Translating Blood Pressure Numbers

Blood pressure is commonly measured by wrapping an inflatable cuff around the upper arm. Air is pumped into the cuff until circulation is cut off; when a stethoscope is placed over the cuff , there is silence. Then as the air is slowly let out of the cuff, blood begins to flow again and can be heard through the stethoscope. This is the point of greatest pressure (called Systolic ), and is usually expressed as how high it forces a column of mercury to rise in a tube.

At its highest normal pressure, the heart would send a column of mercury to a height of about 120 millimeters. At some point, as more and more air is let out of the cuff, the pressure exerted by the cuff is so little that the sound of the blood pulsing against the artery walls subsides and there is silence again. This is the point of lowest pressure (called Diastolic), which normally raises the mercury to about 80 millimeters.

It is crucial to "Know Your Numbers" with respect to Blood Pressure. Life-threatening complications can develop over a course of years when hypertension exists. Increased pressure on the inner walls of blood vessels make the vessels less flexible over time and more vulnerable to the buildup of fatty deposits in a process known as atherosclerosis. Hypertension also forces the heart to work harder to pump adequate blood throughout the body. This extra work causes the muscles of the heart to enlarge, and eventually the enlarged heart becomes inefficient in pumping blood. An enlarged heart may lead to heart failure, in which the heart can not pump enough blood to meet the body's needs.

• Back: Blood pressure guidelines
• Next: Blood Pressure Numbers, continued...