TUESDAY, July 22 (HealthDay News) -- A study links night-time heart attacks with the breathing disorder sleep apnea, which makes people gasp for breath every few minutes.

The link is not fully established, but it seems logical, said Dr. Virend Somers, a cardiologist from the Mayo Clinic who is lead author of the report in the July 29 issue of the Journal of the American College of Cardiology.

Most heart attacks occur in the day, generally between 6 a.m. and noon, Somers said. Having one during the night, when the heart should be most at rest, means that something unusual happened, he said. Somers and his colleagues have been working for a decade to show that sleep apnea is to blame.

Their studies have looked at the most common form, obstructive sleep apnea, in which the tube carrying air to the lungs, collapses periodically, blocking the flow. "About 10 years ago, we showed that obstructive sleep apnea has a powerful effect on the sympathetic nervous system, causing an acute increase in adrenaline flow, high blood pressure and lack of oxygen," Somers said.

That study was followed by another showing that sudden death at night is more common for people with sleep apnea. An obvious cause of sudden death is a heart attack, so in this latest study, Somers and his colleagues studied the breathing patterns of 92 people admitted to the hospital after heart attacks.

"For those who had heart attacks at night, the vast majority had undiagnosed sleep apnea," Somers said. "So, perhaps sleep apnea is acting as a trigger for night-time heart attacks."

The "perhaps" is there because it is an observational study, not the kind of carefully controlled study that is the gold standard of medical research. Prospects for such a study, in which people with and without sleep apnea would be followed for months or years to determine their risk of night-time heart attacks, are dim, Somers acknowledged.

Several studies have shown a link between sleep apnea and cardiac problems, said Dr. Allan Pack, director of the sleep center at the University of Pennsylvania. The largest, done several years ago, followed thousands of individuals. "It showed that people with sleep apnea who refused treatment had a three- to fourfold increased risk of cardiac events," Pack said.

What the new study adds is "a relative difference in the timing of cardiac events," he said. In clinical practice, if someone has a heart attack in the night, "you would strongly suspect sleep apnea," Pack said.

If tests detect sleep apnea, there is an effective treatment available that can reduce the risk of future cardiac events, he said. Continuous positive air pressure (CPAP) keeps airways open continuously by pushing air into the lungs through a face mask.

"It might be cumbersome, but it is effective," Pack said.

More information

Learn about the symptoms and treatment of sleep apnea from the American Sleep Apnea Association  .

FRIDAY, July 18 (HealthDay News) -- Researchers say they have grown in mice the kind of functioning heart blood vessels that cardiac surgeons create with bypass operations.

One ultimate goal is to replace some heart surgery with injections of laboratory-grown cells that would establish themselves in the body, providing a system of blood vessels for damaged hearts that need more oxygen, said Juan M. Melero-Martin, a co-author of a paper in the July 18 issue of the journal Circulation Research: Journal of the American Heart Association.

"We are proving the concept in mice who are compromised so that they don't reject human cells," said Melero-Martin, a research fellow at Harvard Medical School and Children's Hospital Boston. "For clinical use, the way we envision it, if a patient has need to vascularize ischemic tissue, we can get cells from the patient ahead of time, grow them and inject them back into the patient."

Ischemic tissue is starved of blood because of blocked arteries or other damage, and revascularization restores the vessels through which blood can flow to that tissue.

The research team is not using stem cells, which are controversial, because they are obtained from human embryos. Instead, they are using what are called progenitor cells, easily obtained from blood or bone marrow, which can grow to become various sorts of adult cells. The progenitor cells used in the study grew into full-fledged blood vessel systems in the laboratory mice.

The researchers combined two kinds of progenitor cells, one for those that line the surface of blood vessels, the other for cells that surround the lining and provide stability. They found that a mix of the two kinds of progenitor cells derived from adult blood and bone marrow or umbilical cord and adult bone marrow gave the best growth of blood vessels.

"Our next goal down the line is to use them in humans," said Joyce Bischoff, associate professor of medicine at Harvard and senior author of the report.

Much work lies ahead, she said. "We need to do a lot more animal studies to test how these cells behave in different tissues," Bischoff said.

"We have proved that the cells have the ability," Melero-Martin said. "Now we have to see how to implement this in a clinical situation."

A version of the sort of human medical experiment that they envision has already been done by physicians at Goethe University in Frankfurt, Germany. Two years ago, they reported a study with 75 people who had heart attacks. Some were given injections of progenitor cells, derived either from bone marrow or blood. Improved heart function was seen in those who got the progenitor cells, the German researchers reported.

The work being done at Harvard could eventually be used to treat a number of conditions in which new blood vessels would help, such as severe wounds, the researchers said.

A current goal is to lessen the time needed to grow blood vessels outside the body, Bischoff said. Extensive growth now is seen after seven days, and the hope is to reduce that to 24 to 48 hours.

"If you have ischemic tissue, it's dying tissue, so the faster you can establish blood flow, the better," she said.

More information

Learn about the procedures currently used to restore blood flow in the heart from the American Heart Association  .

MONDAY, July 14 (HealthDay News) -- A diagnosis of heart disease darkens a person's outlook on life, a new government study finds.

Adults with cardiovascular trouble scored up to 9 percent lower on four scales measuring their quality of life, according to a report in the July 15 issue of Circulation, from researchers at the U.S. Centers for Disease Control and Prevention.

It's not a surprising finding, but it's a necessary study, said Dr. Jipan Xie, who spearheaded the research while a health scientist at the CDC's Division for Heart Disease and Stroke Prevention. She has since left the agency.

"We kind of expected it," Xie said. "Chronic heart disease does affect the quality of life, but we wanted to quantify it, so we would have a benchmark for a national evaluation."

It's important to know how people with heart disease view life because more of them are living longer, Xie said. "With more and more people living with coronary heart disease, we need to further assess the quality-of-life aspect of these patients and help them adjust."

It's something that physicians should pay attention to, Xie said. "When physicians see patients and say 'coronary heart disease,' usually they are not paying enough attention to their quality of life, especially the social aspect."

The CDC study had data on 2,091 people with a history of coronary heart disease in a national sample of 37,386 Americans. On average, those with heart disease scored 2.4 percent lower mental health scores, 9 percent lower self-ratings of health, 9.2 percent lower physical health scores, and 4.6 percent lower on scores of health utility, which measures mobility, self-care, physical activity, pain and anxiety.

The people with coronary heart disease most likely to report poorer quality of life were those aged 18 to 49, women, blacks and Hispanics, the study found.

"In my opinion, younger patients in the workforce may have higher expectations, and heart disease affects their physical performance," Xie said. "They may not be able to perform the job. They are under more pressure than older people."

And women with heart disease "expect to be healthier, so they think their quality of life is more impaired," she said.

But Dr. Winston H. Gandy Jr., a spokesman for the American Heart Association, said that women and minorities feel worse about their heart disease, because their treatment isn't always as good as it could be.

"Disparities exist in the delivery of care," said Gandy, who is director of the Echo/Vascular Center of Excellence of Piedmont Health Institute in Atlanta. "Women and African-Americans in particular present for treatment much later in the course of their disease."

Gandy found a bright side to the study. Results would have been much worse 20 or 30 years ago, before artery-opening techniques such as bypass surgery and angioplasty were commonplace, he said.

"In the early 1980s, there was not a lot of therapy for those issues," Gandy said. "If you had a coronary event, you would be in the hospital for a week and off work for a month. Fast forward to today, and, all of a sudden, we have people who have a heart attack or blockage, get angioplasty today and are home tomorrow."

Ask those people how they feel, and the answer might not be cheerful, Gandy said. "But I'm very encouraged that we have all these people living longer to be around to enjoy their children and grandchildren," he said.

More information

Coronary heart disease and its treatment are described by the U.S. Heart, Lung, and Blood Institute.

MONDAY, July 14 (HealthDay News) -- Young adults with the borderline high blood pressure called prehypertension are more likely later in life to have calcium deposits in their coronary arteries, a new study finds.

"They're too young to have very many heart attacks and strokes," lead author Dr. Mark J. Pletcher said of the 3,560 participants whose ages were 18 to 30 when the study started. "But looking at coronary calcium is a way of measuring atherosclerosis, which is a strong predictor of heart attacks."

Almost 20 percent of the people in the study developed prehypertension -- which is blood pressure higher than the recommended 120 over 80 but below the 140 over 80 reading of treatable high blood pressure -- before the age of 35. Coronary scans showed accumulation of calcium deposits in their heart arteries during the 20-year study.

"What we have shown is that these low-level elevations, above 120 over 80, appear to be associated with atherosclerosis later in life and probably with heart attacks and stroke," said Pletcher, an assistant professor of epidemiology, biostatistics and medicine at the University of California, San Francisco.

The findings were published in the July 15 issue of the Annals of Internal Medicine.

"This is another bit of evidence that we should pay attention to prehypertension in young people," said Dr. Richard B. Devereux, professor of medicine at Weill Cornell Medical College in New York City. He led a study several years ago of American Indians that found an association between prehypertension in early adulthood and abnormalities of the heart muscles.

"They used a totally different bioassay," Devereux said of the San Francisco researchers. "It helps flesh out a more complete story."

Prehypertension early in life is associated not only with development of atherosclerosis, the formation of plaques that can eventually block arteries, but also with arteriosclerosis, stiffening of the arteries, Devereux said.

The new study found hypertension more common in men, blacks, and people who were overweight and of low socioeconomic status. Participants with annul incomes below $25,000 and no college education were twice as likely to have early prehypertension as those with annual incomes of more than $100,000 and a postgraduate education.

Drug treatment isn't a real option for prehypertension in young people, Pletcher said. "We don't have evidence that treating prehypertension in young adulthood prevents cardiovascular disease, so we don't recommend it," he said.

But physicians should pay attention to borderline high blood pressure in young people, and should recommend preventive measures if it is found, Pletcher said.

"We recommend lifestyle modifications, more exercise, better diet, and so on, to improve cardiovascular health," he said.

Devereux agreed. "Exercise, better diet, getting away from smoking, avoiding things which can be damaging to the arteries," he advised.

More information

Learn more about high blood pressure and prehypertension from the U.S. National Library of Medicine.