Saturday, April 16, 2011

Cath lab activated. What do you think? (#2)

This 45 year old male called 911 for increasing SOB and CP over 2 weeks.  His BP was 220/150.  The medics did a prehospital ECG, shown here.  They tried to activate the cath lab, but the message did not get through.

There are several worrisome findings: Upright T-wave in V1, large T-wave with ST elevation in V1-V4.  The medics activated the cath lab based on this.

What the medics did not see is that the S-waves are cut off.  You can see that they are very wide where they are cut off, and if you project them down they will be very deep S-waves.  On arrival, we cancelled the cath lab activation and started a high dose nitroglycerin drip, up to 200 mcg/min. 

We recorded this ED ECG:

This is similar to the above, but does not cut off the S-waves, which you can now see are very deep.
The patient had pulmonary edema due to severe hypertension, and he ruled out for myocardial infarction. 

One must read the ECG in this order: rate, rhythm, axis, interval, QRS (voltage, morphology), ST, T, U.  If you do that here, you will see that the QRS voltage is extremely high. When you see ST elevation, the first thing you must do is determine if it is secondary to an abnormal QRS.  In this case, it is secondary to high voltage, or LVH. 

His SOB resolved with high dose NTG, his maximal troponin I was 0.115 ng/ml (demand ischemia, type II MI).

5 comments:

  1. These are tough. You've probably covered this before, but is there a clear way to say LVH vs. STEMI?

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  2. I am confident that there is some ratio of ST elevation to S-wave depth that is a good cutoff. I am in the process of formally studying it. The best way now is to see many (click on the LVH label-link at the left to see a few), take the clinical context into account (esp, in this case, BP of 220/150), and if necessary, use echo to evaluate the anterior wall.

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  3. The inital ECg appears to meet the Sokolow-Lyon criteria for LVH based on the R wave height in aVL alone (11mm or more).

    nice tips - we had a similar case in our ED in the past week. The paramedics noted ST elevation in V12 and were concerned abot a STEMI. However, the patient turned out to have LVH and trop negative gastroenteritis...
    Chris

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  4. Replies
    1. No. Not wide enough. Q-waves in aVL. Not LBBB.

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