ECG of the Week – 19th March 2018 – Interpretation

The following ECG is from an 85 yr old male who presented with dizziness and an abnormal gait.

 
Click to enlarge

Rate:

  • Mean ventricular rate 60 bpm

Rhythm:

  • Irregular ventricular complexes
  • Flutter / fib waves best seen in leads aVF & V1

Axis:

  • LAD

Intervals:

  • QRS – Normal (80ms)

Additional:

  • Early R wave transition between V1 & V2
  • Subtle ST depression leads V4-6
  • Flat T wave lead aVL
Interpretation:
  • Atrial fibrillation
    • Rate controlled

Considerations in atrial fibrillation There are a number of things to think about when encountering a patient with atrial fibrillation.

  • Onset
    • Acute vs chronic
    • Duration
  • Rate disturbance
    • Rapid ventricular response
    • Normal rate
    • Bradycardia – may be secondary to therapy or tachy/brady syndrome
  • Complication of AF
    • Cardiac failure
    • Hypotension
    • Ischaemia
    • Thromboembolic / CVA
  • Current therapy
    • Anti-coagulation
    • Anti-arrhythmics
    • Complications of therapy
  • Drug toxicity
    • Bleeding
    • Precipitant / Causative factors
    • Infection / Ischaemia / Structural / Endocrine / Metabolic

Despite being one of the commonest arrhythmia encountered in medicine there is considerable variability in the clinical management of atrial fibrillation. There are a number of international guidelines and protocols regarding AF management, including:

AF Related Calculators (links to MDCalc)

What happened ? This patient had known chronic atrial fibrillation and acute presentation was secondary to an acute embolic CVA.
References / Further Reading

 
Life in the Fast Lane

Textbook

  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.

ECG of the Week – 12th March 2018 – Interpretation

The following ECG is from a 76 yr old male who presented with a 3 week history of progressive shortness of breath and occasional chest heaviness.

 
 
Click to enlarge

Rate:

  • Mean ventricular rate 36 bpm
  • Mean atrial rate 72 bpm

Rhythm:

  • Irregular ventricular rate
    • R-R varies between 1520 – 1680 ms (~36 – 39 bpm)
  • Variability in P-P interval
  • PR prolonged before QRS ~260ms 
  • Apparent 2:1 conduction

Axis:

  • LAD

Intervals:

  • QRS – Prolonged (180ms)

Additional:

  • Voltage criteria for LVH – aVL >11mm
 

Interpretation:

  • 2:1 AV block
    • This is what this ECG appears to show at initial review
    • There is P-P and R-R variability
    • Could represent ventriculophasic sinus arrhythmia although pattern is not entirely predictable
  • Possible CHB
    • QRS Morphology unusual
    • May represent multi-level conduction system pathology
    • ? Isorhythmic dissociation – apparent temporal relationship between P & QRS
  What is Ventriculophasic Sinus 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: 

What happened ?
There was no reversible cause identified for the AV block.
The patient was admitted under cardiology and underwent an uneventful PPM insertion.
  

References / Further Reading
 
 

Textbook

  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.