What you need to know about high blood pressure

Researchers are now beginning to understand precisely how modern life and genetics team up to cause high blood pressure. Here's some insight into their findings.

• Your heart: The harder it has to work — when you're digging the garden, for instance — the happier it is and the healthier you will be. The transient rise in blood pressure when you exercise is quite normal and healthy, unless you already have high blood pressure or atherosclerosis. But unrelenting stress — hourly, day in day out — puts constant pressure on your arteries and causes damage.
• Your arteries: Your arteries are lined with smooth muscle that can expand or contract as blood flows through. The more elastic your arteries, the less resistant they are to the flow of blood and the less the force that's exerted on their walls. But if your arteries are clogged with plaque, your blood pressure will rise as blood is forced through a narrower channel.
• Your kidneys: These organs control how much sodium your body contains and thus how much water stays in your blood (sodium retains water). More water means more fluid trying to get through the blood vessels — and higher blood pressure.
• Your hormones: So-called stress hormones make the heart beat faster and the arteries narrow, which raises blood pressure. Other hormones regulate blood pressure; drugs known as ACE inhibitors control these hormones to lower blood pressure.

Blood pressure measures the force of blood against artery walls while the heart is contracting at full force and while it's resting between beats. Since blood pressure is fairly easy to measure, you can have a doctor or nurse check your blood pressure whenever you go in for a check up or any particular problem.

While high blood pressure is a known killer — it plays a role in 75 percent of all heart attacks and strokes — more than 4 out of 10 Canadians with hypertension don't know they have it. Others know they've got it but don't have it under control.

But doctors are not ignoring the potential risk of high blood pressure. Lower is better, say all doctors, who believe that it's time to get serious about high blood pressure.

Ideally, blood pressure should be less than 120/80, though up to 129/85 is deemed normal. (The first number represents systolic pressure, the force of blood against artery walls during a heartbeat; the second number, or diastolic pressure, is the pressure when the heart is relaxed between beats.)

Damage to arteries actually begins at blood pressure levels that doctors have previously considered optimal. Evidence gathered from 61 studies suggests that for most adults, the risk of death from heart disease and stroke begins to rise when blood pressure is as low as 115/75, although many doctors may view this as over cautious.

The Heart and Stroke Foundation of Canada defines high blood pressure as a systolic blood pressure reading consistently above 140mmHg and/or a diastolic pressure over 90mmHg. The foundation notes, however, that exercising 30 to 45 minutes three times a week can reduce one's systolic pressure by 10.4 mmHg and diastolic by 7.5 mmHg.

BLOOD PRESSURE (mm Hg)CLASSIFICATION

Here's a quick breakdown of the different blood pressure ranges:

• If your blood pressure is below 120/80, it's considered "optimal."
• A blood pressure between 120–129/80–85 is "normal."
• A reading of 130–139/85–89 is "high-normal" blood pressure.
• A reading of 140–159/90–99 is "mild hypertension" blood pressure.
• A blood pressure between 160–179/100–109 means you have "moderate hypertension."
• If your blood pressure is 160/110 or higher, then it's considered "severe hypertension."

Perhaps the least mysterious thing about blood pressure is this: self-help measures can work and may help you to avoid having to take diuretics or other BP lowering drugs.

Even if you are taking medication, healthy lifestyle changes are worthwhile. From proven, practical steps (losing weight cuts blood pressure significantly, as does limiting salt) to mental relaxation techniques, meditation or practising your faith, there are many small daily changes that can help lower blood pressure.

Keep all of this information in mind to help you avoid and overcome high blood pressure and to help improve your health.