d o
t o r e g . c o m
Dr. Mete ALPASLAN
ECGs of Cardiac Pacemaker Dysfunction
ECG 1a. The ECG above belongs to a 65 years-old woman who had been implanted DDDR type pacemaker 2 weeks ago.
As seen in the middle of the tracing, the pacemaker senses atrial depolarization (P wave) by its atrial electrode and after
waiting for a pre-programmed AV delay (150 msec), ventricular electrode gives stimulus (spike) which fails to produce a wide
QRS complex at the expected time (pacemaker fails to capture the ventricle). Thereafter, a short-lasting narrow QRS complex
nodal escape rhythm arises. In this patient, the cause of failure to capture is displacement of the tip of right ventricular
electrode.
Click here for a more detailed ECG
ECG 1b. Another ECG from the same patient, before realignment of the ventricular electrode. Since the electrode in the right
atrium is functioning properly, the pacemaker always senses atrial depolarization (P wave) and gives stimulus (spike) from the
ventricular electrode after 150 msec. However it fails to produce wide QRS complex at the expected time since the tip of the
ventricular electrode does not contact the myocardium. When it recurs for the second time a narrow QRS complex nodal
escape beat arises. Thereafter, the ventricular electrode succeeds in stimulating the ventricle (capturing the ventricle)
and produces a pacemaker induced wide QRS complex .
Click here for a more detailed ECG
ECG 1c. The same patient's ECG, still before revision of the electrode. Since the electrode in the right atrium is functioning
properly, the pacemaker always senses atrial depolarization (P wave) and gives stimulus (spike) from the ventricular electrode
after 150 msec. However it fails to produce wide QRS complex at the expected time since the tip of the ventricular electrode
does not contact the myocardium. When it recurs for the second time a narrow QRS complex nodal escape beat arises .
Thereafter, the ventricular electrode succeeds in stimulating the ventricle (capturing the ventricle) for 5 cardiac cycles and
produces pacemaker-induced wide QRS complexes.
Click here for a more detailed ECG
ECG 1d. The above ECG was recorded after repositioning the ventricular electrode. Now, the pacemaker is functioning
normally. Since atrial rate (P wave rate) is fast enough (above the preprogrammed lower limit of the atrial rate of the
pacemaker), the atrial electrode does not stimulate the right atrium. Therefore no spike is seen before the P waves.
As mild change in atrial rate is normal, a change of the interval between pacemaker-induced QRS complexes
following the P waves is also normal.
Click here for a more detailed ECG
ECG 2. Pacemaker dysfunction. Blue arrows show the spikes which successfully resulted in ventricular stimulation.
Red arrow shows the spike which did not succeed in depolarizing the ventricles (pacing dysfunction, failure to capture).
Green arrow shows the ventricular premature beat.
Click here for a more detailed ECG
ECG 3. 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.
Click here for a more detailed ECG
ECG 4a. The ECG above belongs to a 75 years-old woman with left ventricular systolic dysfunction (LVEF 30%).
A CRT-D pacemaker was implanted 4 years ago.
The ECG shows sinus rhythm with left bundle branch block. Pacemaker spikes are not seen.
Click here for a more detailed ECG
ECG 4b. Threshold elevation was detected.
Above correction of threshold problem, pacing started again and the QRS complex width decreased.
Pacemaker spikes reappeared.
Click here for a more detailed ECG
ECG 5a. The ECG above belongs to a 89 years-old man with coronary artery disease and
severe left ventricular systolic dysfunction (LVEF 20%).
The underlying rhythm is atrial fibrillation (fibrillatory waves are best seen in lead V1).
He also has a CRT-D pacemaker which is working in the VVI mode, not biventricular VVI mode.
The purpose of CRT implantation is to make narrow QRS.
However, the paced QRS complexes in this patient are wide, as expected for classical VVI pacing.
In this classical VVI mode, the patient does not benefit from the pacemaker: no biventricular pacing,
no resynchronization, no benefit.
Click here for a more detailed ECG
ECG 5b. Above ECG belongs to the same patient. It was recorded after correction of pacing mode.
His pacing mode was switched from VVI pacing to Biventricular VVI pacing and paced QRS complexes are narrow again.
Click here for a more detailed ECG
ECG 6a. The ECG above belongs to a 70 years-old woman who had undergone temporary pacemaker implantation
(in VVI mode) for complete AV block.
Unipolar pacemaker electrode results in large pacemaker spikes .
These pacemaker spikes are followed by pacemaker-induced QRS complexes.
Since pacemaker electrode was not placed appropriately in right ventricle, its tip does not contact endocardium continuously.
This results in inadequate pacemaker stimulation.
When pacemaker stimulation is not in anticipated frequency, the patient's own idioventricular rhythm (ventricular escape rhythm) arises.
Since the underlying rhythm is complete AV block and the pacemaker is in VVI mode, P waves have their own rhythm
P waves are unrelated to QRS complexes.
Click here for a more detailed ECG
ECG 6b. The above ECG belongs to the same woman.
The upper tracing shows regular pacemaker spikes (as programmed).
Now, the pacemaker is functioning normally.
P waves are not related to the pacemaker spikes.
Since this pacemaker is in VVI mode, pacemaker spikes do not follow (P waves).
At first glance, coincidental timing of the last P wave in lead V3 falsely gives the impression that
P wave is followed by ventricular depolarization. However, it is not.
Click here for a more detailed ECG
ECG 6c. The above ECG belongs to the same woman.
At first glance, lead V3 may suggest that this pacemaker fails to sense properly.
However, this pacemaker is functioning properly at this time.
The first pacemaker spike in lead V3 results in wide QRS complex.
The small positive deflection preceding this pacemaker spike is a P wave, not a spontaneously occuring QRS complex
(this is not a fusion beat).
Why not?
The timing of this deflection is in accordance with regularly appearing P waves (interval between P waves).
Click here for a more detailed ECG
ECG 1a. The ECG above belongs to a 65 years-old woman who had been implanted DDDR type pacemaker 2 weeks ago.
As seen in the middle of the tracing, the pacemaker senses atrial depolarization (P wave) by its atrial electrode and after
waiting for a pre-programmed AV delay (150 msec), ventricular electrode gives stimulus (spike) which fails to produce a wide
QRS complex at the expected time (pacemaker fails to capture the ventricle). Thereafter, a short-lasting narrow QRS complex
nodal escape rhythm arises. In this patient, the cause of failure to capture is displacement of the tip of right ventricular
electrode.
Click here for a more detailed ECG
ECG 1b. Another ECG from the same patient, before realignment of the ventricular electrode. Since the electrode in the right
atrium is functioning properly, the pacemaker always senses atrial depolarization (P wave) and gives stimulus (spike) from the
ventricular electrode after 150 msec. However it fails to produce wide QRS complex at the expected time since the tip of the
ventricular electrode does not contact the myocardium. When it recurs for the second time a narrow QRS complex nodal
escape beat arises. Thereafter, the ventricular electrode succeeds in stimulating the ventricle (capturing the ventricle)
and produces a pacemaker induced wide QRS complex .
Click here for a more detailed ECG
ECG 1c. The same patient's ECG, still before revision of the electrode. Since the electrode in the right atrium is functioning
properly, the pacemaker always senses atrial depolarization (P wave) and gives stimulus (spike) from the ventricular electrode
after 150 msec. However it fails to produce wide QRS complex at the expected time since the tip of the ventricular electrode
does not contact the myocardium. When it recurs for the second time a narrow QRS complex nodal escape beat arises .
Thereafter, the ventricular electrode succeeds in stimulating the ventricle (capturing the ventricle) for 5 cardiac cycles and
produces pacemaker-induced wide QRS complexes.
Click here for a more detailed ECG
ECG 1d. The above ECG was recorded after repositioning the ventricular electrode. Now, the pacemaker is functioning
normally. Since atrial rate (P wave rate) is fast enough (above the preprogrammed lower limit of the atrial rate of the
pacemaker), the atrial electrode does not stimulate the right atrium. Therefore no spike is seen before the P waves.
As mild change in atrial rate is normal, a change of the interval between pacemaker-induced QRS complexes
following the P waves is also normal.
Click here for a more detailed ECG
ECG 2. Pacemaker dysfunction. Blue arrows show the spikes which successfully resulted in ventricular stimulation.
Red arrow shows the spike which did not succeed in depolarizing the ventricles (pacing dysfunction, failure to capture).
Green arrow shows the ventricular premature beat.
Click here for a more detailed ECG
ECG 3. 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.
Click here for a more detailed ECG
ECG 4a. The ECG above belongs to a 75 years-old woman with left ventricular systolic dysfunction (LVEF 30%).
A CRT-D pacemaker was implanted 4 years ago.
The ECG shows sinus rhythm with left bundle branch block. Pacemaker spikes are not seen.
Click here for a more detailed ECG
ECG 4b. Threshold elevation was detected.
Above correction of threshold problem, pacing started again and the QRS complex width decreased.
Pacemaker spikes reappeared.
Click here for a more detailed ECG
ECG 5a. The ECG above belongs to a 89 years-old man with coronary artery disease and
severe left ventricular systolic dysfunction (LVEF 20%).
The underlying rhythm is atrial fibrillation (fibrillatory waves are best seen in lead V1).
He also has a CRT-D pacemaker which is working in the VVI mode, not biventricular VVI mode.
The purpose of CRT implantation is to make narrow QRS.
However, the paced QRS complexes in this patient are wide, as expected for classical VVI pacing.
In this classical VVI mode, the patient does not benefit from the pacemaker: no biventricular pacing,
no resynchronization, no benefit.
Click here for a more detailed ECG
ECG 5b. Above ECG belongs to the same patient. It was recorded after correction of pacing mode.
His pacing mode was switched from VVI pacing to Biventricular VVI pacing and paced QRS complexes are narrow again.
Click here for a more detailed ECG
ECG 6a. The ECG above belongs to a 70 years-old woman who had undergone temporary pacemaker implantation
(in VVI mode) for complete AV block.
Unipolar pacemaker electrode results in large pacemaker spikes .
These pacemaker spikes are followed by pacemaker-induced QRS complexes.
Since pacemaker electrode was not placed appropriately in right ventricle, its tip does not contact endocardium continuously.
This results in inadequate pacemaker stimulation.
When pacemaker stimulation is not in anticipated frequency, the patient's own idioventricular rhythm (ventricular escape rhythm) arises.
Since the underlying rhythm is complete AV block and the pacemaker is in VVI mode, P waves have their own rhythm
P waves are unrelated to QRS complexes.
Click here for a more detailed ECG
ECG 6b. The above ECG belongs to the same woman.
The upper tracing shows regular pacemaker spikes (as programmed).
Now, the pacemaker is functioning normally.
P waves are not related to the pacemaker spikes.
Since this pacemaker is in VVI mode, pacemaker spikes do not follow (P waves).
At first glance, coincidental timing of the last P wave in lead V3 falsely gives the impression that
P wave is followed by ventricular depolarization. However, it is not.
Click here for a more detailed ECG
ECG 6c. The above ECG belongs to the same woman.
At first glance, lead V3 may suggest that this pacemaker fails to sense properly.
However, this pacemaker is functioning properly at this time.
The first pacemaker spike in lead V3 results in wide QRS complex.
The small positive deflection preceding this pacemaker spike is a P wave, not a spontaneously occuring QRS complex
(this is not a fusion beat).
Why not?
The timing of this deflection is in accordance with regularly appearing P waves (interval between P waves).
Click here for a more detailed ECG