Hypertension (HTN or HT), also known as high blood pressure orarterial hypertension, is a chronic medical condition in which the blood pressure in the arteries is elevated. Blood pressure is expressed by two measurements, the systolic and diastolic pressures, which are the maximum and minimum pressures, respectively, in the arterial system. The systolic pressure occurs when the left ventricle is most contracted; the diastolic pressure occurs when the left ventricle is most relaxed prior to the next contraction. Normal blood pressure at rest is within the range of 100–140 mmHg systolic and 60–90 mmHg diastolic. Hypertension is present if the blood pressure is persistently at or above 140/90millimeters mercury (mmHg) for most adults; different criteria apply to children.
Hypertension usually does not cause symptoms initially, but sustained hypertension over time is a major risk factor for hypertensive heart disease, coronary artery disease, stroke, aortic aneurysm, peripheral artery disease, and chronic kidney disease.
Hypertension is classified as either primary (essential) hypertension orsecondary hypertension. About 90–95% of cases are categorized as primary hypertension, defined as high blood pressure with no obvious underlying cause. The remaining 5–10% of cases are categorized as secondary hypertension, defined as hypertension due to an identifiable cause, such as chronic kidney disease, narrowing of the aorta or kidney arteries, or an endocrine disorder such as excess aldosterone, cortisol, or catecholamines.
Dietary and lifestyle changes can improve blood pressure control and decrease the risk of health complications, although treatment with medication is still often necessary in people for whom lifestyle changes are not enough or not effective. The treatment of moderately high arterial blood pressure (defined as >160/100 mmHg) with medications is associated with an improved life expectancy. The benefits of treatment of blood pressure that is between 140/90 mmHg and 160/100 mmHg are less clear, with some reviews finding no benefit and other reviews finding benefit.
The first line of treatment for hypertension is identical to the recommended preventive lifestyle changes and includes dietary changes physical exercise, and weight loss. These have all been shown to significantly reduce blood pressure in people with hypertension. Their potential effectiveness is similar to and at times exceeds a single medication If hypertension is high enough to justify immediate use of medications, lifestyle changes are still recommended in conjunction with medication.
Dietary change, such as a low sodium diet and a vegetarian diet are beneficial. A long term (more than 4 weeks) low sodium diet is effective in reducing blood pressure, both in people with hypertension and in people with normal blood pressure. Also, the DASH diet, a diet rich in nuts, whole grains, fish, poultry, fruit and vegetables lowers blood pressure. A major feature of the plan is limiting intake of sodium, although the diet is also rich in potassium,magnesium, calcium, as well as protein. A vegetarian diet is associated with a lower blood pressure and switching to such a diet may be useful for reducing high blood pressure. A diet high in potassium lowers blood pressure in those with high blood pressure and may improve outcomes in those with normal kidney function.
Some programs aimed to reduce psychological stress such as biofeedback or transcendental meditation may be reasonable add-ons to other treatment to reduce hypertension. However several techniques, namely yoga, relaxation and other forms of meditation do not appear to reduce blood pressure, and there are major methodological limitations with many studies of stress reduction techniques. There is no clear evidence that the modest reduction in blood pressure with stress reduction techniques results in prevention of cardiovascular disease.
Several exercise regimes—including isometric resistance exercise, aerobic exercise, resistance exercise, and device-guided breathing—may be useful in reducing blood pressure.
Several classes of medications, collectively referred to as antihypertensive medications, are available for treating hypertension. Use should take into account the person's cardiovascular risk (including risk of myocardial infarction and stroke) as well as blood pressure readings, in order to gain a more accurate picture of the person's risks. Benefit of medications is related to a person's cardiac disease risk Evidence for medications in those with mild hypertension (between 140/90 mmHg and 160/100 mmHg) and no other health problems is less clear with some reviews finding no benefit and other reviews finding benefit. Medications are not recommended for people with prehypertension or high normal blood pressure.(Source : wikepedia)