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Technical Problems: Difference between revisions
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* '''Left-right arm reversals''' lead to a negative complex in lead I with a negative P wave in lead I. They are one of the most common causes of right axis deviation on the ECG! | * '''Left-right arm reversals''' lead to a negative complex in lead I with a negative P wave in lead I. They are 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 reversals''' lead to inappropriate R wave progression (increase- decrease-increase) and are often easily recognized. | * '''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"> | ||
<gallery> | <gallery> | ||
Image:cableReversal1.png|Right and left arm lead reversal can be distinguished from the (much rarer) dextrocardia by | Image:cableReversal1.png|Right and left arm lead reversal can be distinguished from the (much rarer) dextrocardia by examination of the precordial R wave progression. | ||
Image:cableReversal2.png|Right arm and left leg lead reversal. Lead II now measures the signal between the left and right leg, which is remote from the heart. | Image:cableReversal2.png|Right arm and left leg lead reversal. Lead II now measures the signal between the left and right leg, which is remote from the heart. | ||
Image:dextrocardia.jpg|A patient with dextrocardia (and previous inferior myocardial infarction) | Image:dextrocardia.jpg|A patient with dextrocardia (and previous inferior myocardial infarction) | ||