What do those blood-pressure numbers mean? Blood pressure is typically recorded as two numbers, each measured in millimeters of mercury (mmHg). The numbers reflect how high the pressure pushes a column of mercury in a device called a sphygmomanometer (much as the mercury rises in a thermometer in response to heat).
The first or top number measures systolic blood pressure, the force in your arteries when the heart muscle contracts in a heartbeat. The second or bottom number measures diastolic pressure, the pressure in your arteries when the heart muscle rests and refills with blood—between heartbeats.
The American Heart Association categorizes blood-pressure levels like this:
In late 2013, a panel of experts published recommendations in the Journal of the American Medical Association calling for raising the cutoff for hypertension for people age 60 and older from 140/90 to 150/90. (People with diabetes and kidney disease should be treated at the original 140/90 level, the experts added.) Based on an extensive evidence review, that update to guidelines issued in 2003 immediately proved controversial; five of the panel members as well as the American Heart Association rejected the change.
Each patient is different, in any case, and the best advice is to talk with your physician. If your high blood pressure is already well controlled by medications, the controversy over the new guidelines shouldn’t affect you.