Long QT Syndrome overview: Difference between revisions
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==Overview== | ==Overview== | ||
==Overview== | |||
The '''long QT syndrome''' ('''LQTS''') is a [[heart]] condition associated with prolongation of repolarisation (recovery) following depolarisation (excitation) of the cardiac [[ventricle (heart)|ventricles]]. It is associated with [[fainting|syncope]] (fainting) and [[sudden death]] due to[[left ventricle|ventricular]] [[cardiac arrhythmia|arrhythmias]]. Arrhythmias in individuals with LQTS are often associated with exercise or excitement. LQTS is associated with the rare, ventricular arrhythmia[[torsade de pointes]], which can deteriorate into [[ventricular fibrillation]] and ultimately death. | |||
Individuals with LQTS have a prolongation of the [[QT interval]] on the[[electrocardiogram|ECG]]. The Q wave on the [[electrocardiogram|ECG]]corresponds to ventricular depolarization while the T wave corresponds to ventricular repolarization. The QT interval is measured from the Q point to the end of the [[Electrocardiogram#T wave|T wave]]. While many individuals with LQTS have persistent prolongation of the QT interval, some individuals do not always show the QT prolongation; in these individuals, the QT interval may prolong with the administration of certain medications. | |||
===Images=== | |||
<div align="left"> | |||
<gallery heights="125" widths="125"> | |||
Image:QRSinterval.jpg|The QT interval start at the onset of the Q wave and ends where the tangent line for the steepest part of the T wave intersects with the baseline of the ECG. | |||
Image:acquired_longQT.jpg|A 12 lead ECG of a patient with acquired long QT syndrome. Notice the QT prolongation. The QTc is about 640ms. | |||
Image:lqts1-3.png|The three most common forms of LQTS can be recognized by the '''characteristic ECG abnormalities''' | |||
</gallery> | |||
</div> | |||
<div align="left"> | |||
<gallery heights="125" widths="125"> | |||
Image:lastigeQT2.png|The ECG does not meet the baseline after the end of the T wave. Still, the crossing of the tangent and baseline should be used for measurements. | |||
Image:lastigeQT3.png|A bifasic T wave. The tangent to the 'hump' with the largest amplitude is chosen. This can change from beat to beat, making it more important to average several measurements. | |||
Image:lastigeQT1.png|The T wave is broad, but the tangent crosses the baseline before the T wave joins the baseline. The QT interval would be overestimated when this last definition of the end of the T wave would be used. | |||
</gallery> | |||
</div> | |||
==References== | ==References== | ||
Revision as of 04:44, 24 August 2012
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Long QT Syndrome Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Long QT Syndrome overview On the Web |
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American Roentgen Ray Society Images of Long QT Syndrome overview |
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Risk calculators and risk factors for Long QT Syndrome overview |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]
Overview
Overview
The long QT syndrome (LQTS) is a heart condition associated with prolongation of repolarisation (recovery) following depolarisation (excitation) of the cardiac ventricles. It is associated with syncope (fainting) and sudden death due toventricular arrhythmias. Arrhythmias in individuals with LQTS are often associated with exercise or excitement. LQTS is associated with the rare, ventricular arrhythmiatorsade de pointes, which can deteriorate into ventricular fibrillation and ultimately death.
Individuals with LQTS have a prolongation of the QT interval on theECG. The Q wave on the ECGcorresponds to ventricular depolarization while the T wave corresponds to ventricular repolarization. The QT interval is measured from the Q point to the end of the T wave. While many individuals with LQTS have persistent prolongation of the QT interval, some individuals do not always show the QT prolongation; in these individuals, the QT interval may prolong with the administration of certain medications.
Images
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The QT interval start at the onset of the Q wave and ends where the tangent line for the steepest part of the T wave intersects with the baseline of the ECG.
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A 12 lead ECG of a patient with acquired long QT syndrome. Notice the QT prolongation. The QTc is about 640ms.
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The three most common forms of LQTS can be recognized by the characteristic ECG abnormalities
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The ECG does not meet the baseline after the end of the T wave. Still, the crossing of the tangent and baseline should be used for measurements.
-
A bifasic T wave. The tangent to the 'hump' with the largest amplitude is chosen. This can change from beat to beat, making it more important to average several measurements.
-
The T wave is broad, but the tangent crosses the baseline before the T wave joins the baseline. The QT interval would be overestimated when this last definition of the end of the T wave would be used.
