Definition: Defining the Meaning of Hypertension
Hypertension (HTN) or high blood pressure, sometimes called arterial hypertension, is a chronic medical condition in which the blood pressure in the arteries is elevated. Blood pressure is summarized by two measurements, systolic and diastolic, which depend on whether the heart muscle is contracting (systole) or relaxed between beats (diastole). This equals the maximum and minimum pressure, respectively. There are different definitions of the normal range of blood pressure. Normal blood pressure at rest is within the range of 100 - 140 mmHg systolic (top reading) and 60 - 90 mmHg diastolic (bottom reading). High blood pressure is said to be present if it is often at or above 140/90 mmHg.
What is Hypertension
Hypertension, also referred to as high blood pressure, HTN or HPN, is a medical condition in which the blood pressure is chronically elevated.
In current usage, the word hypertension without a qualifier normally refers to arterial hypertension. Arteries are vessels that carry blood from the pumping heart to all the tissues and organs of the body.
Hypertension can be classified either essential (primary) or secondary.
- Essential hypertension indicates that no specific medical cause can be found to explain a patient's condition.
- Secondary hypertension indicates that the high blood pressure is a result of (i.e., secondary to) another condition, such as kidney disease or tumors (pheochromocytoma and paraganglioma).
Hypertension risk factors include obesity, drinking too much alcohol, smoking, and family history.
In individuals older than 50 years, hypertension is considered to be present when a person's systolic blood pressure is consistently 140 mm Hg or greater or when the diastolic blood pressure is consistently 90 mm Hg or greater. (see our blood pressure reading chart)
Although no specific medical cause can be determined in essential hypertension, it often has several contributing factors. These include obesity, salt sensitivity, renin homeostasis, insulin resistance, genetics, and age. Over time, the number of collagen fibers in artery and arteriole walls increases, making blood vessels stiffer. With the reduced elasticity comes a smaller cross-sectional area in systole, and so a raised mean arterial blood pressure.
Over 91% of adult hypertension has no clear cause and is therefore called essential/primary hypertension. Often, it is part of the metabolic "syndrome X" in patients with insulin resistance: it occurs in combination with diabetes mellitus (type 2), combined hyperlipidemia and central obesity.
Pulmonary hypertension (PH) is an increase in blood pressure in the pulmonary artery, pulmonary vein, or pulmonary capillaries, together known as the lung vasculature, leading to shortness of breath, dizziness, fainting, and other symptoms, all of which are exacerbated by exertion. Pulmonary hypertension can be a severe disease with a markedly decreased exercise tolerance and heart failure.
The degree to which hypertension can be prevented depends on a number of features including:
- Current blood pressure level
- Changes in end/target organs (retina, kidney, heart - among others)
- Risk factors for cardiovascular diseases
- The age at presentation.
The American Heart Association estimates high blood pressure affects approximately one in three adults in the United States - 73 million people. High blood pressure is also estimated to affect about two million American teens and children, and the Journal of the American Medical Association reports that many are under-diagnosed. Hypertension is clearly a major public health problem.
- Uncontrolled high blood pressure increases your risk of serious health problems, including heart attack and stroke.
- Hypertension is rarely accompanied by any symptoms, and its identification is usually through screening, or when seeking healthcare for an unrelated problem.
- The first line of treatment for hypertension is identical to the recommended preventive lifestyle changes and includes dietary changes, physical exercise, and weight loss.
- You can have high blood pressure (hypertension) for years without any symptoms. Even without symptoms, damage to blood vessels and your heart continues and can be detected.
- The prevalence of hypertension in the United States is increasing and reached 29% in 2004.
- As of 2000, nearly one billion people or ~26% of the adult population of the world had hypertension.
- Hypertension is more common in men (though menopause tends to decrease this difference) and in those of low socioeconomic status.
- As of 2006 hypertension affects 76 million US adults (34% of the population) and African American adults have among the highest rates of hypertension in the world at 44%.
- In 1995 it was estimated that 43 million people in the United States had hypertension or were taking antihypertensive medication, almost 24% of the adult United States population.
- Rates vary markedly in different regions with rates as low as 3.4% (men) and 6.8% (women) in rural India and as high as 68.9% (men) and 72.5% (women) in Poland. In Europe hypertension occurs in about 30 - 45% of people as of 2013.