Cardiovascular: Long QT Syndrome

Question 1

It is associated with sudden loss of consciousness during…

Answer 1

Exercise
Stress
Emotion

Question 2

The symptoms usually occur at what age?

Answer 2

Late childhood

Question 3

What may it mistakenly be diagnosed as?

Answer 3

Epilepsy

Question 4

If unrecognised, what can occur?

Answer 4

Sudden death from ventricular tachycardia

Question 5

How is it inherited?

Answer 5

Autosomal dominant - there are several phenotypes

Question 6

It is associated with delayed repolarisation of the…

Answer 6

Ventricles

Question 7

What causes it?

Answer 7

Inherited - by itself or part of a larger genetic disorder
Medication
Electrolyte abnormalities
Head injury

Question 8

What medications can cause it?

Answer 8

Amiodarone, sotalol, class 1 anti arrhythmias 
TCAs 
SSRIs especially citalopram 
Erythromycin 
Haloperidol 
Ondansetron 
Terfenadine (antihistamine)
Chloroquine

Question 9

What electrolyte disturbances can provoke it?

Answer 9

Hypokalaemia
Hypocalcaemia
Hypomagnesia

Question 10

What is the usual mechanism by which drugs prolong the QT interval?

Answer 10

Blocking K channels

Question 11

A normal corrected QT interval in males and females is?

Answer 11

Less than 430ms in males and less than 450ms in females

Question 12

The most common variants are caused by defects in the alpha subunit of…

Answer 12

The slow delayed rectifier K channels