If these vessels become blocked, a heart attack can occur. High blood pressure puts extra demand on the heart. Over time, the heart muscle enlarges to compensate for the extra work, and ultimately weakens. Over time, uncontrolled high blood pressure can result in narrowing of the blood vessels of the kidney. This causes the kidney to become less efficient and may lead to kidney failure altogether.
Hypertension can result in narrowing of the blood vessels that supply the brain.
If a blood clot forms and occludes a vessel, the subsequent lack of oxygen to the brain can cause a stroke. This condition prevents blood from flowing through the body effectively, and can lead to heart attack and stroke. References National Institutes of Health, National Heart, Lung and Blood Institute National High Blood Pressure Education Program. The Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. NIH Publication 98-4080, November 1997.