20 practice 1
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  • Lets try to get a pretty acurate Axis
  • Does this image look familiar. We start by finding our equiphasic lead.
  • Lead III has some ST depression, but looks to be the most equiphasic lead.
  • We find lead III on our hexaxial reference system. Now we need to figure out which lead is perpindicular to lead III
  • Remember. When the heart ’s mean electrical vector (or QRS axis) moves toward a positive electrode, you get an upright complex in that lead. When it moves away from a positive electrode, you get a negative complex in that lead. When it moves perpendicular to a positive electrode, you get an equiphasic (and/or isoelectric) complex in that lead.
  • Since lead III is equiphasic, that means it is perpendicular to the heart ’s mean electrical exis in the frontal plane. So we find the lead that is perpendicular to lead III because it will be the most in line with the heart’s mean electrical axis. aVR is perpendicular to lead III. So the axis is close to either -150 or 30 degrees. To figure out which one, we need to see if lead aVR is positive or negative.
  • We see that aVR is negative, so we look at the down arrow on the reference system.
  • The down arrow is at the 30 degree mark, so our frontal axis is about 30 degrees.
  • 30 degrees falls in the normal frontal Axis range!
  • The monitor found an R-axis at 34 degrees, so our conclusion of 30 degrees is pretty damn close. What about our precordial axis?
  • Since with normal physiology, the transition zone is in the area of V3 or V4, lets put an arrow in that direction.
  • It looks like the QRS goes from being all negative to all positive between V3 & V4. This is normal.
  • Ok, we are on to the third and fourth steps of the 6 step method. We assess our intervals and morphology.
  • Our intervals look to be within a normal range, the QRS is less than 120ms, the PR-interval is less than 200 ms, and the QTc is less than 460 ms. There does appear to be a biphasic P-wave in V1, but this is probably just indicative of LAE. The most obvious abnormality is those Symmetrical, broad and tall T-Waves in V2 & V3, do you remember a pathology that can cause these?
  • Remember, hyperkalemic T-waves are usually narrow with a sharp peak. These look very much like hyperacute T-waves; which we know are an early sign of a heart attack. We can ’t call this a STEMI based on their presence, but they certainly heighten our degree of suspicion. Lets move on to our next step.
  • We do note some ST-elevation, although it isn ’t in contiguous leads. The ST-elevation is present minimally in aVL, and significantly in V1. We can determine how much in V1 by finding our J-point in a lead below it and drawing a line.
  • We also mark our isoelectric line in V1 by conecting the TP-segments to determine how elevated the ST-segment is in V1. We see that the elevation is at least 2mm in V1. Is their a STE-Mimic present?
  • We already said that the T-wave amplitude is not due to hyperkalemia. The ST-elevation is only in two leads and it is convex, so it probably isn ’t related to pericarditis or early repol. We do have T-wave discordance in all of the precordial leads, but the QRS is too narrow for a LBBB and the amplitude isn’t great enough for LVH, so it probably isn’t LV-strain. This ECG doesn’t appear to have a STE-Mimic. Lets move on to the final step to determine if this ECG has evidence of ischemia, injury, or infarct.
  • Our ST-elevation is not in contiguous leads
  • We note ST-Elevation, but since it isn ’t in two contiguous leads, it doesn’t meet STEMI criteria. We have also discovered Hyperacute T-waves, and it looks like there is some ST-depression in the inferior leads. This could be a reciprocal change or a sign of subendocardial injury. This ECG may not meet STEMI criteria, but we can certainly start our ACS treatment and begin transporting this patient to a cardiac facility based on these findings; especially in the presence of chest pain. We should also make sure to do repeat 12-leads on the way in!
  • Our ST-depression is in the inferior leads, II, III, and aVF, so it would make sense to see some elevation in I, aVL, V5, or V6
  • Here is the next 12-Lead we capture. Do you see the obvious difference??? Lets look at them both together to see how significant the changes are.
  • We now have an obvious Antero-Septal MI that meets STEMI criteria. Whenever you have ECG changes like this, you can be certain you are dealing with a significant cardiac event. Look at the exponential increase in ST-elevation from the first ECG to the second. The precordial axis even shifted slightly between both leads. Look at how V4 changes in amplitude. This type of convex ST-elevation is always significant! And this case proves how important it is to aquire more than one single 12-lead.

20 practice 1 Presentation Transcript

  • 1. 12-LeadElectrocardiography a comprehensive course ra c tice- P 1 Adam Thompson, EMT-P, A.S.
  • 2. Practice• Lets take a look at a 12-Lead recording and use the 6-step method to interpret it.
  • 3. 62 y/o MaleComplaining of Chest Pain
  • 4. 62 y/o MaleRate & Rhythm
  • 5. Rate: 88 Normal Sinus62 y/o Male Axis
  • 6. 62 y/o Male
  • 7. Rate: 88 Normal Sinus62 y/o Male Axis
  • 8. 62 y/o Male
  • 9. Hexaxial Reference System + + A B A + B• When the mean axis is perpendicular to the positive electrode, the QRS is equiphasic.
  • 10. 62 y/o Male
  • 11. Rate: 88 Normal Sinus62 y/o Male Axis
  • 12. 62 y/o Male
  • 13. 62 y/o Male -90° ERAD LAD180° 0° RAD Normal 90°
  • 14. Rate: 88 Normal Sinus Frontal Axis: 30°62 y/o Male Axis
  • 15. Precordial Axis V1 V2 V3 V4 V5 V6Normal transition
  • 16. Rate: 88 Normal Sinus Frontal Axis: 30°62 y/o Male Axis
  • 17. Rate: 88 Normal Sinus Frontal Axis: 30° Precordial Axis: Normal 62 y/o MaleIntervals & Morphology
  • 18. Rate: 88 Normal Sinus Frontal Axis: 30° Precordial Axis: Normal 62 y/o MaleIntervals & Morphology
  • 19. Rate: 88 Normal Sinus Frontal Axis: 30° Precordial Axis: Normal 62 y/o MaleIntervals & Morphology Hyperacute T-Waves
  • 20. Rate: 88 Normal Sinus Frontal Axis: 30° Precordial Axis: Normal Hyperacute T-waves62 y/o Male STE-Mimics
  • 21. Rate: 88 Normal Sinus Frontal Axis: 30° Precordial Axis: Normal Hyperacute T-waves62 y/o Male STE-Mimics
  • 22. Rate: 88 Normal Sinus Frontal Axis: 30° Precordial Axis: Normal Hyperacute T-waves62 y/o Male STE-Mimics
  • 23. Rate: 88 Normal Sinus Frontal Axis: 30° Precordial Axis: Normal Hyperacute T-waves 62 y/o Male STE-MimicsLead I aVR V1 V4 lateral septal anteriorLead II aVL V2 V5 inferior high lateral septal low lateralLead III aVF V3 V6 inferior inferior anterior low lateral
  • 24. Rate: 88 Normal Sinus Frontal Axis: 30° Precordial Axis: Normal Hyperacute T-waves 62 y/o MaleIschemia, Injury, Infarct
  • 25. Rate: 88 Normal Sinus Frontal Axis: 30° Precordial Axis: Normal Hyperacute T-waves 62 y/o Male Ischemia, Injury, Infarct Site Facing Reciprocal Septal V1, V2 NoneAnterior V3, V4 None Lateral I, aVL, V5, V6 II, III, aVFInferior II, III, aVF I, aVLPosterior V7, V8, V9 V1, V2
  • 26. Rate: 88 Normal Sinus Frontal Axis: 30° Precordial Axis: Normal Hyperacute T-waves62 y/o Male 12-Lead #2
  • 27. Rate: 88 Normal Sinus Frontal Axis: 30° Precordial Axis: Normal Hyperacute T-waves62 y/o Male Antero-Septal MI
  • 28. Keep Practicing!!