Diagnostic criteria

  Each sinus beat is followed by an atrial premature beat.

  As all beats originate from the atria,

                  o   QRS complexes are expected to be
narrow if they are normally conducted to the ventricles.

                  o   QRS complexes are expected to be
wide if they are aberrantly conducted to the ventricles.

  The premature atrial beat's morphology (shape of the P wave) is different than that of the sinus P wave.

  The premature atrial beat's morphology may be negative but this is NOT a necessity.

      Negativity only shows that the premature beat has originated from a low atrial focus.

  If all atrial premature beats are blocked (not conducted to the ventricles),

      the rhythm may mimick sinus bradycardia, at first glance.

      In this case,
the configuration of conducted P waves and blocked P waves are usually different,

      since they originate from different atrial foci.




References

  Indian Pacing Electrophysiol J 2013;13(3):114-117.

  Heart Rhythm 2013;10(8):1192-1198.

  Congenit Heart Dis 2012;7(5):E82-84.

  Clin Cardiol 1979;2(2):126-130.








ECG 1. Atrial bigeminal rhythm in a young woman.
Every P wave originating from the sinus node is followed by a premature
P wave originating from an ectopic focus
in the atria. The premature P wave is negative in the above ECG, suggesting a
low atrial focus. However, all atrial premature beats should NOT necessarily be negative. Negativity of the P wave is related to
its focus, but not to its prematurity.


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ECG 2a. The ECG above belongs to a 50 years-old man who has normal blood pressure and normal coronary arteries.
he rhythm is atrial bigeminy.
Every P wave originating from the sinus node is followed by a premature P wave originating from
an ectopic focus
in the atria. The premature P wave is negative in the above ECG, suggesting a low atrial focus.
However, all atrial premature beats should NOT necessarily be negative. Negativity of the P wave is related to its focus,
but not to its prematurity. The presence of a PR interval above 120 msec and the absence of a narrow P wave suggests that
this rhythm is not junctional.


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ECG 2b. The same patient's 3-channel Holter recording is seen above.

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ECG 3. Atrial bigeminal rhythm in a 50 years-old man with normal coronary arteries.
The ectopic atrial focus is probably near the coronary sinus ostium.

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ECG 4. Above is an ECG from a 75 years-old man. The left half of the ECG shows
atrial bigeminal rhythm.
The
q waves in inferior leads show old inferior myocardial infarction.

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ECG 5. Atrial bigeminal rhythm is seen in the above ECG.

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ECG 6. Atrial bigeminal rhythm in the above ECG may not be recognized at first glance.

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