In a blood pressure reading, the top number refers to the amount of pressure in your arteries during contraction of your heart. This is called systolic pressure. The bottom number refers to your blood pressure when your heart is between beats. This is called diastolic pressure.
Hypertension is defined as blood pressure at or above 140/90. In pre-hypertension, the systolic reading is 120-139 or the diastolic reading is 80-89 mmHg. A blood pressure reading of 120/80 used to be considered normal or healthy. It is now considered pre-hypertension and a warning sign that you may get high blood pressure in the future.
If you have a diastolic reading less than 80 but a systolic reading at 140 or greater, you have a common type of high blood pressure called isolated systolic hypertension or ISH. ISH is a risk factor for stroke and heart disease and can cause damage to organs such as the kidneys, brain, heart, or eyes. Bottom line, it should be treated. The American Heart Association estimates that over 100,000 lives could be saved if people would lower their systolic blood pressure to 119 or less.
