Difference between revisions of "Technical Problems"

From ECGpedia
Jump to navigation Jump to search
m (Reverted edits by 195.229.242.57 (Talk); changed back to last version by Drj)
Line 27: Line 27:
 
{{clr}}
 
{{clr}}
  
==Artefacts==
+
==artifacts==
[[Image:Noise_move.png|thumb| Movement artefacts]]
+
[[Image:Noise_move.png|thumb| Movement artifacts]]
[[Image:ECG_Parkinson.png|thumb| Increasing movement artefacts in a Parkinson patient. The patient was in sinus rhythm! (which doesn't show on this short recording)]]
+
[[Image:ECG_Parkinson.png|thumb| Increasing movement artifacts in a Parkinson patient. The patient was in sinus rhythm! (which doesn't show on this short recording)]]
 
[[Image:BaselineDrift.png|thumb| 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|thumb| 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|thumb| Cardioversion from atrial fibrillation to sinusrhythm, with clear baseline drift.]]
+
[[Image:cardioversion_from_afib.jpg|thumb| Cardioversion from atrial fibrillation to sinus rhythm, with clear baseline drift.]]
 
[[Image:electric_noise_ecg.png|thumb| Electrical interference from a nearby electrical appliance. A typical example is a 100 Hz background distortion from fluorescent lights. Not to be confused with [[arrhythmias#atrial fibrillation|atrial fibrillation]].]]
 
[[Image:electric_noise_ecg.png|thumb| Electrical interference from a nearby electrical appliance. A typical example is a 100 Hz background distortion from fluorescent lights. Not to be confused with [[arrhythmias#atrial fibrillation|atrial fibrillation]].]]
 
[[Image:electric_noise_ecg2.jpg|thumb| Another example of an artefact caused by an electrical appliance. The patients rhythm is regular. This strip shows 10 QRS complexes.]]
 
[[Image:electric_noise_ecg2.jpg|thumb| Another example of an artefact caused by an electrical appliance. The patients rhythm is regular. This strip shows 10 QRS complexes.]]
  
Artefacts (disturbances) can have many causes. Common causes are:
+
artifacts (disturbances) can have many causes. Common causes are:
 
*Movement  
 
*Movement  
 
*Electrical interference
 
*Electrical interference
  
 
{{clr}}
 
{{clr}}

Revision as of 00:18, 8 May 2008

Author(s) J.S.S.G. de Jong
Moderator J.S.S.G. de Jong
Supervisor
some notes about authorship

Lead reversals

Right and left arm lead reversal can be distinguished from the (much rarer) dextrocardia by looking at the precordial R wave progression.
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.

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 leg and right arm:
    • Hardly any signal in lead II.
  • 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 of leads aVR and aVF
    • inversion of lead III
  • right arm and left leg:
    • inversion of leads I, II and III
    • reversal of leads aVR and aVF


It is possible to distinguish lead reversal and dextrocardia by watching the precordial leads. Dextrocardia will show an R wave inversion, wheras lead reversal will not.

artifacts

Movement artifacts
Increasing movement artifacts in a Parkinson patient. The patient was in sinus rhythm! (which doesn't show on this short recording)
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.
Cardioversion from atrial fibrillation to sinus rhythm, with clear baseline drift.
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.
Another example of an artefact caused by an electrical appliance. The patients rhythm is regular. This strip shows 10 QRS complexes.

artifacts (disturbances) can have many causes. Common causes are:

  • Movement
  • Electrical interference