an abnormal potassium channel)

Romano-Ward syndrome (no deafness)

Question 6

Drugs which can prolong QT interval

Answer 6

Amiodarone, sotalol, class 1a antiarrhythmic drugs

tricyclic antidepressants, selective serotonin reuptake inhibitors (especially citalopram)

methadone
chloroquine
terfenadine**
erythromycin
haloperidol
ondanestron

Question 7

What are other causes of prolonged QT, other than drugs or congenital?

Answer 7

electrolyte: hypocalcaemia, hypokalaemia, hypomagnesaemia

acute myocardial infarction

myocarditis

hypothermia

subarachnoid haemorrhage

Question 8

How would you diagnose long QT syndrome?

Answer 8

24hr ECG, to confirm diagnosis an exercise ECG will be needed
Genetic testing

Question 9

What is the management for long QT syndrome?

Answer 9

avoid drugs which prolong the QT interval and other precipitants if appropriate (e.g. Strenuous exercise)
beta-blockers***
implantable cardioverter defibrillators in high risk cases