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The Peripheral Vascular System


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  • 15.1

  • 15.2

  • 15.3

  • 15.4

  • 15.5

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  • 15.7

  • 15.8

  • 13.13

  • 14.16

  • 17.11

General Considerations

Diseases of the peripheral vascular system are common and may involve the arteries, veins, or lymphatic vessels. The arterial conditions include cerebrovascular, aortoiliac, femoropopliteal, renal, aortic occlusive, and aneurysmal diseases. The two most important diseases of the peripheral arteries are atherosclerosis of the larger arteries and microvascular disease. Peripheral vascular disease (PVD) is a nearly pandemic condition that has the potential to cause loss of limb or even loss of life.

The most common cause of peripheral arterial occlusive disease is atherosclerosis affecting the medium-sized and large vessels of the extremities. Narrowing of the vessel causes a decreased blood supply, resulting in ischemia. PVD is a common disorder that usually affects men older than age 50. People are at higher risk if they have a history of:

  • Abnormal cholesterol

  • Diabetes

  • Coronary artery disease

  • Hypertension

  • Kidney disease involving hemodialysis

  • Smoking

  • Strokes

Fig. 15.1 summarizes the risk factors for PVD according to the Framingham Heart Study. 1

1 A project of the National Heart Institute (now known as the National Heart, Lung, and Blood Institute) and Boston University (1948).

Fig. 15.1, Risk Factors for Peripheral Vascular Disease: Framingham Heart Study.

The classic symptoms of PVD are pain, heaviness, fatigue, burning, or discomfort in the muscles of your feet, calves, or thighs. These symptoms usually appear during walking or exercise and go away after several minutes of rest. At first, these symptoms may appear only when the patient walks uphill, walks faster, or walks for longer distances. Slowly, these symptoms come on more quickly and with less exercise. The legs or feet may feel numb while at rest. The legs also may feel cool to the touch, and the skin may look pale. When peripheral artery disease becomes severe, the patient may experience:

  • Erectile dysfunction

  • Pain and cramps at night

  • Pain or tingling in the feet or toes, which can be so severe that even the weight of clothes or bed sheets is painful

  • Pain that is worse when raising the leg and improves when dangling the legs over the side of the bed

  • Skin that looks dark and blue

  • Sores that do not heal

Atherosclerosis may become manifest by aneurysmal dilatation. The abdominal aorta is commonly affected. An abdominal aortic aneurysm (AAA) is a focal dilation 50% greater than the normal diameter of the aorta. The aneurysm is commonly below the renal arteries and may extend as far as the external iliac arteries. There are several well-defined risk factors associated with the development of AAA. They include advanced age, male sex, Caucasian race, a positive family history, smoking, the presence of other large vessel aneurysms, and atherosclerosis. AAA is 5 times more common in men than in women and is 3.5 times more common in white men than in African-American men. In 2016 in the United States, AAA-related complications were responsible for 9758 deaths, with a crude rate of 3.0 deaths per 100,000. The Centers for Disease Control ranks AAA as one of the top 15 causes of mortality in the United States in individuals between the ages of 85 to 89 years of age. 2

2 Deaths, percent of total deaths, and death rates for the 15 leading causes of death in 5-year age groups, by race, and sex. United States, 2013. https://www.cdc.gov/nchs/data/dvs/lcwk1_2015.pdf (Accessed on December 3, 2018).

Often, AAA produce few, if any, symptoms. The examiner may discover a pulsatile mass as an incidental finding. Frequently, the first manifestation is the catastrophic rupture of the aneurysm. An AAA larger than 5 cm in diameter carries a 20% risk of rupturing within the first year of discovery and a 50% risk of rupturing within 5 years.

Vesalius described the first AAA in the 16th century. Before the development of a surgical intervention for the process, attempts at medical management failed. The initial surgical attempts at control entailed ligation of the aorta, with poor results. In 1923, Rudolph Matas performed the first successful aortic ligation on a patient. Attempts were made to induce thrombosis by inserting intraluminal wires. In 1948, C. E. Rea wrapped reactive cellophane around the aneurysm to induce fibrosis and limit expansion. This technique was used on Albert Einstein in 1949, and he survived 6 years before dying of rupture. However, not until 1951 was an abdominal aneurysm surgically treated by resection and grafting. In that year, C. Dubost performed the first AAA repair with a homograft. Since then, great strides have been made in understanding the natural history of vascular disease, as well as in developing new technology to help diagnose and treat it.

Microvascular arterial disease occurs in patients with diabetes. Changes develop in the small arterioles that impair circulation to the skin or nerves, especially of the lower extremities, producing symptoms of ischemia. Peripheral neuropathy is a common sequela of microvascular disease. This neuropathy may be manifested as a defect in the sensory, motor, or autonomic system. Microvascular disease affects more than 15 million individuals in the United States. In diabetic patients, there is the tragic “Rule of 15,” which states that:

  • Fifteen percent of all diabetics will develop a foot ulcer sometime in life.

  • Fifteen percent of those foot ulcers will lead to osteomyelitis.

  • Fifteen percent of foot ulcers lead to amputation.

Also, in diabetic patients, the “Rule of 50” states that:

  • Fifty percent of amputations are at the transfemoral/transtibial level.

  • Fifty percent of patients have a second amputation in 5 years or less.

  • Fifty percent of patients die in 5 years or less.

Peripheral venous disease often progresses to venous stasis and thrombotic disorders. One of the dreaded complications of thrombotic disease is pulmonary embolism. In the United States, more than 175,000 deaths per year are attributed to acute pulmonary embolism.

Structure and Physiology

Diseases of the peripheral arterial system cause ischemia of the extremities. When the body is at rest, collateral blood vessels may be able to provide adequate circulation. During exercise, when oxygen demand increases, this circulation may not be sufficient for the actively contracting muscles, and ischemia may result.

The venous system consists of a series of low-pressure capacitance vessels. Nearly 70% of the blood volume is contained in this system. Although offering little resistance, the veins are controlled by a variety of neural and humoral stimuli that enhance venous return to the right side of the heart. In addition, valves aid in the return of blood.

When an individual is in the upright posture, the venous pressure in the lower extremity is the highest. Over many years, the veins dilate as a result of weakening of their walls. As the walls dilate, the veins are unable to close adequately, and reflux of blood occurs. In addition, the venous pump becomes less efficient in returning blood to the heart. Both of these factors are responsible for the venous stasis seen in patients with chronic venous insufficiency. Complications from venous stasis include pigmentation, dermatitis, cellulitis, ulceration, and thrombus formation.

The lymphatic system is an extensive vascular network and is responsible for returning tissue fluid (lymph) back to the venous system. The extremities are richly supplied with lymphatic tissue. Lymph nodes, many of which are located between major proximal joints, aid in filtering the lymphatic fluid before it enters the blood. The most important clinical symptoms of lymphatic obstruction are lymphedema and lymphangitis.

Review of Specific Symptoms

Many patients with PVD are asymptomatic. When patients are symptomatic, vascular disease causes the following:

  • Pain

  • Changes in skin temperature and color

  • Edema

  • Ulceration

  • Emboli

  • Stroke

  • Dizziness

Pain

Pain is the principal symptom of atherosclerosis. Whenever a patient complains of pain in the calf, arch of the foot, thighs, hips, or buttocks while walking, PVD of the arteries must be considered. The symptom of pain in the lower extremity during exercise and relieved by rest is called intermittent claudication. The site of the pain is always distal to the occlusive disease. Supply does not equal demand . As the disease progresses, pain at rest occurs. This is often severe and is aggravated by cool temperatures and elevation, especially during sleep in bed. Pain may also occur with deep vein thrombosis, a condition known as venous claudication. It is the combination of venous valvular incompetence, outflow obstruction, and calf muscle pump function derangement that generates the hemodynamic setting most often associated with the development of venous claudication. A unique feature of venous claudication is that motionless standing is often more difficult than walking. This is because contraction of the muscles in our legs while walking pumps the blood through the veins and back to the heart. Neurogenic claudication is a common symptom of lumbar spinal stenosis, or inflammation of the nerves emanating from the spinal cord. The pain is often related to posture. The combination of the stenosis with certain back postures such as arching puts pressure on lumbosacral nerve roots and the cauda equina. Table 15.1 describes the differences between intermittent claudication, venous claudication, and neurogenic claudication.

TABLE 15.1
Differential Diagnosis of Intermittent Claudication
Intermittent Claudication Venous Claudication Neurogenic Claudication
Quality of pain Cramping Aching, heaviness, tightness “Pins and needles” sensation going down the leg, weakness
Onset Gradual, consistent Gradual; can, however, be immediate Can be immediate
Relieved by Stopping walking Activity, elevation of leg Sitting down, stooping, flexion at the waist
Location Muscle groups (e.g., buttocks, thigh, calf) Whole leg Poorly localized, but can affect whole leg
Legs affected Usually one Usually one Often both

If a male patient complains of pain in the buttocks, hips, or thighs while walking, the examiner should inquire about erectile dysfunction. The patient may also experience leg numbness or weakness. Leriche syndrome is chronic aortoiliac obstruction; the patient presents with intermittent claudication and erectile dysfunction. In this condition, the terminal aorta and iliac arteries are involved by severe atherosclerosis at the aortic bifurcation.

Patients occasionally complain of bilateral leg pain or numbness that occurs while walking, as well as while resting. This is called pseudoclaudication and is a symptom of musculoskeletal disease in the lumbar area.

Skin Changes

Skin color changes are common with vascular disease. In chronic arterial insufficiency, the affected extremity is cool and pale. In chronic venous insufficiency, the extremity is warmer than normal. The leg becomes erythematous, and erosions produced by excoriation result. With chronic insufficiency, stasis changes produce increased pigmentation, swelling, and an “aching” or “heaviness” in the legs. These changes characteristically occur in the lower third of the extremity and are more prominent medially. When venous insufficiency occurs, edema of dependent areas results.

Patients with acute deep vein thrombosis have secondary inflammation of the tissue surrounding the vein. This produces signs of inflammation: warmth, redness, and fever. Swelling is the most reliable symptom and sign associated with venous obstruction. This finding is indicative of severe deep vein obstruction because the superficial veins of the lower extremity carry only 20% of the total drainage and are not associated with swelling. The extremities should be compared, and a difference in circumference of 2 cm at the ankle or midcalf should be considered significant.

Edema

Lymphedema results from either a primary abnormality in the development of the lymphatic system or an acquired obstruction to flow. Whether the congenital or the acquired form is involved, the net result is stasis of lymph fluid in the tissues, producing a firm, nonpitting edema. Over several years, the skin takes on a rough consistency similar to that of pigskin. Because lymphedema is usually painless, the only symptom is “heaviness” of the extremity.

Ulceration

Persistent ischemia of a limb is associated with ischemic ulceration and gangrene. Ulceration is almost inevitable once skin has thickened and the circulation is compromised. Ulceration related to arterial insufficiency occurs as a result of trauma to the toes and heel. These ulcers are painful, have discrete edges that produce a “punched-out” appearance, and are often covered with crust. When infected, the tissue is erythematous.

In contrast to arterial insufficiency ulceration, venous insufficiency leads to stasis ulceration, which is painless and occurs in the ankle area or lower leg just above the medial malleolus. The classic manifestation is a diffusely reddened, thickened area over the medial malleolus. The skin has a cobblestone appearance resulting from fibrosis and venous stasis. Ulceration occurs with the slightest trauma. Rapidly developing ulcers are commonly caused by arterial insufficiency, whereas slowly developing ulceration is usually the result of venous insufficiency. Figs. 15.2 and 15.3 show stasis dermatitis and ulcerations over the medial malleoli. Patients with leg ulcers should be asked the following:

  • “What did the ulcer look like when it first appeared?”

  • “What do you think started the ulcer?”

  • “How quickly did it develop?”

  • “How painful is the ulcer?”

  • “What kind of medications have you been taking?”

  • “Is there a history of any generalized diseases, such as anemia? Rheumatoid arthritis?”

  • “Is there a family history of leg ulcers?”

Fig. 15.2, Stasis Dermatitis and Bilateral Ulceration Over the Medial Malleoli.

Fig. 15.3, Stasis Dermatitis and Ulceration Over the Medial Malleolus.

Emboli

A history of emboli is important. Thrombus formation results from stasis and hypercoagulability. It appears, however, that venous stasis is the most important cause of thrombus formation. Bed rest, congestive heart failure, obesity, pregnancy, recent extended travel on airplanes, and oral contraceptives have been linked to thrombus formation and emboli.

Symptoms secondary to emboli can include shortness of breath from pulmonary emboli; abdominal pain from splenic, intestinal, or renal artery emboli; neurologic symptoms from carotid or vertebrobasilar artery emboli; and pain and paresthesias from peripheral artery emboli.

Neurologic Symptoms

Cerebrovascular occlusive disease causes many neurologic symptoms, including strokes, 3

3 A stroke is also known as a cerebrovascular accident .

dizziness, and changes in consciousness. Occlusion of the internal carotid artery produces a syndrome of contralateral hemiplegia, contralateral sensory deficits, and dysphasia. Vertebrobasilar disease is associated with diplopia, cerebellar dysfunction, changes in consciousness, and facial paresis.

Effect of Vascular Disease on the Patient

A patient with chronic arterial insufficiency has worsening pain while walking. As the condition progresses, ulceration of the toes, feet, and areas susceptible to trauma, such as the shins, develops. Pain may become excruciating. Gangrene of a toe may develop, and amputation of the toe is frequently followed by amputation of the foot and leg. In addition, the patient becomes increasingly depressed as a result of ongoing mutilation of the body.

Physical Examination

The equipment necessary for the examination of the peripheral vascular system consists of a stethoscope, a tourniquet, and a tape measure.

The physical examination of the peripheral vascular system consists of inspection, palpation, auscultation, and some additional tests, if disease is thought to be present.

General Inspection

The patient should be examined in the standing position and suitably undressed to preserve the modesty of the patient but also to permit complete examination of the entire lower extremity from the groin to the toes. The upper extremity should be exposed from the hands to the axilla. Both upper and lower limbs should be inspected carefully from the front and the behind. Examine the four extremities for erythema, cyanosis, swelling, asymmetry, deformities, edema, hair loss, surgical scars, and skin color changes.

Inspect the Upper Extremities

The extremities should be compared for asymmetries in size, color, temperature, and venous patterns. Fig. 15.4 depicts massive lymphedema of the right upper extremity secondary to a right total mastectomy 18 years earlier.

Fig. 15.4, Lymphedema.

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