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When identifying QT abnormality (in ECG) , i have5 modalities:1• New >450 msec2• New >480 msec3• New >500 msec4• Increase from baseline >30 msec5• Increase from baseline >60 msec what is the worst value if two of them accrues, for example:1 and5.
The QT interval is most commonly measured in lead II for evaluation of serial ECGs, with leads I and V5 being comparable alternatives to lead II. Leads III, aVL and V1 are generally avoided for measurement of QT interval.
An "abnormal" QTc in males is a QTc above 450 ms, and in females, above 470 ms.
A Thorough QT (TQT) study is required to determine a drug's effect on the QT interval.
QT is a complex of QRS and ST segment. each segment can vary in time and amplitude.
QT prolongates in bradycardia and shortens in tachycardia/ arrhthymias.
ST segment amplitude incresases with angina /Myocardial infarction.
QRS inversion may be sign of arrhytmias.
