Rapid ECG Interpretation Pearls
Courtesy of S. Donahue

Rhythm

• Regular or Irregular
• Sinus or not sinus: P waves upright in II, QRS following every P?

Rate

• 300, 150, 100, 75, 60, 50, 43, 38, 33, 27
• 60 seconds dived by R-R interval (1 box = 0.2sec)

Axis

• S>R in I = RAD
• S>R in II = LAD

Intervals

• PRI = 0.12-0.20, if prolonged think 1st degree or 2nd degree type I block
• QRS = < 0.12, if prolonged, think BBB:
  LBBB = R and no Q in I, V5, V6
  RBBB = RsR' in V1, wide S in I, AVL, V6
• QTc = < 430 women, < 460 men, if prolonged think drugs, hypocalcemia, torsades

Enlargement

• Right Atrial = Peaked P in lead II (> 2.5mm)
• Left Atrial = wide notched P in lead II
• LVH = AVL R wave > 11mm females, > 18mm males
• RVH = V1 R wave 7mm

R Wave Progression: > 4mm in V4

Ischemia/Infarct

• Pathologic Q waves > 40 msec duration or > 25% height of R
• ST Segment: ischemia = depression > 1mm, infarct = elevation > 1mm