Cigarettes and hypertension: a deadly duo.

Cigarette smoking is the most important proven cause of premature death in the United States. About 35 percent of all smokers die prematurely of a smoking-related disease. Smokers are three times more likely to die of cancer than nonsmokers. The Framingham Heart Study found that men who smoke are 10 times as likely to experience sudden death from cardiac arrest as nonsmokers. Among women smokers, the mortality rate is five times greater.

The combination of cigarette smoking and hypertension increases the risk of stroke and heart attack considerably. If you know you have a genetic predisposition to hypertension 5and you smoke cigarettes, you have greatly increased your risk for having a fatal cardiovascular disease.

How Cigarette Smoke Kills

There are some 4,000 substances identified in cigarette smoke--some highly toxic and carcinogenic (cancer causing). One of the most deadly substances ingested by human beings, nicotine is one of cigarette smoke's main components.

What does nicotine do to the body? When you puff a cigarette, nicotine immediately enters the bloodstream and reaches the brain within six seconds, where more than 15 percent of it is absorbed. When nicotine reaches the brain, it signals the adrenal glands to release norepinephrine and epinephrine (adrenaline), which increase both the systolic and diastolic pressure. Nicotine is absorbed in the mouth as well as the lungs. Therefore, even if you don't inhale, large amounts of nicotine still enter the bloodstream. Your heart beats faster, it pumps more blood, and your arteries work harder to push the blood through your body. This elevates the blood pressure and contributes to blood vessel atherosclerosis.

In addition to directly causing an increase in heart and vessel activity, cigarette smoking also contributes to the advance of atherosclerosis, hypertension's deadly partner. First, nicotine is known to raise the amount of fats and cholesterol circulating in the bloodstream by releasing some of the stored body fat. This increase in circulating fats also contributes to the process that forms plaque on artery walls.

Cigarette smoking has been shown to raise the level of low-density lipoproteins (the bad cholesterol) by as much as 10 percent. Second, another ingredient of cigarette smoke, carbon monoxide, helps the process along by directly damaging the cells that form the inner linings of arterial walls. This makes the vessel lining more susceptible to plaque buildup.

To compound the situation further, the carbon monoxide, a toxic gas, is carried through the bloodstream by the same blood component, hemoglobin, that transports oxygen. The more carbon monoxide in the bloodstream, therefore, the less oxygen is being carried to the vital organs. While nicotine stimulates heart and vessel activity, carbon monoxide prevents oxygen from helping the body do this extra work.

Cigarette smoking also causes chemical changes in the blood itself, causing it to become more viscous, or sticky, which results in the formation of large blood clots, a process called thrombosis. These clots can cause both strokes and heart attacks.

Cigarette smoking may also increase the risk of developing renovascular hypertension, a form of secondary hypertension involving the kidneys. Tobacco smoke also contains cadmium, a substance known to contribute directly to the development of high blood pressure. When cadmium is inhaled through smoking, it tends to be retained in the kidneys, further increasing hypertension levels.

From James M. Salander, M.D., F.A. C. S., and Suzanne LeVert, If It Runs in Your Family, Hypertension, Reducing Your Risk, (New York, Bantam Books, 1993), pp. 113-116.