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Cigarette Smoking

By: Kavanagh, Terence, Take Heart! Key Porter Books 1998, page 59-65.

Everyone is now aware of the connection between cigarette smoking and lung cancer. How many also realize that the smoker is three to four times more likely to experience heart attack than the nonsmoker, and that the attack is more likely to be fatal? The risk increases proportionally with the number of cigarettes smoked and is particularly high in those under the age of 50. The risk of sudden cardiac death increases more than tenfold in men and fivefold in women who smoke.

According to the American Academy of Pediatrics, more than 3,000 children and teenagers in the United States start to smoke each day. Furthermore, while there has been a sharp decline in the number of men in the 20-to-25 age bracket who start the smoking habit, there has been a sharp increase in new women smokers in the same age bracket. If the trend continues, soon we can expect that more women than men will smoke. The British medical authorities have come up with the sobering statistic that of every thousand young adults who smoke, 250 will die of a smoking-related disease. Although there is growing opposition in the West to tobacco advertising and its targeting of the young, the developing countries have yet to take a similar stance; unless they do, they will face a similar epidemic of lung cancer and heart disease. The tobacco industry is now targeting the developing countries, and apparently with considerable success. Will these nations eventually have to face a problem of equal magnitude?

Tobacco smoke contains more than 2,000 known substances, including nicotine, carbon monoxide, nitrogen dioxide, benzine, formaldehyde, and hydrogen cyanide. Many of these compounds are capable of damaging the endothelial lining of the coronary arteries and thereby provoking atherosclerosis. Probably the two major harmful compounds are nicotine and carbon monoxide. The nicotine in cigarette smoke is highly addictive. It is released into the bloodstream within seven seconds of inhaling the smoke and almost immediately triggers the release of adrenaline and a related substance called noradrenaline. These two hormones, which are produced by the adrenals, two small glands just above the kidney, prepare the body for "fight or flight." As a result, blood pressure rises and heart rate goes up, increasing the heart muscle's requirements for oxygen. Unfortunately however, this demand is thwarted by the action of the other substance in tobacco smoke, carbon monoxide, which is also the principal poisonous ingredient in car exhaust fumes. In large doses, carbon monoxide kills by displacing all the oxygen in red blood cells. Actually, hemoglobin, the protein in the red cell that carries oxygen, prefers carbon monoxide and, given the choice, is 200 times more likely to pick it up than oxygen. You can see the paradox. Nicotine increases the heart muscle's oxygen requirements, and carbon monoxide makes sure that those requirements are not met.

If the coronary arteries are already narrowed and the blood supply to the heart limited as a result of atherosclerosis, smoking makes matters worse. Anginal sufferers who smoke experience pain at a much lower level of exertion than nonsmokers. Even in the absence of coronary atherosclerosis, heavy smoking may cause heart attacks. There are reports of young heavy-smoking adults who have suffered a heart attack and yet on subsequent investigation are found to have normal coronary arteries. The mechanism is a shutdown of the coronary artery due to a spasm provoked by exposure to nicotine. In susceptible individuals, nicotine can cause life-threatening irregularities of the heartbeat. Sudden cardiac death is thereby probably another hazard for smokers. A number of investigations have also established that smokers have "sticky" blood and are liable to develop clots in their arteries, particularly the coronary vessels or the vessels in the leg. Finally, it has been noted that habitual smokers have lower levels of the protective HDL-C. Since a high HDL-C is felt to be one of the major mechanisms that protects young women from coronary disease, this might explain who women who smoke seem to have lost that protection.

It is extremely hard for most people to give up smoking. As an ex-smoker myself, I sympathize with anyone trying to quit. Experts in the field have said that in some ways addiction to cigarettes is as strong as, if not stronger than, addiction to heroin. The acute physical withdrawal symptoms may not be so severe, but apparently the craving is never quite extinguished. Many individuals who stopped smoking for 20 or even 30 years have started again after a few casual cigarettes. After 30 years of working with cardiac patients at the Toronto Centre, we are now experiencing this phenomenon. Admittedly the numbers are small, but some people who were enrolled in our program in the late 1960s, and who stopped smoking after their heart attack, have started again after 20 years. To be honest, I have to say that if somebody were to offer me a perfectly safe cigarette now (and such a cigarette is nowhere in sight), even 30 years after quitting I would be tempted to start smoking again !

There is no safe alternative to quitting. Low-tar, low-nicotine filter cigarettes have been found to be just as dangerous as their predecessors, since habitual smokers will continue to get their boost of nicotine by taking deeper more frequent puffs and smoking the cigarette right down to its filter. Pipe and cigar smokers are at slightly less risk than those who smoke cigarettes, but this is apparently not the case for former cigarette smokers. Having once learned to inhale from a cigarette, smokers invariably apply the same practice to a pipe or cigar.

How quickly after you quit can you expect to reduce your risk for a heart attack? Nicotine is quickly cleared from the body ( which is why you experience early withdrawal symptoms). Carbon monoxide takes about 24 hours to clear, but by then its ill effects will have gone. One to two weeks after stopping, the risk starts to decrease, and a number of studies have demonstrated that it reaches almost the level of a nonsmoker at the end of one to two years.

Danger to Nonsmokers
In recent years, there has been increasing recognition of the dangers to nonsmokers of sidestream smoke, that is, the smoke that escapes into the air from the burning end of the cigarette for all to inhale, smokers and nonsmokers alike. In fact, this danger has been the major impetus for the banning of smoking in public places. Actually, sidestream smoke contains a higher concentration of nicotine, carbon monoxide, and other pollutants than exhaled ( mainstream) smoke. Obviously, the danger to the nonsmoker is greater in confined areas. A Scottish study looked at the effect on a nonsmoker living with a spouse who smoked. More than 15,000 men and women were followed up for an average of 11.5 years. The nonsmoking spouses of smokers had two and a half times the incidence of lung cancer and twice the incidence of heart disease compared with the nonsmoking spouses of nonsmokers. Further American and British studies have confirmed that exposure to second-hand smoke can increase the risk of heart attack by 20% - 30%.

CCRF would like to thank Dr. T. Kavanagh for his contribution to the Website.

The articles, on the Cardiac Health Foundation of Canada website, are presented with the understanding that the Foundation is providing information only and not rendering medical advise. Please check with your family physician, specialist or health care professional before implementing any of the ideas expressed in these articles.

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