The diastolic pressure is the pressure between contractions. Elevated blood pressure indicates that the heart is working harder than normal, putting both the heart and the arteries under a greater strain. This may contribute to heart attacks, strokes, kidney failure, and atherosclerosis. If high blood pressure is not treated, the heart may have to work progressively harder to pump enough blood and oxygen to the body's organs and tissues to meet their needs. When the heart is forced to work harder than normal for an extended time, it tends to enlarge.
Arteries also suffer the effects of elevated blood pressure.
Over time they become scarred, hardened, and less elastic. The heart, brain, and kidneys are particularly susceptible to damage by high blood pressure. This type of hypertension is called essential or primary hypertension. Even though scientists do not fully understand the causes of high blood pressure, they have developed drugs that are effective over the long term in treating this disease. In the remaining cases, high blood pressure is a symptom of a recognizable underlying problem such as a kidney abnormality, adrenal gland tumor, or congenital defect of the aorta.