What Is Hypertension?

Wednesday, October 11, 2006 - 11:00am

By John Messmer, MD

Hypertension is the medical word for high blood pressure. The word "hypertension" is often used incorrectly. Because the colloquial "hyper" is often used to describe someone who is excitable and the word "tension" is thought of as mental stress or anxiety, people may not realize how serious the disease of hypertension is. When told they have hypertension, some think the problem will go away if they just relax more or get all the stressful things out of their lives.

Defining the term "hypertension"

The word "hypertension" comes from the prefix "hyper" meaning "excessive" and the root word "tension" for "force." Hypertension literally means "excess force." In this case the excess force refers to the pressure of the blood on the walls of the arteries. To avoid confusion, many doctors use the term "high blood pressure" rather than the term "hypertension" when discussing it with patients. It's not a perfect solution, since some cultures use the term "low blood" to refer to anemia and might misunderstand "high blood" as normal.

Decreasing your stress doesn't lower your blood pressure

Because of the terminology, some people correlate feeling stressed with thinking their blood pressure is high and that if they feel relaxed, their blood pressure is fine. Studies have shown that people can not reliably predict what their blood pressure is simply by how they feel. The only accurate way to know one's blood pressure is to measure it.

Your blood pressure reading: Systolic vs. diastolic

Blood pressure readings consist of two numbers. The higher number is called "systolic" and the lower one, "diastolic." When the muscles of the heart contract, blood is pumped out to the body. The Greek word for contraction is "systole," thus the pressure generated by the heart to pump the blood into the circulation is called the systolic pressure. The Greek word "diastole" means "drawing apart" and is the term used for the phase between heartbeats when the muscles relax and the heart fills with blood to be pumped out again. The diastolic blood pressure is the pressure in the arteries between beats of the heart.

What those numbers mean

The pressure numbers are written as systolic over diastolic, for example, 120/80 which is read as "one twenty over eighty." Blood pressure is measured by wrapping a cuff with an air bag around the upper arm and pumping air in until the pressure against the arm squeezes the artery in the upper arm closed, shutting off the flow of blood. Then the air is slowly released while the person doing the measuring listens with a stethoscope below the level of the cuff. The cuff is attached to a device called a "sphygmomanometer" from "sphygmo-" meaning "pulsation" and "manometer" or "pressure measurer."

For further information on normal blood pressure readings see the following article from TheDietChannel: Overview of High Blood Pressure.

How the blood pressure "cuff" works

In the old days of blood pressure measurement, the cuff was connected to a column of liquid mercury. The more pressure in the cuff, the higher the mercury column moved. As air was released from the cuff, the mercury column dropped lower. At some point, the pressure of the blood inside the arm artery is greater than the squeezing pressure of the cuff and the blood begins to flow down the artery again. The sound of the blood flowing can be heard with the stethoscope. The height of the mercury column at that point is the systolic pressure. When the sound of the blood disappears, the height of the column of mercury is the diastolic pressure. So, blood pressures are in units called "millimeters of mercury" or mm Hg (Hg is the chemical symbol for mercury). Due to the toxicity of spilled mercury, this method is rarely used today. Pressures are read on a dial or electronically.

The heart and hypertension

The heart's left side pumps blood into the body, but the right side pumps blood into the lungs to collect oxygen. The left side of the heart is much stronger since blood must be pumped a greater distance. It's the left side pressures that are the focus of measurement and treatment of high blood pressure, but the right side can also develop high blood pressure. Right-sided high blood pressure is called "pulmonary hypertension" and is a very specialized area in the scope of high blood pressure. Right sided pressures can not be measured by simple means as the left sided or systemic blood pressure can.

Hypertension is a significant issue for the heart and circulation. It is a complex problem, but it can be managed in order reduce a person's risk of cardiovascular damage.