II. Findings: Normal

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

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

  1. Ectopic atrial focus
  2. AV nodal rhythm

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

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

V. Causes: Low Amplitude (short P Wave)

  1. Hyperkalemia (associated with a tall T Wave)

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

  1. Left atrial enlargement

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

  1. Left Atrial Enlargement

VIII. 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

IX. Causes: Peaked P Wave

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

X. 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

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Ontology: P wave feature (C0429084)

Definition (NCI) An electrocardiographic finding of the current of atrial contraction when they are depolarized. The 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
LNC MTHU024602
English p wave, p waves, P Wave, P wave (observable entity), P wave, P wave feature (observable entity), P wave feature
Spanish onda P (entidad observable), onda P