7. Atrial Enlargement

Topics for Study:

1. Right Atrial Enlargement (RAE)
2. Left Atrial Enlargement (LAE)
3. Bi-Atrial Enlargement (BAE)

 

Right Atrial Enlargement (RAE)

• P wave amplitude > 2.5 mm in II and/or > 1.5 mm in V1 (these criteria are not very specific or sensitive)
• Better criteria can be derived from the QRS complex; these QRS changes are due to both the high incidence of RVH when RAE is present, and the RV displacement by an enlarged right atrium.
  • QR, Qr, qR, or qRs morphology in lead V1 (in absence of coronary heart disease)
  • QRS voltage in V1 is < 5 mm and V2/V1 voltage ratio is > 6 (Sensitivity = 50%; Specificity = 90%)

  

Left Atrial Enlargement (LAE)

• P wave duration ≥ 0.12s in frontal plane (usually lead II)
  • Notched P wave in limb leads with the inter-peak duration ≥ 0.04s
  • Terminal P negativity in lead V1 (i.e., "P-terminal force") duration ≥ 0.04s, depth ≥ 1 mm.
  • Sensitivity = 50%; Specificity = 90%

  

Bi-Atrial Enlargement (BAE)

• Features of both RAE and LAE in same ECG
• P wave in lead II > 2.5 mm tall and ≥ 0.12s in duration
• Initial positive component of P wave in V1 > 1.5 mm tall and prominent P-terminal force