ECG 11. The ECG above belongs to a 76 years-old hypertensive woman.
Low amplitude
P waves make it difficult to detect the prolonged PR interval.

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ECG 12. The ECG above is from a 73 years-old man.
Because of baseline drift, the rhythm seems like atrial fibrillation at first glance.
P waves are best seen in precordial leds.
First degree AV block is also present.

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ECG 13. The above ECG is from a 63 years-old apparently healthy woman. Mild prolongation of the PR interval (220 ms) is seen.
She has no known heart disease. She is also not using any medicine that can result in PR interval prolongation.
Prolongation of the PR interval is seen in approximately
1-2% of the general population.

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ECG 14. Oscillating irregular baseline and irregular RR intervals do not always denote atrial fibrillation.
In the presence of baseline drift and/or tremor artifact
P waves may be difficult to detect at first glance.
In the 6-channel ECG above, the basic rhythm is sinus with
first degree AV block ( prolonged PR interval )
The precordial recording shows two VPCs.
Terminal portion of the first VPC and the second VPC are seen.

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ECG 15a. The ECG above belongs to a 47 years-old apparently healthy and asymptomatic woman with no known structural
heart disease. The
low amplitude P waves may be difficult to notice at first glance, resulting in a false diagnosis of nodal
rhythm. In fact, the
low amplitude P waves are barely noticeable in leads V3 and V4.
The PR interval is prolonged (1st degree AV block). There is also
baseline drift artifact in precordial leads.
The above ECG was recorded at a standard calibration of 10 mm/mV.

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ECG 15b. The compact ECG above is the computer interpretation of ECG 15a.
The computer failed to recognize PR interval prolongation.
Also a false diagnosis of "anteroseptal myocardial infarction, age undetermined" is made.
Her ECHOcardiogram showed normal left ventricular systolic function (no sign of old myocardial infarction).




ECG 15c. Another ECG with a different ECG machine was recorded from the same woman, on the same day.
This time the ECG
calibration is at 20 mm/mV.
To be able to accomodate all QRS complexes on a narrow ECG paper, the ECG machine has depicted some leads
at a calibration of 10 mm/mV.
Now the
P waves are easily noticed on leads with a calibration of 20 mm/mV.
The
P waves are barely noticeable at a calibration of 10 mm/mV.

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ECG 16a. The ECG above belongs to a 33 years-old apparently healthy and asymptomatic man without structural
heart disease. It was recorded just before the treadmill exercise test.
The PR interval is prolonged.

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ECG 16b. The ECG above was recorded 1 minute after termination of his treadmill exercise test.
The heart rate is about 167/minute.
Now, the P waves are not visible since they coincide with the preceding T waves.

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ECG 16c. The ECG above was recorded 2 minutes after termination of his treadmill exercise test.
The heart rate is about 143/minute.
The P waves started to reappear.

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ECG 17. The ECG above shows
extremely long PR interval (440 milliseconds).
This may result in pseudo-pacemaker syndrome.

Dr. Peter Kukla has donated the above ECG to our website.

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ECG 18. The ECG above belongs to a 85 years-old man with prolonged PR interval and 2:1 AV block.
Some P waves are conducted to the ventricles while some are blocked.
One of every two
P waves can be conducted to the ventricles.
Heart rate (ventricular rate) is bradycardic (33/minute) but it is not sinus bradycardia since P wave rate (atrial rate) is 66/minute.
Atrial rate is normal but its conduction to the ventricles is the problem.
If you see P waves and the heart rate (ventricular rate) is < 50/minute, then search for a second (blocked) P wave
before diagnosing sinus bradycardia.
The conducted P waves and the blocked P waves have similar configurations, since they originate from the same focus.

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