ECG/EKG Analysis
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Calibration
[edit | edit source]- paper speed is normally 25mm/second
- therefore each 1mm box in the x axis = 0.04sec
- a 1mV test pulse is normally over 10 mm
- therefore each 1mm box in the y axis = 0.1 mV
Rhythm
[edit | edit source]- P wave upright in I, II, AVF
- PR interval > 0.12
- P wave for every QRS
- QRS for every P wave
Rate
[edit | edit source]- 300,150,100,75, 60, 50 rule
- If rhythm is not normal count the number of QRS complexes in 25 big boxes (5 seconds) and multiply by 12
- (an alternative method is to count the number of QRS complexes in a 10 second duration and multiply by 6)
- tachycardia >100bpm
- bradycardia <60bpm
Axis
[edit | edit source]- QRS upright in I and aVF
- If not upright in aVF look @ II
- If upright then axis is normal
- If not then there is left axis deviation
Intervals
[edit | edit source]- PR 0.12-0.20 (3-5 squares)
- QRS < 0.10 (2.5 square)
- QT <0.44 (11 squares)
Atrial enlargement
[edit | edit source]- Right atrium - lead II - p wave wave's initial component is enlarged, taller 2.5mm
- Left atrium - Lead V1 - p wave downward deflection of terminal component
Ventricular hypertrophy
[edit | edit source]- Right ventrical - tall R waves in V1 and V2, deep S in V6
- Left ventrical - tall R wave in V6, deep S in V1, plus one of
- R in V5/6 > 26mm
- S in V1 or 2 + R in V5 or V6 > 35 mm
- R+S in any chest lead > 45mm
- R in aVL > 11mm
- R in I > 15mm
Bundle Branch Blocks
[edit | edit source]note: normally depolarization of the ventricular septum is stimulated by a branch of the left bundle
incomplete block: QRS 0.10-0.12 (2.5-3 squares) complete block: QRS > 0.12 (3)
RBBB
[edit | edit source]- R' in V1
- S in V6
LBBB
[edit | edit source]- absent normal R in V1 and Q in V6 (initial depolarization directed to LV)
- terminal R' in V6 and downward deflection in V1
LAFB
[edit | edit source]- Q wave in I, aVL
- initial R wave in II, III, aVF
LPFB
[edit | edit source]- Q in II, III, aVF
- initial R wave in I, aVL
Q waves
[edit | edit source]- may be normal in V6 and aVL
- pathologic > 0.04, depth >25% QRS height
Inferior: II, III, aVF RCA Anteroseptal: V1-V2 LAD Anteroapical: V3-V4 LAD (distal) Aterolateral: V5-V6, I, aVL CFx Posterior: V1-V2 (tall R, no Q) RCA
MI
[edit | edit source]- ST elevation - returns to baseline in days
- T wave inversion - weeks to months
- Q wave - persists
- if ST remains elevated - fibrotic scar (ventricular anurysm) developed
Pericarditis
[edit | edit source]- diffuse ST elevation
- PR depression
Hyperkalemia
[edit | edit source]- tall "peaked" T waves
- flat p
- wide QRS
Hypokalemia
[edit | edit source]- U wave
- ST depression
- flat T
Hypercalcemia
[edit | edit source]- decreased QT interval
Hypocalcemia
[edit | edit source]- increased QT interval
External link
[edit | edit source]- EKG Reference Guide - Arrhythmia lessons, drills and tracings
- EKG Academy – free EKG lectures, drills and quizzes