Update on long QT syndrome

Abstract

Long QT syndrome (LQTS) is an inherited disorder characterized by a prolonged QT interval in the 12‐lead electrocardiogram and increased risk of malignant arrhythmias in patients with a structurally normal heart. Since its first description in the 1950s, advances in molecular genetics have greatly improved our understanding of the cause and mechanisms of this disease. Sixteen genes linked to LQTS have been described and genetic testing had become an integral part of the diagnosis and risk stratification. This article provides an updated review of the genetic basis, diagnosis, and clinical management of LQTS.

Long QT Syndrome and Perioperative Torsades de Pointes: What the Anesthesiologist Should Know

“…The decrease in outward potassium current causes an increase in calcium uptake by the voltage-dependent calcium channel and subsequent calcium release from the sarcoplasmic reticulum. This increase in cytosolic calcium level then translates into new sodium inward current via calcium-sodium exchanger for afterdepolarization 14 , which leads to the generation of a premature ventricular complex.…”

Surgical Approach in Congenital Long QT Interval Syndrome Patients

“…Medical therapy can be started in patients with normal QTc range, but genetically positive congenital LQTS. 36 Beta-blocker therapy is initiated in patients with resting QTc greater than 470 ms, but with resting QTc less than 470 ms, a beta-blockers can be recommended (4,14). Effectivity of beta-blocker therapy has been proved in clinical studies -cardiovascular events raise from 0.31 case/per year/ per patient, receiving therapy, to 0.97 events/ per year/ per patient without therapy (36) The greatest effect from beta-blockers shows type 1 LQTS patients, as well as type 2 and 3 LQTS patients results, suggest a positive effect (37).…”

“…Surgical approach -left cardiac sympathectomy -has been known for a long period, first reports coming from 1971 (4). At this point this surgery has a very limited list of indications, used for the treatment of congenital ventricular arrhythmias, following:…”

“…LQTS prevalence varies from 1/2000 -1/2500 in live births, in different studies (3,2). Congenital LQTS is caused by 17 different gene mutations (Table 1), that result in prolongation of QT interval, seen in ECG (4,5). Important to highlight that -new mutations are disclosed very dynamically, also literature tells us, in about 10 -15% of LQTS cases the exact mutation isn't found, at the same time other causes of QT prolongation are ruled out as well (30).…”

Long QT interval in Rett syndrome: expanding the knowledge of a poorly understood phenomenon

“…While the longer the QTc, the higher the risk, there is no elevation of QTc that is completely safe. Using Bazett’s correction, 450ms to 460ms are considered cut‐offs, and scoring systems combining clinical and electrocardiographic features have been developed for diagnosis and management …”