Reaching the Boiling Point : Researchers have found that high blood pressure’s cause has more to do with heredity than with environmental factors.

The boss has just done a fandango all over your ego, the baby-sitter canceled, that little rattle in the car just turned into a chewing, grinding sound, and there’s a letter in the mailbox from the IRS marked “urgent.”

You respond to this mother of all bad days by turning the color of a rotten strawberry and throbbing like a locomotive. You feel like you’re going to explode any second. Your blood pressure, you figure, has gone beyond fire hydrant level and could now propel the Space Shuttle into a parking orbit.

But if you slap that cuff on your upper arm and check, you might be surprised to find that you’re not the pressure cooker you thought you were. You may be awash in adrenaline and your heart may be racing, but the pressure pushing all that blood around may only be slightly above normal.

That’s one of the newest findings about one of the more mysterious of all cardiovascular ailments: hypertension, or high blood pressure. Quite a lot was discovered over the years about the effects and treatment of the disease, but nothing was known for certain about the cause.

Today, however, researchers have begun to zero in on the whys of hypertension, while at the same time improving the treatments.

“I just got back from a meeting of the American Society of Hypertension in New York,” said Dr. Michael Weber, chief of the section of hypertension at UC Irvine, “and the single most important thing today is that it’s becoming recognized that hypertension is an inherited condition. Environmental factors might bring it on at an earlier age or they might exaggerate it, but fundamentally it tends to run in families.”

This is potent information in the hands of someone whose parents or grandparents had high blood pressure, since hypertension is impossible to self-diagnose. It has been estimated that as many as 33% of adult Americans suffer from it, but it is called “the silent killer” because there are no symptoms that can be accurately diagnosed without taking a blood pressure reading.

How high is high? The borderline, as defined by the American Heart Assn., is a systolic pressure (when blood is expelled from the heart) of 140 millimeters of mercury and a diastolic pressure (when the heart is resting) of 90. The numbers may soar high above this during exercise, but if they consistently remain at or above 140/90, you have high blood pressure.

The consequences of ignorance could be early death from coronary artery disease or stroke.

Detective work is necessary to discover the full range of effects hypertension has on the body, said Weber, because “a problem is that hypertension very rarely exists only as high blood pressure. It can, but more often than not it’s associated with problems with cholesterol and other fats in the blood. It’s also associated with abnormalities in glucose and insulin metabolism.

“Even though hypertensives do not have diabetes in the usual clinical sense, they share some common underlying problems, such as damage to coronary arteries and other vital arteries in the body,” he said.

Now, the good news. Salt, or sodium, may not be the villain that it has been made out to be in the battle against high blood pressure.

“It hasn’t finally been sorted out,” said Weber, “but I think the truth is that although there are some hypertensive people who are very sensitive to sodium, the majority of the population are not sensitive and can eat (high amounts) without ill effects.”

And, he said, among people with high blood pressure, those who are sensitive to sodium represent only about one-fifth of the patients. This means, said Weber, “that only about 4% or 5% of the population as a whole would have a problem if they stuffed themselves with sodium.”

As a result, he said, fewer hypertension patients are being put on low-salt or no-salt diets. These diets, said Weber, are a problem in that “it’s not hard to cut down salt a little bit, but to cut down to the point where it might actually impact the blood pressure, you have to go on a pretty rigorous diet.

“The general feeling now among hypertension experts is that putting patients in general on those diets is not a productive approach to treatment.”

What is productive, he said, is maintaining a healthy weight. And it isn’t necessary, if you’re overweight, to lose dozens of pounds to see results.

“With a loss of as little as 10 to 15 pounds, people can see a meaningful reduction in blood pressure,” he said.

Also, said Weber, if you routinely have several drinks a day, holding your alcohol consumption down to one or two a day--or none--will produce a “nice reduction” in blood pressure readings.

There’s even good news if you have chronic high blood pressure, known as “essential hypertension.” The drugs used to treat the disease today “are very effective and especially do not cause the symptomatic side effects such as drowsiness, dry mouth and lethargy that the old drugs did,” said Weber.

“Some people would say, ‘I’d rather die sooner than put up with all of this.’ But there has been a big breakthrough in the last 10 years.”