Long QT Syndrome Flashcards
Was is a normal QTc in males and females?
430ms in males
450ms in females
What is the patholophysiology of the most common variants of LQTS (LQT1 & LQT2)?
A defect in the alpha subunit of the slow delayed rectifier potassium channel.
What are some congenital causes of a prolonged QT?
- Jervell-Lange-Nielson syndrome (Deafness and is due to an abnormal potassium channel)
- Romano-Ward syndrome (no deafness)
What drugs can cause a prolonged QT interval?
- Amiodarone and other class 1a antiarrhythmic drugs like sotalol.
- TCA
- SSRI (ESPECIALLY CITALOPRAM)
- Haloperidol
- Erythromycin
What electrolyte abnormalities cause a prolonged QT interval?
- Hypocalcaemia
- Hypokalaemia
- Hypomagnesaemia
What cardiac problems can cause a prolonged QT interval?
- Acute myocardial infarction
- Myocarditis
What other 2 conditions can cause a prolonged QT interval?
(HINT: Temperature and Cerebral in nature)
- Hypothermia
- Subarachnoid haemorrhage
In what 2 ways can a prolonged QT interval be picked up?
- ECG
- Family screening
What is Long QT1 associated with?
Exertional syncope
What is a Long QT2 associated with?
Syncope occuring with emotional stress, exercise or auditory stimuli.
What is a Long QT3 associated with?
Cardiac events occuring at night or at rest.
How is a prolonged QT interval managed?
- Avoid drugs which prolong the QT interval
- Beta Blockers (Except sotalol which can exacerbate QT)
- ICD in high risk cases.
A prolonged QTc can cause what cardiac arrythmia?
Torsades de Pointes
(a type of polymorphic tachycardia)
What can Torsades de Pointes then lead to?
Sudden cardiac arrest
