High blood pressure is a dangerous condition that in adults is a major risk factor for heart attack and stroke. If your child has high blood pressure, an early intervention program offered by the Preventative Cardiology Clinic at Children's Hospital Boston may help prevent heart disease in the future.

Blood pressure is measured in millimeters of mercury (mm Hg) on a sphygmomanometer. When a health professional places the cuff around your arm and inflates it, the main artery in your upper arm (the brachial artery) is compressed, which means that the artery walls are closed. With the artery compressed, no sound is heard through the stethoscope placed over the artery. As air is released from the cuff, a thump will be heard. At that moment, the health professional records the number on the sphygmomanometer.

This number represents the systolic pressure, or pressure exerted with a heartbeat. Systolic pressure is the top number in a blood pressure reading. When the sounds disappear, the diastolic pressure, or pressure exerted as the heart rests, is recorded. Diastolic pressure is the bottom number in a blood pressure reading.

Blood pressure can be measured by several different methods, including an automated method. This is more convenient, but may be less accurate and may over estimate true blood pressure. If the readings are high, your doctor may recheck your blood pressure using the sphygmomanometer.

In general, children with blood pressure between the 90-95th percentile are classified as having "pre-hypertension," which means they are at risk for developing hypertension as they get older. Adolescents with blood pressure above 120/80 mm Hg also are considered to have pre-hypertension.