Long QT

Question 1

Anderson Tawil Syndrome

Answer 1

LQT 7
Loss of function of I k1
KCNJ2 gene

If you see clear isoelectric gap between end of T wave and onset of U wave –> abnormal Q-U prolongation syndrome (seen in Andersen Tawil sx)

Question 2

Epinephrine QT Stress Test

or treadmill stress test

Answer 2

Epi to unmask Type 1 LQTS
Normal response - QT should shorten

Diagnostic response for LQTS:
Paradoxical lengthening of absolute QT interval in LQT1. (LQT2 / 3) –> QT will decrease
> 30 ms lengthening

(Does not work if pt is beta blocked)

Treadmill: money is in recovery.
What is QTc at 3 min into recovery? If Qtc>470ms, 75% PPV Of unmasking LQT1

Question 3

LQT1

Answer 3

KCNQ1
I ks - loss of function mutation
30-35%

Sports / Exertion / swimming

Beta blockers

Question 4

LQT2

Answer 4

KCNH2
I k r
Loss of function
25-30%

Doorbells/Auditory/alarm clocks/Post partum

Beta blockers (but not as good as for LQT1)

Question 5

LQT3

Answer 5

SCN5A
Na channel
Gain of function 
5-10%
Sleep/Non activity

Pro arrhythmic potential with beta blockers - some controversy. But still can use (?)

Question 6

Short QTS

Answer 6

Gain of function potassium channel.
SQT1 - KCNH2 gene (I kr)
SQT2 - KCNQ1 gene. (I ks)
SQT3 - KCNJ2 gene (I k1)

Question 7

Brugada syndrome

Answer 7

BrS1
Loss of function Na channel disease
Loss of function of SCN5A

Question 8

SCN5A

Answer 8

Na channel mutation

Gain of function - LQT3
Loss of function - BrS1

Question 9

LQT 2 ecg

Answer 9

Funny looking, Bifid t waves in lateral leads

Question 10

Definition of brugada syndrome vs brugada ecg

Answer 10

Brugada ECG + fainting

ECG + two 1st degree relatives

Or

ECG + genetic test positive.