That blood pressure plays a role in human health has been known for quite a while. Hypertension - the medical term for high blood pressure - was first described as a disease in the early 1800s, and the inflatable cuff that's used in measuring blood pressure was invented in 1896.
That doesn't, however, mean there's nothing new about hypertension, its triggers and its effects. In fact, recent findings have punctured some long-held beliefs about the condition and the best ways to treat it.
For example, a study led by Dr. Carlos M. Ferrario, professor of surgery and founder of the Hypertension and Vascular Research Center at Wake Forest Baptist Medical Center in Winston-Salem, N.C., found that there were significant differences in the biological mechanisms that cause high blood pressure in women as compared to men.
"The medical community has thought that high blood pressure was the same for both sexes, and treatment has been based on that premise," said Ferrario, an internationally recognized expert in the field and current president of the Inter-American Society of Hypertension. "Our findings suggest a need to better understand the female sex-specific underpinnings of the hypertensive processes to tailor optimal treatments for this population. We need to evaluate new protocols - what drugs, in what combination and in what dosage - to treat women with high blood pressure."
Another Wake Forest Baptist researcher, Dr. Carlos J. Rodriguez, directed a study of people with hypertension which found that lowering their systolic blood pressure - the first number in a standard reading, as in 140/90 ("140 over 90") - below 120 wasn't necessarily beneficial over the long term.
"Frequently we treat patients' blood pressure to the lowest it will go, thinking that is what's best," said Rodriguez, an associate professor of public health sciences. "But our observational study found that treating to low pressures doesn't significantly reduce the risk of dangerous events like heart attack, heart failure and stroke. This calls into question the common notion that lower is always better."
Blood pressure is simply a measure of how hard blood pushes against the walls of arteries as it moves through the body. It is expressed in two numbers, with the systolic reading (when the heart is pumping) followed by the diastolic reading (between heartbeats). Blood pressure is generally considered normal when it's lower than 120/80 and high when it's 140/90 or above. Readings in between are usually classified as pre-hypertension, which indicates a likelihood of developing high blood pressure.
Hypertension can cause damage to the heart and blood vessels and lead to heart attack, stroke and other serious health problems. Approximately one-third of all American adults have high blood pressure, and the rate is substantially higher among men over 55 and women over 65.
The good news is that high blood pressure is treatable, most commonly by a combination of medicine and lifestyle changes.
But even though it's common, easily identified and controllable, hypertension does have its quirks. In most cases there aren't any symptoms; most people don't find out they have high blood pressure until they go to a doctor for another reason. Because a wide variety of factors can contribute to raised blood pressure - including obesity, diabetes, smoking, drinking too much alcohol, eating too much salt, stress, physical inactivity, kidney disease, having a family history of high blood pressure and aging - and because there are nine categories of anti-hypertension drugs, determining the best course of treatment can be complicated. In fact, most people with hypertension need to take two or more prescription drugs to keep their blood pressure at healthy levels.
It is known that ethnicity can be a factor in the effectiveness of medications - African-Americans, for example, are more responsive to drugs classified as calcium channel blockers than those in the angiotensin inhibitor category - but Ferrario's study clearly indicates that gender should also be a primary consideration in selecting the most appropriate treatment. And while Rodriguez's research findings, which are being put to the test in a large clinical study, suggest that less aggressive therapies may be sufficiently beneficial in treating hypertension, other researchers, including Ferrario, believe that pre-hypertension should be treated more aggressively to delay the occurrence of high blood pressure and thus reduce the risk of cardiovascular damage over time.
Ferrario also advocates that clinical trials should look at long-term morbidity and mortality rates of different medications in addition to the magnitude of blood pressure reduction when weighing the effectiveness of hypertension treatments.
But Ferrario is quick to emphasize that research is not an end in itself.
"In a sense, it's not that we need more research, it's that we need to apply what we know in day-to-day care," he said. "What's the point of doing lots of studies if very little of that is translated into immediate benefits for patients?"
To close what he called an "enormous gap" between what has been learned about hypertension and how it is treated, Ferrario said physicians need to be better educated about research findings so they can make appropriate adjustments to their practice patterns. And patients can contribute, too, by learning what they can do about their condition and being proactive about their care.
"It never hurts," he said, "for a patient to ask a doctor why he or she is recommending a particular treatment or drug."
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