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==The chest leads== | ==The chest leads== | ||
The precordial, or chestleads, '''(V1,V2,V3,V4,V5 and V6)''' 'observe' the depolarization wave in the frontal plane | |||
'' | ''Example'': V1 is close to the right ventricle and the right atrium. Signals in these areas of the heart have the largest signal in this lead. V6 isthe closest to the laterale wall of the left ventricle. | ||
==Special leads== | ==Special leads== | ||
In case of an inferior wall infarct, extra leads may be used: | |||
# | #In a right side ECG, V1 and V2 remain on the same place.V3 to V6 are placed on the same place but mirrored on the chest. So V4 is in the middle of the right clavicle. On the ECG it should be marked that it is a ''Right sided ECG''. V4R (V4 but right sided) is a sensitive lead to diagnose right ventricular infarction. | ||
# | #Leads V7-V8-V9 can be used to diagnose a posteriorinfarct. It is means that after V6, leads are pkaced towards the back. See the chapter[[Ischemia]] for other ways of diagnosing posterior infarction. | ||
=Technical problems with the ECG= | =Technical problems with the ECG= | ||
==Lead reversals== | ==Lead reversals== | ||
Sometimes an ECG is made properly. Mistakes do happen and leads can be switched. Always remain careful to check this or you might come to the wrong conclusions. One of the most common mistakes is to switch the right and left arm. This will result in negative complexes in I, indicating a right axis deviation! | |||
Common mistakes are reversal of: | |||
*right and left arm electrodes; | |||
**reversal of leads II and III | |||
**reversal of leads aVR and aVL | |||
*left arm and left leg: | |||
**reversal of leads I and II | |||
**reversal od leads aVR and aVF | |||
**inversion of lead III | |||
*right arm and left leg: | |||
**inversion of laeds I, II and III | |||
**reversal of leads aVR and aVF | |||
It is possible to distinguish lead reversal and[[wikipedia:Dextrocardia|dextrocardia]] to check the precordial leads. Dextrocardia will show an R wave inversion, wheras lead reversal will not. | |||
==Disturbances== | ==Disturbances== | ||
* | *Movementartefacten | ||
*Tremor | *Tremor | ||
* | *Electrical interference | ||
* | *Wrong filter setting | ||
=External links= | =External links= |