Wednesday, 8 January 2014

ECG of the Week - 6th January 2014 - Interpretation

This week's case is from a 97yr old presenting with presyncope. I've included two ECG's as they were performed only 1 minute apart.
A little more information the patient presented with episodic dizziness and pre-syncope for several weeks. Only meds were an angiotensin receptor blocker and an anti-histamine. She was functionally living independently but using walking aids.

Check out the comments on our original post here.




ECG 1
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ECG 1 Numbered Version
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ECG 1

Rate:
  • Mean ventricular rate 42 bpm
  • Atrial rate 78 bpm
Rhythm:
  • Complexes # 1, 2, 3, 4, 6, 7, 8
    • Preceded by P wave
  • Progressive PR lengthening from complexes 1 & 2
    • 240ms --> 280ms
  • Non-conducted atrial complexes between complexes # 2 & 3, 3 & 4, 6 & 7
  • PVC
    • Complex #5
Axis:
  • LAD
Intervals:
  • PR - Prolonged (~240ms)
    • Complexes #1, 3, 4, 6, 7 , 8
    • Complex # 2 PR ~280ms
  • QRS - Normal (100ms)
  • QT - 400ms
Segments:

  • ST Elevation leads III, aVF, V2-4 (all <1mm)
  • Nil ST depression

Additional:

  • Late R wave transition
  • Near voltage criteria for LVH
Interpretation:
  • Initial 2nd Degree AV Block (Mobitz I)
  • 2:1 AV Block
  • Single PVC



ECG 2
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ECG 2 Numbered Version
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ECG 2

Rate:
  • Mean ventricular rate 42 bpm
Rhythm:
  • Sinus complexes 
    • Complexes #3 & 4
  • Junctional escape rhythm
    • Complexes # 1, 2, 6, 7
  • Premature Junctional Complex
    • Complex #5
  • Atrial activity
    • Notching in and after T wave complex #1
    • Notching within T wave complex #4
    • After T wave of complex #7
Axis:
  • LAD (-33 deg)
Intervals:
  • QRS - Normal (100ms)
  • QT - 400ms (QTc Bazette ~ 430 ms)
Segments:
  • ST Elevation leads III, aVF, V2-3
Additional:
  • Late R wave transition
  • Near voltage criteria for LVH
Interpretation:

  • Junctional escape rhythm with intermittent sinus and premature junctional complexes
EP Questions

Our electrophysiologists have looked over these ECG's and posed some questions to think about.

ECG 1 
If you measure very carefully the P-P interval during 2:1 AV block, you will find that the P-P either side of a conducted QRS is shorter then the P-P with no QRS in between.  
  • What is this called, and what is the physiology behind it ?

ECG 2 
After the first QRS there is a p wave right on the end of the QRS and another just after the T wave which is 600 msec (100bpm) after the QRS.  
  • Why didn't this second P wave conduct if it is not complete heart block?


What happened ?

The patient was asymptomatic at rest in the Emergency Department and symptoms had been variable over the preceding weeks.
The patient was admitted under the cardiology team and during her in-patient stay remained relatively asymptomatic despite multiple cardiac rhythm changes, including Mobitz I, Mobitz II, and Complete Heart Block, with ventricular rates as low as 30 bpm being well tolerated.

Echo showed:

  • Mild / Moderate Aortic Stenosis
  • Moderate Pulmonary Hypertension
  • Mitral Stenosis with Moderate Mitral Regurgitation
  • Severe Left Atrial Dilation
  • Normal LV function

Following discussion with the patient and given her functional status a PPM was inserted.

Incidentally she was seen in the Emergency Department over 18 months following PPM insertion for an unrelated problem and remained living independently and enjoying an active lifestyle.

References / Further Reading

Life in the Fast Lane

  • 2nd Degree AV block Mobitz I here
  • Fixed ratio AV block here
  • Premature junctional complex here
Textbook
  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.