Medical Tests & Procedures Archive

A rapid heartbeat can be frightening, but this often-fleeting problem is usually harmless.

 Image: © deeepblue/Thinkstock

If you're exercising or feeling very nervous, you expect your heart to beat faster than normal. But what if your heart sometimes starts racing out of the blue, for no apparent reason? You might have supraventricular tachycardia, or SVT. SVT is an umbrella term that covers several different types of rapid heart rhythms, all of which are caused by an electrical glitch in the upper part of the heart.

The most common SVTs are atrial fibrillation — a rapid, chaotic rhythm that increases the chance of having a stroke—and atrial flutter, a fast but usually regular heartbeat. But when cardiologists talk about SVT, they're usually referring to three different, less-common conditions (see "What is supraventricular tachycardia?").

On call

Q. I have had acid reflux for many years, but it is well controlled with a proton-pump inhibitor. However, I am concerned about long-term damage from my reflux, even though I feel fine now. Should I have an upper endoscopy to look for possible damage?

A. Long-term acid reflux can damage the esophagus and may lead to a condition known as Barrett's esophagus, which is a precursor to esophageal cancer. Barrett's affects about 3% to 10% of older men, but within this group the risk of developing esophageal cancer is only about four in every 1,000 cases. Over all, men with Barrett's are more likely to die from another cause.

Research we're watching

For many women with breast cancer, hair loss is the most distressing side effect of chemotherapy. Although cooling the scalp with ice packs has been tested, the technique has had limited success. However, a newer approach — wearing a cap connected to a cooling system that gradually reduces scalp temperature — has been more successful, according to two reports in the Feb. 14, 2017, Journal of the American Medical Association.

In one study, 67 of 106 women with stage I or stage II breast cancer who used the FDA-approved DigniCap during their treatment with taxane (Taxol and others) lost less than half of their hair. In comparison, 16 women who underwent the same treatment but did not wear the cooling cap lost all of their hair.

Coronary artery calcium tests can reveal early signs of heart disease. But they're not appropriate for everyone.

 Image: © Monkey Business Images/Thinkstock

A special x-ray scan can show specks of calcium inside the walls of the heart's arteries within a matter of minutes. Known as a coronary artery calcium (CAC) scan, it offers one way to predict a person's future risk of heart disease.

However, having this test makes sense only if the results would affect a person's medical treatment. For the most part, that means it's useful primarily for people who are wavering about whether to take a cholesterol-lowering statin drug, says Dr. Ron Blankstein, a cardiovascular imaging specialist and preventive cardiologist at Harvard-affiliated Brigham and Women's Hospital.

Because medications cannot effectively treat aortic stenosis, a stiff, narrowed aortic valve needs to be replaced.

Your aortic valve is the gateway between your heart and body. With every heartbeat, it opens to allow blood to flow to your body, then snaps shut to keep blood from moving back into the heart.

As people age, calcium deposits may collect on the hard-working aortic valve, causing it to stiffen and narrow. Known as aortic stenosis, this condition also can result from a genetic abnormality (see "What is a bicuspid aortic valve?"). But most cases are in older people, often — but not always — those with high blood pressure, high cholesterol, and other risk factors linked to heart disease. In the United States, about three to four of every 100 people ages 75 and older have severe aortic stenosis.

Research we're watching

Aging brains often show signs of microscopic strokes, which result from damage to tiny blood vessels within the brain. Those that occur in the brain's outermost layer — called cortical cerebral microinfarcts (CMIs) — usually don't cause any symptoms. But they are more common in autopsies of people diagnosed with dementia. Now, new research suggests a link between blood markers for early heart disease and CMIs.

The study, published online Feb. 6, 2017, by JAMA Neurology, included 243 people who attended a memory clinic. All had brain scans to check for CMIs and blood tests that measured two substances associated with early signs of heart damage. People who had CMIs (nearly 29% of the participants) were much more likely to have heart disease than those who didn't have CMIs. Higher levels of both substances associated with heart damage were also linked to CMIs — even when the researchers left out people who already had obvious symptoms of heart disease.

Research we're watching

Contrary to conventional wisdom, most people with older implanted cardiac devices may be able to safely get a magnetic resonance imaging (MRI) scan, according to a study in the Feb. 23, 2017, New England Journal of Medicine.

The devices, which include pacemakers and implantable cardioverter-defibrillators (ICDs), help regulate and restore the heart's normal rhythm. Concerns that the powerful magnets in MRIs could damage these battery-operated devices led to the development of newer, MRI-safe devices. But an estimated two million people in the United States have one of the older devices, and at least half of them might need an MRI in the future.

In the journals

People who suffer from migraines have increased risks of stroke and hospital readmission within 30 days after having surgery, according to research published online Jan. 10, 2017, by BMJ.

The study included 124,558 patients (45% of whom were men), who had a history of migraines, either with or without aura (a period of symptoms, such as flashes of light or facial tingling, that precedes the migraine). The researchers monitored the condition of all the patients after either inpatient or outpatient surgery. They then looked at how many had strokes and how many were readmitted to the hospital over the following 30 days.

In the journals

Prostate-specific antigen (PSA) tests are used to help identify men who may have a higher risk of prostate cancer. But a study published online Jan. 12, 2017, by JAMA Oncology, describes a new way to use PSA that may pinpoint men who are likely to die early from prostate cancer that returns after initial treatment.

The researchers used data from a randomized trial of 157 men whose localized cancer was treated with either radiation alone or radiation along with six months of androgen deprivation therapy. The men were then followed for 16 years.

Ask the doctor

Q. I have been smashed, squashed, pulled, and tugged annually for 25 years. Why isn't there a better way to take a mammogram?

A. We hear you! Compression mammography has been the "gold standard" for decades for one reason — it works. Flattening the breast makes ductal tissue easier to distinguish and reduces the amount of radiation required to do so. Studies have demonstrated that it is the most effective approach to breast cancer screening.