775-2 Deleterious Effect of Smoking on the Elastic Properties of the Aorta

Cigarette smoking alters vascular reactivity and thus may alter the elastic properties of the aorta (Ao). To test this hypothesis, serial pressure-diameter loops (figure A) were obtained from the simultaneous recordings of the thoracic Ao diameter (D) and pressure (P) before and atterthe initiation of smoking of one cigarette (nicotine content 1.3mg) in 20 healthy smokers who underwent diagnostic cardiac catheterization. Ao 0 were measured by a Yshaped catheter, developed in our institution, which incorporates at its distal tips a pair of ultrasonic dimension crystals (Crystal Biotech, MA). This highdefinition diameter gauge was validated in in-vitro and experimental studies. Ao Pwere recorded by a Millar micromanometer. The pressure-diameter relationship changed significantly with smoking (figure A). Ao distensibility (=2Δd/dx ΔP, where Δd and ΔP: changes from systole to diastole of the Ao D and P respectively, and d: diastolic Ao D) was decreased significantly after smoking (figure B). These changes suggest that the Ao became stiffer atter smoking.This effect of smoking on the elastic properties of the aorta adds to the multiple other deleterious effects of smoking on human health