HEART DISEASES: HYPERTENSION (HIGH BLOOD PRESSURE)
As you know, the heart pumps blood into the arteries, which distribute it throughout the body. As the blood is forced through the arteries, it presses against the walls of these tubes. The pressure is highest when the blood is being forced ahead by the pump (the systolic pressure) and the lowest between beats, when the heart relaxes (the diastolic pressure), hi typical normal children, the systolic pressure, which is the one people usually have in mind when they think about blood pressure, is from 75 to 100. In young adults, the pressure ranges from 100 to 120; in older people, from 120 to 140.
Sometimes, because of illness, tension, or some other cause, the walls of the arteries are constricted, narrowing the space through which the blood must flow. When this happens, the blood pumped through the arteries presses harder against the walls to force its way through. This strong pressure is called high blood pressure, or hypertension.
In a very high percentage of cases, the cause cannot be determined. Such cases are called essential hypertension, idiopathic hypertension, primary hypertension, or hypertension of unknown cause. The other cases can be traced to definite diseases or to coarctation of the aorta (a congenital narrowing of the main artery).
Malignant hypertension
In some instances, fortunately infrequent, ordinary forms of high blood pressure develop into the malignant form. When this happens, the destructive action of the high blood pressure on the body is speeded up. If malignant hypertension is not checked by prompt treatment, it may prove fatal in a matter of months or a few years. The blood vessels in the retina of the eye, the kidney, the heart, and the brain are the hardest hit in the malignant form.
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