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Low Blood Pressure (cont.)

Low Blood Pressure Causes

If low blood pressure causes clinical symptoms, the cause will be in one of three general categories. Either the heart is not pumping with enough pressure, the artery walls are too dilated, or there is not enough intravascular fluid (intra=within + vascular= blood vessels) within the system.

Heart

The heart is an electrical pump. Problems with either the pump or the electricity can cause problems with low blood pressure.

  • If the heart beats too quickly, blood pressure may fall because there isn't enough time for the heart to refill in between each beat (diastole). If the heart beats too slowly, there may be too much time spent in diastole when blood is not flowing.
  • If the heart muscle has been damaged or irritated, there may not be enough pumping force to maintain blood pressure. In heart attack (myocardial infarction), enough heart muscle may be stunned so that the heart is too weak to pump effectively.
  • The valves of the heart allow blood to flow in only one direction. If a valve fails, blood can regurgitate backwards, minimizing the amount that will flow out to the body. If a valve becomes narrowed (stenotic), then blood flow may be decreased. Both situations may cause hypotension.
Medically Reviewed by a Doctor on 7/28/2015

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