Smoking even a single cigarette can make the heart "stiffen" and not relax normally between contractions, researchers say.

The Arizona Daily Star reported May 16 that a cardiac imaging study at the University of Arizona reveals that any amount of smoking can be dangerous. "What we found is that with just one puff of a cigarette, we see changes in the way the heart relaxes between contractions. It seems to stiffen -- it does not have the vigorous motion it should have," said researcher Vincent Sorrell of the University of Arizona. "And we know that failure to relax properly is an early marker for heart failure."

Karen Martin, manager of Tucson's antismoking program, said she will use the information in her prevention messages. "This dramatically demonstrates how you damage over and over again the vital organs that keep the whole body going," she said. "Our cessation people enjoy passing along the latest information on what smoking does to you. The smokers always say, 'Yeah, yeah, we've heard it all,' but this is new evidence they need to hear."

Researchers decided to conduct the imaging tests after noticing that smokers often complain of shortness of breath, but have normal test results in the doctor's office. "I thought maybe there is something going on transiently while they are smoking, but later, at the doctor's office when they're not smoking, their hearts go back to normal," Sorrell said.

The study involved 27 young adults, half of whom smoked a cigarette while the others chewed nicotine gum. Sorrell found that the smokers' left ventricle did not relax properly. "As a result, the heart filled up with less blood than it normally does," Sorrell said, causing shortness of breath. "I think you can add these results to the growing list of evidence that it doesn't take a lot of cigarettes to cause problems for the heart."