This is the conclusion to 54 year old female CC: BLS intercept.
I did not expect to get so many comments! Great discussion on many points. It even afforded an opportunity to review atrioventricular blocks.
Going back to the case let’s look at the initial 12-Lead ECG.
As many readers noted, there is a lot of baseline wander. This is not the most helpful of 12-Leads. On scene the crew attempted multiple 12-Leads, however, the patient would not sit still and that was the best one.
I think a close look at the Initial 12-Lead has enough information to make a field diagnosis.
Leads III and aVF have subtle ST-elevation and Q-waves, which without any cardiac history are likely new. More importantly, the ST-elevation in III and aVF is proportionately large compared to the QRS amplitude. Leads aVL, V2, and V3 all have at least 1mm of ST-depression without question. I’ve borrowed Tom’s technique of using PowerPoint to stretch the leads vertically while preserving the ST/QRS ratio to help illustrate these findings.
Is ST-elevation present in two or more contiguous leads?
Additionally, we should take into account all of our findings which strongly suggest an MI.
- Chest pain which awoke the patient from sleep
- Left sided paresthesia
- ST-elevation in two contiguous leads, with reciprocal changes
- 3° AV Block, with a junctional escape
This constellation of findings would be expected with an occlusion of the RCA, potentially with right ventricular and/or posterior involvement. We can solidify our hunch with knowledge that the AV node is fed by the RCA in right-dominant individuals. ST-elevation in Lead III > Lead II is suggestive of RCA occlusion.
The crew in this case activated the cath lab from the field. They gave 324 mg ASA, started bilateral lines, gave multiple fluid boluses, placed pads for pacing, and administered 0.5 mg atropine while preparing the patient for transcutaneous pacing.
At the receiving facility, after they switched to the ED’s monitor, the patient’s rhythm changed to a 2° AV Block Type II with a ventricular rate of 70, easily palpable radials, and improved skin color.
In the cath lab, the following was found:
Diagnosis: Acute ST-elevation myocardial infarction.