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Difficult QT: Difference between revisions
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===General considerations=== | ===General considerations=== | ||
* The QT interval should be measured in lead II, because the influence of a possible U-wave are smallest in this lead. If lead II is cannot be used for measurements, than leads V4 or V5 can be used alternatively. | * The QT interval should be measured in lead II, because the influence of a possible U-wave are smallest in this lead. If lead II is cannot be used for measurements, than leads V4 or V5 can be used alternatively. | ||
* Draw a line through the baseline. This is the horizontal line between the P wave and QRS complex. If PTa depression is present, the T - P segment is used alternatively. If there is baseline drifting, it can be difficult to determine the proper baseline and measurements will be less accurate. | * Draw a line through the baseline. This is the horizontal line between the P wave and QRS complex. If PTa depression is present, the T - P segment is used alternatively. If there is baseline drifting, it can be difficult to determine the proper baseline and measurements will be less accurate. | ||
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===QTc is the heart rate corrected QT interval=== | ===QTc is the heart rate corrected QT interval=== | ||
<flash>file=QTc.swf|width=300|height=200|quality=best|align=right|salign=R||bgcolor=#FFF5F5</flash> | |||
* The QT interval should be corrected for the heart rate, as the QT interval shortens with increasing heartrate. | * The QT interval should be corrected for the heart rate, as the QT interval shortens with increasing heartrate. | ||
* Bazetts formula: [[Image:Formule QTc.png]], can be used to calculate the QTc: the heart rate corrected QT. When entering the formula the RR interval should be entered in seconds. The preceding RR interval should be used. You can also use this [[QTc calculator]] | * Bazetts formula: [[Image:Formule QTc.png]], can be used to calculate the QTc: the heart rate corrected QT. When entering the formula the RR interval should be entered in seconds. The preceding RR interval should be used. You can also use this [[QTc calculator]] | ||