Blood Pressure Archive

Known as bradycardia, this heart rhythm disorder can cause fatigue, dizziness, and fainting.

The steady beat of your heart depends on a crescent-shaped cluster of cells in the upper right portion of your heart. Called the sinoatrial or sinus node, it emits a tiny jolt of electrical current that triggers the heart to contract and pump blood throughout the body (see illustration). Because the sinus node determines the heart's pace and rhythm, it is sometimes called the body's natural pacemaker.

Just as your skin, joints, and other parts of your body reveal signs of normal wear and tear as you age, so too can the structures inside your heart. "This age-related degeneration can affect the sinoatrial node and other parts of the heart's conduction system," says Dr. Peter Zimetbaum, director of clinical cardiology at Harvard-affiliated Beth Israel Deaconess Medical Center.

Research we're watching

Although people tend to focus more on the first number in a blood pressure reading, the second number is also important for predicting heart disease risk. That's according to a study based on 36 million blood pressure readings from more than 1.3 million adults, published in the July 18 New England Journal of Medicine.

Systolic pressure (the first number in a blood pressure reading) measures the force with which the heart pumps blood into the arteries. Diastolic pressure (the second, lower number) reflects the pressure in the arteries when the heart rests between beats. Over eight years, more than 44,000 people in the study had a heart attack or stroke. The risk of those events rose among people with systolic readings of 130 and higher, but also in those with diastolic readings of 80 and higher. The findings are a reminder to pay attention to both numbers in your blood pressure reading, and that for most otherwise healthy people, lower blood pressure is better.

Sodium doesn't affect everyone equally, but there's good reason to stick to moderate amounts in your diet.

On average, Americans eat too much salt — more than a teaspoon and a half a day. Most often it doesn't come out of a shaker, but is hidden in the foods you eat. But is it really bad for your heart to eat too much, or is that just a concern for people with certain risk factors? There's been some debate on this topic, even among members of the scientific community. We asked Nancy Cook, a professor of medicine at Harvard Medical School, for her thoughts on salt — or more precisely, sodium, a mineral that makes up 40% of salt — and how it affects your health and your heart.

Is salt really bad for your heart?

"There is a fairly undisputed effect of sodium on blood pressure," says Cook. The effect is stronger in people with high blood pressure (hypertension), a sustained blood pressure reading of 120/80 or higher. The data for an effect on cardiovascular disease are somewhat more controversial, she says, but in general, the bulk of research does seem to link lower sodium intake with both lower blood pressure and a lower risk of cardiovascular disease.

Nerve damage might be causing everything from low blood pressure to gastrointestinal distress without your knowing it.

Doctors have long known peripheral neuropathy as a nerve condition that causes reduced sensation, tingling, weakness, or pain in the feet and hands. But those symptoms may be just the tip of the iceberg. Doctors are now learning that neuropathy can cause many more problems.

What is peripheral neuropathy?

Peripheral neuropathy refers to damage to the peripheral nerves throughout the body. These nerves carry messages to and from the brain.

News briefs

A study published online June 10, 2019, by Circulation suggests that scaling up three healthy lifestyle changes could increase the life spans of almost 100 million people around the world. Researchers — led by a team from the Harvard T.H. Chan School of Public Health — evaluated global data on death rates, blood pressure levels, the use of blood pressure medications, sodium and trans fat intake, country, age, and gender. They estimated that a worldwide push to lower blood pressure, reduce salt intake by 30%, and eliminate the consumption of trans fat could delay more than 94 million deaths from cardiovascular disease in the next 25 years. More than half of those deaths would be among adults ages 70 or older, and more than half of all deaths would be among men. Regions that would see the most benefit are outside the United States — in East Asia, South Asia, the Pacific, and parts of Africa. But we can all benefit from the three lifestyle changes. Trans fat has already been banned in foods in the United States. But if your blood pressure isn't under control, it's time to talk to your doctor about treatment and to reduce sodium intake to well under 2 grams per day.

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Sweet drinks go down easy, but they may be hard on your heart. Aside from plain water, the healthiest choices are unsweetened tea, coffee, and flavored waters.

When you want to quench your thirst with something a little more exciting than plain old water, there are a dizzying array of choices these days. However, many of the beverages in supermarkets and convenience store aisles are loaded with added sugar. Even many of those that sound healthy (such as 100% fruit juice and vitamin-enhanced water) contain as much sugar as regular sodas.

Yes, the sugar in fruit juice is naturally occurring, as opposed to the processed sugar (usually high-fructose corn syrup) found in many carbonated and noncarbonated drinks such as sodas, vitamin water, and the like. But people should still be mindful about consuming too much fruit juice, says Vasanti Malik, a nutrition researcher at the Harvard T.H. Chan School of Public Health.

News briefs

Vitamins and supplements won't help stave off dementia, but a healthy lifestyle might, suggest new guidelines released May 19, 2019, by the World Health Organization (WHO). The WHO warns that the number of new dementia cases around the world — currently 10 million per year — is set to triple by 2050. While there's no cure for any kind of dementia (such as Alzheimer's disease and vascular dementia), the WHO says it may be possible to delay the onset of the disease or slow its progression. The key: managing modifiable risks, such as chronic disease and unhealthy habits. The guidelines recommend that you keep your weight, cholesterol, blood pressure, and blood sugar under control; get lots of exercise; and eat a Mediterranean-style diet (which emphasizes olive oil, fruits, vegetables, nuts, and fish; minimizes red meats and processed meats; and includes a moderate amount of cheese and wine). The WHO also advises that you don't smoke and you avoid harmful use of alcohol (no more than one drink per day for women, no more than two drinks for men). But don't count on supplements to help you stave off dementia. The WHO says there's no evidence that vitamin B, vitamin E, multivitamins, or fish oil supplements help reduce the risk for dementia. The agency recommends against using supplements as a means to ward off cognitive decline.

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Eating too much salt usually boosts blood pressure, but not in everyone. Understanding the genetic basis of these differences may improve treatment of high blood pressure.

Do you know someone who eats lots of salty food — pizza, pickles, pretzels, and the like — but has naturally low blood pressure? That person may be salt-resistant, which means his or her blood pressure doesn't rise very much in response to a diet high in salt (sodium chloride). In contrast, other people are salt-sensitive, which means their blood pressure rises by 5 points or more if they switch from a low-sodium to a high-sodium diet.

Unfortunately, there isn't an easy test to determine who is salt-sensitive, says endocrinologist Dr. Gordon Williams, professor of medicine at Harvard Medical School. "Still, we know that Americans eat far more salt than they actually need, so it makes sense to advise everyone cut back on salt," he says.

Q. Some friends invited me to accompany them to Rocky Mountain National Park. I would love to go, but I have high blood pressure and worry that high altitudes are dangerous for people with  high blood pressure. Is that the case?

A. If you have high blood pressure but are otherwise healthy, your blood pressure is under control, and you take some precautions, a trip to the Rocky Mountains should be fine.

In the journals

Eating a cup of blueberries every day may help your blood pressure, suggests a new study. The results, published online Feb. 16, 2019, by The Journals of Gerontology, Series A: Biological Sciences and Medical Sciences, found that consuming 200 grams of blueberries (about one cup) daily can improve blood vessel function and decrease systolic blood pressure (the top number in a blood pressure reading).

Researchers recruited 40 healthy men and randomly gave them either a drink containing 200 grams of whole wild blueberries or a control drink (which looked and tasted much the same) every day for a month. The team also monitored the men's blood pressure as well as the flow-mediated dilation of the brachial artery in their upper arms. This measures how the artery widens when blood flow increases and is a marker of reduced cardiovascular disease risk.