Hypertension

Hypertension, also known as high blood pressure, is a condition in which the pressure of a person's blood against their arterial walls is consistently too high. Hypertension is often called the ‘silent killer’ because it may present no warning signs or symptoms obvious to the hypertensive individual and therefore may not be detected until another serious medical condition is diagnosed. It is a major risk factor for heart disease, heart failure, and stroke, and can result in other serious medical complications, including blindness and kidney failure.

Blood pressure is measured in millimeters of mercury (mmHg), using a device called a sphygmomanometer. When a person's blood pressure is recorded, it is commonly written as two numbers, for instance, 120/80. The first number is the systolic blood pressure, meaning the pressure when the heart contracts. The second number is the diastolic pressure, meaning the pressure when the heart rests between beats. The Seventh Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressures defines blood pressure levels for adults as follows:

• Hypertension. Systolic blood pressure of 140 mmHg or higher or diastolic blood pressure of 90 mmHg or higher
• Prehypertension. Systolic blood pressure of 120 to 139 mmHg or diastolic blood pressure of 80 to 89 mmHg
• Normal or Normotensive. Systolic blood pressure of less than 120 mmHg and diastolic blood pressure of less than 80 mmHg.

Persons with prehypertension are assumed to be at risk to progress to hypertension. If the systolic and diastolic blood pressures would place the person in different categories, the higher category is used. For instance, someone with a blood pressure reading of 145/85 would be considered hypertensive.

Classifying the blood pressure of children requires consideration of both their own blood pressure and the distribution of blood pressure for other children of their age, sex, and height. Hypertension for children is defined as that at or above the 95th percentile for children of their age, sex, and height, and prehypertension is defined as blood pressure of 120/80 mmHg or high but below the 95th percentile.

Hypertension may be defined as essential or secondary. Essential hypertension is the most common type and does not have a specific treatable cause. Secondary hypertension is due to some underlying condition, such as a kidney disorder or congenital abnormality; blood pressure generally returns to normal when the underlying problem is corrected. In addition, hypertension sometimes appears as a complication of pregnancy and may take two forms. Pregnancy-induced or gestational hypertension first appears when the woman becomes pregnant. Preexisting chronic hypertension is present in the woman before she becomes pregnant but only becomes apparent during the pregnancy. Hypertension is one of the [Page 514]symptoms of preeclampsia, a disorder that appears in 5% to 8% of all pregnancies and is a major health risk for both mother and child. Preeclampsia is the second leading cause of maternal death in the United States and is also a leading cause of fetal complications, including low birthweight, premature birth, and stillbirth.