Peripheral Arterial Disease

PAD, or peripheral arterial disease, is one of the many complications that occur in patients suffering from diabetes. It is a form of atherosclerosis where white blood cells accumulate in the walls of the arteries causing them to thicken. Over time, calcium, cholesterol, triglycerides, and other crystallized materials begin to accumulate at the site of thickening. The condition remains asymptomatic for decades as the arterial walls continue to enlarge with the plaque buildup.

Over time, PAD increases the pulse pressure, which is also one of its major symptoms. According to statistics, PAD affects an estimated NO million people in the United States. Data collated by the Framingham Heart Study revealed that about 20 percent of patients who exhibited symptoms of PAD were diabetic. Due to the asymptomatic nature of the disease, researchers suggest that the actual numbers could be much higher.

One of the most common symptoms of PAD is claudication, which is characterized by aches, pains, and intermittent cramping in areas that include the buttocks, calves, and thighs. Claudication manifests itself during mobility or exercise and is relieved by rest. When left untreated over a period of time, PAD can lead to more severe manifestations that include foot ulceration, tissue loss in the extremities, and gangrene, which can quickly turn life threatening. Complications involving the limbs caused as a result of PAD are collectively known as CLI or critical limb ischemia.

US

PAD leads to Ulceration and Limb

Amputation

Diabetes-induced PAD is one of the leading causes of lower-extremity amputation in the US. This is due to the fact that most patients do not display symptoms of PAD until it reaches a life-threatening stage. Also, if peripheral neuropathy is present, the patient becomes oblivious to the presence of wounds and ulcerations of the feet. The age-adjusted rate of amputation in the US is currently ~8/1000 patient years, with a 3 percent incidence. The potential of PAD to cause ulceration and eventual limb loss due to amputation may be gauged by the progressive symptoms and the cardiovascular health of such patients. Studies have shown that an estimated 27 percent of patients diagnosed with PAD show steadily advancing symptoms over a course of five years. Loss of limb occurred in 4 percent of the patients. Twenty percent of the patients that were surveyed developed a stroke and myocardial infarction (heart attack). The mortality rate for patients with progressive PAD was 30 percent.

Studies have shown that for patients suffering from chronic limb ischemia, there is a 30 percent chance of limb amputation. Another 20 percent will succumb to the disease within a period of 6 months.

Diagnosis of PAD

An early diagnosis of PAD is important for two major reasons. Firstly, it helps to identify patients who are susceptible to the onset of strokes and heart attacks; and, secondly, it enables the identification of patients who are susceptible to developing chronic limb ischemia. Thus, an early diagnosis could prolong a patient’s life while preventing limb loss and other disabilities as a result of CLI. The symptoms of PAD are largely subliminal in diabetic patients as compared to non-diabetics. One of the main reasons for this is that diabetes deadens the nerves, causing impaired sensory perception in patients. Thus, claudication, which is a typical symptom of PAD, is less pronounced in diabetics. Moreover, other symptoms including leg fatigue and slow movement may be passed off as the onset of old age. Hence, a thorough diagnosis and evaluation of the patient should be done, in order to prevent or minimize the risk of limb loss and other long-term disabilities.

• History physical evaluation – The first and most important step in the diagnosis of PAD should begin with a thorough evaluation of the patient’s medical history, followed by a physical examination. This is crucial in identifying patients who are at a high risk of developing complications associated with PAD, as prompt diagnosis and treatment methodologies can curb disease progression. A complete medical history would reveal any classic PAD symptoms including claudication, which would help pinpoint the right diagnosis. The physical evaluation comprises a thorough foot inspection, followed by peripheral pulse palpation. The examining doctor should look for notable signs such as hair growth absence, broken toenails, reddish inflammation of the skin, pallor of the skin when legs are elevated, and fissures on the skin. All these are signs of decreased blood flow due to the build-up of plaque in the arteries. The spaces between toes should also be inspected for any telltale signs of ulceration or infection.
• Palpation of the peripheral pulses – Palpation of the peripheral pulses is an examination technique which consists of feeling the pulse patterns of the extremities to determine signs of PAD. It includes the evaluation of the pedal, popliteal and femoral vessels located in the feet, knee and thigh respectively. A strong indication of vascular disease is the absence of both the dorsalis pedis and posterior tibial pulse upon examination.
• Ankle Brachial Index $%, – The Ankle Brachial Index is a non-invasive procedure that is conducted to gauge the severity of PAD in a patient. It is basically a measure of the ratio of the blood pressure in the ankle to that in the arm, with the patient supine and at rest. An ABI between 0.91 and 1.30 is considered normal. It implies that the blood pressure in the ankle is greater than that in the patient’s arm and hence blood flow is normal. An ABI value between 0.70 and 0.90 is a sign of mild obstruction. An ABI value between 0.40 and 0.69 is indicative of moderate obstruction. An ABI value that is less than 0.40 or greater than 1.30 is a sure sign of severe obstruction. These values are indicative of narrowed arteries as a result of plaque build-up, and increase the patient’s risk of developing a stroke or heart attack.
• Exercise Test – qhe exercise or treadmill test is for patients who have a normal ABI but exhibit symptoms of claudication. The treadmill test gives an accurate value of the cardiovascular pressure, which indicates the possible presence of PAD. A pressure value that is greater than 20 mm Hg in the patient’s ankle after exercise is an indication of obstruction and possible PAD.
• Anatomic Evaluation Procedures – These include contrast angiography, duplex ultrasound and magnetic resonance angiogram or MRA. These procedures are particularly valuable for patients who have undergone revascularization or surgical repair to damaged organs and tissue as a result of ischemia. A duplex ultrasound can directly generate visuals of blood vessels, while an MRA is a noninvasive procedure whose efficiency is comparable to an x-ray angiography. It is especially useful in displaying images of obscured pedal vessels.

Treatment Methodologies for PAD

Rehabilitation through Exercise – The efficacy of supervised exercise training for patients suffering from PAD was discovered in 1966. The procedure involves walking thrice a week on the treadmill for a controlled duration over a period of three months. Exercise therapy has been proven to significantly improve cardiovascular function and reduce the associated risk of morbidity in patients.

Pharmacologic Approach – When it comes to drug treatment, Cilostazol is the gold standard for treating symptoms indicative of PAD, including intermittent claudication. Patients who underwent treatment using Cilostazol have demonstrated better functionality of their limbs and a higher quality of life. Preventive foot care – mreventive foot care is vital for all diabetic patients who have also developed PAD. This involves regular examination of the feet, supervision, and proper footwear to minimize the occurrence of foot complications and eventual limb loss. Patients who have developed neuro-ischemia in the feet are more susceptible to gangrene, traumatic ulceration, and infection. Alternatively, patients who have developed ischemic ulcers will display signs of ulceration around the edges of their feet, in-between the inter-digital spaces of the toes, and behind their heels. These are mostly brought on as a result of trauma, or wearing ill-fitting shoes that constrict or cause injury to the feet.

Conservative Management – Conservative management of the foot requires a multipronged approach that includes removal of debris and other necrotic tissue, offloading of the ulcer, and administering appropriate surgical dressing, followed by additional wound healing techniques. Debridement or removal of debris and necrotic tissue is the first step, and is done in a hospital using a sharp scalpel. Offloading of wounds is done by draining the pus and other discharge from the affected area. Non-adherent dressings are used to cover the affected area. The dressing used should ideally be easy to remove and should not disintegrate when pressure is applied during mobility. As most infections associated with diabetic foot syndrome are microbial in nature, broad-spectrum antibiotics are used effectively to reduce the severity of infection. Revascularization – oevascularization or surgical intervention of the affected organ or tissue consists of two techniques: open surgery and endovascular intervention. Endovascular intervention has shown to be valuable for patients suffering from focal disease, where an obscure infection has spread microorganisms and toxins to other regions of the body. It is also effective in patients who have stenosis or constricted arteries, and successfully relieves claudication. Open surgical procedures, on the other hand, are effective in treating lesions and are proven to be more durable than endovascular intervention. However, just like any other surgical procedure, they are associated with a small risk of infection and mortality. Selecting which of the two modalities is suited to the patient is often a complex decision, and is arrived at after a thorough medical evaluation and team consultation.

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