Monday, December 9, 2013

How to measure ST Elevation at 60 milliseconds after the J-point in lead V3, relative to the PR Segment

The formula for differentiating early repol and anterior STEMI requires one measurement which many have found difficult to understand.

Here is the paper we published on the topic.

Here is a diagram to demonstrate the measurement:

Lower black line: PR segment.        Red line: tangent to the tracing, where the angle on either side of the tangent is equal; this is the J-point (end of the QRS and beginning of the ST segment).      Blue arrow: points to the J-point.    Green line is 1.5 little boxes, or 60 milliseconds, after the J-point.   Upper black line intersects the tracing where the green line demonstrates 60 ms after the J-point.                     Measure voltage difference (black arrows) (1 mm = 0.1 mV, but we measure in mm) between black lines.        So the STE at 60 ms after the J-point in lead V3 = 3.75 mm here.  It is usually not possible to be more accurate than 0.5 mm, but here it is so enlarged that one can do it.   FYI: ST elevation at the J-point in this diagram is about 2.5 mm.

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