Cardiovascular Medicine Book

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Orthostatic HypotensionAka: Postural Hypotension, Orthostatic Blood Pressure, Orthostasis, Orthostatic Syncope

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  1. Definition
    1. Blood Pressure drop on standing of >20/10
    2. Occurs within 3 minutes of standing
  2. Physiology
    1. Event: Rising from lying to standing position
      1. 300 to 800 ml of blood pools in legs
    2. Physiologic response
      1. Lower extremity Muscle contraction compresses veins
      2. Autonomic response
        1. Baroreceptors in aorta and carotids sense BP change
        2. Sympathetic nervous system response
          1. Increases vascular tone
          2. Increases Heart Rate and cardiac contractility
  3. Symptoms
    1. Dizziness or light headedness on standing
  4. Causes
    1. Cardiogenic
      1. Myocardial Infarction
      2. Arrhythmia
      3. Aortic Stenosis
      4. Myocarditis
      5. Pericarditis
      6. Bradycardia
    2. Hypovolemia (tachycardia present, most common)
      1. Dehydration
      2. Hemorrhage
      3. Anemia
      4. Burn injury
      5. Adrenal Insufficiency
      6. Diabetes Insipidus
      7. Straining
        1. Heavy lifting
        2. Urinating (Micturition Syncope)
    3. Medications
      1. Methyldopa
      2. MAO inhibitors (e.g. Phenelzine)
      3. Tricyclic Antidepressants (e.g. Amitriptyline)
      4. Phenothiazine medications (e.g. Chlorpromazine)
      5. Clonidine
      6. Alpha adrenergic blockers (e.g. Prazosin)
      7. Beta Blockers (e.g. Atenolol)
      8. Vasodilator medications
        1. Nitrates (Nitroglycerin)
        2. Calcium Channel Blockers
        3. ACE Inhibitors
        4. Hydralazine
      9. Diuretics
      10. Quinidine
      11. Levodopa
      12. Barbiturates
      13. Opiates (e.g. Morphine)
      14. Vincristine
      15. Insulin
      16. Sildenafil (Viagra)
    4. Neurogenic Causes
      1. Diabetic Neuropathy
      2. Spinal cord injury
      3. Guillain-Barre Syndrome
      4. Parkinsonism
      5. Tabes dorsalis
      6. Amyloidosis
      7. Alcohol Abuse
      8. Vitamin B12 Deficiency (Pernicious Anemia)
      9. Syringomyelia
      10. Post-sympathectomy
      11. Human Immunodeficiency Virus (HIV)
      12. Idiopathic orthostatic hypotension
      13. Shy-Drager Syndrome
      14. Carotid Sinus Hypersensitivity
        1. Cardioinhibitory Syncope
        2. Vasodepressor Syncope
    5. Venous pooling
      1. Large leg varices
      2. Prolonged bed rest
      3. Strenuous Exercise
      4. Fever
      5. Sepsis
      6. Heat exposure
      7. Postprandial
      8. Alcohol
    6. Miscellaneous causes
      1. Aging (may be normal over age 70 years)
      2. Hypokalemia
  5. Diagnosis
    1. Orthostatic Blood Pressure and Pulse
      1. Supine Blood Pressure, pulse after 3-5 minutes
      2. Standing Blood Pressure, pulse after 3-5 minutes
      3. Abnormal if Blood Pressure drops >20/10
    2. Response to 15 second Valsalva maneuver
      1. Normally pressure falls, then rises over baseline
      2. Abnormal if pressure does not overshoot baseline
    3. Pulse variation on deep breathing (sinus arrhythmia)
      1. Normal response
        1. Tachycardia on inspiration
        2. Bradycardia on expiration
      2. Abnormal if <9 beat/min difference during cycle
  6. Evaluation of orthostatic hypotension
    1. Consider intravascular volume replacement (IV Fluids)
    2. Consider causes above (including medications)
  7. Complications
    1. Orthostatic Syncope
  8. Management
    1. Avoid medications related to orthostasis
    2. Modify diet
      1. Increase salt and water intake
      2. Avoid Alcohol
      3. Eat smaller, more frequent meals
    3. Modify activity
      1. Avoid heat exposure or strenuous Exercise
      2. Sleep with head of bed slightly elevated
      3. Rise from bed slowly allowing for equilibration
      4. Avoid standing for long periods of time
      5. While standing, move frequently
      6. Avoid work with arms above shoulder height
      7. Dorsiflex feet several times before standing
      8. Consider Compression stockings
    4. Consider medication therapy
      1. Review precautions before using
      2. Fludrocortisone (Florinef)
      3. Midodrine (ProAmitine)
      4. Erythropoietin has been used if comorbid Anemia
  9. References
    1. Engstrom (1997) Am Fam Physician 56(5):1378
    2. Mathias (1995) Neurology 45:S6

Orthostasis (C0149746)

ConceptsSign or Symptom (T184)
EnglishOrthostasis
CreditsDerived from the NIH UMLS (Unified Medical Language System)



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