Understanding Blood Pressure

What Is Blood Pressure?

To understand blood pressure there are two figures to look at:

• The higher figure (systolic) is the maximum blood pressure when the heart is pumping.
• The lower (diastolic) blood pressure is the resting pressure that is there all the time when when the heart is resting between beats..

Blood pressure is measured as millimetres of mercury (mmHg) because it was first measured as the height of a column of mercury that  could be supported by the pressure of the blood. Blood pressure monitors using mercury monitors are now being phased out due to the hazards of mercury spillage if these fragile instruments are broken, and electronic monitors are  normally used now.

The typical blood pressure usually regarded as 120 mm systolic and 80 mm diastolic. This is normally written as 120/80 mm and spoken as "one twenty over eighty". This is an ideal blood pressure of a healthy adult at rest. Pressure varies throughout the day depending on physical activity, meals, stress and emotion, and is lower during the night. Therefor you don't just have one blood pressure, as this varied over 24 hours, and so any reading is just a snapshot of the pressure at that moment.

Know Your Numbers

• 120/80 or below is ideal.
• 121/81 to 139/89 is on the high side. If your reading is at the upper end of this range your doctor may want to have it checked more regularly, and if you have other risk factors such as diabetes your doctor will normally set the target levels even lower.
• 140/90 or above is too high, leading to a diagnosis of high blood pressure (hypertension) and needing to be lowered. by antihypertensive medicines,

What Causes High Blood Pressure?

Blood pressure usually increases as we get older, and this was thought to be natural, however many primitive tribes show no such increase while living to the same age, so this increase isn't automatic. It has now been established that high blood pressure is a risk factor at any age, which has lead to blood pressure treatment becoming a priority, especially as you get older. This emphasis has lead to the UK's appalling record of heart disease starting to gradually improve.

HIgh blood pressure has three main causes:

• Hardening of the arteries. The flexibility of the artery walls helps to even out the pulses in blood pressure as the heart pumps. Loss of elasticity increase the blood pressure and also increase the difference between the two readings, which is called pulse pressure. An increase in pulse pressure is a warning sign of increased risk of heart problems. The process of atherosclerosis builds up deposits, called plaque, in the walls of the arteries, which makes them narrower and less flexible. These deposits can be fatty in nature, or can be hardened by calcium deposits which makes them more rigid.
• Constriction of muscles in the artery wall.. The artery walls have a layer of muscle tissue, and the muscle tone of this varies to control the flow of blood. Increased tone causes narrowing of the arteries, reduced blood flow and increased blood pressure; and relaxation causes widening of the arteries, increased blood flow and lower blood pressure. This muscle tone is under complex control by nerves and hormones circulating in the blood.
• Thicker Blood. Thicker blood is harder for the heart to push around and results in higher blood pressure.

Many lifestyle factors can contribute to high blood pressure, and when these are added together they can significantly raise your blood pressure. Such things as being overweight, not taking enough exercise, smoking, poor diet (especially eating too many simple carbohydrates which causes insulin resistance) and drinking too much alcohol. Stress and lack of sleep also increase blood pressure.

Genetic factors can predispose you to high blood pressure, but this effect is usually small compared with other factors, and is at best a poor excuse that some people use to justify living with high blood pressure.

How Can You Lower Your Blood Pressure?

You can very often lower your own blood pressure significantly by following lifestyle advice suggested in our article on How To Lower Blood Pressure, or detailed more fully in our suggested Books On High Blood Pressure.

Medicines called antihypertensives can lower your blood pressure, and can be prescribed by your doctor. Your doctor will suggest these if lifestyle changes don't lower your blood pressure back to a safer level. Most people don't really put their full energy into lifestyle changes because it is a lot of effort, and they fall back on using medicines, instead of changing the things that are causing the problem in the first place. Antihypertensive medicines are not without their problems and can cause side effects. Even if you take these medicines you should still follow the healthy lifestyle advice, because it can mean that you can then  take the lowest dose of antihypertensive medicine or reduce and come off them completely. Always check with your doctor first before changing any medication, though.

Why Is High Blood Pressure A Problem?

High blood pressure is a silent killer and is the major risk factor in heart attack and stroke.One big problem is that such a high blood pressure doesn't produce any symptoms, and so you don't know that you are suffering from it.

There is a common myth that raised blood pressure produces headaches, and this gives a clue to it's presence, but this isn't the case. Certainly if you keep having headaches your doctor will check your blood pressure, but is is usually only exceptionally high blood pressure that can cause this, and then not every time.

Lowering your blood pressure by only 5mm at the upper end (systolic) decreases your chances of having a heart attack by a fifth, and your risk if having a stroke by a third.

High blood pressure can contribute to these illnesses -

• Heart attack
• Stroke
• Heart failure
• Angina
• Diabetes
• Kidney failure

High blood pressure is common:

• 1 in 2 people have ideal blood pressure
• 1 in 3 adults have raised blood pressure
• 1 in 10 adults are taking blood pressure medicines
• 3 out of 4 people over 60 have high blood pressure
• 1 in 4 people over 60 are taking blood pressure medicines

The Rule Of Halves

The 'Rule Of Halves' is a common expression among doctors to reinforce the fact that high blood pressure is recognised as a big problem, both for diagnosis and for treatment.

1. Half the people with high blood pressure have not been diagnosed
2. Of those diagnosed - half are not being treated
3. In half of those being treated it is not properly controlled

If you add up all the halves it means that only one in eight people with high blood pressure are being effectively treated and have their blood pressure under control. This shows why this is so regularly checked by doctors to constantly identify the people at risk.

These figures show that high blood pressure is widespread and not properly treated or controlled, and this is a big factor in the high levels of heart disease in the UK. So make sure that you are looking after your health by having your blood pressure checked regularly, either by your doctor or using your own blood pressure monitor, and by applying all the healthy  lifestyle advice to your own life.

References

• Your Blood Pressure Result - NHS Health Check