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.





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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