Blood Pressure Stroke Connection

Mechanisms of Stroke from Hypertension (High Blood Pressure)

How does hypertension contribute to strokes?  

Hypertension can lead to a stroke in a couple of different ways depending on the type of stroke.  There are two basic types of stroke: Ischemic and hemorrhagic.  A transient ischemic attack (TIA), caused by a temporary clot, is often referred to as an "mini stroke".  Symptoms of a TIA typically last less than 5 minutes and there is no permanent damage but having a TIA is often a warning sign of a permanent stroke in the future so TIAs are taken very seriously.

(American Heart Association & American Stroke Association, 2014)

Here is a video about TIA from the American Heart Association:


(American Heart Association, n.d.)

Ischemic Stroke

Ischemic stroke, accounts for approximately 87% of all strokes (American Stroke Association & American Heart Association, 2012).  Ischemic stroke occurs when there is obstruction within the blood vessel supplying blood to the brain.   Hypertension causes damage to the inner lining of the arterial walls (endothelium).  This damage is an important factor in the formation of an atheroma, which then forms a plaque called atherosclerosis.   The plaque ruptures and a blood clot forms, which blocks blood flow from reaching part of the brain.  The lack of blood flow to the brain reduces blood flow to the brain cells (ischemia).  If deprived long enough, these brain cells die (Joseph, 2011).

http://www.zonahealth.co.uk/eu-images/eu-ah3.jpg

Hemorrhagic Stroke

Although there are other causes of hemorrhagic stroke, the most common cause of hemorrhagic stroke is hypertension (American Stroke Association & American Heart Association, 2012).  High blood pressure damages the fragile walls of the vessels in the brain.  Hemorrhagic strokes are caused by weakened vessels that are called aneurysms.  These aneurysms can then rupture and bleed into the brain.  

(National Heart, Lung, and Blood Institute, 2012)

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References

American Heart Association. (n.d.). Transient ischemic attack. Retrieved from http://watchlearnlive.heart.org/CVML_

American Heart Association, American Stroke Association. (2014). Types of strokes. Retrieved from http://www.strokeassociation.org/STROKEORG/AboutStroke

Joseph, R. (2011). Stroke: Thrombi, emboli, hemorrhage, aneurysms, athersclerosis, transient ischemic attacks, cerebral vascular disease University Press.

National Heart, Lung, and Blood Institute. (2012). What is a stroke? Retrieved from http://www.nhlbi.nih.gov/health/health-topics/topics/stroke/