Medical Tests & Procedures Archive

Telomeres — made of your DNA — are biomarkers of aging.

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There's no crystal ball in medicine that can predict how fast you're aging or how long you'll live. But the latest trend in private screening tests claims to provide a tantalizing clue. The tests offer a snapshot of the length of your telomeres — the protective caps at the ends of chromosomes in your cells.

"The concept is very attractive. There's this visual idea of something acting like a clock counting down to the end, and that's why it's powerful. The problem is that just because it's appealing it doesn't mean it's true," says Dr. William Hahn, a Harvard Medical School professor and chief research strategy officer at Harvard-affiliated Dana-Farber Cancer Institute.

Catheter ablation, a procedure that destroys faulty electrical pathways in the heart, is gaining ground.

Atrial fibrillation — called afib for short — is a rapid, irregular heartbeat caused by errant electrical signals in the heart's upper chambers (atria). This heart rhythm disorder becomes more prevalent with age, affecting about one in 11 people ages 65 and older.

The chaotic heartbeat that characterizes afib usually comes and goes and may last anywhere from a few seconds to many hours — or much longer (see "Atrial fibrillation: Defined by its duration"). Although about 20% of people with afib don't notice any symptoms, it can trigger a range of unsettling problems. These include a fluttering or thumping sensation in the chest, breathlessness, dizziness, anxiety, weakness, fainting, confusion, and fatigue.

Research we're watching

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Your doctor may one day be able to use a simple blood test to find out if you have cancer. Researchers from Johns Hopkins University reported in the January 19 issue of Science that they have developed a blood test that can spot early signs of cancer.

The researchers screened blood for DNA and proteins related to eight different types of cancer. They were able to identify early cancers from more than 1,000 patients with different types of cancer that had not yet spread. Over all, the test found 33% to 98% of cancers, depending on tumor type.

When, why, and how you might get an electrocardiogram.

Although the first recorded electrocardiogram dates back more than a century, this noninvasive test remains one of medicine's essential tools. It's quick and painless, produces results right away, and helps diagnose dozens of heart conditions. Any heart-related symptoms, such as chest pain or palpitations, warrant an electrocardiogram, also known as an ECG or EKG (from the German elektrokardiogramm).

Some primary care providers include an ECG as part of an annual physical exam. Last year, the U.S. Preventive Services Task Force (USPSTF) recommended against routine ECGs in people at low risk of heart disease. But what about people at higher risk, such as those with high blood pressure, elevated cholesterol levels, or even just advancing age? For them, the jury's still out, according to the USPSTF. One possible reason: the task force set a high bar — looking for conclusive proof that a routine ECG led directly to an improvement in outcomes, such as complications related to coronary artery blockages.

Liquid biopsies may offer a less invasive alternative than a traditional biopsy.

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A tissue biopsy is the standard test for identifying cancer. Your medical team will use needles or other devices to capture pieces of actual tumor to see if it's malignant or benign. But another approach, called a liquid biopsy, is less invasive and may provide a diagnosis when a biopsy doesn't.

This test uses a person's blood to look for signs of cells or mutated DNA that a tumor has shed into the bloodstream. "By sampling DNA or circulating tumor cells in the blood, we can predict and monitor responses to cancer treatments without subjecting patients to invasive biopsy procedures — and perhaps detect cancer early, before it has had a chance to spread," says Dr. David Miyamoto, assistant professor of radiation oncology at Harvard Medical School.

Research we're watching

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March is National Colorectal Cancer Awareness month. Have you been screened? Colon cancer is the second leading cause of cancer deaths in the United States, but is also highly preventable through recommended screenings. These screenings enable doctors to spot precancerous lesions that can lead to colon cancer and remove them before they become a problem. Screenings can also find cancers early, when they are most treatable. All people ages 50 to 75 should get recommended colon cancer screenings. Some people should start getting screened earlier if they have certain risk factors for colon cancer, including a family history, a personal history of inflammatory bowel disease (such as Crohn's disease or ulcerative colitis), or a genetic condition that makes colon cancer more likely (such as familial adenomatous polyposis).

There are several tests used for colon cancer screening, including colonoscopy, which uses a device to examine the full length of the colon and rectum; stool tests; flexible sigmoidoscopy, which uses a device to examine a portion of the colon; and CT colonography, a scanning technique that produces images of the colon that are examined by the doctor.

Here's what Harvard physicians advise you to do at your next appointment.

You know the routine: you're waiting in the exam room, and your doctor comes in for what seems like a very quick visit before leaving to see the next person. You're left feeling that you didn't ask all of your questions or get a good understanding of your treatment plan. What happened?

"We're under incredible pressure, and we're scrutinized to be sure we're seeing enough patients," explains geriatrician Dr. Suzanne Salamon, an assistant professor at Harvard Medical School. "We don't have many minutes, and yet we have to go over each person's medical issues, medications, and even end-of-life issues. That doesn't leave a lot of time to talk."

A study questioned the benefit of stents for some heart patients. What does this mean for people with chest pain?

Last fall, many news outlets highlighted a study suggesting that a common heart procedure — inserting a stent to open a narrowed heart artery — was no better than a sham procedure (see "Stent vs. sham: A short summary"). But the big picture isn't quite so simple.

For instance, it's worth noting that six weeks prior to undergoing the procedures, all of the 200 people who completed the study were prescribed increasing doses of heart medications. Referred to as optimal medical therapy, this approach is a proven strategy for treating chest pain brought on by physical activity or emotional stress that promptly goes away with rest or nitroglycerin (so-called stable angina).

Dozens of clinics offer unproven stem cell therapies for heart failure. Despite steady progress, this experimental treatment is not ready for prime time.

 Illustration: Scott Leighton

A heart attack cuts off blood flow to part of the heart's muscle, usually causing lasting damage. Over time — especially in people with repeat heart attacks — the resulting scar tissue can hinder the heart's ability to function normally, leading to heart failure.

For nearly two decades, scientists have studied how stem cells might repair a damaged heart and restore its function. These unique cells, which have the potential to grow into a variety of heart cell types, can be made from other cells (see "What's new in cardiac regeneration?").

Precision medicine offers a personalized approach for prevention and treatment of cancer and other diseases.

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If you have a stomachache or cold, you go to the pharmacy and grab the same remedy that everyone else uses, and it often works. But is that always the best approach? Your reaction to an infection may be quite different from someone else's, so perhaps you need a treatment designed just for you and your ailment.

That's the philosophy behind precision medicine (sometimes referred to as personalized medicine), an emerging approach to prevention and treatment that takes into account a person's genes, environment, and lifestyle and eliminates the one-size-fits-all approach to health care.