HealthPeripheral Arterial Disease: A Silent Threat to Circulatory Health

Peripheral Arterial Disease: A Silent Threat to Circulatory Health

The circulatory system and the heart work together to supply vital oxygen and other nutrients to your body. Diseased arteries are a threat to this process and can lead to potentially life-threatening consequences. Peripheral Arterial Disease (PAD) is one such disease process. PAD affects millions of people worldwide. It is a common disease of the arteries wherein fatty deposits (atherosclerosis) build up in the walls of the arteries, restricting blood flow to the muscles and other tissues. It can happen in any artery, but it is more common in the legs than the arms. Just like clogged arteries in the heart, clogged arteries in the legs mean you are at risk for a heart attack or stroke. Specific symptoms can include pain with walking, which is relieved by rest (termed claudication), or pain in the toes and feet while lying in bed at night. More dangerous symptoms could include non-healing wounds of the feet or toes, or pain in the legs with any elevation of the heart. PAD can be a marker for the narrowing of the more vital arteries in the heart and neck. As such, it is a red flag and a potential cause for more serious health problems. It is definitely worth addressing early.

Definition of Peripheral Arterial Disease

Atherosclerosis is the accumulation of fatty, calcium, and other deposits in the intima of the arteries. This can lead to a narrowing of the artery, causing reduced blood flow to an organ. If an artery becomes completely blocked, symptoms may develop quickly (e.g. leg ischemia), or in some cases, there may be no symptoms at all. Atherosclerosis is a generalized process; not all areas of the body are affected equally at the same time. Disease in the arteries that supply blood to the legs is termed lower extremity PAD. The aorta and the carotid arteries are also common sites for atherosclerotic disease. Patients with PAD have a six to seven-fold increase in mortality compared with age-matched controls without PAD. Mortality rates are similar to those with coronary artery disease and those with a history of myocardial infarction. Atherosclerotic lower extremity disease is associated with a functional decline in walking, and peripheral artery disease is an independent marker for increased cardiovascular morbidity and mortality.

Prevalence and Impact

There is little doubt that PAD has reached epidemic proportions in contemporary society. With over one in five of the elderly North American population estimated to be affected by the disease, and more than half of diabetics aged 50 years or older predicted to be afflicted, the enormity of the problem is clear. The associated health care costs are vast and increase with disease severity, ranging from two and a half times the cost for treating ischemic heart disease to six times the cost of managing diabetes. In the Western world, PAD is recognized as the leading cause of amputation, with diabetic patients having a 15-40% risk of amputation within 3 years of PAD diagnosis. Cardiovascular events affect about one in three patients within five years of initial diagnosis, and as the global population continues to grow and live longer, the burden of PAD on health care resources will be substantial. High rates of smoking in developing countries will add to this increasing burden, and in total, it is estimated that there will be an 18 million increase in prevalent PAD cases worldwide from 2000 to 2010. In contrast to these concerning statistics, awareness of PAD among patients and primary care physicians is low, with approximately 60% of people with PAD not experiencing symptoms, and many of those who do being asymptomatic at the primary care level. This may be due to symptoms being subtle and misattributed to normal aging or the lack of routine physical examination of the lower limbs. Measures such as the ankle brachial pressure index (ABPI), a useful tool for both diagnosing and as a marker of CVD risk, need to be more frequently implemented if the full breadth of symptomatic and asymptomatic patients are to be successfully managed.

Importance of Circulatory Health

A few common circulatory conditions revolve around leg pain and clogged arteries. Regarding the legs, the ability to walk is often taken for granted; however, it is a complex function that can be completely interrupted from compromised blood flow. Intermittent claudication is pain caused from walking due to decreased blood flow to the legs. This is a serious risk factor as it is known to precede a stroke or heart attack. Critical limb ischemia is the most severe form of PAD, leading to sores or ulcers on the legs or feet that will not heal. This occurs from chronic lack of oxygen to the limbs and can lead to infection, gangrene, or amputation. Each of these conditions are signs of insufficient blood flow and are strong indicators for further systemic cardiovascular damage.

One of the most essential yet often overlooked aspects of being that affects overall health is proper circulatory function. Arteries are the vessels that supply the body with oxygen and nutrient-rich blood. Any problem in the arteries interferes with the efficient transportation of oxygen throughout the body. This increases the risk for developing peripheral artery disease (PAD), a condition arising from the buildup of plaque leading to blocked arteries in the legs. PAD is known as a marker for atherosclerosis, the buildup of plaque in the arteries, a known factor for coronary artery disease and increased risk of heart attack or stroke. Those with PAD are at an increased risk for coronary artery disease and have a greater chance of heart attack or stroke compared to non-PAD patients. This is why it is critical to address circulatory issues immediately in order to prevent further harm to oneself.

Causes and Risk Factors

In extreme cases of vessel blockage, there is a risk of critical limb ischemia. This occurs when blood flow to the extremities is so severely decreased that it poses a high risk of tissue damage and death.

In relation to PAD, atherosclerosis does not occur evenly throughout the body. It occurs first in large vessels where it’s possible to have 60-70% blockage and experience no symptoms. It is when lower limb vessels (femoral and popliteal arteries) become more severely blocked that its effects are noticed. Being that the area of plaque buildup has narrowed the artery, it follows that any increase in blood flow demand by the leg muscles, i.e. walking, will not be able to be met. This will cause an onset of ischemia in the muscles, which leads to the muscle pain that is typically felt by PAD sufferers.

Atherosclerosis is a gradual process whereby damage occurs to the inner layer of the blood vessel, which can occur at any age. It can be caused by high blood pressure, smoking, high cholesterol, and high blood sugar. This damage leads to a buildup of bad cholesterol and white blood cells in the affected area of the blood vessel, and an inflammatory process is triggered. Over time, this causes the buildup of plaque on the blood vessel walls.

Atherosclerosis and Plaque Formation

An atheroma is an accumulation of degenerative material in the tunica intima layer of an artery wall. The material consists of mostly macrophage cells or debris containing lipids (cholesterol and fatty acids), calcium, and a variable amount of fibrous connective tissue. The atheroma can grow to such a size that it can protrude into the lumen of the artery, and in extreme cases, the atheroma can occlude the blood flow or rupture and cause a blood clot to form on the artery wall. Although atheroma are more likely to rupture if they are rich in macrophages, atheroma with a big cholesterol core and a thin fibrous cap can also rupture. When a rupture occurs, platelets are recruited to the site of the rupture. This is because the exposure of the highly thrombogenic material in the atheroma is a very potent activator of platelets.

Atherosclerosis means “hardening of the arteries”. Atherosclerosis is a specific type of arteriosclerosis in which an artery wall thickens as a result of invasion and accumulation of white blood cells (predominantly macrophages and T-lymphocytes) and proliferation of intimal-smooth-muscle cells, creating a fibro-fatty plaque. The accumulation of white blood cells is stimulated by unhealthy dietary and lifestyle patterns and is initiated by endothelial dysfunction resulting from high blood pressure, smoking, and high concentrations of glucose (diabetes).

Smoking and Tobacco Use

Diabetes is a very significant damaging factor for the arteries in the peripheral circulation. High blood sugar from diabetes attacks the arteries on many fronts. Sugar attaches to proteins in the blood, creating “molecular AGEs” which damage both the function and structure of proteins. This damage makes the artery more susceptible to atherosclerosis. High blood sugar also leads to a condition of insulin resistance and an increase in production of free radicals, which also causes damage to the artery. This cycle leads to the stiffening of arterial walls and narrowing of the arteries, effectively accelerating the processes of PAD. With diabetics living longer due to medical advances, the long-term effects of PAD as a disease of the elderly will take an increasing toll.

Tobacco use is directly related to the build-up of fatty substances in the arteries, a primary characteristic of atherosclerosis. Tobacco is a dangerous atherogen. Cigarette smoking causes a shortage of oxygen in the blood; this is particularly damaging to the peripheral arteries and the patient suffering from PAD. Damage to the arterial walls is another effect of smoking. The nicotine in cigarettes causes the blood vessels to constrict. This damage to the vessel wall, combined with the high cholesterol from a smoking habit, almost always leads to a complete blockage of the artery. People who smoke are two to three times more likely to develop some form of PAD than those who do not.

Diabetes and Metabolic Syndrome

Diabetes is second only to age as a risk factor for P.A.D. It is well known that high blood sugar levels damage the arteries and that diabetics frequently suffer from atherosclerosis, susceptibility to infection of the lower extremities, and nerve damage. A study called the Eurodiale study included 822 diabetic patients with foot sores in 14 European countries, found that 46% of the patients had P.A.D. while only 25% were aware they had the condition. High blood sugar levels cause an inflammatory response throughout the body and though the exact mechanism is not known, it is part of the reason why diabetics have poorer outcomes when they develop P.A.D. or have interventional procedures done to treat the disease. Diabetics suffer higher rates of morbidity and mortality from cardiovascular events. This is because people with diabetes have an increased risk of heart attack or stroke and a decreased likelihood of surviving these events. High blood sugar can cause nerve damage where the person no longer feels chest pain or other symptoms of C.V.D, leaving the P.A.D. or other atherosclerotic disease to go untreated and undiagnosed. Moreover, when compared with non-diabetics, the development of P.A.D. and the progression to limb loss or function is much higher in diabetics. An Australian study showed that compared with non-diabetics, the relative risks of developing intermittent claudication was 3.4 and critical limb ischemia was a whopping 26.3. Given the high morbidity and mortality rates from P.A.D., it is imperative for the medical care of diabetics to include screening for P.A.D. and aggressive management of the disease and underlying conditions.

Hypertension and High Cholesterol

High blood pressure, also known as hypertension, increases the pressure on arteries, causing damage to the inner lining of the artery walls. This increases the speed at which plaque develops, thereby increasing the likelihood for a blood clot to form. It reduces the flow of blood to the legs and can also cause an aneurysm (a bulge in the artery wall) which can be dangerous if it bursts. On the other hand, people diagnosed with high cholesterol levels were found to have a higher risk of developing PAD. Researchers have found that people with high cholesterol levels have twice the risk of developing PAD compared to those with normal cholesterol levels. This is because cholesterol is a major ingredient used to repair the damage to the inner lining of the artery walls. High levels of cholesterol increase the buildup of plaque in the arteries, significantly increasing the narrowing of the arteries and hence the severity of PAD.

Symptoms and Diagnosis

This sudden, severe form of PAD is more aptly characterized by its symptoms. Unlike silent PAD, severe PAD can cause pain in the legs and feet while walking or climbing stairs called intermittent claudication. If the pain is due to PAD, it will occur consistently after the same amount of activity and will be relieved by rest. Ironic as it may seem, pain caused by intermittent claudication is actually a good sign because it means there is adequate blood flow to the affected body part, however it is a strong indicator of more widespread atherosclerosis and a warning that medical attention is needed.

The first aspect of PAD that often surprises individuals is its asymptomatic state. Patients are accustomed to associating health problems with pain or other uncomfortable symptoms, so it is difficult for them to comprehend a disease that shows no obvious signs. This can lead to a false sense of security. Just because PAD is not causing any pain does not mean it is not causing harm. It is still possible for silent PAD to progress to more severe forms. In fact, many people with silent PAD do not know they have the disease until they are faced with a severe blockage that restricts blood flow to the limbs.

Silent Nature of Peripheral Arterial Disease

The development of symptomatology and its effect on function (claudication) This longitudinal study aims to examine the pattern of symptom development and the impact of symptomatic PAD on physical functioning. Symptomatology associated with PAD includes intermittent claudication, atypical leg pain, and critical limb ischemia. Intermittent claudication is the most common symptom associated with PAD and is characterized as a cramping pain in the calves, thighs, or buttocks which occurs on exertion and is relieved by rest. The nature and location of claudication pain can hinder the identification and distinction from other conditions such as arthritis or neurogenic lower back pain. Patients may also experience atypical leg pain which is either ischemic or neurogenic in origin, as well as those with critical limb ischemia who can present with rest pain or ulceration. A limitation of previous cross-sectional studies is the assumption that patients with claudication are stable and can therefore be compared to those with more severe PAD. Few studies have attempted to longitudinally examine symptoms associated with PAD, and there is limited information on the timeframe over which patients with intermittent claudication progress to more severe disease. It is unclear why some patients with PAD complain of leg pain while others are asymptomatic. Behavioral changes such as reduced exercise in an attempt to avoid claudication pain have been commonly observed in PAD patients and can lead to a more rapid decline of physical functioning. A recent study using the San Diego claudication questionnaire suggested that it can take many years for intermittent claudication to significantly affect a patient’s walking ability and HRQOL. The natural history of PAD and its effect on the development of a WIfI stage and subsequent Limb Loss Specific Of social and Personal Function in PAD Outcome Indicator (Limb Loss SOS) are consistent with a deteriorative disease process. The ability to identify this process in terms of symptomatology and its impact on physical functioning provides an opportunity for interventions to prevent or slow the worsening of disease. Despite this, the trajectory from lower levels of functioning to critical limb ischemia is poorly understood and minimally assessed in current studies.

Common Symptoms and Warning Signs

Symptoms associated with PAD are varied, but the most widely recognized are intermittent claudication and pain in the lower extremities. Claudication is derived from the Latin word for limp, and was fairly accurately described by a 17th century physician as “a troublesome pain in the legs while walking, which compels the sufferer to stop and stand still.” Pain in the leg muscles brought on by activity, such as walking, that is relieved after a few minutes of rest is the classic symptom of intermittent claudication. The location of the pain depends on the site of the arterial obstruction. The common and external iliac arteries are affected in 10% of cases each, resulting in pain in the buttocks and thigh respectively. Obstruction of the superficial femoral artery accounts for 40% of cases of claudication and results in pain in the upper leg or anterior thigh. Calf pain is the most common presentation and is usually caused by disease in the popliteal artery, which supplies blood to the lower leg. Gastrocnemius and soleus muscles are most frequently affected due to their high metabolic energy requirements. A similar type of muscular ischemia caused by thrombosis in the aortic bifurcation or aneurysm of the abdominal aorta is known as “aorto-iliac disease” and is included as a subset of PAD. Unlike other symptoms of PAD, aorto-iliac disease can cause pain in the lower back and in the abdomen.

Diagnostic Tests and Procedures

There are a number of tests available to diagnose Peripheral Arterial Disease. The most commonly known test is the Ankle Brachial Pressure Index. The ankle brachial pressure index (ABPI) is a ratio of the blood pressure in the lower legs to the blood pressure in the arms. It is simple, quick, and non-invasive. Doppler ultrasound is often used in combination with ABPI. It uses sound waves to listen to the blood flow in the arteries and gives an indication as to whether there is a narrowing or blockage. High-frequency sound waves bounce off the body structures being examined, and the “echoes” are recorded and transformed into video. Doppler uses changes in sound frequency to help determine if the blood is moving erratically. There is also a test known as the toe brachial index, used for patients where ABPI may be inaccurate. This test measures the blood pressure at the toes and compares it to that in the arm. Magnetic Resonance Angiography (MRA) and Computed Tomography Angiography (CTA) provide clear and detailed pictures looking at the blood vessels in the legs. They are very effective but may not be the first choice of test due to their cost and availability. Digital Subtraction Angiography is an invasive test and is considered to be a gold standard of P.A.D diagnosis. It involves the injection of a dye and taking continuous X-rays to look at the leg arteries and spatial changes in blood flow. This will often lead to other treatments during the procedure such as angioplasty or stent.

Treatment and Prevention

The simplest and usually most effective way to improve P.A.D symptoms is to alter your lifestyle. Risk factors such as smoking, high blood pressure, high cholesterol, and diabetes greatly increase the severity of the disease, and by managing these, the symptoms can be significantly reduced. This can involve many things such as ceasing smoking, eating a healthy diet, reducing your stress levels, and if relevant, improving blood sugar levels for diabetes sufferers. An exercise program which increases in difficulty over time can also lower symptoms. It is also important for people with P.A.D to avoid certain activities which could put their health at risk such as standing for long periods, sitting with legs crossed, using ice packs or heating pads, and taking certain over-the-counter medications. These lifestyle changes can be hard to adapt to, but they are the most effective method of reducing P.A.D symptoms and preventing the disease from getting worse.

There is no medical cure for peripheral artery disease, but there are many methods to manage the symptoms or to reduce the risk of the illness getting worse. These include both lifestyle and habit changes, medication, surgical interventions, and methods of keeping the disease in check. All of these methods are vital in increasing the standard of living for P.A.D sufferers and to prevent the onset of critical limb ischemia.

Lifestyle Modifications and Healthy Habits

The following BP recording comes from a 44-year-old female with Lyme disease (+ for Lyme Ab) who describes having daily lower extremity pain regardless of activity. She has known Raynaud’s for the last 8 years. She states that she sometimes uses Viagra with some benefit. Her pedal pulses and ABI’s are normal, but the toe pressures are decreased. This allows us to more fully understand the extent of her microvascular disease. In simple terms, it tells us whether or not the patient has a wound that will never heal. Stepwise progression to transcutaneous oximetry (TcPO2) and possible angiogram may be indicated at a later date if the patient’s symptoms are not improving.

The role of angioplasty is variable and evolving in the treatment of PVD, and may be best determined on a case-by-case basis according to the patient’s status in our office, likely using the WIQ. Angioplasty probably has its best role in patients with less complex disease and discrete long segment lesions.

Justification for Jun 6, 2014: new referral in a patient with known diagnosis of PVD

Phase II of the Walking Impairment Questionnaire (WIQ) determines walking distance. The patient’s PVD status is monitored according to the scale provided in the following publication: Regensteiner JG, Steiner JF, Panzer RJ, et al. Evaluation of walking impairment by questionnaire in patients with peripheral arterial disease. J Vasc Med Biol 1990; 2:142-152.

Medications and Medical Interventions

The treatment for Peripheral Arterial Disease (PAD) often begins with lifestyle changes and treatments to control risk factors. In some patients, the discomfort and disability resulting from PAD is serious enough that they require medical or surgical treatment. While the lifestyle changes and treatment of risk factors have clear benefits in reducing the risk of heart attack and stroke, as well as death from cardiovascular causes, the extent to which medical and surgical treatments reduce symptoms of PAD, improve function and quality of life, and prevent complications is less clear. Therefore, it is important that the treatment of PAD, whether it be medical, invasive, or a combination of both, be tailored to each individual patient, weighing the benefits of the proposed treatment against the potential risks and its impact on the patient’s lifestyle.

Surgical Procedures and Interventions

Angioplasty was first introduced in New Zealand in 1974 and is now performed worldwide. It is a less invasive option that can be used to effectively treat intermittent claudication and is often a suitable option for elderly patients or those with co-existing health problems. The procedure involves the insertion of a catheter that is passed through the obstructed artery. The balloon at the catheter’s tip is inflated, causing compression of the atheromatous plaque against the artery wall, subsequently restoring blood flow.

Endarterectomy is a minimally invasive procedure involving the removal of the lining from an obstructed artery. It is mostly used to treat the arteries supplying blood to the brain, but there are some cases where it is beneficial for PAD patients. This form of surgery, however, has been proven to be less effective for the treatment of intermittent claudication when compared to angioplasty and supervised exercise.

The most aggressive and invasive form of treatment, surgical intervention, is usually only resorted to if limb-threatening ischemia persists or if acute limb ischemia occurs. The aims of surgery are to relieve symptoms, restore arterial blood flow to the affected limb, and prevent the disease from advancing to the point where amputation is considered. There are various surgical options for PAD patients, ranging from endarterectomy and angioplasty to the more drastic options of arterial bypass and amputation.

Importance of Regular Check-ups and Follow-up Care

Patients often feel that once a procedure has been performed or medication prescribed, there is no further need for regular follow-up. However, many of the therapies provided for PAD, such as medications to control high blood pressure or cholesterol, are aimed at reducing risk factors that affect the entire cardiovascular system. Therefore, regular follow-up is important in monitoring the effectiveness of these treatments and the progression of a patient’s overall cardiovascular health. Often, the improvement in symptoms following treatment for PAD can be dramatic and patients feel they no longer need the same level of medical care. If this is the case, information given to the patient should stress the importance of at least annual check-ups and making the physician aware if any symptoms return or there is a worsening in the condition of their legs.

Regular follow-up is important, as it allows the doctor to monitor the progression of the disease and provide appropriate treatment. This may include changes in medication or diet, revascularization procedures, or supervised exercise. Often, this is the stage at which further intervention can halt the progress of PAD and improve the patient’s quality of life. Even if you are not currently experiencing symptoms, regular check-ups can help prevent the onset of intermittent claudication and more serious conditions, such as critical limb ischemia. People with diabetes should have regular check-ups because they have a very high risk of developing complications from PAD, including foot ulcers and ultimately amputation. Studies have shown that PAD patients who see a vascular specialist for their care have better outcomes, including reduced amputation rates and improvement in walking distance.

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