EKG Analysis

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Contents 1 Calibration 2 Rhythm 3 Rate 4 Axis 5 Intervals 6 Atrial enlargement 7 Ventricular hypertrophy 8 Bundle Branch Blocks 8.1 RBBB 8.2 LBBB 8.3 LAFB 8.4 LPFB 9 Q waves 10 MI 11 Pericarditis 12 Hyperkalemia 13 Hypokalemia 14 Hypercalcemia 15 Hypocalcemia 16 Other OSCE modules

[edit] Calibration

• 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

[edit] Rhythm

• P wave upright in I, II, AVF
• PR interval > 0.12
• P wave for every QRS

[edit] Rate

• 300,150,100,75, 60, 50 rule
• If rythm is not normal count the number of QRS complexes in 25 big boxes (5 seconds) and multiply by 12
• tachycardia >100bpm
• bradycardia <60bpm

[edit] Axis

• 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

[edit] Intervals

• PR 0.12-0.20 (3-5 squares)
• QRS < 0.10 (2.5 square)
• QT <0.44 (11 squares)

[edit] Atrial enlargement

• 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

[edit] Ventricular hypertrophy

• 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

[edit] Bundle Branch Blocks

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)

[edit] RBBB

• R' in V1
• S in V6

[edit] LBBB

• absent normal R in V1 and Q in V6 (initial depolarization directed to LV)
• terminal R' in V6 and downward deflection in V1

[edit] LAFB

• Q wave in I, aVL
• initial R wave in II, III, aVF

[edit] LPFB

• Q in II, III, aVF
• initial R wave in I, aVL

[edit] Q waves

• 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

[edit] MI

• 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

[edit] Pericarditis

• diffuse ST elevation
• PR depression

[edit] Hyperkalemia

• tall "peaked" T waves
• flat p
• wide QRS

[edit] Hypokalemia

• U wave
• ST depression
• flat T

[edit] Hypercalcemia

• decreased QT interval

[edit] Hypocalcemia

• increased QT interval

[edit] Other OSCE modules