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Q. After several episodes where my heart suddenly started racing, I was diagnosed with supraventricular tachycardia. My doctor said I could try gagging or coughing to help slow down my heart when these episodes occur. Why would those things help?

A. Supraventricular tachycardia (SVT) is caused by an electric problem in the area above the heart's lower chambers, or ventricles. This uncommon disorder can cause the heart to beat more than twice as fast as normal—even up to 300 times a minute. It is more common in younger people than in older folks.

Sometimes it's hard to tell the difference between a heart attack, heartburn, and lung problems.

ÌýImage: © PeopleImages/Getty Images

Many kinds of health problems can cause chest discomfort, with symptoms so intense that you rush to the hospital. "I see older adults with chest pain or something related to it every time I work in the emergency department," says Dr. Kei Ouchi, an emergency medicine physician at Harvard-affiliated Brigham and Women's Hospital.

The big fear

You may worry that chest pain is due to a heart attack, which occurs when blood flow to the heart is blocked, typically by a blood clot and narrowed arteries. Classic symptoms include pressure or squeezing in the chest, lightheadedness, and pain in the shoulder, arm, neck, jaw, or back.

Ask the doctor

Q. A friend recently had what his doctor called a "3D echocardiogram." How is that different from a standard echocardiogram?

A. All echocardiograms use high-frequency sound waves (ultrasound) to create still and video images of your heart. But there are two different procedures for getting the images and several variations of this common test, which doctors often refer to simply as an echo.

Stressful experiences are hard to avoid and impossible to predict. But taking steps to bolster your resilience may help.

The palpable stress stemming from the COVID-19 pandemic has made things once considered stressful � such as deadlines or traffic jams � seem pretty trivial in comparison. But while you may not be able to avoid the stressful situations that come your way, there are ways to mitigate your body's response to those events.

So far, the evidence that stress management strategies can protect your heart is limited but growing. Yet there's no doubt that stress contributes to heart problems. "The link between stress and cardiovascular disease is well established," says cardiologist Dr. Ahmed Tawakol, an associate professor of medicine at Harvard Medical School.

The novel coronavirus is especially risky for people who have or are at risk for cardiovascular disease.

Editor's note: Research and news about COVID-19 change rapidly. For updated information about the pandemic, see www.health.harvard.edu/cvrc.

When cases of COVID-19 began to surge across the globe earlier this year, doctors quickly realized the infection was particularly dangerous for people with heart disease and related conditions, especially high blood pressure. These health problems become more prevalent with age, so could that explain why COVID-19 is more deadly in older people?

Every year, hundreds of people in the United States die waiting for a heart transplant. A new procedure may make more donated hearts available.

In this country, more than 7,300 people are on the waiting list for a new heart during the course of a year. The majority are in their 50s and early 60s, and most have severe, debilitating heart failure. But because of a shortage of suitable donor hearts, fewer than half will receive a heart transplant. However, an emerging technique known as donation after circulatory death may help address that gap in coming years.

For decades, all heart transplants done in the United States have used hearts donated after brain death, which is defined as the irreversible loss of all brain function. Organs other than the heart � including lungs, kidneys, and livers � are donated after either brain death or after circulatory death, a circumstance known as donation after circulatory death, or DCD (see "What is donation after circulatory death?"). But in recent years, researchers in Australia and England began pioneering heart transplants following circulatory death.

Ten years ago, the Harvard Heart Letter published a story about the potential health benefits of chia seeds. At the time, people were more familiar with the ceramic figures known as Chia Pets (see ) than the idea of chia seeds as a health food. But today, you can find these nutritious seeds in major grocery stores, sold in packages or in products such as crackers, cereals, energy bars, and beverages.

The small, black seeds are among the richest plant sources of the omega-3 fatty acid known as alpha-linolenic acid (ALA). Diets high in ALA have been linked to a lower risk of heart disease. Chia seeds are also high in insoluble fiber, which may help lower harmful LDL cholesterol levels.

Research we're watching

Thanks to marketing strategies that tout coconut oil as healthy, many people consider this solid, white fat a health food. But a new analysis confirms what nutrition experts have said for years: Coconut oil raises harmful LDL cholesterol (a well-known contributor to heart disease) much more than other vegetable oils.

The study, published online March 10, 2020, by the journal Circulation, pooled findings from 16 trials involving a total of 730 people. Most of the trials lasted one to two months and compared coconut oil consumption with that of other fats, including other vegetable oils such as soybean, safflower, canola, and olive oils. Compared with these vegetable oils, coconut oil raised LDL cholesterol by 10 points, on average. An editorial accompanying the study states "In culinary practice, coconut oil should not be used as a regular cooking oil, although it can be used sparingly for flavor or texture."

Research we're watching

Most home blood pressure monitors sold in Australia are not carefully tested for accuracy, according to a study published online April 10, 2020, by the journal Hypertension.

Because more than 90% of the devices the researchers studied were purchased from international online platforms such as Amazon and eBay, that means many devices purchased in the United States and elsewhere might give inaccurate readings, the authors say.