=====Long QT (including) syndrome==== *a genetic syndrome of many different gene mutations with resultant K+ (60% cases) or Na+ channel dysfunction *QT>450ms, QTc>440ms in men & QTc>460ms in women *life-threatening cardiac arrhythmia syndrome and leading cause of sudden death in young people. Without treatment ~20% mortality in 1st year of 1st syncope *prolonged ventricular repolarisation predisposes to malignant tachyarrhythmia - especially Torsade's de Pointes Often stimulated by: *stress and activities with increased sympathetic activity. *variety of drugs including amiodarone, TCA's, antibiotics, opioids and antipsychotic agents *Metabolic derangement including low K+, Ca++, Mg++ *hypothermia ==NOT just an ECG diagnosis - requires supporting Hx== *History of syncope especially exercise induced, cardiac arrest, FHx of long QT *3 main types recognised on ECG: *LQTI - broad T waves *LQT2 - notched or bifid T in V2,3 and inferior leads *LQT3 - long isoelectric ST with normal T wave |{{:wiki:cardiovascular:ecgs:lqt1.jpg?400}}| ===Management=== *β blockers *treat metabolic abnormalities *avoidance of increased sympathetic tone (stressful exercise) *avoidance of hypokalaemia *review of medications to avoid enhanced risk *pacing, ICD ---- *there is some interest in what has become known as //**QT dispersion**//, defined as the difference between the max & min QT interval on a 12 lead ECG *some suggestion that there is a link between increased QT dispersion and death from a cardiac cause *a variation of >50ms or probably >80ms is seen to be more predictive ---- **References include**\\ https://www.thecardiologyadvisor.com/home/decision-support-in-medicine/cardiology/long-qt-syndromes-and-torsade-de-pointes/\\ https://litfl.com/long-qt-syndrome/\\ [[https://www.ahajournals.org/doi/full/10.1161/CIRCEP.111.962019|Circulation - arrhythmia and electrophysiology: Long QT syndrome]]\\ [[https://heart.bmj.com/content/80/5/421|BMJ: QT dispersion article]]\\