High Blood Pressure

What is high blood pressure?

High blood pressure or hypertension means high pressure (tension) in the arteries. The arteries are the vessels that carry blood from the pumping heart to all of the tissues and organs of the body. High blood pressure does not mean excessive emotional tension, although emotional tension and stress can temporarily increase the blood pressure. Normal blood pressure is below 120/80; blood pressure between 120/80 and 139/89 is called “pre-hypertension”, and a blood pressure of 140/90 or above is considered high blood pressure. The systolic blood pressure, which is the top number, represents the pressure in the arteries as the heart contracts and pumps blood into the arteries. The diastolic pressure, which is the bottom number, represents the pressure in the arteries as the heart relaxes after the contraction. The diastolic pressure, therefore, reflects the minimum pressure to which the arteries are exposed.

An elevation of the systolic and/or diastolic blood pressure increases the risk of developing heart (cardiac) disease, kidney (renal) disease, hardening of the arteries (atherosclerosis or arteriosclerosis), eye damage, and stroke (brain damage). These complications of hypertension are often referred to as end-organ damage because damage to these organs is the end result of chronic (long duration) high blood pressure. Accordingly, the diagnosis of high blood pressure in an individual is important so that efforts can be made to normalize the blood pressure and, thereby, prevent the complications. Since hypertension affects approximately 1 in 4 adults in the United States, it is clearly a major public health problem.

Whereas it was previously thought that diastolic blood pressure elevations were a more important risk factor than systolic elevations, it is now known that for individuals older than 50 years of age systolic hypertension represents a greater risk.

How is the blood pressure measured?

The blood pressure usually is measured with a small, portable instrument called a blood pressure cuff (sphygmomanometer). (Sphygmo in Greek means pulse, and a manometer measures pressure.) The blood pressure cuff consists of an air pump, a pressure gauge, and a rubber cuff. The instrument measures the blood pressure in units called millimeters of mercury (mm Hg).

The cuff is placed around the upper arm and inflated with the air pump to a pressure that blocks the flow of blood in the main artery (brachial artery) that travels through the arm. With the arm extended at the side of the body at the level of the heart, the pressure of the cuff on the arm and artery is gradually released. As the pressure in the cuff decreases, the health practitioner listens with a stethoscope over the artery at the front of the elbow. The pressure at which the practitioner first hears a pulsation over the artery is the systolic pressure. As the cuff pressure decreases further, the pressure at which the pulsation finally stops is the diastolic pressure.

How is high blood pressure defined?

Since blood pressure can be affected by several factors, it is important to standardize the environment with this in mind when blood pressure is determined. For at least one hour before measuring the BP one should avoid eating, strenuous exercise (which can lower blood pressure), smoking, and caffeine intake. Other stresses may alter the blood pressure and need to be considered when blood pressure is measured.

Even though most insurance companies, quite reasonably, consider high blood pressure to be 140/90 and higher for the general population, these levels may not be appropriate cut-offs for all individuals. As a matter of fact, many experts in the field of hypertension view blood pressure levels as a continuum, or range, from lower levels to higher levels. Such a continuum implies that there are no clear or precise cut-off values to separate normal blood pressure from high blood pressure. Individuals with so-called pre-hypertension as defined above may benefit from lowering of blood pressure by life style modification and possibly medication especially if there are other risk factors for end-organ damage such as diabetes or kidney disease (appropriate life style changes are discussed below).

For some people, blood pressure readings that are lower than 140/90 may be a more appropriate normal cut-off level. For example, in certain situations, such as in patients with long duration (chronic) kidney diseases that spill (lose) protein into the urine (proteinuria), the blood pressure is ideally kept at 130/80, or even lower. The purpose of reducing the blood pressure to this level in these patients is to slow the progression of kidney damage. Patients with diabetes (diabetes mellitus) may likewise benefit from blood pressure that is maintained at a level lower than 130/80. In addition, African Americans, who have an increased risk for developing the complications of hypertension, may decrease this risk by reducing their systolic blood pressure to less than 135 and the diastolic blood pressure to 80 mm Hg or less.

In line with the thinking that the risk of end-organ damage from high blood pressure represents a continuum, statistical analysis reveals that beginning at a blood pressure of 115/75 the risk of cardiovascular disease doubles with each increase in blood pressure of 20/10. This type of analysis has led to an ongoing "rethinking" in regard to who should be treated for hypertension, and what the goals of treatment should be.

Milk Protein May Reduce High Blood Pressure
By Alison McCook

NEW YORK (Reuters Health) - A section of a protein derived from milk appears to reduce blood pressure in people with hypertension, results from a small study suggest.

After taking the casein peptide, called C12, a group of ten people with high blood pressure experienced an average drop of 9 points in systolic pressure, the upper number in a blood pressure reading. Diastolic pressure, the lower number, fell by an average of 6 points. Lead author Dr. Raymond R. Townsend of the University of Pennsylvania in Philadelphia stressed that with only ten people in the study, these findings cannot be used to make treatment recommendations. "We're not going to stand up and say this is how you need to manage high blood pressure," he said. "It's not the be all and end all for blood pressure. But it's intriguing."

However, he noted that he and his team are continuing their research, now asking 50 people to take the milk protein fragment every day for 8 weeks. Both studies are funded by DMV International, a Dutch company that sells ingredients to the food and pharmaceutical industries. In an interview, Townsend told Reuters Health that this experiment came out of a long history of research. In the 1960s, for instance, investigators found they could help control high blood pressure using sour milk. Previous studies in rodents and humans have suggested that the C12 section of casein may reduce blood pressure as well as conventional medicines called angiotensin-converting enzyme (ACE) inhibitors. To investigate further, Townsend and his colleagues asked ten people with hypertension to take C12 either alone or combined with a seaweed extract called alginic acid, which research suggests may help the body excrete sodium in urine. As part of the study, participants took an inactive placebo pill for 5 days and then one of five treatments: a placebo treatment, or high or low doses of C12 either alone or combined with alginic acid. Each participant repeated this five times, in order to try each treatment. When people received the high dose of C12 along with alginic acid, their systolic pressure and diastolic pressure fell significantly more than after the placebo, Townsend and his team write in the American Journal of Hypertension. No patients reported any side effects. Townsend explained that people likely would not get the same benefits of C12 by drinking lots of milk. Dairy contains a lot of salt, which can be bad for blood pressure, he said, and people would have to consume an impossible amount. "The amount of milk you would need to get this effect would be on the order of gallons," Townsend said.
SOURCE: American Journal of Hypertension, November 2004.

Important Note
The information provide by World Canadian Pharmacy is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist or other health care professional. Consult your health care professional for more information regarding these health topics.