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 ?
The exclusion criteria were as follows: a prolonged QT interval sufficient to induce fatal arrhythmia, electrolyte imbalances, hypothyroidism, the patient was taking medication that affects QT intervals, and a preoperative QTc >450 ms.
1] Another effect of arsenic is that it can cause QT interval prolongation and can even result in life-threatening ventricular arrhythmia, torsades de pointes, which is can even lead to cardiac death.
Patients with a previous drug reaction or allergy should avoid it, and experts advise prescribing it with caution for patients who have (or are at increased risk for) a prolonged QT interval, including those on other QT-prolonging medications.
The QT interval was measured manually in the 12 ECG leads and was rated with time interval between the initial deflection of the QRS complex and the point at which a tangent drawn to the steepest portion of the terminal part of the T wave crossed the isoelectric line.
The QT interval was measured from the beginning of the QRS complex to the end of the downslope of the T wave (crossing the isoelectric line); when U wave present, QT interval was measured to the nadir of the curve between the T and U waves.
QT interval, one of the most important duration, is defined as the time lapse between the beginning of the depolarization and the end of the repolarization in heart ventricles.
and patients who were using drugs which prolong QT interval or antiarrhythmic drugs were not included in the study.
Consequently, it can be interpreted whether the QT interval was found in the expected value range or if it was abnormally prolonged, while taking into consideration the heart rate.
It is also very useful in counteracting the individual differences in the heart rate and QT interval (22).
Keywords: Thalassaemia major, TM, Iron overload, Cardiac iron, Ferritin, QT interval.
The QT interval was measured from the beginning of the QRS complex to the end of the T wave and corrected for heart rate using the Bazett's formula: cQT = QTV (R-R interval).
Since the heart rate is the major determinant of QT interval, the QT interval was reduced due to increased heart rate.