UNFAVORABLE EFFECTS OF PASSIVE SMOKING ON AORTIC FUNCTION IN MEN

Background: The aorta acts as both a conduit and an elastic buffering chamber that modulates left ventricular function and coronary blood fl ow. Previous studies have shown that active smoking has unfavorable ef fects on aortic elasticity. Objective: To study the association betwee n passive smoking and the elastic properties of the human aorta. Desig n: Comparison of nonsmokers during passive smoking studies and smokers during active smoking or sham smoking studies. Setting: Academic medi cal 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 p atients) studies. Intervention: All participants underwent diagnostic catheterization. In the passive smoking group, environmental tobacco s moke was vented into an exposure cham-ber for 5 minutes (mean carbon m onoxide level, 30 parts per million). Each participant in the active s moking 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 unli t cigarette. Measurements: Aortic elastic properties were studied by m easuring the aortic pressure-diameter relation before and for 20 minut es after passive, active, or sham smoking. Instantaneous diameter of t he thoracic aorta was measured with a high-fidelity ultrasonic dimensi on catheter. Instantaneous aortic pressure and diameter were measured at the same site. Results: Both passive and active smoking were associ ated 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) cm(2) 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) cm(2) dyne(-1) [f or comparisons of time course between active and sham smoking groups. P < 0.001]). These changes represent decreases of 21% and 27%, respect ively. No changes in aortic elasticity were seen in the sham smoking g roup. Conclusions: Both passive and active smoking are associated with an acute deterioration in the elastic properties of the aorta. This a ssociation between exposure to tobacco smoke and aortic elasticity ind icates that aortic function deteriorates during passive or active smok ing.