ECG Case 090

70 yr old male who presented following an episode of syncope. Nil significant medical history or medications. He complained of light-headiness at the time of clinical review. BP, Sats, RR, temp and BSL were all within normal limits.

ECG Case 090 LITFL Top 100 EKG

Describe and interpret this ECG

ECG ANSWER and INTERPRETATION

Rate:

  • Ventricular rate 42 bpm
  • Atrial rate 84 bpm

Rhythm:

  • Irregular atrial activity
  • Short P-P (Green) followed by long P-P (Red) – see image below
ECG Case 090b LITFL Top 100 EKG
  • The shorter P-P interval occurs when a ventricular (QRS) complex occurs between the P waves whilst the longer P-P interval occurs when there is no ventricular (QRS) complex between the P waves
  • This phenomenon is known as Ventriculophasic Arrhythmia
  • 2:1 AV Block with ventricular (QRS) complexes only occurring after every second P wave

Axis:

  • LAD

Intervals:

  • QRS – Prolonged (160ms)

Segments:

  • Subtle ST elevation leads II, III, aVL

Additional:

  • RBBB Morphology

Interpretation:

  • 2:1 2nd Degree AV Block
  • Bifascicular block
    • RBBB + LAFB
  • Ventriculophasic Sinus Arrhythmia
  • Symptomatic Patient with syncope

OUTCOME

The patient was referred to the cardiology team and had an uneventful PPM insertion.

Ventriculophasic Sinus Arrhythmia

This ECG is a nice example of ventriculophasic arrhythmia, this phenomenon can be seen in up 40% of case of complete AV block and, as in this case, can be seen with 2nd degree AV block also.
You get a shorter P-P interval when there is an associate QRS complex with a longer P-P when there is no QRS between the P waves. Several mechanisms have been proposed including  alterations in sinus node perfusion related to ventricular contraction and the mechanical effects of atrial stretch.

To make things more confusing there is a much rarer paradoxical phenomenon when the P-P is longer when a QRS is contained between them.

It is important to recognized as the P-P variability may be mistaken for other ECG features such as U waves for example.

You can read more about ventriculophasic sinus arrhythmia in this nice case report of the paradoxical version here:


FURTHER READING

TOP 150 ECG SERIES



Emergency Medicine Specialist MBChB FRCEM FACEM. Medical Education, Cardiology and Web Based Resources | @jjlarkin78 | LinkedIn |

2 Comments

  1. How can I in this case distinguish between a ventriculophasic arrhythmia and U-waves? Just because of the concomitant presence of an AV-Block?

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