Time to Take a New Look at Your Blood Pressure

An age-old measure of circulatory health has been turned on its head. On Thursday, the National Heart, Lung and Blood Institute issued an advisory for health care providers who take patients' blood pressure: Watch the top number more than the bottom one. That's a reversal of conventional wisdom, which dictated that the bottom figure, for diastolic pressure, was the more important indicator of blood pressure because it showed how hard the heart was working to refill itself with blood between pumps. With this new recommendation, the NHLBI focuses attention on systolic pressure — the top figure.

Why the sudden turnaround? Research has been piling up for years supporting the NHLBI's position, according to TIME medical contributor Dr. Ian Smith. "Systolic pressure can show what's happening throughout the circulatory system, rather than only within the heart itself." For example, Smith explains, a systolic reading not only shows the force the heart is required to exert in order to push blood past resistance points, it also measures the pressure generated within vessels to keep blood moving to different organs — which can pinpoint a patient's risk for stroke or general damage to blood vessels.

Of course, just because your doctor or nurse may start keeping a closer eye on a new element of your blood pressure reading doesn't mean you're off the hook to keep your pressure down. According to generally accepted standards, no one should maintain a reading above 140/90, and some people may be advised to keep their pressure even lower. And that's where the work comes in: Cutting salt from your diet, losing weight and, yes, getting out there and exercising.