A team of researchers at the School of Public Health has discovered that psychological stress has an important effect on the stability of the heart and may, in extreme cases, lead to a heart attack.

The researchers, led by Dr. Bernard Lown, associate professor of Cardiology, have experimented on dogs to develop a model which permits the study of stress factors on the rhythm of the heart.

Dr. Richard L. Verrier, a research associate, said yesterday the team is trying to determine the causes of "sudden death," a total heart failure which claims more than 400,000 American lives each year.

By comparing the effect of electrical impulses in dogs that are in states of stress or calm, the researchers found that stress made the heart more unstable.

A key breakthrough in the research, Verrier said, was the discovery of "echo beats," a pattern of heartbeats which signals imminent cardiac failure. This finding allowed the researchers to induce heart failure in dogs without killing them.

Verrier said he is "cautions" in applying the experiment's results to humans. "If it is transferable," he said, "the conclusion is that psychological stress factors such as anxiety or fear affect the stability of human cardiac rhythm to a greater degree than we expected."

It was previously thought that psychological factors might cause a heart attack, Verrier said. The new findings on dogs, he said, represent the first definite measurement of those effects of the nervous system on the heart.

Verrier said that in future experiments the research team will try to find exactly how the neural mechanism works on the heart and what treatment is effective in preventing heart failure. He said it may be possible to develop drug or psychological therapy to strengthen the heart through the nervous system.

"In general," Verrier said, "it's important physicians become more aware of the role of the nervous system in heart care. They should concern themselves more with the mental well-being and anxieties of the patient."

"We know that psychological stress has an important effect," Verrier said. "Now for the first time we can systematically study that effect on cardiac rhythms and with our model, try to devise approaches to therapy in humans."