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Inferior Wall M.I. With Subtle ST Elevation

Submitted by Dawn on Sun, 07/08/2012 - 20:34

When students are learning to recognize ST elevation M.I. (STEMI), they often want to know, "How many blocks does the ST segment have to be elevated for it to be a STEMI?". Counting blocks simply does not work. Depending on the experience level of your students, it is important to introduce other characteristics of the ST elevation.

Even subtle elevations can indicate acute M.I. when other features are present. These include, ST elevation in related leads, a flat or coved upward ST segment, associated signs such as T wave inversion and pathological Q waves, reciprocal depressions, and of course patient presentation.

This ECG shows subtle ST elevations. The LifePak 15 (PhysioControl) has read it as "Meets ST Elevation MI Criteria". LifePak 15 uses the University of Glasgow criteria, which takes into consideration the age and gender of the patient, among other things. The paramedics who cared for this patient were confused because she had chest pain, and the LifePak said she had MI criteria, but they counted blocks and did not find 1 mm ST segment elevation as they were taught. To the experienced eye, of course, this ECG looks like the CLASSIC inferior wall MI, with the classic bradycardia (junctional rhythm) often seen. This patient was evaluated in the cath lab, and treated for acute STEMI.

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AWMI With Recent IWMI

Submitted by Dawn on Fri, 02/24/2012 - 21:10

Patient AW103: This 88 year old woman had been sick for several days, but had not sought treatment. Her family found her nearly unresponsive and called 911. She presented to the Emergency Department as a STEMI Alert, and was in cardiogenic shock, with very poor perfusion. The ECG from the ED shows a large antero-lateral M.I., with ST elevation in V2 through V6, and also I and aVL. In addition, there are pathological Q waves, indicating necrosis, in the precordial leads, V2 through V6. The inferior wall leads, II, III, and aVF, also have pathological Q waves and abnormally shaped ST segments - no longer distinctly elevated, but coved upward.

This is a good tracing to teach students about Q waves and "old", "new", and "recent" M.I., and also about the clinical effects of hypokinesis or akinesis of the ventricles.

Unfortunately, this patient suffered a cardiac arrest in the cath lab while having her LCA reperfused with balloon angioplasty. She was resuscitated, on a ventilator and intraaortic balloon pump, and admitted to the CVICU, where she passed away within a few hours.

You will find photos from her cardiac cath in the Other Instructor Resources section, labelled as patient AW103. Click here for RCA Image, LCA Occluded Image, LCA Angioplasty Image. Videos of her ventriculogram and left coronary artery angiogram can be found in the Resources section of this website.

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Paced Rhythm With Acute Anterior Lateral M.I.

Submitted by Dawn on Mon, 11/28/2011 - 18:57

We caution students that the signs of acute M.I. (ST elevation) cannot reliably be seen in cases of wide QRS. This is because, in wide QRS situations like left bundle branch block, ventricular rhythms, or right ventricular pacing, the ST segments will elevate in leads with downward QRS complexes, and depress when the QRS is upright. These is called discordant ST changes.

In this ECG, a man in his 60's presented with chest pain. His ECG showed AV sequential pacing, with ventricular pacing from the right ventricle. The QRS is 162 ms in duration. He has ST segment elevation in Leads I, aVL, and Leads V2 through V6.

The ST elevations are more pronounced than expected in this paced patient. But, the real clue here is the ST elevation in Leads I, aVL, and V2 - leads that should have ST depression because of their upright QRS complexes, have elevation! This patient was taken to the cath lab and the left coronary artery wass reperfused and stented. For more information about ST elevation in wide QRS complex rhythms, see this LINK.