– An intermittent or sustained elevation in systolic blood pressure (above 140 mm Hg) or diastolic blood pressure (above 90 mm Hg) or a systolic and diastolic pressure 20 mm Hg above the individual’s baseline pressure.
Causes and Incidence
The cause of primary (essential) hypertension is unknown. However, known risk factors include a familial history of the disease, race, obesity, tobacco smoking, stress, and a high-fat or high-sodium diet in genetically susceptible individuals. Secondary hypertension is related to an underlying disease process such as renal parenchymal disorders, renal artery disease, endocrine and metabolic disorders, central nervous system disorders, and coarctation of the aorta. It is estimated that 60 to 85 million Americans have hypertension, which is a major factor in strokes and cardiac and renal disease.
Hypertension is a disease of the vascular regulatory system in which the mechanisms that usually control arterial pressure within a certain (normal) range are altered. The central nervous system and renal pressor system, as well as extracellular volume, are the predominant mechanisms that control arterial pressure. Some combination of factors effects changes in one or more of these systems, ultimately leading to increased cardiac output and increased peripheral resistance. This elevates the arterial pressure, reducing cerebral perfusion and the cerebral oxygen supply, increasing the myocardial workload and oxygen consumption, and decreasing the blood flow to and oxygenation of the kidneys.
Hypertension is generally asymptomatic until complications develop. It is usually discovered on routine examination.
Complications include atherosclerotic disease, left ventricular failure, cerebrovascular insufficiency with or without stroke, retinal hemorrhage, and renal failure. When the pathologic process is accelerated, malignant hypertension results, the blood pressure becomes extremely high, and nephrosclerosis, encephalopathy, and cardiac failure rapidly ensue.
Elevated pressures on at least two occasions from measurements taken on three separate days are needed to label a person hypertensive. Secondary causes are then ruled out to make a determination of primary hypertension.
Diuretics, alphaor beta-adrenergic blocking agents, or antihypertensives to reduce blood pressure (prescribed according to the stepped-care approach outlined by the 1988 Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure).
Treatment of underlying disease in secondary hypertension; systematic exercise, moderate restriction of dietary sodium, decreased alcohol intake, quitting smoking, stress reduction, and weight loss, if indicated; regular monitoring of blood pressure; instruction in the importance of taking medications consistently and the potential long-term complications.