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In addition, factors such as rapid infusion, concurrent use of more than one drug known to prolong QT interval, diuretic treatment, electrolyte derangements (hypokalemia, hypomagnesemia, or hypocalcemia), advanced age, bradyarrhythmias, and female sex have all been shown to be risk factors for developing drug-induced QT prolongation. [2]
As the QT prolonging effects of both genetic variants and acquired causes of LQTS are additive, those with inherited LQTS are more likely to experience TdP if given QT prolonging drugs or if they experience electrolyte problems such as low blood levels of potassium (hypokalaemia).
Torsades occurs as both an inherited (linked to at least 17 genes) [6] and as an acquired form caused most often by drugs and/or electrolyte disorders that cause excessive lengthening of the QT interval. [7] Common causes for torsades de pointes include drug-induced QT prolongation and less often diarrhea, low serum magnesium, and low serum ...
There’re at least 10 specific gene mutations that are known to be linked to Long QT syndrome, which are referred to as, for example, LQT1, LQT2, and so on, all of which have some effect on one or more ion channels. Aside from congenital causes though, sometimes the QT interval can be prolonged by certain medications which affect ion channels.
The predisposition to this problem usually manifests on the ECG as a prolongation of the QT interval. QT prolongation may be congenital or acquired. Congenital problems include long QT syndrome and catecholaminergic polymorphic ventricular tachycardia. Acquired problems are usually related to drug toxicity or electrolyte abnormalities, but can ...
EADs can be triggered by hypokalemia and drugs that prolong the QT interval, including class Ia and III antiarrhythmic agents, as well as catecholamines. [1] Afterhyperpolarizations can also occur in cortical pyramidal neurons. There, they typically follow an action potential and are mediated by voltage gated sodium or chloride channels.
The most common causes of first-degree heart block are AV nodal disease, enhanced vagal tone (for example in athletes), myocarditis, acute myocardial infarction (especially acute inferior MI), electrolyte disturbances and medication. The medications that most commonly cause first-degree heart block are those that increase the refractory time of ...
Inherited or sporadic KCNE gene mutations can cause Romano–Ward syndrome (heterozygotes) and Jervell Lange-Nielsens syndrome (homozygotes). Both these syndromes are characterized by Long QT syndrome, a delay in ventricular repolarization. In addition, Jervell and Lange-Nielsen syndrome also involves bilateral sensorineural deafness.