Long QT syndrome (LQTS)
Background
- Prolonged ventricular repolarization = prolongation of the QT interval
- Risk of torsade de pointes and sudden death
- Congentital or acquired
- Acquired
- Class IA and III antiarrhythmics, TCAs, antihistamines
- Phenothiazines (ahloperidol)111 ( and quinolone antibiotics
- Electrolytes e.g. ↓K+ ↓Mg++
- Cocaine +/- myocardial ischaemia.
- Congenital
- Romano-Ward syndrome - autosomal dominant
- Lange-Nielsen syndrome - autosomal recessive (assoc congenital deafness
- F > M, usually childhood or adolescence
- Once identified, first degree relatives should be screened
Normal QTc |
Prolonged QTc |
|
|---|---|---|
| Males or females <15 years old | <0.44 s |
>0.46 s |
| Males > 15 years | <0.43 s |
>0.45 s |
| Females > 15 years | <0.45 s |
>0.46 s |
Clinical Presentation
- Palpitations, syncope or near syncope, seizures, or cardiac arrest.
- ECG findings
- QTc = QT/R-R-2. >0.45 sec abnormal
- Abnormal T-wave (notched or biphasic)
- T-wave alternans
Treatment
- "lifestyle modifications," (avoidance competitive sports and of all drugs known to prolong QT interval) (list)
- Treat with Β-blockers (shorten the QT interval, reduce risk of torsade and suden death)
- High risk patients - implantable cardioverter-defibrillators (ICDs)
- Left cervicothoracic sympathectomy (block sympathetic to heart so reduce event rate)
