It causes the heart to work harder than normal putting both the heart and arteries at greater risk of damage. High blood pressure, or hypertension, increases the risk of heart attacks, strokes, kidney failure, damage to the eyes, congestive heart failure and atherosclerosis.
Hypertension exists where the pressure at which blood is pushing against blood vessel walls is consistently above average.
Blood pressure changes throughout the day. In particular, it increases during exercise and decreases during sleep.
Untreated high blood pressure can cause the heart to become abnormally large and less efficient (ventricular hypertrophy) causing heart failure and increased risk of heart attack.
Although high blood pressure can cause headaches, dizziness and problems with vision, the majority of people suffer no symptoms at all. As a result many people with hypertension remain undiagnosed because they have no symptoms to motivate them to see a doctor or get their blood pressure checked.
However, despite the lack of symptoms hypertension can lead to heart attack, stroke, kidney damage, and many other medical problems
In over 90 per cent of cases, the cause is unknown. In the remaining cases, high blood pressure is a symptom of a recognisable underlying problem such as a kidney abnormality, tumour of the adrenal gland or congenital defect of the aorta (in these cases when the root cause is corrected, blood pressure usually returns to norma).
This type of high blood pressure is called secondary hypertension.
If high blood pressure isn't treated and is combined with obesity, smoking, high blood cholesterol levels or diabetes, the risk of heart attack is several times higher.
Arteries also suffer the effects of high blood pressure, becoming scarred, hardened and less elastic. Though this hardening of the arteries often occurs with age, high blood pressure accelerates the process. The hardened or narrowed arteries are unable to supply the amount of blood the body's organs need, preventing them working effectively. Another risk is that a blood clot may lodge in an artery narrowed by atherosclerosis, blocking blood supply.