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Good Question: What Do Your Blood Pressure Numbers Mean?

MINNEAPOLIS (WCCO) -- The results of a landmark federal government study released on Monday could mean the guidelines for healthy blood pressure are about to change.

The data, presented at the annual meeting of the American Heart Association, found a 27 percent lower risk of dying from a heart problem when the blood pressure was lowered from 140 to 120 for older people with high blood pressure.

Right now, 120 over 80 is considered normal and 140 over 90 is considered high.  But, what do those numbers mean? Good Question.

"With high blood pressure, the heart is squeezing against this pressure, the harder the heart has to squeeze or to work," Dr. Kimara March, a cardiologist with University of Minnesota Heart, said.  "It's like a hose. If you put a kink in the hose, the pressure on the other side is higher so you can see that hose is building up pressure to get that blood or water through."

The top number is the systolic pressure and measures the pressure in the arteries when the heart beats.  The bottom number is the diastolic pressure and measures the pressure in the arteries between the heartbeats.

"The bottom number is a relaxation number so the pressure that's left after the heart has pumped out," Dr. March said.

Dr. March says both numbers concern her and she'll treat, with either counseling or medication, if either number is too high.

In the government study, some people did report dizziness, fainting and kidney problems with too-low blood pressure.

"In these people that are older, you can push the blood pressure down to 120. It is well-tolerated, and there is a benefit in terms of reducing cardiovascular risk and heart failure specifically," Dr. George Bakris of the University of Chicago Medicine told CBS News.

Dr. March says it's likely more studies will be needed before there are major overhauls to the blood pressure guidelines.

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