Skip to main content
Hi all. This is a case from a few days ago. I loved it, as it was one of those slam dunk diagnosis, even when everything looked normal, thanks to the ECG. A 63 year old woman presents with sudden onset of shortness of breath. It began, whilst she was in the supermarket, shopping. The shortness of breath only occurs on exertion. She has a past medical history of pulmonary embolism 15 years previously, for which she had a 3 month course of Coumadin. Her recent history is of an operation to her lumbar spine 8 weeks previously. On examination she looks comfortable. Vitals are Temp 36.9, HR 90bpm, BP 135/73, Sats 100% on room air. Heart sounds are dual, lung fields are clear, with equal air entry bilaterally. Abdo is soft and there is no leg swelling, nor calf pain. You perform an ECG. Describe the ECG. What might be your diagnosis?
USING THE ECG IN 20 SECONDS Approach to read this:
Now, my differential is Pulmonary Embolism, Pulmonary Embolism and Pulmonary Embolism.
Rate: 15 complexes x 6 = 90
: There are P waves before each QRS and in lead II , P waves are upright inverted in aVR, which means limb leads are on the right way. So sinus rhythm.
QRS: Narrow with normal Morphology Now, in the ECG in 20 SECONDS approach I don’t do axis unless there is a bundle brach block. However in this case as I’m concerned about a potential PE, I want to see if there is Right axis deviation. The QRS’s are positive in I and aVL, so Normal axis.
ST Segments
: There is some ST elevation in leads V2 and V3.
T Waves
: There are inverted T waves in V1-6, II, III and aVF
PR interval is normal, the QT interval is a little borderline, without calculations.
Other things to look for: If I’m concerned about a PE the other things I look for include, right BBB, which does not appear here. How about S1Q3T3 (S waves in I, Q waves in III and inverted T waves in III). This occurs in about 12% of cases of PE. It is present in this case. One other thing I look for is inverted T waves in III and V1. They are present here. They have a specificity of 99% and a positive predictive value of 97% for a PE Am J Cardiol, March 2007. In summary, this ECG increases my suspicion for a pulmonary embolism. In fact, the patient had a CTPA and had bilateral large emboli! The power of this little piece of paper…wow! Let’s remember to keep getting good at it!


  • Brian says:

    I don’t think there’s really an S1Q3T3 pattern, as there’s a small r in front of the ‘Q’ wave. Honestly, though, I don’t really find that sign all that useful, as despite being touted as “pathognemonic” it’s really neither sensitive or specific for PE.

    This ECG also demonstrates another soft sign for PE, the incomplete RBBB.

    All in all, great case!

    • admin says:

      Good points. The S1Q3T3 isnt that strong I agree. I must admit, when I see it however, and the story’s good, I get a warm feeling.

  • VinceD says:

    What Christopher said…
    Just out of curiosity, was this patient rather obese? Those are some pretty small complexes in the lateral precordials.

    Nice pickup, and thanks for sharing

Leave a Reply