Hypertension: Understanding your numbers and taking action

It's called the silent killer, and the expression is not an exaggeration. High blood pressure affects nearly one in four Canadian adults, according to Statistics Canada data, and half of those affected are unaware of it. No pain, no outward signs, no clear warning. Pressure builds silently, year after year, as arteries, the heart, and kidneys take the toll. On World Hypertension Day, celebrated on May 17, it's an opportunity to take stock of what your numbers really mean and what you can concretely do.

What is blood pressure?

With each beat, your heart pumps blood through a network of arteries, vessels, and capillaries that supply every organ in the body. Blood pressure measures the force this blood exerts against the walls of your arteries. It is not constant. It naturally rises during exertion, stress, or a cup of coffee, then drops again at rest. This cycle is normal. What becomes problematic is when the pressure remains chronically high, even at rest, even at night, even for no apparent reason.

This persistence is precisely what distinguishes hypertension from a simple temporary surge. Arteries, designed to withstand variations, eventually stiffen under constant pressure. Their walls thicken, their diameter narrows, and the heart's ability to pump effectively deteriorates progressively.

Reading Your Numbers: Systolic vs. Diastolic

A blood pressure measurement always gives two values, expressed in millimeters of mercury (mm Hg), in the following format: 120/80, for example.

The first digit, the highest, is the systolic pressure. It indicates the force exerted on the arteries at the precise moment the heart contracts and ejects blood. It is the pressure peak that the arterial network must absorb with each beat.

The second digit, the lowest one, is the diastolic pressure. It corresponds to the pressure that remains in the arteries between two contractions, when the heart is in its filling phase. A high diastolic number indicates that the arteries are under tension even at rest.

Both values matter. For a long time, more importance was given to systolic blood pressure in people over 60 and to diastolic blood pressure in younger individuals. Current Hypertension Canada guidelines consider both in the overall risk assessment.

What thresholds define hypertension?

The Canadian guidelines published by Hypertension Canada are the references used by Quebec doctors. Here's how the values are interpreted in the office:

• Normal. Less than 120/80 mm Hg
• Elevated (prehypertension). 120-129 / less than 80 mm Hg
• Stage 1 hypertension. 130-139 / 80-89 mmHg
• Stage 2 hypertension. 140/90 mm Hg and above
• Hypertensive crisis (medical emergency). Over 180/120 mmHg

For home measurements, the thresholds differ slightly. Hypertension Canada considers an average of 135/85 mm Hg or higher, obtained by self-measurement, to be equivalent to hypertension in a clinical setting. This distinction is important: blood pressure measured at the doctor's office can sometimes be artificially higher due to stress related to the consultation, a phenomenon known as white-coat hypertension.

For people with diabetes or chronic kidney disease, targets are generally stricter, below 130/80 mmHg. Your doctor will determine the appropriate target based on your profile.

High blood pressure is dangerous because it can damage your blood vessels and lead to serious health problems. It increases your risk of heart attack, stroke, kidney failure, and vision loss.

Chronically high blood pressure damages blood vessels from the inside. Over the years, lipid and calcium plaques accumulate more easily on weakened walls, progressively narrowing the arteries. This process of atherosclerosis affects vessels throughout the body.

The most serious consequences are well-documented:

• Stroke. Hypertension is the main modifiable risk factor for stroke. It can cause rupture or blockage of cerebral blood vessels.
• Myocardial infarction. Arteries narrowed by atherosclerosis can become completely blocked, depriving the heart muscle of oxygen.
• Heart failure. A heart forced to pump against high resistance eventually enlarges and weakens, progressively losing its ability to meet the body's needs.
• Chronic kidney disease. The kidneys, highly sensitive to pressure changes, are slowly damaged. Hypertension is one of the two most frequent causes of end-stage renal disease, along with diabetes.
• Hypertensive retinopathy. The small blood vessels in the retina can break or become blocked, threatening vision.

What makes all of this particularly insidious is that this damage accumulates without warning. Most people with high blood pressure feel nothing special, no pain, no discomfort that would prompt them to consult a doctor. That is why regular measurement remains the only reliable tool for early detection.

How to correctly measure your blood pressure

A poorly taken measurement can distort the diagnosis in one direction or the other. A few basic rules apply, whether at the office or at home.

In a doctor's office. The doctor or nurse measures the blood pressure after a few minutes of rest in a sitting position. If the reading is high, a second measurement is taken a few minutes later. Hypertension Canada recommends basing the diagnosis on at least two separate visits, unless the initial reading is very high.

Ambulatory blood pressure monitoring (ABPM). This is a portable device that the patient wears for 24 hours, which automatically measures blood pressure every 15 to 30 minutes. ABPM is particularly useful for detecting white-coat hypertension, masked hypertension, and for evaluating the effectiveness of treatment over the entire daily cycle, including at night.

Home self-monitoring. Hypertension Canada recommends a clinically validated cuff, placed on the bare arm, at heart level. The recommended technique:

• Sit and rest for 5 minutes before measuring
• avoid coffee, tobacco, and physical exercise in the 30 minutes prior
• take two consecutive measurements, one minute apart, morning and evening
• repeat for 7 consecutive days
• Calculate the average of the measurements (excluding the first day) to send to the doctor

Wrist cuffs are less reliable and generally not recommended for regular monitoring. An arm cuff validated by the British and Irish Hypertension Society or Hypertension Canada is the recommended standard.

Lifestyle habits to lower blood pressure

For mild to moderate hypertension, lifestyle changes can reduce systolic pressure by 5 to 15 mm Hg, sometimes more, according to data compiled by Hypertension Canada. These modifications are recommended as a first-line approach before considering medication, and they remain effective as complementary treatment even when medication is prescribed.

The DASH Diet. The diet Dietary Approaches to Stop Hypertension is the dietary approach with the best documented antihypertensive effect. It focuses on fruits, vegetables, whole grains, low-fat dairy products, legumes, and lean proteins, while limiting fatty meats, added sugars, and saturated fats.

Sodium reduction. The recommended target is about 2,000 mg of sodium per day, which is the equivalent of one teaspoon of salt. Most of the sodium in the Quebec diet doesn't come from the salt shaker, but from processed foods: cold cuts, canned soups, prepared sauces, industrial bread, and cheeses. Reading labels makes all the difference.

Physical activity. 30 to 45 minutes of moderate-intensity aerobic activity five days a week lowers systolic blood pressure by an average of 5 to 8 mm Hg. Brisk walking, cycling, swimming, and dancing count. You don't have to run a marathon.

Weight management. Each 10 kg of weight lost is associated with a 5-10 mmHg drop in systolic blood pressure in overweight individuals. The effect is proportional and occurs even without reaching a so-called ideal weight.

Alcohol. Regular alcohol consumption is a well-established risk factor for high blood pressure. Hypertension Canada recommends limiting intake to two drinks per day, with alcohol-free days each week. Reducing alcohol intake can lower blood pressure by 3 to 4 mm Hg.

Sleep and stress. Insufficient or fragmented sleep and chronic stress maintain prolonged activation of the autonomic nervous system, which keeps blood pressure elevated. Stress management (meditation, heart coherence, decompression activities) is among the overall recommendations.

Medical options

When changes in habits are not enough or when the pressure is too high to wait, the doctor may prescribe medication. There are several classes of antihypertensives, each with a different mechanism of action:

• angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs), which relax blood vessels
• calcium channel blockers, which reduce arterial constriction
• thiazide diuretics, which decrease fluid volume in circulation
• beta-blockers, which slow the heart rate and reduce the force of contraction

The choice of medication depends on the patient's profile, their comorbidities, their age, and their tolerance to side effects. There is no universal treatment. Gradual adjustment is often necessary before finding the optimal combination. This content is for informational purposes only: never self-medicate or change treatment without your doctor's agreement.

The role of the family doctor in follow-up

High blood pressure is a chronic condition that requires long-term management. The family doctor plays a central role in this follow-up, going far beyond simply prescribing medication.

Regular monitoring includes checking blood pressure at each visit, blood and urine tests to monitor kidney function and electrolyte balance, electrocardiograms to detect thickening of the heart muscle, and assessment of overall cardiovascular risk (including cholesterol, blood sugar, and lifestyle habits).

If blood pressure control remains difficult despite two or three well-dosed medications, the doctor may refer the patient to a specialist (cardiologist or internist) to investigate secondary hypertension or optimize treatment. In the vast majority of cases, primary hypertension is managed in primary care.

In Quebec, access to a family doctor remains a real issue for many people. Medical clinics offering comprehensive health check-ups are a viable option for individuals without a designated doctor who wish to have their blood pressure and cardiovascular risk factors assessed.

Clinique Omicron and blood pressure monitoring

Our service points in Quebec offer health check including blood pressure measurement, cardiovascular risk factor assessment, and, if necessary, further tests. Whether you don't have a family doctor or simply want closer monitoring, you can book an appointment online. See our rates to know the available services.

Knowing your numbers, understanding what they mean, and knowing when to act is the best starting point for taking control of your cardiovascular health.

Medical consultation | Clinique Omicron