What is hypertension (high blood pressure)?
Blood pressure is the force exerted by the blood against the walls of blood vessels, and the magnitude of this force depends on the cardiac output and the resistance of the blood vessels.
The blood flowing inside vessels exerts a force against the walls – this is blood pressure.
More information on the biology and physics of normal blood pressure is available, along with details of how blood pressure is measured, what normal measurements look like, and how they change with age and exercise.
Hypertension is defined as having a blood pressure higher than 140 over 90 mmHg, with a consensus across medical guidelines.
This means the systolic reading (the pressure as the heart pumps blood around the body) is over 140 mmHg (millimeters of mercury) and/or the diastolic reading (as the heart relaxes and refills with blood) is over 90 mmHg.
This threshold has been set to define hypertension for clinical convenience as patients experience benefits once they bring their blood pressure below this level.6
However, medical experts consider high blood pressure as having a continuous relationship to cardiovascular health. They believe that, to a point, the lower the blood pressure the better.
1. Normal blood pressure is below 120 systolic and below 80 diastolic
2. Prehypertension is 120-139 systolic or 80-89 diastolic
3. Stage 1 high blood pressure (hypertension) is 140-159 systolic or 90-99 diastolic
4. Stage 2 high blood pressure (hypertension) is 160 or higher systolic or 100 or higher diastolic
5. Hypertensive crisis (a medical emergency) is when blood pressure is above 180 systolic or above 110 diastolic.
Symptoms of hypertension
High blood pressure itself is usually asymptomatic, meaning that patients do not experience any direct symptoms of the condition. This is why hypertension is often referred to as “the silent killer,” as it can quietly causes damage to the cardiovascular system.
Hypertension can also lead to problems in the organs affected by high blood pressure. Long-term hypertension can cause complications through arteriosclerosis, where the formation of plaques results in narrowing of blood vessels.
The complications associated with hypertension-related arteriosclerosis can include:
1. An enlarged or weakened heart, to a point where it may fail to pump enough blood (heart failure)
2. Aneurysm – an abnormal bulge in the wall of an artery (which can burst, causing severe bleeding and, in some cases, death)
3. Blood vessel narrowing – in the kidneys this can lead to possible kidney failure; in the heart, brain and legs, this can lead to heart attack, stroke or the need for amputation, respectively
4. Blood vessels in the eyes my rupture or bleed, leading to vision problems or blindness (hypertensive retinopathies – classified by worsening grades one through four).
Treatments for hypertension
Lifestyle changes are important for both treatment and prevention of high blood pressure, and they can be as effective as a drug treatment. These lifestyle changes can also have wider benefits for heart health and overall health.6
The lifestyle measures shown to reduce blood pressure and recommended by experts include:6
1. Salt restriction –
typical salt intake is between 9 and 12 g a day and modest blood pressure reductions can be achieved even in people with normal levels by lowering salt to around 5 g a day – the greatest effects are seen in people with hypertension
2. Moderation of alcohol consumption –
expert guidelines say moving from moderate to excessive drinking is “associated both with raised blood pressure and with an increased risk of stroke”
3. High consumption of vegetables and fruits and low-fat –
people with, or at risk of, high blood pressure are advised to minimize intake of saturated fat and total fat and to eat whole-grain, high-fibre foods, at least 300 g of fruit and vegetables a day, beans, pulses, and nuts, and omega-3-rich fish twice a week
4. Reducing weight and maintaining it –
hypertension is closely correlated with excess body weight, and weight reduction is followed by a fall in blood pressure
5. Regular physical exercise –
guidelines say “hypertensive patients should participate in at least 30 min of moderate-intensity dynamic aerobic exercise (walking, jogging, cycling or swimming) on 5 to 7 days a week”
6. Stress reduction –
avoiding sources of stress, where possible, and developing healthy coping strategies for managing unavoidable stress can help with blood pressure control, especially as many people turn to alcohol, drugs, smoking and unhealthy foods or overeating to cope with stress.
Smoking can also raise blood pressure, and because of its wider effects on heart health and the rest of the body, giving up smoking is highly recommended for people with high blood pressure.