About Systolic Blood Pressure

In the cardiac cycle in which the heart beats, blood pumps throughout the body. This pumping action creates a force, or pressure, which is measured in two parts--the systolic and the diastolic. The systolic is the highest pressure created in the cycle, and occurs after the contraction of the heart's left ventricle.

Getting a Reading

The cuff and instrument used to take your blood pressure is called a sphygmomanometer. As the inflating cuff tightens around your arm, it stops the blood flow in your artery. Letting the air out of the cuff allows a healthcare professional listening through a stethoscope to hear a thumping sound.

The Systolic Beat

That thumping sound represents your systolic pressure. Systolic blood pressure is what results from your heart muscle contracting.

The Top Reading

Whether measuring blood pressure manually or with a machine, the top (or first) number is the systolic reading. Normally, this is the larger number of the two.

The Bottom Reading

Between contractions, the heart relaxes, or dilates. This phase of the cardiac cycle measures diastolic blood pressure. In manual readings, a healthcare professional listens for when the thumping sound starts to fade to take the diastolic measurement.

Range

Your body does not maintain a constant blood pressure. So when measuring blood pressure, it is normal to have variations throughout the day. In general, a systolic reading below 130 is normal. A high normal reading is between 130 and 139. And anything from 140 and higher is considered high.