WEDNESDAY, Jan. 20 (HealthDay News) -- Heart and lung function appear to be intimately intertwined, so that even mild cases of chronic lung disease affect the heart's ability to pump blood, a new study finds.
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"It suggests that a larger subset of heart failure may be due to lung disease," said Dr. R. Graham Barr, an assistant professor of medicine and epidemiology at Columbia University Medical Center and lead author of a report in the Jan. 21 issue of the New England Journal of Medicine.
It's long been known that severe chronic obstructive pulmonary disease (COPD) can have damaging effects on the heart, Barr said. But the new report, which covered 2,816 people in a long-running lung study, shows that "even a mild decrease in lung function affects heart function," he said.
Barr and his colleagues used two imaging techniques, computed tomography (CT) scanning and MRI, to measure both heart and lung structure and function. "We observed a linear straight-line relationship," Barr said.
The probable cause of the loss of ability to pump blood, he said, is a reduced blood supply to the heart.
COPD is the fourth-leading cause of death in the United States. One form of COPD is emphysema, in which lung tissue is destroyed. Another form is chronic obstructive bronchitis, which causes narrowed airways, a persistent cough and excess mucus production. Lung disease is strongly associated with smoking.
The immediate application of the finding to medical practice would be in diagnosis, Barr said. "Our study was not of possible intervention," he said. "Future studies will show how much treatment of the lung affects the heart and how much treatment of the heart affects the lung."
Barr has begun such a study, which he said is in an early stage. "These problems take a long time to develop, and so they take a long time to study," he said. The study is expected to last several years.
Meanwhile, physicians seeing people who report such lung problems as shortness of breath might consider testing their heart function, Barr said.
The report is an offshoot of a large study, supported by the U.S. National Heart, Lung and Blood Institute, that focused on finding early stages of heart, lung and blood diseases.
"What makes it a novel finding is that just a slight degree of lung disease can have an overall impact on cardiovascular health," said James P. Kiley, director of the institute's lung disease division. "What we are seeing here is the ability to bring the two conditions together."
There is a distinct benefit in looking at the two conditions together, Kiley explained. "Understanding cardiovascular disease might help understand lung disease and vice versa," he said. "We can put more emphasis on the possibility that these two do have a link and that the link needs to be explored further, even in the clinical assessment of a patient."
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SOURCES: R. Graham Barr, M.D., Dr.P.H., assistant professor, medicine and epidemiology, Columbia University Medical Center, New York City; James P. Kiley, Ph.D., director, division of lung diseases, U.S. National Heart, Lung and Blood Institute, Bethesda, Md.; Jan. 21, 2010, New England Journal of Medicine