4) History of ischemic cardiac disease, pulmonary embolism, retinal thrombosis, or thrombophlebitis; any subject with risk factors for thrombo-embolic phenomena including cigarette smokers; varicose veins, patients with prolonged periods of immobilization (including prolonged travel), and active heart disease. The literature suggests that although both smoking and hormone replacement/oral contraceptives have associated risks of thromboembolic phenomena and cardiovascular events, these individual risks do not become significantly greater when combined until greater than 10 cigarettes a day are consumed. Thus we wish to exclude only subjects for this study who smoke greater than 10 cigarettes per day.