Blood pressure readings consist of two numbers: the top number, or systolic pressure and the bottom number, or diastolic pressure. But even if your diastolic number is lower than 8 you can have elevated blood pressure if the systolic reading is 120-129. If your blood pressure is normal, maintaining or adopting a healthy lifestyle can prevent or delay the onset of high blood pressure or other health problems.
The diastolic pressure is the force within the blood vessels between heartbeats. It represents the minimum pressure in the arteries when the heart is at rest. Blood pressure readings are measured in millimeters of mercury (mmHg) and are provided as a pair of numbers.
Low diastolic blood pressure is when the lower number in your blood pressure reading falls below mm HG.
Blood Pressure : Blood pressure chart
Using this blood pressure chart: To work out what your blood pressure readings mean, just find your top number (systolic) on the left side of the blood pressure chart and read across, and your bottom number (diastolic) on the bottom of the blood pressure chart.