Background : High Blood Pressure
What is high blood pressure?
High blood pressure or hypertension means high pressure (tension) in the arteries. The arteries are the vessels that carry blood from the pumping heart to all of the tissues and organs of the body.
Description
As blood flows through arteries, it pushes against the inside of artery walls. The more pressure the blood exerts on the artery walls, the higher the blood pressure is. The size of arteries also affects the blood pressure. When the muscular walls of arteries are relaxed, or dilated, the pressure of the blood flowing through them is lower than when the artery walls narrow, or constricted.
Blood pressure is highest when the heart beats to push blood out into the arteries. When the heart relaxes to fill with blood again, the pressure is at its lowest point. Blood pressure when the heart beats is called systolic pressure. Blood pressure when the heart is at rest is called diastolic pressure. When blood pressure is measured, the systolic pressure is stated first and the diastolic pressure second. Blood pressure is measured in millimeters of mercury (mm Hg).
Adult Blood Pressure Criteria
Normal blood pressure for adults 18 years of age or older is a systolic BP of less than 120 mm Hg and a diastolic BP of less than 80 mm Hg. Blood pressures ranging from 120 to 139 mm Hg systolic or 80 to 89 mm Hg diastolic are considered prehypertensive. People with BP in this range are at increased risk for the development of target organ injury and for progression to definite hypertension over time. For people with diabetes or renal disease, BP in the prehypertensive range poses a significantly higher risk than for healthy persons, and a lower threshold for intervention is indicated for these people: above 130 mm Hg systolic or 80 mm Hg diastolic. For the general population, hypertension is defined as a systolic BP of 140 mm Hg or higher or a diastolic BP of 90 mm Hg or higher.
Hypertension is further divided into two stages, based on the highest level of either the systolic or diastolic BP. Isolated systolic hypertension (
What is hypertension?
The cause of high blood pressure in 90 percent of people suffering from it is unknown. This is called 'primary' or 'essential hypertension'.
In the remaining 10 percent or so, there is an underlying cause. This is called 'secondary hypertension'.
Description
Hypertension makes the heart work harder to pump blood through the body. The extra workload can make the heart muscle thicken and stretch. When the heart becomes too enlarged it cannot pump enough blood. If the hypertension is not treated, the heart may fail.
The kidneys remove the body's wastes from the blood. If hypertension thickens the arteries to the kidneys, less waste can be filtered from the blood. As the condition worsens, the kidneys fail and wastes build up in the blood. Dialysis or a kidney transplant is needed when the kidneys fail. About 25% of people who receive kidney dialysis have kidney failure caused by hypertension.
Risk factors for hypertension include:
- age over 60
- male sex
- race
- heredity
- salt sensitivity
- obesity
- inactive lifestyle
- heavy alcohol consumption
Some of the main causes for secondary hypertension are:
- chronic kidney diseases
- diseases in the arteries supplying the kidneys
- chronic alcohol abuse
- hormonal disturbances
- endocrine tumours.
Medicines commonly used to treat hypertension
Ø ACE inhibitors stop the production of a hormone called angiotensin II that makes the blood vessels narrow. As a result, the vessels expand, improving blood flow. Tension in the circulation is also lowered by the kidneys filtering more fluid from the blood vessels into urine. This also helps reduce blood pressure. If your blood pressure is not easily controlled on simple medication, your doctor will probably use a medicine of this type.
Ø Angiotensin-II receptor antagonists work in a similar way to ACE inhibitors. But instead of stopping the production of angiotensin II, they block its action. This allows the blood vessels to expand, improving blood flow and reducing blood pressure.
Ø Beta-blockers block the effect of the hormone adrenaline and the sympathetic nervous system on the body. This relaxes the heart so that it beats more slowly, lowering the blood pressure.
Ø Alpha-blockers cause the blood vessels to relax and widen. Combining them with beta-blockers has a greater effect on the resistance in the circulation.
Ø Calcium-channel blockers reduce muscle tension in the arteries, expanding them and creating more room for the blood flow. In addition, they slightly relax the heart muscle so it beats more slowly, reducing blood pressure.
Ø Diuretics help the body get rid of excess salt and fluids via the kidneys. In certain cases, they relax blood vessels, reducing the strain on your circulation.
High Blood Pressure Statistics
Ø High blood pressure (hypertension) killed 54,186 people in the
Ø As many as 72 million people in the
Ø One in three
Ø Twenty-eight percent of people with high blood pressure don't know they have it.
Ø Of all people with high blood pressure, 71.8 percent are aware of their condition, 61.4 percent are under treatment, 35.1 percent have it under control and 64.9 percent do not have it controlled.
Ø The cause of 90–95 percent of the cases of high blood pressure isn't known; however, high blood pressure is easily detected and usually controllable.
Ø From 1994 to 2004 the age-adjusted death rate from high blood pressure increased 25.2 percent.
Ø It is estimated that about 90% of middle–aged adults will develop high blood pressure in the remainder of their lifetime
Ø People with lower educational and income levels tend to have higher levels of blood pressure.
Ø In 2004 the death rates per 100,000 population from high blood pressure were 15.6 for white males, 49.9 for black males, 14.3 for white females and 40.6 for black females.
Ø The total annual (2006) cost of high blood pressure and its complications to the
