Sinus P WAVES

Now that you know it is sinus, look for any abnormal Sinus P waves

Left Atrial Enlargement

Features:
  • V1: Terminal Negativity > 1mm (sensitive, not specific)
  • Lead I or II: P wave is wide (>2.5 mm) and bifid (specific, not sensitive) 
  • 1st degree AV block (PR interval > 5 little boxes, 0.2sec)
  • PR segment Depression in II

 Clinical Significance of LAE

Findings on of LAE on EKG may suggest​
  • True left atrial enlargement
  • Left atrial hypertrophy
  • Left atrial scarring
  • Biatrial abnormality
These, and frequent PACs, are risk factors for atrial fibrillation

R​IGHT ATRIAL ENLARGEMENT

Features
  • V1: initial upgoing component > 1mm (specific, not sensitive)
  • II, III, aVF: Tall and peaked P (2.5mm or 1/3 QRS height in 2 of 3 (sensitive, not specific)
  • Flat line in lead I, and inverted P, QRS in aVL (strongly suggests emphysema)​

Clinical Significance of RAE

  • RAE suggests pulmonary disease or right heart failure (especially with Reactive Airways)
  • Flatline in lead 1 and negative P and QRS in aVL suggests emphysema (vertical lie of the heart)​
  • RAE is a risk factor for Atrial Flutter
ECG has limited specificity for RAE:
  • Sinus Tachycardia is frequently accompanied by tall peaked Ps
Picture
Emphysema
Picture
Biatrial enlargement