<unk><unk>  is a measure of delayed ventricular repolarisation, which means the heart muscle takes longer than normal to recharge between beats. It is an electrical disturbance which can be seen on an electrocardiogram (ECG). Excessive<unk><unk>  can trigger tachycardias such as torsades de pointes (TdP).<unk><unk>  is an established side effect of antiarrhythmics, but can also be caused by a wide range of non-cardiac medicines, including antibiotics, antihistamines, opioids, and complementary medicines. On an ECG, the<unk>  interval represents the summation of action potentials in cardiac muscle cells, which can be caused by an increase in inward current through sodium or calcium channels, or a decrease in outward current through potassium channels. By binding to and inhibiting the “rapid” delayed rectifier potassium current protein, certain<unk> s are able to decrease the outward flow of potassium ions and extend the length of phase 3 myocardial repolarization, resulting in<unk><unk> .
Drug-induced QT prolongation
Benign early repolarization
Catecholaminergic polymorphic ventricular tachycardia
Tachycardia-induced cardiomyopathy
Sudden arrhythmic death syndrome
Toxic anterior segment syndrome
Pre-excitation syndrome
Long QT syndrome