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Long QT syndrome is principally diagnosed by measuring the QT interval corrected for heart rate (QTc) on a 12-lead electrocardiogram (ECG). Long QT syndrome is associated with a prolonged QTc, although in some genetically proven cases of LQTS this prolongation can be hidden, known as concealed LQTS. [23]
The QTc interval is longer in females, as well as having a stronger response to IKr-blocking agents. In males, the presence of testosterone upregulates IKr channels and therefore decreases QT interval. [2] Stated otherwise, estrogens prolong the QT interval, while androgens shorten it and decrease the response to IKr-blocking agents. [citation ...
[19] [39] Almost half of patients with type 1 diabetes have a prolonged QTc interval (> 440 ms). [19] Diabetes with a prolonged QTc interval was associated with a 29% mortality over 10 years in comparison to 19% with a normal QTc interval. [19] Anti-hypertensive drugs increased the QTc interval, but were not an independent predictor of ...
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.
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 ...
Romano–Ward syndrome is principally diagnosed by measuring the QT interval corrected for heart rate (QTc) on a 12-lead electrocardiogram (ECG). Romano–Ward syndrome is associated with a prolonged QTc, although in some genetically proven cases of Romano–Ward syndrome this prolongation can be hidden, known as concealed Long QT syndrome. [13]
The cardiac features of JLNS can be diagnosed by measuring the QT interval corrected for heart rate (QTc) on a 12-lead electrocardiogram (ECG). The QTc is less than 450 ms in 95% of normal males, and less than 460 ms in 95% of normal females. In those with Jervell and Lange-Nielsen syndrome the QTc is typically greater than 500 ms. [8]
Intermittent QT prolongation, or intermittent prolongation of the QTc (corrected QT interval) on the ECG (electrocardiogram) is noted. The implications of intermittent QTc prolongation predispose to life-threatening cardiac electrical instability (and this is therefore a more critical condition than constant QTc prolongation).