Hey guys this post will be on Long QT syndrome as evident from the title :P.
In a brief introduction, it can be said that LQTS is simply because of abnormal myocardial repolarization most often due to a mutation in ion channel-associated gene. It can lead to fatal ventricular arrhythmias such as torsades de pointes.
So there is increased risk of Sudden Cardiac Death.
It has 3 common variants:
1. LQT1: Loss of function mutation in KCNQ1 gene. And in ECG you see early-onset broad-based T wave.
2. LQT2: Mutation in KCNH2 gene. In ECG T waves are of low amplitude, broad based and maybe bifid.
3. LQT3: Mutation in SCN5A gene. In ECG, there is prolonged ST segment with late-appearing T wave.
We use the ECG to diagnose LQTS and we estimate the probability by using Schwartz score.
Some of the important criteria are :-
1. QTc more than 480msec
2. T wave alternans (Varying amplitudes)
3. Torsades de pointes
4. Notched T waves in atleast 3 leads
5. Syncopal attacks with and without stress
6. Congenital deafness
7. Significant family history