Wednesday, 5 December 2012

ECG of the Week - 3rd December 2012 - Interpretation


Back to our patient from last week
What happened next ?
 




 
Click to enlarge


Rate:
  • Sinus rate ~35
  • Ventricular rate ~70
Rhythm:
  • Regularly irregular
  • 1:1 Sinus complex : PVC

Sinus complexes

Axis:
  • LAD (<-30 deg)
Intervals:
  •  PR - Normal (~180-200ms)
  • QRS - Prolonged (140ms)
Additional: 
  • rsR' Pattern V1
  • T Inversion aVR, V1, V2
  • Broad Notched P wave Lead II
Intervals:
  • PR - Normal (~200ms)
  • QRS - Normal (100ms)
  • QT - 400ms (QTc Bazette ~ 430 ms)

PVCs

Axis:
  • Inferior (+90 deg)
Intervals:
  •  QRS - Prolonged  (~140-160 ms)
Additional:
  • ST depression & T wave inversion II, III, aVF, V3,4,5

Interpretation:
  • Bigeminy
  • Bifasicular block
  • P Mitrale
What about the notching in V1, V2 ?

  • You can see notching in the ST segments of the PVCs in leads V1 & V2
  • These are most likely retrograde p waves as highlighted by Christopher in his comments.
  • They are not really visible in the inferior leads so we can't see whether they have the inverted morpholgy expected from retrograde conduction
  • I'm unsure as to their origin or significance and I've asked our cardiology blog members to have a look and will update this post with their thoughts.
  • There is a nice case with retrograde p waves here from The ECG Blog.

Update

Our cardiology blog memebers have cast their expert eye over this week's ECG and given us their thoughts:

  • The ectopic beats have a LBBB like morphology
    • High to low activation in leads II,III and aVF
    • Early transition from negative QRS complex to positive QRS complex in lead V2-V3
    • The differential diagnosis indicates a left coronary cusp of the aortic valve source of ectopy and the anteroseptal right ventricular outflow tract source of ectopy.
  • On the ST segment notching
    • The differential is a p wave or artefact.
    • If it was a retrograde p wave, the morphology would not be upright but rather inverted which makes this unlikely.
    • If it is an antegrade p wave, then it is likely to be a non conducted p wave due to retrograde concealed conduction from the ventricular ectopic up to the AV node. I think this is the most likely diagnosis. 
They have also recommended two papers worth reading, linked to below.
 
  • Bala R, Marchlinski FE. Electrocardiographic recognition and ablation of outflow tract ventricular tachycardia. Heart Rhythm. 2007 Mar;4(3):366-70. Epub 2006 Nov 17. PMID: 17341405 Full text here.
  • Haqqani HM, Morton JB, Kalman JM. Using the 12-lead ECG to localize the origin of atrial and ventricular tachycardias: part 2--ventricular tachycardia.J Cardiovasc Electrophysiol. 2009 Jul;20(7):825-32. PMID: 19302478

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.