II. Mechanism

  1. Heart apex rotates forward with systole

III. Normal impulse location

  1. Fifth intercostal space
  2. Left of mid-Sternum by 7 to 9 cm
  3. Medial to left midclavicular line by 1-2 cm

IV. Accentuated Impulse

  1. Findings suggestive of Left Ventricular Hypertrophy
    1. Impulse > 3 cm diameter (stethoscope diaphragm size)
      1. Patient in Left Lateral Decubitus
      2. Palpation of apex
    2. Accuracy (Compared with Echocardiogram)
      1. Sensitivity: 92%
      2. Specificity: 91%
    3. Reference
      1. Eileen (1983) Ann Intern Med 99(5):628-30 [PubMed]
  2. Causes
    1. Left Ventricular Hypertrophy
    2. Increased myocardial tone
      1. Exertion
      2. Emotion
      3. Thyrotoxicosis
      4. Digoxin Toxicity

V. Shifted Position of PMI

  1. PMI shifted left
    1. Cardiac dilatation suggestive of CHF
      1. Test Sensitivity: 66%
      2. Test Specificity: 95%
    2. Other causes
      1. Right Pneumothorax
      2. Left pleural adhesions
  2. PMI shifted right
    1. Left Pneumothorax
    2. Right pleural adhesions

VI. References

  1. Degowin (1987) Bedside Diagnostics, Macmillan, p. 344

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