Thursday, November 20, 2008
NSTEMI with subtle ST depression.
EKG from 11-12. Symptoms on 11-12 were also subtle, but present for 5 days, so if a single troponin was sent, it might have been positive. Pt. returned 2 days later (11-14) with similarly difficult symptoms [right neck pain, bilateral foot swelling (due to increase in amlodipine dose), recurrent abd pain (CT 2 days earlier had shown massive amount of stool), BRBPR and heme positive stools, and an aside that this abdominal pain goes up "into my esophagus and left neck." The ECG shown is from 11-12 and is the most diagnostic, with ST depression in V4 and V5. V3 is slightly negative. There is also a long QTc (484ms) and large T waves in V2-V4. These "hyperacute" T waves can be due to acute LAD ischemia OR due to posterior reperfusion (patient is pain free, posterior wall motion abnormality, posterior artery). In this case it is the latter. REMEMBER: in V2 and V3, there is almost always some ST elevation. Absence of ST elevation may be relative depression. A troponin on 11-14 was 2.0 and going down. It might have been much more elevated if measured on 11-12. The ECG pon 11-14 had very minimal ST depression. Cath showed occluded RCA and large OM, 80% LAD (severe 3-vessel disease).
THE SECOND CASE is ST depression from hypokalemia. The patient was a 17 year old with syncope. She has tachycardia of unknown etiology. There is diffuse ST depression. There is no CP or SOB. I guessed it would be 2.4, but it was actually 3.0. There is more ST depression than one usually finds with a K of 3.0. Notice there is a bump just before the P wave (leads II, III, V3-V5). One might be tempted to call this a T-wave. But it is a U-wave. The ECG completely normalized with K supplementation.
Monday, November 10, 2008
65 yo male with recent rule out presents with unrelated complaint but also states he is SOB.
What are the worrisome EKG findings, and what is the differential diagnosis? What is the most likely diagnosis? What info would you like to have to make a decision?
LV aneurysm with Right Bundle Branch Block
This is a really hard one. But we had a patient 10 years ago who received tPA twice for an EKG like this before we reali zed that it was old MI with persistent ST elevation. LV aneurysm (persistent ST elevation after old MI) usually has no (or minimal) R-wave. But RBBB automatically provides an R' wave, which makes it difficult to realize that the anterior wall is dead. Additionally, RBBB with acute MI can look very similar. That is why, before you diagnose RBBB with acute MI, you should see if there is a previous EKG. In this case, the previous EKG was found and looked pretty identical. Previous echos confirmed dense anterior, septal, and apical wall motion abnormality with akinesis (I don't think there was dyskinesis).
Friday, November 7, 2008
This patient presented with alcohol intoxication and possible overdose. No ischemic symptoms.
There is ST depression in V4-V6 (minimal). She is in alcohol intoxicated: high risk for hypokalemia.
Differential of ST depression is:
Secondary to abnormal QRS (LVH, LBBB, RBBB, etc.)
This patient had a K of 2.8. Difficult case because she does not have prominent U waves (though they are there). I just finished a study of patients with proven hypokalemia compared to a control group. The QTc was the single best differentiator, with 450 ms the best cutoff. ST depression had good specificity but very poor sensitivity. Prominent U-waves were specific but not sensitive, and presence of any U-wave was sensitive but not specific. The best combination of factors was: Subjective diagnosis + QTc > 450 + Prominent U-waves, vs. none of the 3, with sensitivity of 86%, specificity of 100%, and accuracy of 92%. This held true when the subjective interpretation was done by residents who had had a short tutorial by me.