Dear Dr. Roach: There’s lots of info out there regarding systolic blood pressure, but what about diastolic blood pressure? My top number is always fine, but the bottom goes between 82-88 regularly. I’ve been diagnosed with diastolic dysfunction and would like more info regarding this bottom number that’s not mentioned as much as the top number. — M.P.A. 
Answer: The left ventricle, which pumps blood to the body, has two phases: systole, when the chamber squeezes the blood out and the aortic valve is open, and diastole, when the aortic valve is closed and the ventricle refills. The peak blood pressure, represented by the top number, is systolic, while the bottom number (diastolic) is the blood pressure when the left ventricle is filling up. Both systolic and diastolic numbers are important, as elevations in either of them increases risk of heart disease and stroke.
However, if the systolic number is not elevated and the diastolic number averages around 85, the magnitude of your risk is small.
Diastolic blood pressure elevations mostly represent an issue with the blood vessels in the body, while diastolic dysfunction refers to a decreased ability of the heart to relax, sometimes called a “stiff ventricle.”
Longstanding high blood pressure is a major risk for diastolic dysfunction. Diastolic dysfunction and high diastolic blood pressure do not have to be linked, but often are.
