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Saturday, May 12, 2012

All that elevates isn't STEMI


Further confounding the already difficult job done by EMTs and paramedics is the idea of falsely positive ST segment elevation. Even when the EMS provider's eyes are focused on the STE prize, there are lots of distractors out there. This ECG was transmitted as a "priority one" STEMI patient. The cath lab was NOT activated from the field.

Of course, providers should ALWAYS err on the side of caution and transport patients with concerning ECG findings to the closest appropriate hospital. That said, this ECG is a bit more reassuring when placed under a bit more intensive scrutiny.

The patient as an otherwise healthy 30 year old male. The patient had no previous medical history and reported constant chest discomfort over the past week. The patient denies nausea, vomiting, shortness of breath, syncope, or other associated symptoms.  Vitals were unremarkable except for a blood pressure of 140/76. The patient appeared non toxic and in no acute distress.

12 lead ECG:


12 Lead ECG and Discussion


There is a baseline sinus bradycardia. Tall R waves are present in the limb leads and in the precordial leads V4 and V5. These tall R waves are most appropriately called, "high left ventricular voltage." Left ventricular hypertrophy is not technically correct since this patient is (1) young and (2) we don't have a formal echocardiogram. High left ventricular voltage may be a physiologic finding in young and otherwise healthy patients. Slight ST segment elevation is present in leads V2 and V3. There is J point elevation in lead II as well. Slight ST segment elevation may also be a physiologic finding- in the ABSENCE of a concerning patient presentation. This particular patient had no concerning medical history and appeared well. Also reassuring is the ABSENCE of reciprocal change.

The shape of the ST segment can also help guide your medical decision making. Pathologic ST segments are typically more horizontal in shape. Convex ST segments are also associated with worsent outcomes. Test for convexity by drawing a line from the J point to the peak of the T wave. If the line superimposes the ST segment or if the T wave appears above the drawn line, the ST segment is classified as convex. Convex shape= NOT reassuring. Broad based and wide ST segments also favor ischemia.

Here is an "ugly" appearing ST segment. No offence intended to the poor ST segment depicted:


Another NOT reassuring ST segment :


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