Chamber Enlargement & Hypertrophy
Key criteria and pitfalls for atrial enlargement and ventricular hypertrophy on the EKG.
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Questions Covered in This Set
11 cards to master
Why do we say atrial 'enlargement' but ventricular 'hypertrophy'?
Thin-walled atria stretch and dilate (enlargement); thick muscular ventricular walls get thicker (hypertrophy). Either way, more muscle = more voltage and more time to depolarize.
Normal P wave dimensions in lead II
Less than 2.5 mm tall and less than 120 ms wide (< 3 small boxes).
Criteria for right atrial enlargement (P pulmonale)
P wave ≥ 2.5 mm tall in II, III, or aVF (tall, peaked, symmetric), or initial positive deflection in V1 ≥ 1.5 mm. Causes: COPD, pulmonary HTN, tricuspid/congenital disease.
Criteria for left atrial enlargement (P mitrale)
P duration in II ≥ 120 ms with notching (humps ≥ 40 ms apart), or terminal negative deflection in V1 ≥ 1 mm deep and ≥ 40 ms wide (P terminal force). Causes: mitral disease, HTN, LV failure.
Sokolow–Lyon criteria for LVH
S in V1 + R in V5 or V6 > 35 mm, or R in aVL > 11 mm.
Cornell voltage criteria for LVH
R in aVL + S in V3 > 28 mm in men, > 20 mm in women.
Romhilt–Estes point score
Points for voltage, ST-T strain, LAE, axis deviation, wide QRS, and delayed intrinsicoid deflection; ≥ 5 points = LVH, 4 = probable LVH.
What does the LV strain pattern look like?
Downsloping ST depression with asymmetric T-wave inversion in I, aVL, V5–V6 — a supporting feature that greatly increases confidence in LVH.
EKG hallmarks of right ventricular hypertrophy
R > S in V1 (upright QRS in V1), right axis deviation > +100°, deep S waves persisting into V5–V6, often RAE and T inversions in V1–V3.
Mimics of a tall R in V1 to exclude before calling RVH
Posterior MI, right bundle branch block, WPW, dextrocardia, and lead misplacement.
How sensitive and specific are LVH voltage criteria?
Specific but not sensitive: sensitivity only ~20–50% vs echo, specificity often > 90%. Thin/young/athletic patients can have high voltage with normal hearts; obesity can mask it.
