The first study to investigate how heat affects people with heart failure shows that one of two ways the body can cool itself is not as effective in those with congestive heart failure relative to healthy individuals. The results, published in today's issue of the journal Circulation, emphasize the need for people with heart failure to take special care when the weather is hot, said Dr. Benjamin Levine, professor of internal medicine at UT Southwestern Medical Center and one of the study's two senior authors.

"We wondered whether either sweating or skin/blood responses would be impaired in heart failure patients," said Dr. Craig Crandall, associate professor of internal medicine at UT Southwestern and the other senior author of the study. "We found that for the same level of internal temperature, the heart failure patient does not dilate blood vessels of the skin as much."

He and his colleagues discovered no difference in sweating responses among study participants with heart failure or healthy subjects. However, the skin/blood flow response in those with heart failure was significantly impaired, by as much as 50 percent when compared to the control group.

"The purpose of this study was to find out why patients with heart disease and heart failure are at great risk for having complications when the weather gets hot," said Dr. Levine, director of the Institute for Exercise and Environmental Medicine, a collaboration between UT Southwestern and Presbyterian Hospital of Dallas. "We saw this in particular in the heat wave that hit Chicago in 1995. Of the reported deaths, a large number had a prior heart condition. We wondered why."

The study included 28 participants between the ages of 47 and 55 half with congestive heart failure and half w
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Contact: Katherine Morales
katherine.morales@utsouthwestern.edu
214-648-3404
UT Southwestern Medical Center
10-Oct-2005