What type of mutation is responsible for long QT syndrome?
What type of mutation is responsible for long QT syndrome?
Congenital long QT syndrome (LQTS) is caused by single autosomal-dominant mutations in a gene encoding for a cardiac ion channel or an accessory ion channel subunit. These single mutations can cause life-threatening arrhythmias and sudden death in heterozygous mutation carriers.
Which antiarrhythmic drugs prolong QT interval?
Sotalol and amiodarone, class III antiarrhythmics, are known to prolong the QT interval by blocking the IKr.
What is KCNQ1 mutation?
Mutations in the KCNQ1 gene are thought to be the most common cause of Romano-Ward syndrome, accounting for approximately one-third of cases. This condition is a form of arrhythmia called long QT syndrome. In people with Romano-Ward syndrome, the heart muscle takes longer than usual to recharge between beats.
Does Flexeril prolong QTc?
The combination of cyclobenzaprine and fluoxetine resulted in significant QT prolongation in our patient that progressed to torsade de pointes after preoperative droperidol administration. Resolution of QT abnormalities after cyclobenzaprine discontinuation provided further evidence of a drug-induced etiology.
Does Zofran prolong QT?
ECG changes including QT interval prolongation have been observed in patients receiving ondansetron. In addition, Torsade de Pointes, an abnormal, potentially fatal, heart rhythm, has been reported in some patients receiving ondansetron. The use of a single 32 mg intravenous dose of ondansetron should be avoided.
How do beta blockers work in Long QT Syndrome?
Beta-blockers have differential effects on the duration of the QT interval dependent on heart rate in type 1 long QT syndrome. Beta-blockers shorten the QT interval at faster heart rates and lengthen the QT interval at slower heart rates in type 1 long QT syndrome.
Why does Long QT cause syncope?
Nine out of 10 patients had a positive HUT. The syncope resulted from a combined vasodepressor and bradycardiac response. There were no cases of TdP. No syncope occurred in a 42-year-old asymptomatic male LQTS patient with a borderline prolonged QTc of 0.45 s and a HERG mutation.
Does ciprofloxacin prolong QT?
Purpose: Ciprofloxacin may prolong the QT interval and increase the risk of Torsade de Pointes (TdP). Intravenous administration of ciprofloxacin in patients with additional risks may elevate the risk of QTc interval prolongation.
Which antibiotics prolong QT interval?
Antimicrobials that are associated with QT prolongation include the macrolides/ketolides, certain fluoroquinolones and antimalarials, pentamidine, and the azole antifungals.
What does hERG stand for?
The human ether-a-go-go-related gene (hERG) encodes the pore-forming subunit of the rapidly activating delayed rectifier potassium channel (IKr), which is important for cardiac repolarization.
How does the hERG channel affect QT interval?
Inherited mutations (loss of function) of the hERG gene lead to type 2 LQTS. Medications that prolong QT interval act on the same hERG channel. The distinct molecular structure of the hERG channel makes it more susceptible to medications. The structure of the hERG channel
What are the mechanisms of congenital long QT syndrome?
Mutations of the genes that encode the protein channels (IKr, IKs and Na) result in congenital long QT syndrome (LQTS) [Ching and Tan, 2006]. In acquired LQTS, the mechanism is almost always due to blockage of the inward potassium rectifier (IKr) channel, also known as the hERG (ether a go go) channel.
Where are mutations found in long QT genes?
Most of them were found in KVLQT1 (n=66) and HERG (n=41), and fewer in SCN5A (n=9), KCNE1 (n=7), and KCNE2 (n=3). These mutations were identified in regions with known intron/exon structure, primarily the transmembrane and pore domains.
What is the risk of Excessive QT prolongation?
The mechanism of TdP in the setting of QT prolongation. The danger inherent in a prolonged QT is that excessive QT prolongation carries a risk of sudden cardiac death (SCD) due to polymorphic tachycardia, also known as TdP.
