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Conduction: Difference between revisions
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→Correct measurement of the QT interval: how to measure the end of the T wave
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===Correct measurement of the QT interval: how to measure the end of the T wave=== | ===Correct measurement of the QT interval: how to measure the end of the T wave=== | ||
[[Image:Surawicz.jpg|100px| Dr Surawicz, is one of the inventors of the tangent mehod<cite>Lepeschkin</cite>. This picture was taken in November 2006, when he was 89 years old and still active.]] | |||
Although QT prolongation is potentially lethal, measurement of the QT interval by physicians is poor as different definitions of the end of the T wave exist.<cite>Viskin</cite> Most QT experts define the end of the T wave as the intersection of the steepest tangent line from the end of the T-wave with the base line of the ECG.<cite>Lepeschkin</cite> This leads to the following stepwise approach: | Although QT prolongation is potentially lethal, measurement of the QT interval by physicians is poor as different definitions of the end of the T wave exist.<cite>Viskin</cite> Most QT experts define the end of the T wave as the intersection of the steepest tangent line from the end of the T-wave with the base line of the ECG.<cite>Lepeschkin</cite> This leads to the following stepwise approach: | ||
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In a (serious) prolonged QT time, is takes longer for the myocardial cells to be ready for a new cardiac cycle. There is a possibility that some cells are not yet repolarized, but that a new cardiac cycle is already initiated. These cells are at risk for uncontrolled depolarization and induce a [[Arrhythmias#Torsade_de_pointes|torsade de pointes]], a ventricular tachycardia. | In a (serious) prolonged QT time, is takes longer for the myocardial cells to be ready for a new cardiac cycle. There is a possibility that some cells are not yet repolarized, but that a new cardiac cycle is already initiated. These cells are at risk for uncontrolled depolarization and induce a [[Arrhythmias#Torsade_de_pointes|torsade de pointes]], a ventricular tachycardia. | ||
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===Short QT syndrome=== | ===Short QT syndrome=== | ||
If QTc is < 340ms [[Short_QT_Syndrome|short QT syndrome]] can be considered. | If QTc is < 340ms [[Short_QT_Syndrome|short QT syndrome]] can be considered. | ||