Computer misinterpretation

  Automatic interpretation by the ECG computer may be incorrect and may need confirmation.

  Sometimes ECG computer may fail to diagnose atrial fibrillation or

      may inadvertently diagnose as atrial fibrillation.

  Brief episodes of baseline drift may result in a false diagnosis of APC or VPC.

  2:1 atrioventricular (AV) block may be misperceived as QT interval prolongation.

  "Probable Digoxin effect" may be overdiagnosed.

  Many ECG computers usually underdiagnose interatrial block.

  Sometimes, computer may fail to recognize the small pacemaker spikes and pacemaker rhythm, and

      may inadvertently interpret the ECG as "old myocardial infarction".

 
Sometimes, ECG computer's software may calculate the heart rate erroneously.

      Especially, when
QRS complexes and T waves have similar amplitudes ECG software may

      fail to discriminate them, and may
inadvertently report the heart as doubled.

  ECG computer's software may miscalculate QRS width
.





ECG 1a. The above ECG shows that a brief
baseline drift may give the impression of a wide QRS complex at first glance.
However, the R wave (initial part of the QRS complex) is not affected by the baseline drift.
Therefore, the R wave morphology is similar to other QRS complexes in the precordial leads.
This finding excludes the presence of a ventricular premature contraction (VPC).

Click here for a more detailed ECG




ECG 1b. Above is the compact report of the ECG 1a including the comment of the computer.
Erroneously, it reports the presence of ventricular premature contraction (VPC).





ECG 2a. The above ECG shows sinus rhythm, tremor artifact and baseline drift.

Click here for a more detailed ECG




ECG 2b. Above is the compact ECG and computer report of the ECG 2a.
Erroneously, it reports the presence of atrial fibrillation.





ECG 3a. The above ECG shows 2:1 atrioventricular block.
The blocked P waves are embedded in the descending limb of the T wave.

Click here for a more detailed ECG




ECG 3b. Above is the compact ECG and computer report of the ECG 3a.
Since it misperceives the blocked P wave as terminal part of the T wave, it erroneously reports the presence of QT interval
prolongation.





ECG 4a. The rhythm in the above ECG is atrial fibrillation.
The patient is NOT under Digoxin therapy.

Click here for a more detailed ECG




ECG 4b. Above is the compact ECG and computer report of the ECG 4a.
It erroneously reports "Moderate ST depresion, probably digitalis effect".
The patient is NOT under Digoxin therapy.





ECG 5a. The above ECG belongs to a 67 years old-man. The rhythm is sinus.
Amplitudes of
the P waves and the T waves are similar.
The PT interval looks similar to the TP interval at first glance.

Click here for a more detailed ECG




ECG 5b. Above is the compact ECG and computer report of the ECG 5a.
Since it misperceives T waves as blocked P wave, it erroneously reports the presence of 2nd degree AV block, Mobitz Type II.
In reality, there is no 2nd degree AV block in this patient.





ECG 6a. The ECG above is from a 81 years-old man who had previous acute myocardial infarction.
After the infarction, left ventricular systolic dysfunction developed (Ejection Fraction of about 35%).
Three-vessel (extensive) coronary artery disease was detected, and his LAD and RCA coronary arteries were stented.

Click here for a more detailed ECG




ECG 6b. Above is the compact ECG and computer report of the ECG 6a.
Diagnosis of old "anteroseptal myocardial infarction" is correct.
However this report does not include "interatrial block".





ECG 7. Above is the compact ECG and computer report from a 37 years old man.
He had experienced acute inferior myocardial infarction 3 days ago.
However, the computer failed to diagnose the subacute myocardial infarction, and reported "Sinus rhythm, normal ECG".





ECG 8. Above ECG is from an 87 years-old man with a cardiac pacemaker.
The ECG computer failed to recognize
the small pacemaker spikes.

Click here for a more detailed ECG





ECG 9. Above ECG is from an 74 years-old man with a coronary artery disease, chronic heart failure and chronic renal failure.
His left ventricular ejection fraction was about 20%. He has a CRT-D (CRT with Implantable cardioverter defibrillator).
The ECG computer failed to recognize
the small pacemaker spikes.

Click here for a more detailed ECG





ECG 10. Above is an ECG from a 75 years-old woman with hypertension, COPD, and chronic renal failure.
When the above ECG was recorded, her serum potassium level was measured as 8.6 mmol/L (hyperkalemia).
She was also under Digoxin therapy.
Nodal rhythm is seen. P waves are not visible.
QRS complexes are widened and the T waves in right precordial leads are relatively prominent.
This ECG was recorded at a standart calibration of 25 mm/second.
Hyperkalemia may result in tall, pointed T waves.
In the above ECG, many leads show QRS complexes and T waves with similar amplitudes.
Because of this, the ECG software counts
QRS complexes and T waves as seperate QRS complexes,
which results in
inadvertently doubling the heart rate as 62/minute.
The actual heart rate in this patient is 31/minute.

Click here for a more detailed ECG





ECG 11. The ECG above belongs to a 33 years-old man who had undergone surgery for ToF.
ECHOcardiography on the same day with the above ECG showed a dilated and hypokinetic right ventricle.
Right bundle branch block is seen.
QRS width is about 160-170 milliseconds, but the ECG computer's software miscalculated it as 76 milliseconds.

Click here for a more detailed ECG