Diagnostic criteria

  Heart rate is 40-60/minute.

  QRS complexes are
narrow ( <120ms ) since the impulses do not originate from the ventricles.

  This is the AV nodal rhythm that arises that arises when no impulse arises from sinus node

      or ectopic atrial focus (
atrial mutism).

      Therefore no P waves precede QRS complexes.




References

  Neth Heart J 2012;20:294-295.

  N Engl J Med 1988;318:358-365.

  Josephson ME. Clinical cardiac electrophysiology: techniques and interpretations.

      Lippincott Williams & Wilkins, 2008:226.






ECG 1. Junctional rhythm. Narrow QRS complexes with no preceding P waves.

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ECG 2. Junctional rhythm in another patient. P waves are absent and QRS complexes are narrow.

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ECG 3. This heart failure patient under digoxin therapy also has accompanying hypothyroidism. There are intermittent
nodal
beats
with no preceding P waves. Some sinus beats have P waves preceding the QRS complex. The U waves are best seen in
middle chest leads (in C2 of the above figure) and especially during bradycardia. The amplitude of the
U wave increases in
patients under digoxin treatment
.

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ECG 4. (Idio)nodal rhythm. P waves are not seen. QRS complexes are narrow. Heart rate is about 40/minute.

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ECG 5a. The ECG above belongs to a 58 years-old man with chest pain and shows acute inferior myocardial infarction.
There is also nodal rhythm. No P waves preceed QRS complexes. The
ST elevation and tall T waves in inferior leads show
acute inferior myocardial infarction. The
ST segment depression in I, aVL and anterior leads are reciprocal changes.
After this ECG was recorded, the patient underwent immediate coronary angiography and the right coronary artery was
stented successfully.

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ECG 5b. The next day, nodal rhythm disappeared and sinus rhythm was restored. Second beat from the left is atrial premature
contraction. There are only
small q waves to suggest old inferior myocardial infarction.

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ECG 6. The ECG above belongs to a 67 years-old woman who is taking Digoxin.
There is (idio)nodal rhythm and right bundle branch block.
P waves are absent. QRS complexes are wide.

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ECG 7. The 3-channel rhythm tracing above shows junctional rhythm and
retrograde atrial activation which results in the
appearance of
negative P waves in the ST segment.
The heart rate is about 40/minute. The narrow QRS complexes lack preceding P waves (nodal rhythm).

The ECG above has been donated by Assoc. Prof. Dr. Ilyas Atar to our website.

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