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Q . Can you explain exactly what "ejection fraction" means? And is there any way to increase it?

A. Ejection fraction refers to the volume of blood that's pumped out of the heart's left ventricle each time it contracts. Contrary to what many people believe, a normal ejection fraction is not 100%. Even a healthy heart pumps out only about half to two-thirds of the volume of blood in the chamber in one heartbeat. So a normal ejection fraction lies somewhere in the range of 55% to 65%.

Q. My cardiologist told me to take clopidogrel for a year after I received a stent. Now the year is up. I haven't had any bleeding problems. Should I keep taking it?

A. In addition to aspirin, doctors routinely prescribe clopidogrel (Plavix) for people who receive stents, the tiny metal mesh tubes placed in clogged blood vessels to improve blood flow. This medication stops blood components called platelets from clumping together and forming clots. The current guidelines generally recommend that people take the drug for a year. This advice assumes they don't have any side effects such as unusual bleeding, which can show up as severe nosebleeds or blood in the urine or stools. However, these guidelines are still evolving. Experts are currently reviewing new findings from large studies on the benefits and risks of taking clopidogrel and similar drugs for extended periods of time.

Cardiopulmonary resuscitation (CPR) not only saves lives, it may also help survivors of cardiac arrest recover well enough to return to work, according to a study in the May 12, 2015, issue of Circulation.

Researchers studied more than 4,300 people in Denmark who were employed before they suffered a cardiac arrest. In cardiac arrest, the heart suddenly stops working. More than 75% of survivors who had a cardiac arrest outside a hospital were able to return to work in a median time of four months. Those who received CPR from a bystander were nearly 40% more likely go back to work compared with those who didn't get CPR. The chest compressions given during CPR keep blood circulating to the brain, minimizing brain damage caused by a lack of oxygen.

Physical therapy is helpful for wear-and-tear knee osteoarthritis, especially if you start doing it early. But injecting a painful knee with an anti-inflammatory steroid medication before starting physical therapy offers no additional benefit, according to a clinical trial in JAMA Internal Medicine.

Studies have shown that physical therapy modestly reduces pain and improves daily functioning in people with knee osteoarthritis. That could mean being able to walk farther with less pain or to continue leisure activities such as gardening. Before you start physical therapy, your doctor may offer to inject the knee with a cocktail of anti-inflammatory steroid medication and an anesthetic. Hypothetically, this could make it easier for you to stick with exercise and therefore lead to better results.

Wear sunscreen, and avoid direct exposure to the sun.

Fatty plaque in the arteries that feed the kidneys poses a danger to the heart and brain.

Some research has suggested that older people who take blood pressure medications may be prone to falls, perhaps because the drugs make them dizzy or lightheaded when they stand up. But a new study in the May 2015 Hypertension found no increased risk of falls in people taking blood pressure drugs.

For the study, nearly 600 people with chronic high blood pressure reported their falls to researchers via mail-in postcards and phone calls. Almost half of the participants, whose average age was 78, reported one or more falls during the yearlong study. Neither standard nor high doses of blood pressure drugs were linked to falls. In fact, people who took two commonly prescribed types of blood pressure medications鈥擜CE inhibitors and calcium-channel blockers鈥攈ad a lower rate of falling compared with people not taking those drugs. Given the known benefits of treating high blood pressure in older people, the authors say, withholding blood pressure medication for fear of causing a fall may not make sense.

Serious health problems are uncommon after drugs or surgery to treat chronic heartburn, according to a recent study in Alimentary Pharmacology and Therapeutics. Many men take acid-reducing drugs called proton-pump inhibitors (PPIs), such as omeprazole (Prilosec, others) and lansoprazole (Prevacid), for chronic heartburn. One alternative is a surgical procedure to tighten the entrance to the stomach and prevent acidic stomach contents from backing up into the esophagus.

The new study drew on findings from two different clinical trials that tracked the health of people treated with either drugs or surgery. One trial involved about 300 people who were followed for up to 12 years; the other involved about 500 people who were followed for five years.

It appears that cognitive behavior therapy may help people with chronic insomnia and no underlying medical problems fall asleep faster.

When your back is bothering you and you don't want to take prescription drugs, over-the-counter solutions and physical therapies can help relieve symptoms.