Because smoking restricts blood flow, it is a major cause of coronary heart disease and stroke.
Smoking narrows the blood vessels and increases the body’s tendency to form blood clots, restricting the flow of blood to vital organs. Smoking also raises the blood carbon monoxide level, which may increase the risk of injury to the lining of the arterial walls. Cholesterol is more likely to be trapped on the inside of the blood vessels and forms plaques, which could further restrict blood flow. Where this happens in the coronary arteries (the main arteries to the heart), it may lead to coronary heart disease or heart attack; in a blood vessel in the brain, it could result in stroke.
Smoking increases the risk of heart disease by two or three times and by 10 times for a woman on the Pill. Risk of a fatal heart attack is double that of a non-smoker. This risk rises even higher if you smoke 10 -15 per day or more, or have any other risk factors for heart disease. Smoking doubles the risk of stroke.
Peripheral vascular disease
Smoking is the most important risk factor for developing peripheral vascular disease (PVD), in which arteries, usually in the legs, become narrowed and blocked through arteriosclerosis.
During exercise, the muscles need an increased amount of oxygen and nutrients. If an artery is obstructed, then sufficient oxygen and nutrient-laden blood can’t reach the muscle tissue. The muscles are temporarily starved of oxygen and pain results during exercise. In advanced PVD, the pain may severe enough to prevent movement. Major surgery may be needed to improve circulation in the leg. Sometimes, when the blood supply cannot be restored to a limb, gangrene (tissue death due to insufficient blood supply) results and it may be necessary to amputate the limb. Smoking increases the risk of gangrene by over five times. For diabetics, the risk is even higher: nearly all diabetics who have had a leg amputated before the age of 60 are smokers.