ECG 1. How do isolated pacemaker spikes appear? This ECG was recorded after an unsuccessful resuscitation attempt.
Although there is no cardiac contraction the pacemaker still continues to give
pacemaker spikes which do not result
in cardiac contraction. This ECG was recorded just after the death of a patient with advanced heart failure who was implanted
a permanent cardiac pacemaker one year ago.

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ECG 2. Blue arrows show the vertical pacemaker spikes preceding the QRS complexes in a patient with VDD.

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ECG 3. In pacemakers with bipolar electrodes, the pacemaker spikes may be difficult to recognize at first glance.
Spikes are seen in leads C4, C5 and C6.

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ECG 4. DDD (double chamber pacemaker) ECG.
Red arrows show the spikes resulting in atrial stimulation. Blue arrows show
the spikes resulting in ventricular stimulation.

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ECG 5.
Red arrows show ventricular premature systole (VPS) in a patient with permanent pacemaker.
Blue arrows show pacemaker spike stimulating the ventricles.

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ECG 6. The ECG above belongs to a 65 years-old woman with a normal functioning DDDR type pacemaker.

Baseline drift
should not be misdiagnosed as pacemaker dysfunction.

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ECG 7. Pace dysfunction.
Blue arrows show the spikes which successfully resulted in ventricular stimulation. Red arrows
show the spikes (pacing dysfunction) which did not succeed in depolarizing the ventricles.
Green arrows show the ventricular escape rhythm.

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ECG 8. Atrial flutter in a patient with permanent pacemaker.
Red arrows show the flutter waves.

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ECG 9. Red arrows show the
normally conducted impulses, blue arrows show the pacemaker induced ventricular
depolarizations
. The green arrow shows the fusion beat.

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ECG 10. VDD pacemaker.
P waves have no preceding pacemaker spikes since this type of pacemaker follows the atria
but
stimulates only the ventricles (arrows). This ECG is from a 70 years-old woman.

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ECG 11. The R-R intervals need not be equal in all cardiac pacemaker patients. The ECG above is from a patient with VDD type
pacemaker. A VDD pacemaker paces only the Ventricle but senses both the atrium and the ventricle. So, these pacemakers
follow the atrial P waves. When P waves are irregular, the succeeding pacemaker-induced QRS complexes will be also irregular.
Such a finding does not imply pacemaker dysfunction.

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ECG 12. The ECG above is from a patient with DDDR type pacemaker. Since the rate of the P waves (atrial rate) is within normal
limits, the pacemaker only follows the P waves but does not give atrial stimulus. So there are no pacemaker spikes preceding
the P waves. The pacemaker was implanted because of AV block. Since P waves are not regularly conducted to the ventricles,
the pacemaker stimulates only the ventricles, hence there are pacemaker spikes preceding the wide QRS complexes.
Since change in the rate of atria (rate of P waves) is a physiological phenomenon, the succeeding
pacemaker-induced QRS
complexes
may be irregular.

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ECG 13a. At a first glance, the ECG above looks like an ECG with first degree AV block. The
P waves seem to have prolonged
PR interval.
Careful inspection shows that the P waves are getting closer to the QRS complexes This ECG is from a man with
VVI type pacemaker. The pacemaker senses from and paces only the ventricle. Therefore P waves are not related to the
pacemaker-induced QRS complexes.
Small pacemaker spikes are seen on some precordial leads.

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ECG 13b. Another ECG from the same patient is seen above. This time it looks like Wenkebach AV block at first glance.
The timing of
P waves is so that it gives the impression of gradual prolongation of the PR interval . The timing is accidental
and actually the
P waves are not related to the pacemaker-induced QRS complexes. Small pacemaker spikes are seen on
some precordial leads.

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ECG 14. The ECG above is from a one year-old baby who had undergone operation for AV canal defect.
ECHOcardiogram has shown pulmonary hypertension (systolic 70mmHg) and 3rd degree (severe) tricuspid regurgitation.
She has a VVI type pacemaker (
pacemaker spikes ).
As expected for a VVI type pacemaker, the
P waves are NOT related to the QRS complexes.

Pediatric cardiologist Dr. Mahmut Gokdemir has donated this ECG to our website.

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ECG 15. The ECG above is from a 9 months-old baby with congenital complete AV block for which she has undergone
epicardial pacemaker implantation. Unipolar leads result in prominent
pacemaker spikes.
Since the pacemaker operates in the VVI mode, there is no atrioventricular synchronization and
P waves are not related to the pacemaker spikes.
The P wave rate is high when compared with adult heart rates (normal for babies).
Some P waves are not obvious since they coincidentally occur at the same time with the pacemaker-induced QRS .

Pediatric cardiologist Dr. Mahmut Gokdemir has donated this ECG to our website.

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ECG 16. Pacemaker stimulation from the atria does not interfere with ECG diagnosis of ventricular ischemia or infarction.
The ECG above is from a 91 years-old woman with extensive coronary artery disease and atrial pacemaker.
Some leads show atrial pacemaker spikes clearly . Some leads barely show atrial pacemaker spikes .
The presence of q waves and
negative T waves in leads II, III and aVF suggest the diagnosis of old inferior wall myocardial
infarction.





ECG 17a. The ECG above is from a 61 years-old hypertensive woman who has a dual chamber cardiac pacemaker.
Because of the bipolar electrodes, it is very difficult to recognize the pacemaker rhythm at first glance.

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ECG 17b. Above is the compact ECG and computer report of the preceding ECG.
Atrial pacemaker spikes preceding the P waves are now easily discernible.
Abnormal P wave axis during atrial pacing is an expected finding (as is above).






ECG 18. Above ECG is from a 51 years-old man with old inferior myocardial infarction and previous coronary artery bypass
surgery. He also has a permanent cardiac pacemaker operating in the VDD mode, but the pacemaker spikes are not clear.
Wide QRS complexes are due to the pacemaker stimuli.
These pacemaker beats are not suitable to look for ECG signs of myocardial ischemia or infarction.
In these patients, you have to wait for
the normally conducted, narrow supraventricular beats to diagnose ischemia or infarction.
The q waves of narrow QRS complexes in leads III and aVF suuggest the diagnosis of old inferor wall myocardial infarction.
ECHOcardiography showed inferior wall akinesia (old inferior wall myocardial infarction).

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ECG 19. The above ECG shows coexistence of ventricular pacing and atrial flutter.
Flutter waves are seen only in lead V1.
Pacemaker spikes are barely visible in some of the leads.
The pacemaker is functioning normally.
Underlying atrial flutter has nothing to do with ventricular pacing.

Esra Dogan has donated the above ECG to our website.

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ECG 20. The ECG above is from a middle-aged woman with atrial fibrillation and permanent cardiac pacemaker.
P waves are lacking. Undulating baseline due to atrial fibrillation is best seen in lead V1.
Unipolar electrode results in very high amlitude pacemaker spikes.
The pacemaker is functioning normally and the pacemaker rhythm is not related to atrial fibrillation.
Regular pacemaker output results in a regular ventricular rhythm despite the presence of atrial fibrillation.

Esra Dogan has donated the above ECG to our website.

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ECG 21. The ECG above is from a 78 years-old woman with a DDDR pacemaker.
Pacemaker spikes originating from the atrial electrode are seen in some leads.
Pacemaker spikes originating from the ventricular electrode are also seen.

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ECG 22. The ECG above is from a 82 years-old woman with a DDDR pacemaker, left heart failure and pulmonary hypertension.
Pacemaker spikes originating from the atrial electrode and
Pacemaker spikes originating from the ventricular electrode are clearly seen.
Two
ventricular premature contractions (VPCs) are seen
A fusion beat is also seen.

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ECG 23. During atrial fibrillation, a wide QRS complex may not be due to aberrancy or a VPC.
The ECG above belongs to a 74 years-old woman and the basic rhythm is atrial fibrillation.
She also has a VVI-pacemaker.
The pacemaker spike is not easy to notice, at first glance.
The QRS complex is widened not due to aberrancy or a VPC but due to stimulation from ventricular pacemaker.

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ECG 24. The above ECG is from a 45 years-old woman with a permanent cardiac pacemaker.
ECHOcardiography showed dilated right atrium and right ventricle.
Leads I and V4 show giant
pacemaker spikes which must not be confused with increased QRS voltage.

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ECG 25. The above ECG is from an 8 years-old girl with a permanent cardiac pacemaker.
She had undergone pacemaker implantation when she was one month-old.
P waves are seen.

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ECG 26. The above ECG is from an 90 years-old man with a DDDR type permanent pacemaker.
Atrial and ventricular pacemaker spikes are prominent.
Prominent pacemaker spikes resulted in miscalculation (double counting) of the heart rate.
His actual heart (ventricular) rate is about 61/minute but the ECG computer calculated it as 123/minute.

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ECG 27. The ECG above belongs to a 74 years-old man with heart failure and permanent pacemaker.
The basic rhythm is atrial fibrillation.
On the left side of the ECG, a relatively long pause is followed by a wider QRS complex, which is
not due to Ashman phenomenon.
The wider QRS is initiated by a
pacemaker spike(demand type pacing).
Tiny pacemaker spikes are barely noticeable.

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ECG 28a. The ECG above belongs to a 68 years-old woman with hypertension, heart failure and permanent pacemaker.
Pacemaker rhythm is seen in the above ECG.
Would you anticoagulate this patient?

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ECG 28b. The ECG above belongs to the same woman.
It was recorded 25 minutes after the ECG 28a. The rhythm is irregular.
Now, the rhythm is atrial fibrillation with intermittent pacemaker-induced beats.
She needs anticoagulation.
Sometimes pacemaker rhythm may mask the underlying atrial fibrillation
(with slow ventricular rate, as in 42a)

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ECG 28c. The ECG above belongs to the same woman.
It was recorded one minute after the ECG 28b. The rhythm is irregularly irregular.
The rhythm is atrial fibrillation with no pacemaker-induced beats.

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ECG 29. Above is a 3-channel ambulatory ECG (Holter) recording from a 55 years-old woman. Her
basic rhythm is atrial fibrillation. A temporary pacemaker was implanted before the onset of Holter monitoring. However, lead dislodgement caused pacing dysfunction which resulted in pacemaker spikes unable to initiate QRS complexes. Some pacemaker spikes are difficult to notice at first glance.

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