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Hypertension or High Blood Pressure

What is hypertension or high blood pressure? Hypertension or high blood pressure is a medical condition in which constricted arterial blood vessels increase the resistance to blood flow, causing blood to exert excessive pressure against the walls of a person's arteries. This causes the heart to work harder to pump blood through narrowed arteries and can lead to long term damage to the heart and blood vessels. If this condition persists it increases the risk for stroke, heart attack, kidney disease and heart failure. It is estimated to cause 1 in every 8 deaths worldwide.1

How many people have high blood pressure? Hypertension affects 25 percent of people living in North America and an even higher percentage of people in Europe.2 Almost one-third of people with hypertension are unaware of their condition and about one-quarter do not have their blood pressure under control when they are on medications.2

Why is it difficult to reduce high blood pressure? Some hypertension patients have a difficult time reducing their blood pressure even when they are taking medications. Hypertension patients who have other medical conditions such as heart failure, diabetes, kidney disease, or coronary artery disease often have the most difficult time managing their hypertension condition. These patients often take multiple medications to treat their other medical conditions. Patients with resistant or refractory hypertension are not reaching their blood pressure goal, even though they are adhering to full doses of an appropriate three-drug regimen that includes a diuretic.

How is blood pressure measured? Two measurements are used to describe blood pressure and include systolic and diastolic blood pressure. Systolic pressure is measured as the heart contracts to pump out blood. Diastolic pressure is measured as the heart relaxes to allow blood to flow into the heart. Normal blood pressure in an adult is 120 (systolic pressure) /80 (diastolic pressure) mmHg. A blood pressure of 140/90 mmHg or higher is considered high.

What causes high blood pressure? In most cases, the cause of high blood pressure cannot be clearly identified. Family history and genetic factors may play a role in triggering high blood pressure. In a small percent of patients, hypertension develops as a result of another medical problem such as kidney disease. Hypertension can sometimes be a side effect of a medication. Factors that contribute to hypertension include: obesity, excessive salty diet, abnormal cholesterol, family history of hypertension, physical inactivity, age (> 54 men, > 64 women) and tobacco use. It is important to prevent and control hypertension whenever possible through multiple strategies such as adoption of a healthier lifestyle, additional use of anti-hypertension medications or management with other therapies.

Why is it important to control blood pressure? When a person has high blood pressure, small blood vessels can become damaged and less effective in supplying the body's vital organs (brain, kidneys and heart) with oxygen and nutrients. Each increase in blood pressure of 20 mmHg in systolic blood pressure or 10 mmHg in diastolic blood pressure above normal level is associated with two-fold differences in death rates from stroke, ischemic heart disease and other vascular causes.

 Controlling Blood Pressure

The longer a person has high blood pressure, the greater the risk of developing stroke, heart attack, kidney disease or heart failure. A person with high blood pressure is four times more likely to have a stroke, than a person with normal blood pressure.2,3 Kidney disease can lead to the deterioration of the kidney to excrete fluid and salts and may lead to the need for dialysis or kidney transplant.4 Heart failure can significantly shorten life expectancy and reduce quality of life.

Sources:

(1) Heart Disease and Stroke Statistics. American Heart Association - 2009 Update.

(2) Prospective Studies Collaboration. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of individual data for one million adults in 61 prospective studies. Lancet 2002;360:1903-1913.

(3) Chobian AV. JAMA 2003;289:2560-2572.

(4) U.S. Renal Data Systems. USRDS 2003 Annual Data Report. National Institutes of Health, National Institutes of Diabetes and Digestive and Kidney Diseases. 2003.