12-Lead EKG Confidence

Kevin Hodges

Vice Chair, Emergency Medicine

Chris Anderson

Vice Chair, Pediatrics

In this material

I. Overview of Heart Function and the EKG

III. Common Clinical Arrhythmias

V. Ischemic Disorders: EKG Changes Related to Ischemia and Myocardial Infarction

12 critical concepts

heart illustration — 1. Check the P wave direction to make sure the EKG was taken correctly.

2. Measure the HR and interpret it clinically. It is always relevant.

3. Measure the QRS Diagnose BBB if it is 0.12 seconds. Diagnose right or left bundle by looking only at the end of the QRS. Do not diagnose LVH, RVH, ischemia, or infarction with LBBB.

4. Visualize the overall QRS direction. Diagnose hemiblock if the QRS points superiorly (LAHB) or rightward (LPHB).

5. Measure the QT interval and check the corrected QT (QTc) against a chart. This can be a clue to dangerous drug or electrolyte toxicity.

6. The First Rule of the T Wave: On a single EKG, neither T wave inversion nor ST depression proves either timing or reversibility.

7. The Second Rule of the T Wave: When both ST depression and T wave inversion are present, ST depression takes precedence. It is more specific and carries a worse prognosis.

8. The Third Rule of the T Wave: When ST elevation is present in two contiguous leads, it takes precedence over ST depression and T wave inversion. Therapeutic intervention should be instituted ASAP to open the artery.

9. Q waves evolve from undertreated ST elevation pathophysiology. Interpret associated T or ST segment abnormalities according to the three rules of the T wave.

10. LVH can cause ST changes and PRWP due to the hypertrophy process or due to consequent coronary disease.

11. Anterior ST depression may be due to LV disease in the septum or posterior wall, or to RV strain due to acute pulmonary embolism.

12. Specific patterns of hyperkalemia, pericarditis, and pulmonary embolism should be looked for on every EKG.

Source

12-Lead EKG Confidence: A Step-By-Step Guide, 3rd ed., 2015

Image credits

Unless otherwise noted, images are from Adobe Stock.