Background: The aorta acts as both a conduit and an elastic buffering chamber that modulates left ventricular function and coronary blood flow. Previous studies have shown that active smoking has unfavorable effects on aortic elasticity.
Objective: To study the association between passive smoking and the elastic properties of the human aorta.
Design: Comparison of nonsmokers during passive smoking studies and smokers during active smoking or sham smoking studies.
Setting: Academic medical center.
Participants: 16 male nonsmokers were assigned to passive smoking studies, and 32 current, long-term, male smokers were randomly assigned to either active smoking (16 patients) or sham smoking (16 patients) studies.
Intervention: All participants underwent diagnostic catheterization. In the passive smoking group, environmental tobacco smoke was vented into an exposure chamber for 5 minutes (mean carbon monoxide level, 30 parts per million). Each participant in the active smoking group smoked one filtered cigarette (1.0 mg of nicotine) under standardized conditions within 5 minutes; each participant in the sham smoking group performed a similar pattern of inhalation with one unlit cigarette.
Measurements: Aortic elastic properties were studied by measuring the aortic pressure-diameter relation before and for 20 minutes after passive, active, or sham smoking. Instantaneous diameter of the thoracic aorta was measured with a high-fidelity ultrasonic dimension catheter. Instantaneous aortic pressure and diameter were measured at the same site.
Results: Both passive and active smoking were associated with changes in the aortic pressure-diameter relation (change in mean distensibility in the passive smoking group, from 2.02 to 1.59 x 10(-6) cm2 x dyne(-1) [for comparisons of time course between passive and sham smoking groups, P < 0.001]; change in mean distensibility in the active smoking group, from 2.08 to 1.51 x 10(-6) cm2 x dyne(-1) [for comparisons of time course between active and sham smoking groups, P < 0.001]). These changes represent decreases of 21% and 27%, respectively. No changes in aortic elasticity were seen in the sham smoking group.
Conclusions: Both passive and active smoking are associated with an acute deterioration in the elastic properties of the aorta. This association between exposure to tobacco smoke and aortic elasticity indicates that aortic function deteriorates during passive or active smoking.