| High blood pressure or hypertension occurs when smaller blood vessels (arterioles) become narrowed, forcing blood to exert excessive pressure against the blood vessel walls and making the heart work harder. Although blood pressure usually varies during the day and often increases as a normal response to stress and physical activity, an individual with hypertension has high blood pressure even at rest. This type of primary or essential high blood pressure does not have a direct cause although it can be influenced by both heredity and certain triggers or risk factors such as obesity, high dietary salt (sodium) intake, tobacco use, high-fat diet, excessive use of alcohol, stressful lifestyle, and lack of exercise. It represents the largest percentage (90%) of hypertension in middle-aged and older individuals. Up to 50% of adults over age 50 may have primary or essential hypertension. Secondary hypertension is the result of another (primary) disorder such as kidney disease or arteriosclerosis, accounting for only 10% of cases. Secondary high blood pressure may be classified as acute if associated with acute renal failure.
Blood pressure is recorded as two numbers. The top number (systolic pressure) represents pressure in the arteries when the heart muscle contracts to pump blood. The bottom number (diastolic pressure) represents pressure in the arteries between heartbeats when the heart is at rest. Hypertension is usually defined as a resting systolic pressure greater than or equal to 140 mm Hg (millimeters of mercury) or resting diastolic pressure greater than or equal to 90 mm Hg. Normal blood pressure is considered below 130/85. Mild hypertension ranges from 140-159/90-99, moderate from 160-179/100-109, and severe from 180-209/110-119. Very severe hypertension is over 210/120. According to current World Health Organization (WHO) guidelines, individuals with kidney disease are considered to have high blood pressure if systolic blood pressure is greater than 125 mm Hg or diastolic blood pressure is greater than 75 mm Hg. In diabetes, diastolic blood pressure over 80 is considered elevated.Risk: Several genetic and environmental or lifestyle factors increase the risk of essential high blood pressure, including obesity, high dietary salt (sodium) intake, tobacco use, high-fat diet, excessive use of alcohol, stressful lifestyle, lack of exercise, anxiety or depression, and living in the southeast region of the US. Essential hypertension may be inherited; specific genetic risk factors include abnormalities in angiotensin-renin genes and inherited abnormalities of the sympathetic nervous system controlling heart rate, blood pressure, and blood vessel diameter. Men and postmenopausal women have a higher risk of developing hypertension. Diabetes also increases the risk of hypertension. Incidence and Prevalence: Hypertension is an extremely common disorder affecting approximately 29% of the US population; 58 million adults have been diagnosed and are taking antihypertensive medication (Schwartz). 90% of all cases of hypertension (essential, primary, or benign) have no obvious cause. Secondary hypertension, a result of another (primary) disorder such as kidney disease or arteriosclerosis, accounts for the remaining 10% of cases. Hypertension occurs 4 times more frequently among blacks than whites at all ages (Schwartz). Blood pressure is known to increase with increasing age; up to 50% of the population over age 50 suffer from primary or essential hypertension. |
Source: Medical Disability Advisor