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P Wave
Aka: P Wave, P Pulmonale, P Mitrale
- See Also
- Cardiac Electrophysiology Anatomy
- Electrocardiogram
- Definitions
- P Wave
- Electrical signal on EKG representing depolarization (and contraction) of the atria
- Start of the P Wave represents right atrial depolarization, and the end of the P Wave represents left atrial depolarization
- Findings: Normal
- Upright: I, II, avF, V4, V5, V6
- Inverted: aVR
- Variable: III, avL, V1, V2, V3
- Causes: P Wave Inversion (other than aVR)
- Ectopic atrial focus
- AV nodal rhythm
- Causes: High Amplitude - Atrial hypertrophy or atrial dilatation
- Mitral valve or tricuspid valve disease
- Hypertension
- Cor Pulmonale
- Congenital Heart Disease
- Causes: Low Amplitude (short P Wave)
- Hyperkalemia (associated with a Tall T Wave)
- Causes: Wide P Wave (width >0.11 sec)
- Left atrial enlargement
- Causes: Biphasic P Wave (second half negative in III or V1)
- Left Atrial Enlargement
- Causes: M shaped or notched P Wave
- M-Mitral or P-Mitrale: Left atrial enlargement
- Findings
- Over 0.04 seconds between peaks
- Taller in I than in III
- Causes: Peaked P Wave
- P-Pulmonale: Right atrial enlargement
- Findings
- Tall and pointed P Wave >2.5 mm in the inferior leads
- P Wave is taller in Lead III than in I
- Causes: P Waves absent
- Precaution
- Look closely for regularly spaced "artifact" on the ekg (e.g. low voltage P Waves)
- Atrial Fibrillation or Atrial Flutter
- Sinoatrial Node block
- AV Nodal rhythm