UNFAVORABLE EFFECT OF SMOKING ON THE ELASTIC PROPERTIES OF THE HUMAN AORTA

Background Smoking is a major risk factor for cardiovascular morbidity and mortality. Because previous studies have shown that smoking affec ts vasomotor response, we hypothesized that smoking may also acutely a lter aortic elastic properties. Methods and Results We studied 40 male current and longterm smokers who underwent diagnostic cardiac cathete rization for chest-pain evaluation. Twenty subjects (age, 48+/-2 years , mean+/-SEM) were randomly assigned to smoking and 20 (age, 47+/-2 ye ars) to sham smoking studies. Aortic elastic properties were studied w ith the determination of the aortic pressure-diameter relation before smoking, every minute for the first 5 minutes after the initiation of smoking or sham smoking, and every 5 minutes for the following 15 minu tes. Instantaneous diameter of the thoracic aorta was measured with a special ultrasonic dimension catheter developed in our laboratory and previously validated. Instantaneous aortic pressure was measured at th e same site as was diameter with a Millar micromanometer. Smoking was associated with significant changes in the aortic pressure-diameter re lation that denote deterioration of the elastic properties and were ma intained during the whole study period: the slope of the pressure-diam eter loop became steeper (baseline, 35.43+/-1.38; minute 1, 45.26+/-1. 65; peak at minute 10, 46.36+/-1.69 mm Hg/mm; P<.001) and aortic diste nsibility decreased (baseline, 2.08+/-0.12; minute 1, 1.60+/-0.08; nad ir at minute 5, 1.54+/-0.07 x 10(-6) cm(2) . dyne(-1); P<.001). In con trast, no changes in aortic elasticity indexes were observed with sham smoking. Conclusions Smoking is associated with an acute deterioratio n of aortic elastic properties. This effect of smoking may contribute to the unfavorable consequences of smoking on the cardiovascular syste m.