Diagnostic criteria

  Atrial rate is usually between 150-250/minute but may also be as low as 110/minute .

  Every P wave is
NOT followed by a QRS complex.

  Block is generally 2:1 or 3:1. Wenkebach type block may also be observed.

      Complete AV block is seen very infrequently.

  Since the impulse originates form an ectopic focus, the P wave shape may be different than that of

      the sinus P wave. P wave shape depends on the site of atrial focus.

  Since the impulse originates in the atrium, QRS complexes are expected to be narrow (<120ms).

 
Isoelectric baseline is observed between P waves.


For differential diagnosis

  Atrial flutter : Atrial tachycardia with block is most commonly misdiagnosed as atrial flutter.

      In atrial flutter the atrial rate is
> 250/minute and there is no isoelectric baseline between P waves.

      Instead, the baseline oscillates in atrial flutter. If the atrial rate is between
200-250/minute ,

      it may be difficult to differentiate the two arrhythmias by surface ECG.


  Atrial fibrillation : If block level varies frequently, then atrial tachycardia with block may easily be

      confused with atrial fibrillation at first glance. Atrial tachycardia with varying degrees of AV block is

      expected to show
regularly irregular QRS complexes, while atrial fibrillation is an irregularly irregular

      rhythm.





ECG 1. In the ECG above,
atrial tachycardia with 3:1 block is seen. Only 1 of every 3 P waves is conducted to the ventricles.
The atrial rate is about 200/minute and isoelectric baseline can be observed between P waves.

Dr. Peter Kukla has donated this ECG to our website.

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ECG 2. The above ECG belongs to a patient with subacute cor pulmonale due to pulmonay embolism.
Atrial tachycardia with
complete AV block is seen. P waves are not related to the QRS complexes . There is isoelectric baseline between P waves.
The atrial rate is about 166/minute.

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ECG 3.
Atrial tachycardia with complete AV block during acute inferior wall myocardial infarction. The rate of
P waves (atrial rate) is about 125/minute. P waves are not related to QRS complexes.

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ECG 4. Atrial tachycardia with 3:1 AV block. Of every 3
P waves , only 1 is conducted to the ventricles .
Some P waves are buried in the T waves .

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ECG 5. The ECG above belongs to a 50 years-old woman with postoperative pulmonary embolism. Intravenous amiodarone
infusion was started when she developed atrial fibrillation. Twelve hours later, the ECG above was recorded.
There is "
atrial tachycardia with complete AV block ". The rate of the P waves is approximately 135/minute.
The QRS complexes are NOT related to the P waves. Narrow QRS complexes denote to nodal rhythm.

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ECG 6. The rhythm strip above was recorded during acute inferior myocardial infarction.
Atrial tachycardia with block and
a ventricular premature contraction at the right end of the tracing is seen.

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ECG 7a. The above ECG is from a late admitting, 63 years-old man with acute anterior wall myocardial infarction.
It was recorded one day after stenting of his LAD coronary artery.
Right bundle branch block and sinus rhythm is seen.
Anterior leads show Q waves without ST segment elevation.
In addition, 1st degree AV block and left posterior fascicular block are also seen.

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ECG 7b. The above ECG was recorded a few hours after the ECG 7a and shows
atrial tachycardia with complete AV block.
The P waves of the above ECG have a different configuration than that of the P waves in ECG 7a:
ectopic atrial tachycardia
with block
.
The wide QRS complexes do not resemble the wide QRS complexes of right bundle branch block: idioventricular rhythm.

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ECG 8a. The ECG above is from a 83 years-old woman who had applied to the hospital 2 days after acute anterior wall
myocardial infarction. This ECG was recorded just before stenting of her LAD coronary artery.
She had a normal dominant Cx coronary artery and a normal RCA.
The rhythm is atrial tachycardia with complete AV block.
While
many of the P waves are easily discernible, the ones on the QRS complex are indiscernible.
Some are hard to notice.

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ECG 8b. The above ECG belongs to the same woman. It was recorded one day after stenting of her LAD coronary artery.
Atrial tachycardia with complete AV block is not present any more.
The limb leads of the above ECG was recorded at a calibration of 20mm/mV.

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ECG 9a. The ECG above belongs to a 46 years-old woman.
Because of complete AV block, she had undergone a DDDR pacemaker implantation 5 years ago.
This ECG was recorded at a calibration of 10 mm/mV.

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ECG 9b. The ECG above belongs to the same woman.
It was recorded immediately after the ECG 9a (this time at a calibration of 20 mm/mV).
Pacemaker spikes are seen. Ventricles are stimulated by the pacemaker.
However the
atrial rate is about 200-230/minute. P wave rate is compatible with atrial tachycardia.
Due to coincidental timing,
some P waves are buried in the ST segment.
Atria and ventricles are depolarizing independently: complete atrioventricular (AV) block.
The rhythm is
atrial tachycardia with block and ventricular pacemaker rhythm.
P waves are seperated by a flat baseline: no atrial flutter.

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ECG 10a. The ECG above belongs to a 85 years-old woman with coronary artery disease.
She complains of palpitation. Right bundle branch block is seen.
The heart rate is 121/minute. What is the rhythm?
Is it sinus tachycardia? Can you see the P waves?
Do you think that the PR interval is normal? Is it sinus tachycardia?
At a ventricular rate of 121/minute, it is easy to misdiagnose this rhyhtm as sinus tachycardia, at first glance.

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ECG 10b. The ECG above belongs to the same woman.
It was recorded 30 seconds after the ECG 10a.
What is the rhythm?
Do you see the P waves? Do you think that the PR interval is normal?
Do you think that there is sawtooth appearance?

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ECG 10c. The above rhythm tracing belongs to the same woman.
It was
recorded at a calibration of 20 mm/mV to better see the details.
P waves are clearly seen. Atrial rate (P wave rate) is 240/minute.
Not all P waves are conducted to ventricles. This is
ectopic atrial tachycardia with block.
This is not atrial flutter, there is no sawtooth appearance: a flat baseline between the P waves is seen.
Since frequent temporary increases in AV block level revealed ectopic P waves, we did not need to use Adenosine
in this patient.

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ECG 10d. The above rhythm tracing belongs to the same woman.
It was
recorded at a calibration of 10 mm/mV
P waves are seen. Not all P waves are conducted to the ventricles.
This is
ectopic atrial tachycardia with block.
Since frequent temporary increases in AV block level revealed ectopic P waves, we did not need to use Adenosine
in this patient.

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