With all the talk of how cigarette smoking causes lung cancer and other respiratory problems, it's easy to overlook the impact it can have on your heart and the rest of the cardiovascular system. In the United States, about 20 percent of deaths from heart disease are directly related to cigarette smoking.The heart is damaged by smoking because the chemicals in cigarette smoke encourage the buildup of plaque - a fatty substance-- along artery walls. Over time, the plaque thickens and hardens, narrowing the arteries and reducing blood flow to the heart. This sets the stage for angina, stroke and heart attack. The nicotine in cigarettes is another heart attacker. It increases blood pressure, heart rate and blood clotting, while it decreases levels of available oxygen. The result is damage to cells that line coronary arteries and other blood vessels. If you happen to be a smoker who also has high blood pressure, high cholesterol, or are overweight, well, your chances of developing heart disease are even greater. The MORE you smoke, the greater your risk for developing heart disease, period. People who smoke a pack of cigarettes a day are more than twice as likely to have a heart attack as nonsmokers. But your risk of heart disease is cut IN HALF just ONE YEAR after quitting. For more information on preventing heart disease, watch the other videos in this series.