I. Findings: Normal

  1. Upright: I, II, avF, V4, V5, V6
  2. Inverted: aVR
  3. Variable: III, avL, V1, V2, V3

II. Causes: P Wave Inversion (other than aVR)

  1. Ectopic atrial focus
  2. AV nodal rhythm

III. Causes: High Amplitude - Atrial hypertrophy or atrial dilatation

  1. Mitral valve or tricuspid valve disease
  2. Hypertension
  3. Cor Pulmonale
  4. Congenital Heart Disease

IV. Causes: Low Amplitude (short P Wave)

  1. Hyperkalemia (associated with a tall T Wave)

V. Causes: Wide P Wave (over .11 sec)

  1. Left atrial enlargement

VI. Causes: Biphasic P Wave (second half negative in III or V1)

  1. Left Atrial Enlargement

VII. Causes: M shaped or notched P Wave

  1. M-Mitral: Left atrial enlargement
  2. Findings
    1. Over 0.04 seconds between peaks
    2. Taller in I than in III

VIII. Causes: Peaked P Wave

  1. P-Pulmonale: Right atrial enlargement
  2. Findings
    1. Tall and pointed
    2. Taller in Lead III than in I

IX. Causes: P Waves absent

  1. Precaution
    1. Look closely for regularly spaced "artifact" on the ekg (e.g. low voltage P Waves)
  2. Atrial Fibrillation or Atrial Flutter
  3. Sinoatrial node block
  4. AV Nodal rhythm

Images: Related links to external sites (from Google)

Ontology: P wave feature (C0429084)

Definition (NCI) P wave is the electrical signature of the current that causes atrial contraction - the portion of the EKG tracing that represents depolarization of the atrial myocardium. Initial portion of the P wave is largely a reflection of right atrial depolarization and the terminal portion reflects depolarization of the left atrium.
Concepts Organism Attribute (T032)
SnomedCT 142070006, 33405001
Spanish P wave, onda P (entidad observable), onda P
English P wave (observable entity), p wave, p waves, P wave, P wave feature (observable entity), P wave feature, EKG P Wave, P Wave