Posted by: medicblog999 | April 9, 2010

ECG Geek 7 – Update

heart-angiogram-sd3453-gaRight then, one major thing that needs pointing out.

The final ECG shown in the last post was actually 3-4 minutes BEFORE the patient arrested. That is not a post arrest ECG. In the original post, I stated that “3 mins after this last ECG, the patient arrested”.

That may change some of your interpretations of these ECGs.

All of the answers have been interesting so far, but a couple have been a little puzzling. There are a couple of interesting comments on the JEMs facebook page too, so go and have a look at them.

No one has specifically mentioned the one thing I was looking at and wondering about, which makes me wonder if I am going right down the wrong path this time.

Here is my interpretation – rightly or wrongly (deep breath, and opening myself up for ridicule!!)

It is obviously a regular rhythm but the poor data quality may be the reason why some thought of AF. I was going down the path of thinking a LAFB as Matt suggested in the comments, but Toms reply to that has made me look again. I still cant come to a definative interpretation myself yet and am looking forward to hearing more from Tom.

I saw the ST depression as ischaemia in the lateral leads, even with the discordant T waves, but what really interests me and what I cannot explain is the change in the V2, V3 leads moving through the tracings (especially V3)

There is obviously very deep q waves present, but looking through the 4 ECG strips, I see the remainder of the QRS complex changing as we move closer to the arrest. If you look closely at V3 on all of the ECGs (see below from top left to bottom right) the RS wave following on from the q wave seems to be developing and makes a noticable change especially from ECG 3 to ECG 4. This may be nothing specific, but I am wondering if this was actually ST elevation developing in the presence of an old Q wave infarct. If the patient hadnt arrested, would the S wave continued on its journey upward to then show positive ST elevation?

File1-ECG Crops

Click to Enlarge

As I said initially, I may be barking completely up the wrong tree here, but that is what I am thinking and that is what I am hoping someone cleverer than I can tell me.

I have managed to find out what happened post arrest, after I asked the crew to go and get some information for me….

After the patient arrested, his ECG showed an acute Anterior/Lateral MI. He was transferred to the PPCI centre which the crew had tried to get him into already, where he was stented, and by all accounts made a fair recovery. They could not get his post arrest ECG to share unfortunately, but the staff sis tell them that there was clear ST Elevation in the Anterior leads.

So what do you think? Does this confuse matters more? Are I trying to look too deep into something? Do I just have it wrong?

Let me know.

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Responses

  1. As a cardiac technician at a local heart center I see stuff like this all the time. What this probably is is SR With low atrial focus, which gives it the impression that if its irregular (which i cant tell without a full 6 sec. strip) I do see what looks like a T Wave abnormality as well which could be a pre-cursor to a STEMI or it could just be an electrolyte issue. But without the entire strip I cant tell you anything else

  2. I may be wrong, but I don't believe the S-wave and ST-segment have that much correlation. If the S-wave continued on it's journey, I believe it would simply become positive; without subsequent changes of the ST-segment. There is definitely a progressive change, even in the T-wave. Maybe the remaining left fascicle is lacking adequate perfusion, with this being the beginning of a LBBB. Very interesting finding here though, I am curious to see what Tom thinks. I know he concluded LVH before, but that doesn't explain the MI.

  3. Tom's statement was confusing enough, the follow up just ads to it. Kudos on the people involved to keep this guy alive and well. Can't wait for more discussion on the interpretation of the 12 Leads. Thanks again Mark for posting the case.

  4. Sometimes it's helpful to think in terms of risk stratification rather than a specific diagnosis when the ECG is equivocal. If a patient has signs and symptoms of ACS, the emergency physician acts as the gatekeeper to the hospital's resources and is responsible to set the patient out on the correct trajectory. This a physician-level skill that requires a lot of education, training, and experience. It's part of the art of medicine.Some of the factors to be considered are the patient's age, risk factors for CAD, documented presence of CAD, aspirin use within 24 hours, severity of signs and symptoms, ST-segment changes (dynamic ST-segments and T-waves), and/or positive troponins.In this case, the history of the present illness, the patient's signs and symptoms, and most importantly, the fact that the patient experienced cardiac arrest, all combine together to suggest an extremely high risk patient that should be cathed as early as possible. As for the ECG itself, I'm leaning against LAFB for several reasons, but mostly because the lateral leads look like a strain pattern to me. In addition, with LAFB an S-wave usually persists all the way through to lead V6. Regardless, whether it's LVH, LAFB, incomplete LBBB, or some other thing, it's enough of a baseline abnormality to take the ST/T complexes with a grain of salt. So again, I would consider this an equivocal ECG.The serial ECGs show changes. That's bad, and would increase the patient's risk score. Beyond that, it's a mistake to interpret an ECG in isolation. It's just one piece of the puzzle. Do these ECGs show STEMI? No, they do not. That doesn't mean it's not a very sick patient who is experiencing life-threatening ACS.

  5. Tom, out of interest I am going to question your response. Why couldn't it be LAFB with LVH? A dominant S-wave through to V6 or just the presence of one? I had never heard of precordial changes from LAFB other than when the entire Left bundle is blocked. You remain the master.

  6. Adam – Just an observation. When LAFB is present there is usually a late (or no) transition in the precordial leads. It's not uncommon for the equiphasic lead to show up in lead V6. Even when the transition happens in V3 or V4 I don't think I've ever seen a LAFB with a monphasic R wave in lead V6. Tom

  7. as the dictum says treat the patient not the machine. based on the clinical hx I will go for MI. Maybe they could have managed pt as non ST MI and could have started heparin if they are waiting of cath. As per ECG, I am not so sure of SR with low atrial focus. I think the old name low atrial rhythm is now JR. It cannot also be low atrial rhythm becasue of obvious p waves in lead II.Just fot the sake of discussion…my computed QTc is prolonged though not very prolonged. the Qrs pattern is interesting on V2 and V3. Can anybody explain this phenomenon? Second on the discussion of LAFB., by “excitement” left axis deviation, rS in II,III, AVF, qR in I/aVL – fits all the criteria. LAFB mimics other entities – one of w/c is anteroseptal MI as in this case. QS in V1 and V2 and qR in aVL. So my vote goes against LAFB. Can anybody see a delta wave or I am just imagining? In ecg 4 lead II there is a hump in the take-off of the R. Though there is no short RP.

  8. as the dictum says treat the patient not the machine. based on the clinical hx I will go for MI. Maybe they could have managed pt as non ST MI and could have started heparin if they are waiting of cath. As per ECG, I am not so sure of SR with low atrial focus. I think the old name low atrial rhythm is now JR. It cannot also be low atrial rhythm becasue of obvious p waves in lead II.Just fot the sake of discussion…my computed QTc is prolonged though not very prolonged. the Qrs pattern is interesting on V2 and V3. Can anybody explain this phenomenon? Second on the discussion of LAFB., by “excitement” left axis deviation, rS in II,III, AVF, qR in I/aVL – fits all the criteria. LAFB mimics other entities – one of w/c is anteroseptal MI as in this case. QS in V1 and V2 and qR in aVL. So my vote goes against LAFB. Can anybody see a delta wave or I am just imagining? In ecg 4 lead II there is a hump in the take-off of the R. Though there is no short RP.


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