Monday, July 18, 2005

High blood pressure

What is High Blood Pressure?

High blood pressure, sometimes called hypertension, means high pressure (tension) in the arteries. It does not mean excess emotional stress, though doctors’ believe that stress might contribute to high blood pressure over a longer period of time

Your blood pressure rises and falls with each heartbeat, even normal blood pressure does this. These levels can change with everyday activity, for example, during exercise or when you are asleep and this is also normal. However, in some people, and as we get older, these changes in blood pressure start to happen at higher pressure levels than normal and this is what high blood pressure means.

  • Your blood pressure is usually measured with a blood pressure cuff placed around the upper arm that registers the pressure in units called millimetres of mercury (or mm Hg).
  • Your blood pressure is usually considered to be high when it is at a level exceeding 140/90 mm Hg (“140 over 90”) on several readings under various conditions. However, defining normal and abnormal is not always so clear-cut and your doctor or healthcare professional will make the necessary recommendations.
  • Blood pressure rises and falls with each heartbeat. Systolic blood pressure, the higher number, represents the pressure in the arteries as the heart contracts and sends blood into the circulation. Diastolic pressure, the lower number, occurs as the heart relaxes following a beat. It represents the lowest pressure to which the arteries are exposed between heartbeats.

How do you get High Blood Pressure?

No specific cause is found in 95% of patients with hypertension – this is called primary hypertension or sometimes essential hypertension

  • Most patients have primary, or essential hypertension. Most cases of primary hypertension are due to increased stiffness and narrowing of the smaller (peripheral) arteries.
  • This results in increased resistance to the flow of blood and is what makes the blood pressure go up.
  • Increased peripheral artery resistance is associated with genetics (family history), obesity, lack of exercise, over use of salt, and the natural ageing process.
  • A few patients have high blood pressure with a known cause (secondary hypertension). Long-lasting (chronic) kidney disease accounts for most of these patients where there is excessive fluid accumulation in the body that raises blood pressure. Hypertension can also occur during some pregnancies.

How serious is High Blood Pressure?

It is rare these days for blood pressure to be so high as to pose an immediate threat to life. In almost all cases, the problem with blood pressure is that over time it can cause damage to the tiny blood vessels and this may affect the function of the heart, eyes, and kidney. Again, over time it can affect the larger arteries as well and contribute to hardening of the arteries. This explains why people with untreated high blood pressure have a higher risk of suffering from a stroke, heart attack, heart failure, hardening of the arteries, eye and kidney problems.

For this reason it is important that treatment with a blood pressure lowering medicine is given for a long period of time, which in most cases is for life.

And, because blood pressure tends to go up as you get older anyway, it means we should have our blood pressure checked regularly, even if our blood pressure is ‘normal’.

How long does High Blood Pressure last?

High blood pressure may be present for several years before it is detected and is often found during a routine check-up, for example, for insurance purposes. Usually there are no symptoms and consequences may only become apparent after many years.

How is High Blood Pressure treated?

Doctors know that there is a benefit from treating high blood pressure at any age, even in older patients of 65 years and over. Depending on the level of the blood pressure, different things are recommended. In some people with only mild elevations in blood pressure a change in diet and adopting a more healthy lifestyle may reduce the blood pressure to normal. Your healthcare professional will provide you with the right diet for you. Its not just lowering the amount of salt you eat, although this is important: there are other things you can change in your diet that can help. Also, if you are overweight, getting slimmer may help.

If necessary, high blood pressure can be treated with a range of different medicines, including:

  • Beta-blockers, which make the heart beat more slowly and less strongly. They work by blocking the action of nerves supplying the heart that release a chemical called noradrenaline. This helps to control the rhythm and force of heart muscle movement. They also block a hormone called adrenaline (a chemical carried in the blood) which is similar to noradrenaline.
  • Diuretics, which work in the kidneys to make you pass urine more often and get rid of excess fluid.
  • Calcium-channel blockers, which relax arterial blood vessels making them less narrow. These lower the resistance to blood flow, allowing blood to flow more easily. They work by preventing calcium from entering the muscles in blood vessels because calcium is important in narrowing down blood vessels.
  • ACE inhibitors and angiotensin II antagonists, which in general relax the blood vessels. They do this by preventing a hormone called angiotensin II from working, either by preventing its production or blocking its action. Like other hormones, angiotensin II is an active chemical signal in the blood. It controls the function of many organs or systems including the narrowing of blood vessels and prevents the kidneys from getting rid of excess fluid. Doctors believe that angiotensin II is involved as one of the causes of high blood pressure

It is also important to follow any lifestyle instructions that your doctor has given to you, like trying to give up smoking, reducing your weight, doing more exercise and eating a healthy diet. When these and other risk factors are present together with high blood pressure, then this means there is even higher risk of serious disease. It is also important to continue taking any medications you have been given, even if you feel normal.