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Smoking and Peripheral Arterial Disease: Breaking the Deadly Connection

More than one billion people smoke, which is about one third of the global population. Worldwide, tobacco is the second most common risk factor for progressing peripheral arterial disease (PAD). What’s worse is that the risk is exponentially higher in current smokers. PAD occurs when there is a build-up of fatty deposits in arteries which supply blood to the limbs. This build-up reduces or blocks the flow of blood which can cause leg pain, numbness and non-healing wounds, leg ulcers and in severe cases: gangrene and limb amputation. Smokers with PAD have more severe symptoms and a faster progression of the disease. Reason would therefore denote that with disease progression and worsening leg ischemia, the rate of smoking will have to decrease as a smoker will simply not be able to walk to smoke more. The most common cause of PAD is atherosclerosis and even though smoking is a known risk factor for all cardiovascular diseases, the association between atherosclerosis and smoking is quite striking. There is ample evidence to support the theory that the increased risk of atherosclerosis in smokers is not just due to the general health of the smoker but also a direct toxic effect of tobacco on the blood vessel wall. This is particularly relevant when considering the effects of smoking on the progression of PAD because atherosclerosis of the aortoiliac vessels is a key disease site and if progressing PAD is to force a smoker to quit due to symptoms in both legs, he/she still has the option to sit and smoke.

The harmful effects of smoking on health

The magnitude of the effect of smoking on health is seen in the large difference in health outcomes between smokers and non-smokers for all smoking-related conditions. Smokers have a two to four-fold increase in the relative risk of developing coronary heart disease compared to non-smokers, and this risk increases with the number of cigarettes smoked. Similarly, the risk of developing a wide range of other conditions is increased for smokers compared to non-smokers, including a seven-fold increase in peripheral vascular disease, a two-fold increase in aortic aneurysm, a four-fold increase in developing oral cancers and lung cancer, as well as a twenty-fold increase in developing chronic obstructive lung disease. In addition to developing disease, smokers have a higher risk of dying from smoking-related conditions. This is highlighted in research that showed that smokers with coronary heart disease had a 39% mortality rate compared to non-smokers, who had a 17% mortality rate.

Introduction Cigarette smoking is one of the strongest modifiable risk factors for peripheral artery disease (PAD). Not only can smoking cause disease, it is a major cause of morbidity and mortality across a wide range of health conditions. Understanding the magnitude of the effect of smoking on health, and the mechanisms by which smoking causes disease, is an important prelude to understanding how to prevent and treat smoking-related disease, including PAD.

Understanding Peripheral Arterial Disease (PAD)

In the Western culture, cigarettes and tobacco have been around for 500 years, and from 1910 to 1965, cigarette smoking increased. It was not until the 20th century that smoking was identified as a cause of coronary heart disease. The issue of cigarette smoking is not a contemporary one but is rooted deeply within many cultures and societies. With smoking being a prime risk factor for most cardiovascular diseases, it is no surprise that this is the case with peripheral arterial disease (P.A.D). P.A.D is a very common but serious disease. It occurs when the buildup of fatty deposits in the arteries restricts the blood supply to leg muscles. This disease is dangerous, as one in every five people with leg pain indicating P.A.D will face amputation, heart attack, or stroke within five years. Unfortunately, most people are unaware of what the disease entails and are also unaware of the link between the disease and smoking. This essay will seek to explain P.A.D and the effects of smoking on the disease in detail, in doing so revealing the dire consequences of smoking on people suffering from P.A.D.

The Link between Smoking and PAD

In conclusion, the cause and effect relationship between smoking and PAD is clear. Smokers have a higher risk and the more one smokes, the higher the risk. With millions of people addicted to smoking worldwide, this could have a major impact in the high and rising PAD prevalence during the next few decades.

Cigarette smoke contains carbon monoxide, which displaces the oxygen in your blood and damages the lining of your blood vessels, and nicotine, which increases your heart rate and blood pressure. Additionally, the chemicals in tobacco cause your blood to become sticky and make it easier for clots to form. Blood carries everything that your organs need to function properly, and when there is a narrowing in your blood vessels, it can prevent your organs from getting enough blood and cause various problems throughout the body.

Smoking takes an enormous toll on blood vessels throughout the body. In addition to doubling the risk of cardiovascular disease, it permanently alters blood vessels, accelerating atherosclerosis, the process in which fatty deposits build up in vessels, narrowing them. This condition occurs in all blood vessels, including those in the legs. Among smokers, PAD is diagnosed two to six times more often than in non-smokers or former smokers. The more cigarettes smoked, the higher the risk for developing PAD. Inhaling second-hand smoke also increases the risk of developing PAD.

How smoking increases the risk of PAD

It is clear that present smoking raises the risk of lower extremity peripheral arterial disease (LEPAD). Numerous studies have reported a strong association in both men and women, and in diverse population groups including urban and rural, and various countries, both industrialized and developing. Ischemic symptoms in the legs and LEPAD as defined by arbitrary measures of Ankle Brachial Pressure Index have been reported, but the strongest association is with clinical events and diagnostic procedures such as surgery, angioplasty, and stenting. Biochemical tests for smoke exposure such as plasma cotinine levels or urinary thiocyanate levels have been used, in some reports confirming the association with a dose-response like the examination of quantity of smoking. Cessation of smoking has been linked with regression or slowed progression of LEPAD, and at least one report suggests a longer claudication onset time in quitters compared with those continuing to smoke.

One study recommends that there is a different relationship of quantity of smoking to PAD in men and women, with the incidence in middle-aged men rising in relation to the amount of smoking, and in women, both middle-aged and older, the occurrence of PAD being raised by even light smoking (3-9 cigarettes/day). The disease might be more severe in people who have stopped smoking; found that the effective duration of smoking was a stronger risk factor for surgical treatment for PAD than the quantity. Urgency for surgical treatment for PAD than the amount smoked.

The impact of smoking on blood vessels

The alarming statistics regarding smoking and PAD are not widely appreciated by the general public or the medical community. An important groundbreaking meta-analysis, which pooled the data from 19 cohort studies involving over two million subjects and over 37,500 patients with PAD, recently provided compelling evidence that cigarette smoking is a major risk factor for the development of PAD. Compared to never smokers, current smokers had a 10-19 years younger age of PAD onset and an approximately two-fold risk of developing PAD. A strong dose-response relation was noted, with heavy smoking defined as >20 cigarettes per day, increasing the risk of PAD by nearly fourfold! The analysis showing the different levels of risk and the tangent line of current smokers differing from that of never smokers is easily understandable and will help to reinforce the awareness of smoking as an important risk factor for PAD.

The harmful effects of smoking on the heart and blood vessels are well established and well known. What is less well known is the vast array of diseases caused by smoking that damage the vascular system and other organs, or contribute to atherosclerotic and inflammatory processes to cause conditions such as peripheral arterial disease (PAD). PAD is a common and serious disorder of the arteries. It occurs when fatty deposits (plaque) or blood clots restrict blood flow to the arms, organs, and especially the legs. This often results in pain, fatigue, and slow healing of infections in the areas that are deprived of oxygen and nutrients from a lack of blood flow. A simple and practical test to determine if leg symptoms are due to poor blood flow is to compare the time it takes to walk 50 feet at a comfortable pace as compared to the time while walking the same distance on a treadmill with an uphill slope.

The damage that smoking does to blood vessels can be difficult to see because it happens gradually. A picture of a major blood vessel supplying blood to the legs of two elderly individuals can help make the point (fig 15). Note that the blood vessel is nearly normal in the 64-year-old man who never smoked. The vessel of the 59-year-old smoker is narrowed by more than half, and five bypass grafts were needed to revascularize his leg because of severe leg pain due to insufficient blood flow. This clinical situation on the left is the same as for the woman in her 80s. After seeing the photo, she commented that she doesn’t smoke, but she has the legs of a smoker.

The toxic, persistent chemicals in cigarette smoke can harm the heart and blood vessels in many ways. For example, they can damage the linings of blood vessels, causing them to become narrow and blocked. They can also cause the aorta to enlarge and the blood to become thicker and more likely to clot. Blood clots can further narrow the blood vessels and block them entirely, leading to a heart attack, stroke or damage to the legs from lack of blood flow. Compared with nonsmokers, smoking increases the risk of heart attacks and strokes. People who smoke are also more likely to get high blood pressure or have a heart attack or die from one.

Smoking as a major risk factor for PAD

Arising over thirty years ago, researchers were faced with the similarity that humans with PAD presented with individuals who had the disease of the aorta. In no other group of individuals is a correlation between atherosclerosis and aortic disease so prominently displayed as in smokers. Over three decades, a slowly but steadily evolving story has unfolded, the results of which have made smoking the strongest and most independent risk factor for atherosclerotic disease of the aorta and PAD. A smoker can increase his risk of claudication from 1.9 to 9.7 times that of a non-smoker. The association of heavy smoking with lower extremity arterial disease and vascular surgery is striking. In addition, lifestyle changes aimed at reducing cardiovascular risk factors have occurred in the general population. Among these changes, cessation of smoking has been the most difficult to achieve for smokers with claudication. This is unfortunate in that evidence shows that individuals who modify their lifestyles in accordance with established medical and surgical PAD treatments have a greater reduction in cardiovascular events and PAD progression.

Breaking the Deadly Connection

“Our primary care doctor gave us a ‘no buts about it’ warning to quit. For me and my husband, that gave us the help we needed to make the decision to try,” said Mae, a former smoker of 44 years. These words capture the essence of what breaking the deadly connection is all about. This is a topic that is foreign and difficult to discuss with most patients suffering from PAD and intermittent claudication. Attempts to educate patients on the dangers of smoking and the theory that it is a primary causative factor for their disease can often be met with resistance or skepticism. For many patients, the message that their arterial disease is related to their cigarette habit is far too simplistic an explanation for a disease that causes them considerable disability and affects their quality of life. This is especially true in patients with advanced disease or those who suffer from other diseases such as coronary artery disease or diabetes, which they feel are more serious. Unfortunately, many of these patients will continue to smoke and harbor hope that their leg symptoms can be cured with a quick fix, such as angioplasty or surgery. This group of patients presents a considerable challenge as the benefits of cessation are large, but convincing them to stop can be difficult. There are fewer things that a patient can do that are of greater benefit to their PAD than quitting smoking, and the tangible reduction in claudication symptoms is seen within weeks of cessation.”

Strategies for quitting smoking

Smoking is an addiction, and it is often best approached by admitting this and using strategies known to be effective in aiding smokers to quit. Many smokers are aware of the problems caused by smoking and may admit to it being an “expensive habit” both in terms of health and finances. Setting a quit date is an effective start, and some patients may be willing to make a contract with a clinician to stop. Providing information on the damage caused by smoking, which will impact the quality of life, mobility, and independence of patients with PAD, can be effective in increasing motivation to quit. The positive benefits of smoking cessation, including an improvement in symptoms, increased walking distance, and general health, may need to be outlined more than once to patients. This can be helpful in maintaining motivation, but again, it is only likely to be effective in patients who are genuinely willing to quit.

Although many patients with peripheral arterial disease are aware of the effects of smoking, many continue to smoke. Anecdotal evidence shows that some even continue smoking after surgical procedures to revascularize their limbs. There is no doubt that this group of patients requires a skilled and persistent approach to encourage smoking cessation. Most patients will require pharmacological treatment, and referring the patient to their general practitioner is probably the best initial step in achieving this.

Lifestyle changes to reduce the risk of PAD

Eating a healthy diet and increasing physical activity can help prevent or mitigate the adverse effects of PAD. A balanced diet should include a variety of fruits and vegetables, lean meats, and whole grains. Consumers should limit saturated and trans fats. Eliminate pedal fat by trimming away from meats and replace butter with margarine. Regular physical activity such as walking can increase your pain-free walking distance and slow the progression of PAD. Develop an exercise program to avoid leg ischemia. If at all possible, avoid using a car and walk to your destinations. People with limb ulcers should seek professional advice about an activity program geared to their condition.

Smoking is an addictive and robust addiction. It’s the main preventable cause of demise and illness in the United States. Smoking increases the risk of having PAD, and quitting smoking is the single best way to reduce the danger of having or getting worse PAD. People who smoke generally develop PAD 10 years in advance than non-smokers, and it can have very severe results. 50% of people with PAD who keep smoking will face loss of a limb or death within 10 years. On the flip side, those who quit smoking can slow the progression of PAD. The benefits of smoking cessation are vast, but quitting can be a long and difficult process. Individuals who are thinking about quitting need to seek information from their doctor to find the best approach to fit their needs. Seeking help from friends and family can also enhance motivation and commitment to quit smoking.

Medical interventions for PAD

Bypass surgery is considerably more effective than exercise therapy at improving treadmill walking performance and is now a Class I recommendation for the treatment of severe claudication or critical limb ischemia. In cases where the site of a stenosis is anatomically suitable, percutaneous transluminal angioplasty with or without stenting may be performed. This is less invasive than surgical revascularization and is associated with a short hospital stay and wound healing time but is more prone to failure and recurrence of symptoms. A randomized controlled triple-blind trial of angioplasty demonstrated no significant difference between the real and placebo procedures, except in patients who had iliac artery lesions, in whom there was improvement in symptoms and walking capacity. These patients form the minority of those with PAD but are likely to gain the most from the procedure.

A careful search for alternate causes of leg symptoms (e.g. arthritis, spinal canal stenosis, neuropathy from diabetes, chronic fatigue syndrome) will, in some cases, demonstrate that the leg discomfort is not ischemic in nature. Assuming that PAD is the cause, any strategy that can improve blood flow to the affected limb has the potential to improve limb outcomes. The most invasive method is surgical revascularization. This involves either bypass grafting (in which a vessel bypasses the site of occlusion or stenosis and is anastomosed to the affected artery at two points) or, less commonly, endarterectomy. Both procedures are effective means of improving blood flow to the affected limb and are particularly useful in patients with severe aortoiliac disease, those with more extensive iliofemoral disease, and those with more proximal superficial femoral artery disease.

Cigarette smoking is of such importance to peripheral arterial disease that its cessation must constitute a fundamental part of the treatment plan in every patient. Some patients with very mild claudication or those with atypical leg symptoms may achieve a sufficient change in their cardiovascular risk factor profile to result in a disappearance of symptoms purely through smoking cessation and aggressive anti-lipid treatment. In most patients, however, further measures to control symptoms and improve prognosis will be necessary.

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