Systolic blood pressure is the pressure in your arteries when your heart beats and pushes blood through your arteries to the rest of your body. It is the first number in a blood pressure reading and is usually expressed as the higher number. Blood pressure is measured using two numbers: systolic blood pressure and diastolic blood pressure. The diastolic blood pressure is the pressure in your arteries when your heart rests between beats. It is the second number in a blood pressure reading and is usually expressed as the lower number. Blood pressure is usually expressed in terms of the systolic pressure over diastolic pressure in the cardiac cycle. Blood pressure levels are classified based on these two numbers. Elevated blood pressure is defined as a systolic pressure between 120 and 129 with a diastolic pressure of less than 80. High blood pressure is defined as systolic pressure of 130 or higher, or a diastolic pressure of 80 or higher.