1. Jason Ryan, MD Intern Report
How to Read an EKG
Jason Ryan, MD
Intern Report

2. How to read an EKG Rate and Rhythm Axis and Intervals Hypertrophy
how fast/slow
regular/irregular
wide/narrow
Axis and Intervals
PR, QRS, QT
Hypertrophy
LAE/RAE
LVH/RVH
ST Changes and Q waves

3. How to read an EKG
Rate
300
100 60 40
150 75 50

4. How to read an EKG Axis QRS Lead aVF (+) (-) -90o LAD Lead I (-) (+)
RAD
Normal Axis
90o

5. How to read an EKG Intervals Correct QT 1. QTc=QT/(RR)1/2 (Bazett)
2. QTC=QT (HR-60) (Hodges)
QRS
QTc
<0.46 PR

6. How to Read and EKG
Atrial Enlargement

7. How to Read and EKG
Ventricular Enlargement

9. Sinus Rhythm Rate between 60 to 100 P wave before every QRS
Smooth contour
Either all positive or all negative except V1
<0.12s and <0.2mv
Upright P waves in I, II, aVF
Negative P wave in aVR

11. Limb Lead Reversal Right and Left arm reversed
P wave positive aVR
P wave negative aVL and I
Limb leads look normal
Right arm and Right leg reversed
P wave negative I, L
Lead II isoelectric (almost no QRS)

14. Left Bundle Branch Block
Criteria:
QRS > 120ms (3 small boxes)
Broad, notched, or slurred R waves in I, aVL, and V5-V6
Secondary ST-T changes in I, aVL, and V5-V6
Absence of Q waves in I, V5-V6
R-wave peak time >60ms (1.5 small boxes) V5-V6
Separate criteria for STE AMI

16. Right Bundle Branch Block
Criteria:
QRS >120ms (3 small boxes)
R’ in the right precordial leads with R’>R
Secondary ST-T changes in R precordial leads
Supporting findings:
Slurred S wave in I, aVL, left precordial leads
Usual criteria for STE AMI apply

18. Left Ventricular Hypertrophy
SV1orV2+ RV5orV6>35mm
>40 if 30-40yrs old
>60 if 16-30yrs old
RaVL>11mm
RI + SIII >25mm
RaVL + SV3 >28mm(men) or 20mm(wmn)

19. Left Ventricular Hypertrophy
Associated ST-T wave abnormalities
STD and TWI in V5-V6
Leads where QRS is mainly positive
Slight STE with upright T in V1-V2
Leas where QRS is mainly negative

21. Sinus Tachycardia All sinus rhythm criteria Rate >100
P before every QRS
Upright P in I, II, aVF
Inverted P aVR
Rate >100

23. T Wave Inversions Indicative of subendocardial or evolving ischemia
Can be a normal variant in several leads or in the presence of BBB
Can be caused by several other conditions
Hypertrophic obstructive cardiomyopathy
Intracranial processes (hemorrhage)
Medications or electrolyte abnormalities
Myocarditis/pericarditis or pulmonary embolism

25. ST depressions
Horizontal ST depressions are strongly suggestive of ischemia in the appropriate clinical setting
Don’t necessarily localize
Stress testing
Reciprocal changes
Several other conditions can provoke ST depressions:
LVH
Medications or electrolytes
Bundle Branch Block
Pulmonary embolism

27. ST Elevations Localizes best of all ischemic EKG changes
Usually indication of acute myocardial injury (occluded artery)
Several conditions can also cause ST elevations:
Pericarditis
Early repolarization
LBBB
LVH

28. Evolution of EKG changes
ST Elevation MI
Evolution of EKG changes
Normal
Acute
Hours
1-2 Days
3-7 Days
> 7 Days

29. Leads go together
Anterior

30. Leads go together
Lateral

31. Leads go together
Inferior