In a study published in today's (Jan. 7) issue of the American Heart Association journal Circulation, Christodoulos Stefanadis, M.D., and his colleagues report that the flexibility and elastic properties of the aorta deteriorated as soon as one minute after people started smoking and the effect was sustained for at least 20 minutes after smoking.
This finding is important, the researchers say, because a stiff and inflexible aorta reduces the ability of the heart's main pumping chamber, the left ventricle, to maintain its maximum allowable output of blood. For someone with diagnosed left ventricular dysfunction, smoking may then increase the severity of the disease state.
Smoking also forces the left ventricle to pump more furiously, increasing its demand for oxygen. However, the ability of the coronary arteries to supply heart muscle with oxygen is decreased by the stiffening of the aorta. Consequently, the left ventricle is unable to fulfill its task, Stefanadis explains.
In the study, 20 long-term male smokers inhaled a five-second puff from a filtered cigarette every 15 seconds for five minutes. Twenty other long-term male smokers went through the same pattern with an unlit cigarette. The researchers measured output from each person's left ventricle at the beginning of the process and at five, 10 and 20 minutes after initiating smoking or sham smoking.
The scientists also measured blood pressure in the aorta and associated that with the assessed diameter of the blood vessel at the same site. In men who smoked, pressure increased while the ability of the aorta to relax and widen -- what the scientists called "pulsatile diameter" -- decreased. But no such change was observed with sham smoking.
"This acute effect of smoking may be a contributing factor to its deleterious consequences for human health," the scientists report.