For the Record: Can Patients Record Clinical Consultations?

St Emlyns - Meducation in Virchester #FOAMed

Somewhere in the ITV archives is television footage of me, on my first day in the PED as an ST3 doctor, assessing a child with a scald in resus. I knew before I started my six month PEM rotation that the crew weren’t quite finished their filming commitments but at no point had I considered that, […]

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ECG of the Week – 22nd September 2014 – Interpretation

Sorry but I don't have any clinical information on this ECG at all but that hasn't stopped us before.

So what's going on here ?

Check out the great discussion on this ECG in the comments section from our original post.

Click to enlarge

Numbered Ventricular Complexes
Click to enlarge



Rate:
  • Mean ventricular rate 54 bpm
Rhythm:
  • Interesting !
  • P waves
    • Precede all ventricular complexes
    • P waves occur regularly every 760 ms
    • EXCEPT between complexes #2/3, 4/5, 7/8 where the P waves is dropped
    • The gap between the P waves either side of the pause is 1520 ms 
      • i.e. double the normal P-P interval
  • QRS Complexes
    • Progressive PR lengthening
    • Progressive R-R shortening
    • Grouped beatings
    • The dropped QRS is not preceded by a P wave
      • Not just 2nd Degree AV Wenckebach
Axis:
  • Normal
Intervals:
  • PR - Initially normal (180ms) then progressive lengthening
  • QRS - Normal (100ms)
  • QT - 440ms 
Segments:

  • ST Depression leads II, III, aVF, V2-6

Additional:

  • T wave inversion Leads III, aVR, V1-3
  • rSR' Pattern V1
  • Deep inferior Q waves with smaller lateral Q waves
  • Baseline irregularity
  • Lead I rhythm strip makes P waves more difficult to identify

Interpretation

So we have clear evidence of a AV Wenckebach but where do the P waves go ?

Frequent ECG of the Week commenter / ECG author / blogger / legend Ken Grauer shares his thoughts on our missing P waves:

I strongly suspect that there is a blocked PAC that causes the pause (and terminates the Wenckebach cycles) - but unfortunately in the long lead I it is very difficult to be certain of this ... I do think I see tiny-but-real differences in the T wave of the beats that initiate the pause (in lead II for beat #2; in aVF for beat #4; and in V2 for beat #7)

My other theory:

Presence of a 2nd Degree Type II SA exit block in addition to our 2nd Degree Type I AV block !
There is a regular P-P interval with the interval including the dropped P wave being twice that of the normal P-P interval. The causative factors for both types of block are virtually identical - ischaemia, drugs, electrolyte abnormality, cardiomyopathy, myocarditis etc.

Do I have a definitive answer ? No

I don't have any other ECG's or clinical information on this case. A longer rhythm strip, serial ECG's, old ECG's, more clinical information, and ideally lead II as the rhythm strip may shed more light on the likely rhythm disturbance and causative factors.

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.

Normal blood gas values: CO2

Download PDF

Download this Thunderbox Paper:

Normal blood gas values: CO2

 

A Thunderbox is Australian slang for an old style outside toilet that was little more than a drafty wooden shed over a hole in the ground.

They also used a wad of papers (usually out of a magazine or newspaper) stuck on an old piece of wire for toilet paper. Life was rough back then. Hardcore.

These pdf files are a one page overview of a particular topic that you can print out and stick on the door of your toilet (hence thunderbox).

  • They will always be only one page.
  • Sometimes it will be VERY short (just a few lines).

The trick is to make it ONE thing for you to remember before the next paper is published.

To make this work you must commit to posting on your toilet door (you could even consider posting on the toilet door at work) and taking a moment to read over each time you………well, you know. Business.

The goal is to commit each paper to your long-term memory before the end of the week. So repetition is essential (as is business regularity).

Print it, stick it, study it.

Pinpoint Pupils

Which of the following does not cause miosis?

a) Clonidine

b) Pilocarpine

c) Scopolamine

d) Pontine bleed

e) Edrophonium

c) Scopolamine: anticholinergic medication (hence may cause mydriasis but not miosis), used for motion sickness, postoperative nausea and vomiting, sometimes used in the units to control secretions

Clonidine is an opioid mimic hypertensive medication

Pilocarpine is a parasypathomimetic medication used to treat glaucoma or dry mouth

Pontine bleed causes miosis due to compression of descending sympathetic fibers in the pons, which resulting in unopposed parasympathetic input and subsequent b/l miosis

Edrophonium is a cholinergic medication used often in diagnosis/treatment of myesthenia gravis

 

Per Rosh review, a good mnemonic for remembering meds that cause miosis is “COPS”

C – cholinergics and clonidine

O – opioids and organophosphates

P- phenothiazines, pilocarpine, pontine bleed

S- sedative hypnotics

 

Pinpoint Pupils

Which of the following does not cause miosis?

a) Clonidine

b) Pilocarpine

c) Scopolamine

d) Pontine bleed

e) Edrophonium

c) Scopolamine: anticholinergic medication (hence may cause mydriasis but not miosis), used for motion sickness, postoperative nausea and vomiting, sometimes used in the units to control secretions

Clonidine is an opioid mimic hypertensive medication

Pilocarpine is a parasypathomimetic medication used to treat glaucoma or dry mouth

Pontine bleed causes miosis due to compression of descending sympathetic fibers in the pons, which resulting in unopposed parasympathetic input and subsequent b/l miosis

Edrophonium is a cholinergic medication used often in diagnosis/treatment of myesthenia gravis

 

Per Rosh review, a good mnemonic for remembering meds that cause miosis is “COPS”

C – cholinergics and clonidine

O – opioids and organophosphates

P- phenothiazines, pilocarpine, pontine bleed

S- sedative hypnotics