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Technical Problems: Difference between revisions
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==Lead reversals== | ==Lead reversals== | ||
Lead switches are a common mistake when ECGs are made and can lead to wrong diagnoses. Common mistakes are: | Lead switches are a common mistake when ECGs are made and can lead to wrong diagnoses. Common mistakes are: | ||
* '''Left - right arm reversals''' | * '''Left-right arm reversals'''this lead to a negative complex in lead I with also a negative P wave in lead I. It is one of the most common causes of right axis deviation on the ECG! | ||
* '''Arm - foot switches''' lead to a very small or 'far field' signal in leads II or III. | * '''Arm-foot switches''' lead to a very small or 'far field' signal in leads II or III. | ||
* '''Chest lead | * '''Chest lead reversals''' lead to inappropriate R wave progression (increase - decrease - increase) and are often easily recognized. | ||
Therefore '''any right axis or small signal in an extremity lead''' should be reason enough to check lead positioning. A previous ECG can be very helpful. | Therefore '''any right axis or small signal in an extremity lead''' should be reason enough to check lead positioning. A previous ECG can be very helpful. | ||
<div style="float:right"> | <div style="float:right"> | ||
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More specific patterns with every lead reversal: | More specific patterns with every lead reversal: | ||
*right leg and right arm: | *right leg and right arm: | ||
** | **diminished signal in lead II | ||
*right and left arm electrodes | *right and left arm electrodes: | ||
**reversal of leads II and III | **reversal of leads II and III | ||
**reversal of leads aVR and aVL | **reversal of leads aVR and aVL | ||
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<gallery perRow="4"> | <gallery perRow="4"> | ||
Image:Noise_move.png|Movement artifacts | Image:Noise_move.png|Movement artifacts | ||
Image:ECG_Parkinson.png|Increasing movement artifacts in a Parkinson patient. The patient was in sinus rhythm | Image:ECG_Parkinson.png|Increasing movement artifacts in a Parkinson's patient. The patient was in sinus rhythm (which doesn't show on this short recording)! | ||
Image:BaselineDrift.png|Baseline drift. The amplifier in the ECG machine has to re-find the 'mean'. This often occurs right after lead connection and after electric cardioversion. | Image:BaselineDrift.png|Baseline drift. The amplifier in the ECG machine has to re-find the 'mean'. This often occurs right after lead connection and after electric cardioversion. | ||
Image:cardioversion_from_afib.jpg|Cardioversion from atrial fibrillation to sinus rhythm, with clear baseline drift. | Image:cardioversion_from_afib.jpg|Cardioversion from atrial fibrillation to sinus rhythm, with clear baseline drift. | ||
Image:electric_noise_ecg.png|Electrical interference from a nearby electrical appliance. A typical example is a 100 Hz background distortion from fluorescent lights. Not to be confused with [[Atrial_Fibrillation|atrial fibrillation]]. | Image:electric_noise_ecg.png|Electrical interference from a nearby electrical appliance. A typical example is a 100 Hz background distortion from fluorescent lights. Not to be confused with [[Atrial_Fibrillation|atrial fibrillation]]. | ||
Image:electric_noise_ecg2.jpg|Another example of an | Image:electric_noise_ecg2.jpg|Another example of an artifact caused by an electrical appliance. The patients rhythm is regular. This strip shows 10 QRS complexes. | ||
File:DVA2162.jpg|An artifact that was originally diagnosed as a VT | File:DVA2162.jpg|An artifact that was originally diagnosed as a VT | ||
</gallery> | </gallery> | ||