The chemicals in tobacco smoke harm your heart and blood vessels in many ways. For example, they:
                
Contribute to inflammation, which may trigger plaque buildup in your arteries.
                
Damage blood vessel walls, making them stiff and less elastic (stretchy). This damage narrows the blood vessels and contributes to the damage caused by unhealthy cholesterol levels.
                
Disturb normal heart rhythms.
                
Increase your blood pressure and heart rate, making your heart work harder thannormal.
                
Lower your HDL (good) cholesterol and raise your LDL (bad) cholesterol. Smoking also increases your triglyceride level. Triglycerides are a type of fat found in theblood.
                
Thicken your blood and make it harder for your blood to carry oxygen.
                
Smoking and Heart Disease Risk
                
Smoking is a major risk factor for coronary heart disease, a condition in which plaque builds up inside the coronary arteries. These arteries supply your heart muscle with oxygen-rich blood.
                
When plaque builds up in the arteries, the condition is called atherosclerosis.
                
Plaque narrows the arteries and reduces blood flow to your heart muscle. The buildup of plaque also makes it more likely that blood clots will form in your arteries. Blood clots can partially or completely block blood flow.
                
Over time, smoking contributes to atherosclerosis and increases your risk of having and dying from heart disease, heart failure, or a heartattack.
                
Compared with nonsmokers, people who smoke are more likely to have heart disease and suffer from a heart attack. The risk of having or dying from a heart attack is even higher among people who smoke and already have heart disease.
                
For some people, such as women who use birth control pills and people who have diabetes, smoking poses an even greater risk to the heart and blood vessels.
                
Smoking is a major risk factor for heart disease. When combined with other risk factorssuch as unhealthy blood cholesterol levels, high blood pressure, and overweight or obesitysmoking further raises the risk of heart disease.
                
Smoking and the Risk of Peripheral Artery Disease
                
Peripheral artery disease (P.A.D.) is a disease in which plaque builds up in the arteries that carry blood to your head, organs, and limbs. Smoking is a major risk factor for P.A.D.
                
P.A.D. usually affects the arteries that carry blood to your legs. Blocked blood flow in the leg arteries can cause cramping, pain, weakness, and numbness in your hips, thighs, and calf muscles.
                
Blocked blood flow also can raise your risk of getting an infection in the affected limb. Your body might have a hard time fighting the infection.
                
If severe enough, blocked blood flow can cause gangrene (tissue death). In very serious cases, this can lead to leg amputation.
                
If you have P.A.D., your risk of heart disease and heart attack is higher than the risk for people who dont have P.A.D.
                
Smoking even one or two cigarettes a day can interfere with P.A.D. treatments. People who smoke and people who have diabetes are at highest risk for P.A.D. complications, including gangrene in the leg from decreased blood flow.
                
Secondhand Smoke Risks
                
Secondhand smoke is the smoke that comes from the burning end of a cigarette, cigar, or pipe. Secondhand smoke also refers to smoke thats breathed out by a person who is smoking.
                
Secondhand smoke contains many of the same harmful chemicals that people inhale when they smoke. It can damage the heart and blood vessels of people who dont smoke in the same way that active smoking harms people who do smoke. Secondhand smoke greatly increases adults risk of heart attack and death.
                
Secondhand smoke also raises the risk of future coronary heart disease in children and teens because it:
                
Damages heart tissues
                
Lowers HDL cholesterol
                
Raises blood pressure
                
The risks of secondhand smoke are especially high for premature babies who have respiratory distress syndrome and children who have conditions such asasthma.
                
Cigar and Pipe Smoke Risks
                
Researchers know less about how cigar and pipe smoke affects the heart and blood vessels than they do about cigarette smoke.
                
However, the smoke from cigars and pipes contains the same harmful chemicals as the smoke from cigarettes. Also, studies have shown that people who smoke cigars are at increased risk of heart disease.