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High Blood Pressure and Stroke

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Updated December 09, 2006

According to the American Heart Association, almost 5 million people suffer some form of stroke each year. Of these, up to 70% can be directly linked to existing high blood pressure, making high blood pressure the single most important controllable stroke risk factor, especially in the elderly. 1

What is Stroke?:

A stroke is a temporary interruption in the supply of blood to one or more areas of the brain. Specifically, the lack of blood means that the brain tissue is deprived of oxygen. Because brain tissue uses oxygen at an exceptionally high rate, even an interruption for a few seconds can cause potentially serious complications.

Blood Supply to the Brain:

There are two main ways that blood supply to the brain can be interrupted

  1. A blood vessel can become blocked by a clot or other debris, impeding the actual flow of blood
  2. A blood vessel can rupture, causing bleeding into the brain tissue and interrupting the supply of the blood for brain tissue located at points past the rupture

Each of these mechanisms is serious, and there is no single set of data that can say which of the two types of interruption is more likely or more dangerous.

The Influence of High Blood Pressure:

High blood pressure can

  • Speed up buildup in arteries, narrowing blood vessels that supply the brain
  • Break exiting fatty deposits loose so they may lodge in a vessel and interrupt flow to the brain
  • Cause either weak artery walls or thick artery walls, which can contribute to blood vessel rupture and impedance of blood flow, respectively

The increased stroke risk from high blood pressure is directly related to how high the blood pressure is, and decreases along with blood pressure readings. High blood pressure patients who are well controlled with treatment have less risk than patients who are poorly controlled.

Warning Signs of Stroke:

There are a very large number of vessels which feed the brain, and an almost innumerable amount of distinct regions in the brain. Because of this, the precise symptoms of stroke vary dramatically depending on severity, vessel involvement, and area of the brain affected. In general the following symptoms are cause for concern:

  • Numbness or Weakness in any part of the body
  • Trouble speaking or understanding conversation
  • Sudden visual changes in one or both eyes
  • Dizzyness, suddenly poor balance, or unexplained falls
  • Confusion or unexplained mood change
  • Loss of consciousness

Stroke is a serious and potentially life threatening emergency. Because the symptoms may come and go in just a few seconds, or can last up to a full day, never second guess yourself. If you are concerned, you should visit an Emergency Room immediately.

1Kario, et al. Morning Hypertension: The Strongest Independent Risk Factor for Stroke in Elderly Hypertensive Patients. Hypertension Research, 29(8):581-7, August 2006.

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