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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 segment]] 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 tangent against the steepest part of the end of the T wave. If the T wave has two humps (as in a camel back), the tallest hump should be picked. If the T wave has a positive and negative hump (or the other way around), the hump with the largest amplitude should be picked (see third example, the first hump has the largest amplitude and should be picked to draw the tangent). | * Draw a tangent against the steepest part of the end of the T wave. If the T wave has two humps (as in a camel back), the tallest hump should be picked. If the T wave has a positive and negative hump (or the other way around), the hump with the largest amplitude should be picked (see third example, the first hump has the largest amplitude and should be picked to draw the tangent). | ||
* The QT interval starts at the beginning of the QRS complex: the beginning of the first deflection (either positive of negative) of the QRS complex. | * The QT interval starts at the beginning of the QRS complex: the beginning of the first deflection (either positive of negative) of the QRS complex. | ||