EMCrit Podcast 42: A phD in EKG with Steve Smith

Today, I got to interview Dr. Stephen Smith. Dr. Smith is faculty at the Hennepin Program and author of one of the best books on EKGs in the ED, The ECG in Acute MI.

Dr. Smith’s EKG Blog is probably the best free EKG site out there for Emergency Physicians and Intensivists.

Here are the points we covered:

1. Ischemia Doesn’t Localize

If you see depressions in just one anatomic area, think reciprocal changes to subtle ST-elevations elsewhere

2. If you see Inferior Depressions, think High Lateral Wall STEMI

here are two good cases from Dr. Smith’s Blog:

  • Case: This is a 35 yo woman who had LAD occlusion that was very subtle on ECG, but easily seen with inferior ST depression
  • Case: This is one of a high lateral MI due to OM-2 occlusion that shows up mostly with inferior ST depression.

3. Lateral Wall STEMIs are often Subtle

4. Absolute millimeter criteria for STEMI will often fail you, it is the Pattern that Matters.

5. Benign Early Repolarization and LAD Occlusion can look very similar–You may need to do the math.

Dr. Smith derived this formula:

(1.196 x STE60 in V3 in mm) + (0.059 x computerized QTc in milliseconds) – (0.326 x RA in V4 in mm),

where RA is R-wave amplitude and STE60 is ST elevation at 60ms after the J-point relative to the PR interval.

If the value of the formula is greater than or equal to 23.4, it is MI (Sens, spec, accuracy all around 90%); if less, then it’s early repolarization.

  • Case: Here is a case that illustrates this, it shows a very subtle anterior STEMI, and how use of the complicated new rule that he developed. One need not use the complicated rule; among other  features, it was the long QTc of 455ms that made it unlikely to be normal.   The followup ECG is also very instructive.

You can also see a video of the concept

6. If you are calling it BER, there need to be R waves in the Precordial Leads

7. Q-waves can develop instantly after a STEMI

qR waves can develop instantly and are not indicative of poor response to lytics or PCI (J Am Coll Cardiol 1995;25:1084); this concept is not  applicable to a QS pattern.

8. If you see a wide (>190 ms) QRS, think Hyperkalemia

9. The treatment for VT with hyper-K is Calcium, Calcium, Calcium

10. Check Out these Two Other Great Sites

HQMEDED: High Quality Medical Education and Ultrasound

The Prehospital 12-lead ECG Blog which despite the name, is great for all levels

 

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Comments

  1. Might I add that Paramedics should not shy away from Dr. Smith’s blog either! Invaluable resource for us folks in the field, it helps us build our ECG “Spidey Sense”. Thoroughly enjoyed the podcast.

  2. Matt L. Wong says:

    I’m a fourth year med student and coming up I’m doing a month long elective just in EKGs. What would you consider the essential reading list — books, workbooks, or literature — that I should try to cover?

    • Not sure as to your comfort level, but Garcia and Holtz’s 12-Lead ECG: The Art of Interpretation is fantastic at ensuring you have your basics covered. The approach taken in the book considers the clinical correlation along with your electrical findings. You’ll find yourself saying, “consider the company it keeps,” every time you read an ECG. Garcia also has an arrhythmia recognition book along the same lines.

      Amal Mattu and William Brady has a 2 volume set: ECGs for the Emergency Physician. Between the two books you’ll have 400 ECGs explained in either short answer or as a case study. These were great once I got my feet underneath me.

      Some folks will say Marriott’s Practical Electrocardiography is a staple, although I’ve heard the latest edition has numerous errata. Others swear by Dubin’s Rapid Interpretation of EKG’s. I’ve not read either.

      The last text I’d recommend is Chou’s Electrocardiography in Clinical Practice. It has quite a number of example tracings, but is better as a desk reference than a study guide. I use it to look up questions I have about tracings or to get the rules for various findings (e.g. ECG voltage criteria for LVH).

      Online you should utilize Harvard’s WaveMaven as a quiz and reference. It includes other multimedia–such as ultrasound or angiography–with certain cases, and can help bring the clinical diagnosis full circle.

      Hope that helps!

    • I’m biased, of course, but if you want to learn about acute coronary syndrome, then the best is my book: The ECG in Acute MI. However, it is out of print and now even out of stock at Amazon. I am negotiating with the published to make an electronic version, perhaps for iPad or iPhone.

      Next best is “Critical Decisions in Acute Care Electrocardiography” (Eds. Brady and Truwit). I wrote the ACS section of that book, and it is extensive, with many ECGs and cases. The other sections are good, too.

    • Ken Grauer has a series of “pocket books” that are well worth a look. His 12 lead ECG book has an amazing amount of information for a little book. It is cheap and is a very good book for medical students and junior doctors. You can buy it from his web site http://www.kg-ekgpress.com. (I have no connection to the site but have bought multiple copies to give to my students.)

      • I’d second Grauer’s pocket books to get you started. They’ll give you a system for reading EKGs that you can use to tackle tracings. Use the other references mentioned above to then fill in the finer detail.

  3. Great podcast, thank you!
    One situation where Calcium may not be a benign therapy for wide QRS/hyperkalaemia is when there is concomitant digoxin toxicity. Giving truck loads of calcium in this situation will make your dig toxicity worse!

  4. I pursued M.S. in Pharmacology. Currently, I am working on hERG assay. hERG assay is done by patch clamp technique (In vitro electrophysiology) on single cell to assess QT prolongation liability in drug discovery.

    As I work on preclinical electrophysiology, but I am very much interested in clinical electrocardiogram.
    Can you please suggest me any course or Ph.D. speciality in ECG.

  5. Marta K says:

    Hello there!
    I was wondering if someone could explain why ST depressions (Other than reciprocal ones) don’t localize MI.
    Also wondering if T wave inversions do localize?
    Thank you!

Trackbacks

  1. [...] [Click here to read more and to Hear the Podcast] [...]

  2. [...] EMCrit Podcast 42: A PhD in EKG with Steve Smith — could it be that Scott Weingart is turning into the Larry King of EM blog-casting? (minus the 9 or so divorces of course…). Scott press gangs ECG maven Stephen Smith into appearing in the audiosphere. The end result? Some whoppingly useful, but not widely known, insights into how to extract information from squiggly lines drawn on an orange grid. [...]

  3. [...] You can hear Dr. Smith expand on this by listening to him on  EMCRIT podcast 42. [...]

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