QT interval


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QT in·ter·val

time from electrocardiogram Q wave to the end of the T wave corresponding to electrical systole.

QT Interval

Cardiac pacing The interval between the beginning of a paced QRS complex and the peak of the subsequent T wave–evoked QT in response to metabolic needs in a normal EKG; QT shortening signals a need for an ↑ in pacing rate. See Electrocardiogram.

QT interval

the portion of an electrocardiogram between the onset of the Q wave and the end of the T wave, representing the total time for ventricular depolarization and repolarization.
References in periodicals archive ?
Prolonged QT interval predicts cardiac and all-cause mortality in the elderly.
Methadone is known to prolong the QT interval and was used to verify the sensitivity of the analysis.
We expected that the increased awareness of the cardiotoxicity of psychotropics and interaction between medications would have made psychiatrists more adept at QT interval and ECG abnormality interpretation, but this study indicates that the problem remains," the researchers wrote (The Psychiatrist 2008;32:291-4).
Doctors are generally concerned if patients experience an additional 30 milliseconds in their QT interval from baseline," Sachin A.
The researchers included the methadone patients for comparison because this drug (used for pain relief and to wean addicts off heroin) is known to prolong QT interval.
The QT interval consists of a short depolarization (the QRS complex) and a longer repolarization part (the ST segment and the T wave) (6).
Short QT syndrome is a rare form of hereditary channelopathy with an abnormally short QT interval and a high propensity to atrial and ventricular fibrillation.
R-R interval was used to compute heart rate in order to calculate corrected QT interval (QTc) with Bazett's formula.
Drugs that substantially prolong the QT interval have been associated
12,14,24,25) The QT interval represents the total time needed for the ventricles to depolarize and repolarize.
A comprehensive analysis of QT interval assessments including the QTc interval was performed in AMP-516 per ICH E14 Guidance: Clinical Evaluation of QT/QTc Interval Prolongation and Proarrhythmic Potential for Non-Anti-arrhythmic Drugs (October 2005, ICH).