Systolic blood pressure the blood pressure when the heart is contracting. It is the maximum pressure of blood on the arteries during contraction of the left ventricle. The time at which ventricular contraction occurs is called systole. Blood pressure readings are usually given as two numbers. Normal blood pressure is 120 over 80 , written as 120/80 mm Hg. The top number is systole pressure and the bottom number is diastole pressure. If figures are significantly higher than these values, then it is an indication of High blood pressure.