Vascular Diseases of the Extremities
Arterial
Disorders
Peripheral Arterial Disease
Atherosclerosis
(arteriosclerosis obliterans) is the leading cause of occlusive arterial
disease of the extremities in patients over 40 years old; the highest incidence
occurs in the sixth and seventh decades of life. As in patients with
atherosclerosis of the coronary and cerebral vasculature, there is an increased
prevalence of peripheral atherosclerotic disease in individuals with diabetes
mellitus, hypercholesterolemia, hypertension, or hyperhomocysteinemia and in
cigarette smokers.
Pathology
Segmental
lesions causing stenosis or occlusion are usually localized in large and
medium-sized vessels. The pathology of the lesions includes atherosclerotic
plaques with calcium deposition, thinning of the media, patchy destruction of
muscle and elastic fibers, fragmentation of the internal elastic lamina, and
thrombi composed of platelets and fibrin. The primary sites of involvement are
the abdominal aorta and iliac arteries (30% of symptomatic patients), the
femoral and popliteal arteries (80 to 90% of patients), and the more distal
vessels, including the tibial and peroneal arteries (40 to 50% of patients).
Atherosclerotic lesions occur preferentially at arterial branch points, sites
of increased turbulence, altered shear stress, and intimal injury. Involvement
of the distal vasculature is most common in elderly individuals and patients
with diabetes mellitus.
Clinical Evaluation
The
most common symptom is intermittent claudication, which is defined as a
pain, ache, cramp, numbness, or a sense of fatigue in the muscles; it occurs
during exercise and is relieved by rest. The site of claudication is distal to
the location of the occlusive lesion. For example, buttock, hip, and thigh
discomfort occurs in patients with aortoiliac disease (Leriche syndrome),
whereas calf claudication develops in patients with femoral-popliteal disease.
Symptoms are far more common in the lower than in the upper extremities because
of the higher incidence of obstructive lesions in the former region. In
patients with severe arterial occlusive disease, critical limb ischemia may
develop. Patients will complain of rest pain or a feeling of cold or numbness
in the foot and toes. Frequently, these symptoms occur at night when the legs
are horizontal and improve when the legs are in a dependent position. With
severe ischemia, rest pain may be persistent.
Important
physical findings of peripheral arterial disease include decreased or
absent pulses distal to the obstruction, the presence of bruits over the
narrowed artery, and muscle atrophy. With more severe disease, hair loss,
thickened nails, smooth and shiny skin, reduced skin temperature, and pallor or
cyanosis are frequent physical signs. In addition, ulcers or gangrene may
occur. Elevation of the legs and repeated flexing of the calf muscles produce
pallor of the soles of the feet, whereas rubor, secondary to reactive
hyperemia, may develop when the legs are dependent. The time required for rubor
to develop or for the veins in the foot to fill when the patient's legs are
transferred from an elevated to a dependent position is related to the severity
of the ischemia and the presence of collateral vessels. Patients with severe
ischemia may develop peripheral edema because they keep their legs in a
dependent position much of the time. Ischemic neuritis can result in numbness
and hyporeflexia.
Noninvasive Testing
The
history and physical examination are usually sufficient to establish the diagnosis
of peripheral arterial disease. An objective assessment of the severity of
disease is obtained by noninvasive techniques. These include digital pulse
volume recordings, Doppler flow velocity waveform analysis, duplex
ultrasonography (which combines B-mode imaging and pulse-wave Doppler
examination), segmental pressure measurements, transcutaneous oximetry, stress
testing (usually using a treadmill), and tests of reactive hyperemia. In the
presence of significant peripheral arterial disease, the volume displacement in
the leg is decreased with each pulse, and the Doppler velocity contour becomes
progressively flatter. Duplex ultrasonography is often useful in detecting
stenotic lesions in native arteries and bypass grafts.
Arterial
pressure can be recorded noninvasively along the legs by serial placement of
sphygmomanometric cuffs and use of a Doppler device to auscultate or record
blood flow. Normally, systolic blood pressure in the legs and arms is similar.
Indeed, ankle pressure may be slightly higher than arm pressure due to
pulse-wave reflection. In the presence of hemodynamically significant stenoses,
the systolic blood pressure in the leg is decreased. Thus, if one were to
obtain a ratio of the ankle and brachial artery pressures, it would be 
1.0
in normal individuals and <1.0 in patients with peripheral arterial disease.
A ratio of <0.5 is consistent with severe ischemia.
Treadmill
testing allows the physician to assess functional limitations objectively.
Decline of the ankle-brachial systolic pressure ratio immediately after
exercise may provide further support for the diagnosis of peripheral arterial
disease in patients with equivocal symptoms and findings on examination.
Exercise testing also allows simultaneous evaluation for the presence of
coronary artery disease.
Contrast
angiography should not be used for routine diagnostic testing but is performed
prior to potential revascularization. It is useful in defining the anatomy to
assist operative planning and is also indicated if nonsurgical interventions
are being considered, such as percutaneous transluminal angioplasty (PTA) or
thrombolysis. Recent studies have suggested that magnetic resonance angiography
has diagnostic accuracy comparable to that of contrast angiography.
Prognosis
The
natural history of patients with peripheral arterial disease is influenced
primarily by the extent of coexisting coronary artery and cerebral vascular
disease. Studies using coronary angiography have estimated that approximately
one-half of patients with symptomatic peripheral arterial disease also have
significant coronary artery disease. Life-table analysis has indicated that
patients with claudication have a 70% 5-year and a 50% 10-year survival rate.
Most deaths are either sudden or secondary to myocardial infarction. The
likelihood of symptomatic progression of peripheral arterial disease appears
less than the chance of succumbing to coronary artery disease. Approximately
75% of nondiabetic patients who present with mild to moderate claudication
remain symptomatically stable or improve. Deterioration is likely to occur in
the remainder, with approximately 5% of the group ultimately undergoing
amputation. The prognosis is worse in patients who continue to smoke cigarettes
or who have diabetes mellitus.
Treatment
Therapeutic
options include supportive measures, pharmacologic treatment, nonoperative
interventions, and surgery. Supportive measures include meticulous care of the
feet, which should be kept clean and protected against excessive drying with
moisturizing creams. Well-fitting and protective shoes are advised to reduce
trauma. Sandals and shoes made of synthetic materials that do not
"breathe" should be avoided. Elastic support hose should be avoided,
as they reduce blood flow to the skin. In patients with ischemia at rest, shock
blocks under the head of the bed together with a canopy over the feet may
improve perfusion pressure and ameliorate some of the rest pain.
Treatment
of associated factors that contribute to the development of atherosclerosis should
be initiated. The importance of discontinuing cigarette smoking cannot be
overemphasized. The physician must assume a major role in this life-style
modification. It is important to control blood pressure in hypertensive
patients but to avoid hypotensive levels. Treatment of hypercholesterolemia is
advocated, although reduction in cholesterol levels has not been shown
unequivocally to reverse peripheral atherosclerotic lesions. However, it has
been shown to prevent or to slow progression of the disease and to improve
survival in patients with coronary atherosclerosis. Patients with claudication
should also be encouraged to exercise regularly and at progressively more
strenuous levels. Supervised exercise training programs may improve muscle
efficiency and prolong walking distance. Patients also should be advised to
walk for 30 to 45 min daily, stopping at the onset of claudication and resting
until the symptoms resolve before resuming ambulation.
Pharmacologic Management
This
form of treatment of patients with peripheral arterial disease has not been as
successful as the medical treatment of coronary artery disease (Chap. 244). In
particular, vasodilators as a class have not proved to be beneficial. During
exercise, peripheral vasodilation occurs distal to sites of significant
arterial stenoses. As a result, perfusion pressure falls, often to levels less
than that generated in the interstitial tissue by the exercising muscle. Drugs
such as 
-adrenergic
blocking agents, calcium channel antagonists, papaverine, and other
vasodilators have not been shown to be effective in patients with peripheral
arterial disease. Pentoxifylline, a substituted xanthine derivative, has been
reported to decrease blood viscosity and to increase red cell flexibility,
thereby increasing blood flow to the microcirculation and enhancing tissue
oxygenation. Several placebo-controlled studies have reported that
pentoxifylline increased the duration of exercise in patients with
claudication, but its efficacy has not been confirmed in all clinical trials.
Cilostazol, a phosphodiesterase inhibitor with vasodilator and antiplatelet
properties, has been reported to increase claudication distance and recently
received an indication for treatment of peripheral arterial disease by the U.S.
Food and Drug Administration. Other drugs are being studied that potentially
may improve claudication, such as L-arginine, which is the precursor of the
endothelium-dependent vasodilator, nitric oxide, and vasodilator
prostaglandins. Several studies have suggested that long-term parenteral
administration of vasodilator prostaglandins decreases pain and facilitates
healing of ulcers in patients with severe limb ischemia. Clinical trials with
angiogenic growth factors such as vascular endothelial growth factor (VEGF) and
basic fibroblast growth factor (bFGF) are proceeding. A preliminary report
suggested that intramuscular gene transfer of DNA encoding VEGF may promote
collateral blood vessel growth in patients with critical limb ischemia.
Platelet
inhibitors, particularly aspirin, reduce the risk of adverse cardiovascular
events in patients with peripheral atherosclerosis. Clopidogril, a drug that
inhibits platelet aggregation via its effect on ADP-dependent
platelet-fibrinogen binding, appears to be more effective than aspirin in
reducing cardiovascular morbidity and mortality in patients with peripheral
arterial disease. The anticoagulants heparin and warfarin have not been shown
to be effective in patients with chronic peripheral arterial disease but may be
useful in acute arterial obstruction secondary to thrombosis or systemic
embolism. Similarly, thrombolytic intervention using drugs such as
streptokinase, urokinase, or recombinant tissue plasminogen activator (tPA) may
have a role in the treatment of acute thrombotic arterial occlusion but is not
effective in patients with chronic arterial occlusion secondary to atherosclerosis.
Revascularization
Revascularization
procedures, including nonoperative as well as operative interventions, are
usually reserved for patients with progressive, severe, or disabling symptoms
and ischemia at rest, as well as for individuals who must be symptom-free
because of their occupation. Angiography should be performed mainly in patients
who are being considered for a revascularization procedure. Nonoperative
interventions include PTA, stent placement, and atherectomy (Chap. 245). PTA of
the iliac artery is associated with a higher success rate than PTA of the
femoral and popliteal arteries. Approximately 90 to 95% of iliac PTAs are
initially successful, and the 3-year patency rate is in excess of 75%. Patency
rates may be higher if a stent is placed in the iliac artery. The initial
success rate for femoral-popliteal PTA is approximately 80%, with a 60% 3-year
patency rate. Patency rates are influenced by the severity of pretreatment
stenoses; the prognosis of total occlusive lesions is worse than that of
nonocclusive stenotic lesions.
Several
operative procedures are available for treating patients with aortoiliac and
femoral-popliteal artery disease. The preferred operative procedure depends on
the location and extent of the obstruction(s) and general medical condition of
the patient. Operative procedures for aortoiliac disease include aortobifemoral
bypass, axillofemoral bypass, femoral-femoral bypass, and aortoiliac
endarterectomy. The most frequently used procedure is the aortobifemoral bypass
using knitted Dacron grafts. Immediate graft patency approaches 99%, and 5- and
10-year graft patency in survivors is in excess of 90 and 80%, respectively.
Operative complications include myocardial infarction and stroke, infection of
the graft, peripheral embolization, and sexual dysfunction from interruption of
autonomic nerves in the pelvis. Operative mortality ranges from 1 to 3%, mostly
due to ischemic heart disease.
Operative
therapy for femoral-popliteal artery disease includes in situ and reverse autogenous
saphenous vein bypass grafts, placement of polytetrafluoroethylene (PTFE) or
other synthetic grafts, and thromboendarterectomy. Operative mortality ranges
from 1 to 3%. The long-term patency rate depends on the type of graft used, the
location of the distal anastomosis, and the patency of runoff vessels beyond
the anastomosis. Patency rates of femoral-popliteal saphenous vein bypass
grafts at 1 year approach 90% and at 5 years, 70 to 80%. Five-year patency
rates of infrapopliteal saphenous vein bypass grafts are 60 to 70%. In
contrast, 5-year patency rates of infrapopliteal PTFE grafts are less than 30%.
Lumbar sympathectomy alone or as an adjunct to aortofemoral reconstruction has
fallen into disfavor.
Preoperative
cardiac risk assessment may identify individuals especially likely to
experience an adverse cardiac event during the perioperative period. Patients
with angina, prior myocardial infarction, ventricular ectopy, heart failure, or
diabetes are among those at increased risk. Noninvasive tests, such as
treadmill testing (if feasible), dipyridamole thallium or sestamibi
scintigraphy, dobutamine echocardiography, and ambulatory ischemia monitoring
permit further stratification of patient risk (Chap. 245). Patients with
abnormal test results require close supervision and adjunctive management with
antianginal medications. It is not known whether coronary angiography and
coronary arterial revascularization reduce overall perioperative mortality in
high-risk patients undergoing peripheral vascular surgery, but cardiac
catheterization should be considered in patients suspected of having left main
or three-vessel coronary artery disease.
Fibromuscular Dysplasia
This
is a hyperplastic disorder affecting medium-sized and small arteries. It occurs
predominantly in females and usually involves renal and carotid arteries but
can affect extremity vessels such as the iliac and subclavian arteries. The
histologic classification includes intimal, medial, and periadventitial dysplasia.
Medial dysplasia is the most common type and is characterized by hyperplasia of
the media with or without fibrosis of the elastic membrane. It is identified
angiographically by a "string of beads" appearance caused by
thickened fibromuscular ridges contiguous with thin, less involved portions of
the arterial wall. When limb vessels are involved, clinical manifestations are
similar to those for atherosclerosis, including claudication and rest pain. PTA
and surgical reconstruction have been beneficial in patients with debilitating
symptoms or threatened limbs.
Thromboangiitis Obliterans
Thromboangiitis
obliterans (Buerger's disease) is an inflammatory occlusive vascular disorder
involving small and medium-sized arteries and veins in the distal upper and lower
extremities. Cerebral, visceral, and coronary vessels may also be affected.
This disorder develops most frequently in men under age 40. The prevalence is
higher in Asians and individuals of eastern European descent. While the cause
of thromboangiitis obliterans is not known, there is a definite relationship to
cigarette smoking in patients with this disorder.
In
the initial stages of thromboangiitis obliterans, polymorphonuclear leukocytes
infiltrate the walls of the small and medium-sized arteries and veins. The
internal elastic lamina is preserved, and thrombus may develop in the vascular
lumen. As the disease progresses, mononuclear cells, fibroblasts, and giant
cells replace the neutrophils. Later stages are characterized by perivascular
fibrosis and recanalization.
The
clinical features of thromboangiitis obliterans often include a triad of
claudication of the affected extremity, Raynaud's phenomenon (p. 1438), and
migratory superficial vein thrombophlebitis. Claudication is usually confined
to the calves and feet or the forearms and hands, because this disorder
primarily affects distal vessels. In the presence of severe digital ischemia,
trophic nail changes, painful ulcerations, and gangrene may develop at the tips
of the fingers. The physical examination shows normal brachial and popliteal
pulses but reduced or absent radial, ulnar, and/or tibial pulses. Arteriography
is helpful in making the diagnosis. Smooth, tapering segmental lesions in the
distal vessels are characteristic, as are collateral vessels at sites of
vascular occlusion. Proximal atherosclerotic disease is usually absent. The
diagnosis can be confirmed by excisional biopsy and pathologic examination of
an involved vessel.
There
is no specific treatment except abstention from tobacco. The prognosis is worse
in individuals who continue to smoke, but results are discouraging even in
those who do stop smoking. Arterial bypass of the larger vessels may be used in
selected instances, as well as local debridement, depending on the symptoms and
severity of ischemia. Antibiotics may be useful; anticoagulants and
glucocorticoids are not helpful. If these measures fail, amputation may be
required.
Vasculitis
Other
vasculitides may affect the arteries supplying the upper and lower extremities.
Takayasu's arteritis and giant cell (temporal) arteritis are discussed in Chap.
317.
Acute Arterial Occlusion
This
results in the sudden cessation of blood flow to an extremity. The severity of
ischemia and the viability of the extremity depend on the location and extent
of the occlusion and the presence and subsequent development of collateral
blood vessels. There are two principal causes of acute arterial occlusion:
embolism and thrombus in situ.
The
most common sources of arterial emboli are the heart, aorta, and large
arteries. Cardiac disorders that cause thromboembolism include atrial
fibrillation, both chronic and paroxysmal; acute myocardial infarction;
ventricular aneurysm; cardiomyopathy; infectious and marantic endocarditis;
prosthetic heart valves; and atrial myxoma. Emboli to the distal vessels may
also originate from proximal sites of atherosclerosis and aneurysms of the
aorta and large vessels. Less frequently, an arterial occlusion results
paradoxically from a venous thrombus that has entered the systemic circulation
via a patent foramen ovale or other septal defect. Arterial emboli tend to
lodge at vessel bifurcations because the vessel caliber decreases at these
sites; in the lower extremities, emboli lodge most frequently in the femoral
artery, followed by the iliac artery, aorta, and popliteal and tibioperoneal
arteries.
Acute
arterial thrombosis in situ occurs most frequently in atherosclerotic vessels
at the site of a stenosis or aneurysm and in arterial bypass grafts. Trauma to
an artery may also result in the formation of an acute arterial thrombus.
Arterial occlusion may complicate arterial punctures and placement of
catheters. Less frequent causes include the thoracic outlet compression
syndrome, which causes subclavian artery occlusion, and entrapment of the
popliteal artery by abnormal placement of the medial head of the gastrocnemius
muscle. Polycythemia and hypercoagulable disorders (Chaps. 110 and 118) are
also associated with acute arterial thrombosis.
Clinical Features
The
symptoms of an acute arterial occlusion depend on the location, duration, and
severity of the obstruction. Often, severe pain, paresthesia, numbness, and
coldness develop in the involved extremity within 1 h. Paralysis may occur with
severe and persistent ischemia. Physical findings include loss of pulses distal
to the occlusion, cyanosis or pallor, mottling, decreased skin temperature,
muscle stiffening, loss of sensation, weakness, and/or absent deep tendon
reflexes. If acute arterial occlusion occurs in the presence of an adequate
collateral circulation, as is often the case in acute graft occlusion, the
symptoms and findings may be less impressive. In this situation, the patient
complains about an abrupt decrease in the distance walked before claudication
occurs or of modest pain and paresthesia. Pallor and coolness are evident, but
sensory and motor functions are generally preserved. The diagnosis of acute
arterial occlusion is usually apparent from the clinical presentation.
Arteriography is useful for confirming the diagnosis and demonstrating the
location and extent of occlusion.
Treatment
Once
the diagnosis is made, the patient should be anticoagulated with intravenous
heparin to prevent propagation of the clot. In cases of severe ischemia of
recent onset, and particularly when limb viability is jeopardized, immediate
intervention to ensure reperfusion is indicated. Surgical thromboembolectomy or
arterial bypass procedures are used to restore blood flow to the ischemic
extremity promptly, particularly when a large proximal vessel is occluded.
Intraarterial
thrombolytic therapy is effective when acute arterial occlusion is caused by a
thrombus in an atherosclerotic vessel or arterial bypass graft. Thrombolytic
therapy may also be indicated when the patient's overall condition
contraindicates surgical intervention or when smaller distal vessels are
occluded, thus preventing surgical access. One approach for administering
intraarterial urokinase is to give 240,000 IU/h for 4 h, followed by 120,000
IU/h for a maximum of 48 h. Intraarterial recombinant tPA may be administered
at infusion rates of 1 mg/h or 0.05 mg/kg per hour. Meticulous observation for hemorrhagic
complications is required during intraarterial thrombolytic therapy.
If
the limb is not in jeopardy, a more conservative approach that includes
observation and administration of anticoagulants may be taken. Anticoagulation
prevents recurrent embolism and reduces the likelihood of thrombus propagation.
It can be initiated with intravenous heparin and followed by oral warfarin.
Recommended dosages are the same as those used for deep vein thrombosis (see
below). Emboli resulting from infectious endocarditis, the presence of
prosthetic heart valves, or atrial myxoma often require surgical intervention
to remove the cause.
Atheroembolism
Atheroembolism
constitutes a subset of acute arterial occlusion. In this condition, multiple
small deposits of fibrin, platelet, and cholesterol debris embolize from
proximal atherosclerotic lesions or aneurysmal sites. Atheroembolism may occur
after intraarterial procedures. Since the emboli tend to lodge in the small
vessels of the muscle and skin and may not occlude the large vessels, distal
pulses usually remain palpable. Patients complain of acute pain and tenderness
at the site of embolization. Digital vascular occlusion may result in ischemia
and the "blue toe" syndrome; digital necrosis and gangrene may
develop. Localized areas of tenderness, pallor, and livedo reticularis (see
below) occur at sites of emboli. Skin or muscle biopsy may demonstrate
cholesterol crystals.
Ischemia
resulting from atheroemboli is notoriously difficult to treat. Usually neither
surgical revascularization procedures nor thrombolytic therapy is helpful
because of the multiplicity, composition, and distal location of the emboli.
Some evidence suggests that platelet inhibitors prevent atheroembolism.
Surgical intervention to remove or bypass the atherosclerotic vessel or
aneurysm that causes the recurrent atheroemboli may be necessary.
Thoracic Outlet Compression Syndrome
This
is a symptom complex resulting from compression of the neurovascular bundle
(artery, vein, or nerves) at the thoracic outlet as it courses through the neck
and shoulder. Cervical ribs, abnormalities of the scalenus anticus muscle,
proximity of the clavicle to the first rib, or abnormal insertion of the
pectoralis minor muscle may compress the subclavian artery and brachial plexus
as these structures pass from the thorax to the arm. Patients may develop
shoulder and arm pain, weakness, paresthesia, claudication, Raynaud's
phenomenon, and even ischemic tissue loss and gangrene. Examination is often
normal unless provocative maneuvers are performed. Occasionally, distal pulses
are decreased or absent and digital cyanosis and ischemia may be evident.
Tenderness may be present in the supraclavicular fossa. Abducting the affected
arm by 90° and externally rotating the shoulder may precipitate symptoms.
Several additional maneuvers are used to confirm the diagnosis of vascular
compression and to suggest the location of the abnormality. These include the
scalene maneuver (extension of the neck and rotation of the head to the side of
the symptoms), the costoclavicular maneuver (posterior rotation of shoulders),
and the hyperabduction maneuver (raising the arm 180°), which may cause
subclavian bruits and loss of pulses in the arm. A chest x-ray will indicate
the presence of cervical ribs. The electromyogram will be abnormal if the
brachial plexus is involved.
Treatment
Most
patients can be managed conservatively. They should be advised to avoid the
positions that cause symptoms. Many patients benefit from shoulder girdle
exercises. Surgical procedures such as removal of the first rib or resection of
the scalenus anticus muscle are necessary occasionally for relief of symptoms
or treatment of ischemia.
Arteriovenous Fistula
Abnormal
communications between an artery and a vein, bypassing the capillary bed, may
be congenital or acquired. Congenital arteriovenous fistulas are the result of
persistent embryonic vessels that fail to differentiate into arteries and
veins; they may be associated with birthmarks, can be located in almost any
organ of the body, and frequently occur in the extremities. Acquired
arteriovenous fistulas are either created to provide vascular access for
hemodialysis or occur as a result of a penetrating injury such as a gunshot or
knife wound or as complications of arterial catheterization or surgical
dissection. An infrequent cause of arteriovenous fistula is rupture of an
arterial aneurysm into a vein.
The
clinical features depend on the location and size of the fistula. Frequently, a
pulsatile mass is palpable, and a thrill and bruit lasting throughout systole
and diastole are present over the fistula. With long-standing fistulas,
clinical manifestations of chronic venous insufficiency, including peripheral
edema, large, tortuous varicose veins, and stasis pigmentation become apparent
because of the high venous pressure. Evidence of ischemia may occur in the distal
portion of the extremity. Skin temperature is higher over the arteriovenous
fistula. Large arteriovenous fistulas may result in an increased cardiac output
with consequent cardiomegaly and high-output heart failure (Chap. 232).
Diagnosis
The
diagnosis is often evident from the physical examination. Compression of a
large arteriovenous fistula may cause reflex slowing of the heart rate
(Nicoladoni-Branham sign). Arteriography can confirm the diagnosis and is
useful in demonstrating the site and size of the arteriovenous fistula.
Treatment
Management
of arteriovenous fistulas may involve surgery, radiotherapy, or embolization.
Congenital arteriovenous fistulas are often difficult to treat because the
communications may be numerous and extensive, and new ones frequently develop
after ligation of the most obvious ones. Many of these lesions are best treated
conservatively using elastic support hose to reduce the consequences of venous
hypertension. Occasionally, embolization with autologous material, such as fat
or muscle, or with hemostatic agents, such as gelatin sponges or silicon
spheres, is used to obliterate the fistula. Acquired arteriovenous fistulas are
usually amenable to surgical treatment that involves division or excision of
the fistula. Occasionally, autogenous or synthetic grafting is necessary to
reestablish continuity of the artery and vein.
Raynaud's Phenomenon
Raynaud's
phenomenon is characterized by episodic digital ischemia, manifested clinically
by the sequential development of digital blanching, cyanosis, and rubor of the
fingers or toes following cold exposure and subsequent rewarming. Emotional
stress may also precipitate Raynaud's phenomenon. The color changes are usually
well demarcated and are confined to the fingers or toes. Typically, one or more
digits will appear white when the patient is exposed to a cold environment or
touches a cold object. The blanching, or pallor, represents the ischemic phase
of the phenomenon and results from vasospasm of digital arteries. During the
ischemic phase, capillaries and venules dilate, and cyanosis results from the
deoxygenated blood that is present in these vessels. A sensation of cold or
numbness or paresthesia of the digits often accompanies the phases of pallor
and cyanosis.
With
rewarming, the digital vasospasm resolves, and blood flow into the dilated
arterioles and capillaries increases dramatically. This "reactive hyperemia"
imparts a bright red color to the digits. In addition to rubor and warmth,
patients often experience a throbbing, painful sensation during the hyperemic
phase. Although the triphasic color response is typical of Raynaud's
phenomenon, some patients may develop only pallor and cyanosis; others may
experience only cyanosis.
Pathophysiology
Raynaud
originally proposed that cold-induced episodic digital ischemia was secondary
to exaggerated reflex sympathetic vasoconstriction. This theory is supported by
the fact that -adrenergic
blocking drugs as well as sympathectomy decrease the frequency and severity of
Raynaud's phenomenon in some patients. An alternative hypothesis is that the
digital vascular responsiveness to cold or to normal sympathetic stimuli is
enhanced. It is also possible that normal reflex sympathetic vasoconstriction
is superimposed on local digital vascular disease or that there is enhanced
adrenergic neuroeffector activity.
Raynaud's
phenomenon is broadly separated into two categories: the idiopathic variety,
termed Raynaud's disease, and the secondary variety, which is associated
with other disease states or known causes of vasospasm (Table 248-1).
Table 248-1: Classification of Raynaud's
Phenomenon
|
Collagen
vascular diseases: scleroderma, systemic lupus erythematosus, rheumatoid
arthritis, dermatomyositis, polymyositisRaynaud's Disease
This
appellation is applied when the secondary causes of Raynaud's phenomenon have
been excluded. Over 50% of patients with Raynaud's phenomenon have Raynaud's
disease. Women are affected about five times more often than men, and the age
of presentation is usually between 20 and 40 years. The fingers are involved
more frequently than the toes. Initial episodes may involve only one or two
fingertips, but subsequent attacks may involve the entire finger and may
include all the fingers. The toes are affected in 40% of patients. Although
vasospasm of the toes usually occurs in patients with symptoms in the fingers,
it may happen alone. Rarely, the earlobes and the tip of the nose are involved.
Raynaud's phenomenon occurs frequently in patients who also have migraine
headaches or variant angina. These associations suggest that there may be a
common predisposing cause for the vasospasm.
Results
of physical examination often are entirely normal; the radial, ulnar, and pedal
pulses are normal. The fingers and toes may be cool between attacks and may
perspire excessively. Thickening and tightening of the digital subcutaneous
tissue (sclerodactyly) develop in 10% of patients. Angiography of the
digits for diagnostic purposes is not indicated.
In
general, patients with Raynaud's disease appear to have the milder forms of
Raynaud's phenomenon. Fewer than 1% of these patients lose a part of a digit.
After the diagnosis is made, the disease improves spontaneously in
approximately 15% of patients and progresses in about 30%.
Secondary Causes of Raynaud's Phenomenon
Raynaud's
phenomenon occurs in 80 to 90% of patients with systemic sclerosis
(scleroderma) and is the presenting symptom in 30% (Chap. 313). It may be the
only symptom of scleroderma for many years. Abnormalities of the digital
vessels may contribute to the development of Raynaud's phenomenon in this
disorder. Ischemic fingertip ulcers may develop and progress to gangrene and
autoamputation. About 20% of patients with systemic lupus erythematosus (SLE)
have Raynaud's phenomenon (Chap. 311). Occasionally, persistent digital
ischemia develops and may result in ulcers or gangrene. In most severe cases,
the small vessels are occluded by a proliferative endarteritis. Raynaud's
phenomenon occurs in about 30% of patients with dermatomyositis or polymyositis
(Chap. 382). It frequently develops in patients with rheumatoid arthritis and
may be related to the intimal proliferation that occurs in the digital
arteries.
Atherosclerosis
of the extremities is a frequent cause of Raynaud's phenomenon in men over age
50. Thromboangiitis obliterans is an uncommon cause of Raynaud's phenomenon but
should be considered in young men, particularly in those who are cigarette
smokers. The development of cold-induced pallor in these disorders may be
confined to one or two digits of the involved extremity. Occasionally,
Raynaud's phenomenon may follow acute occlusion of large and medium-sized
arteries by a thrombus or embolus. Embolization of atheroembolic debris may
cause digital ischemia. The latter situation often involves one or two digits
and should not be confused with Raynaud's phenomenon. In patients with the
thoracic outlet syndrome, Raynaud's phenomenon may result from diminished
intravascular pressure, stimulation of sympathetic fibers in the brachial
plexus, or a combination of both. Raynaud's phenomenon occurs in patients with
primary pulmonary hypertension (Chap. 260); this is more than coincidental and
may reflect a neurohumoral abnormality that affects both the pulmonary and
digital circulations.
A
variety of blood dyscrasias may be associated with Raynaud's phenomenon.
Cold-induced precipitation of plasma proteins, hyperviscosity, and aggregation
of red cells and platelets may occur in patients with cold agglutinins,
cryoglobulinemia, or cryofibrinogenemia. Hyperviscosity syndromes that
accompany myeloproliferative disorders and Waldenström's macroglobulinemia
should also be considered in the initial evaluation of patients with Raynaud's
phenomenon.
Raynaud's
phenomenon occurs often in patients whose vocations require the use of
vibrating hand tools, such as chain saws or jackhammers. The frequency of
Raynaud's phenomenon also seems to be increased in pianists and typists.
Electric shock injury to the hands or frostbite may lead to the later
development of Raynaud's phenomenon.
Several
drugs have been causally implicated in Raynaud's phenomenon. These include
ergot preparations, methysergide, 
-adrenergic
receptor antagonists, and the chemotherapeutic agents bleomycin, vinblastine,
and cisplatin.
Treatment
Most
patients with Raynaud's phenomenon experience only mild and infrequent
episodes. These patients need reassurance and should be instructed to dress
warmly and avoid unnecessary cold exposure. In addition to gloves and mittens,
patients should protect the trunk, head, and feet with warm clothing to prevent
cold-induced reflex vasoconstriction. Tobacco use is contraindicated.
Drug
treatment should be reserved for the severe cases. The calcium channel
antagonists, especially nifedipine and diltiazem, decrease the frequency and
severity of Raynaud's phenomenon. Adrenergic blocking agents, such as
reserpine, have been shown to increase nutritional blood flow to the fingers.
Some, but not all, patients achieve satisfactory results with long-term
reserpine therapy. Moreover, systemic use of this drug is limited by side
effects of hypotension, nasal stuffiness, lethargy, and depression. The
postsynaptic 1-adrenergic
antagonist prazosin has been used with favorable responses. Doxazosin and
terazosin may also be effective. Other sympatholytic agents, such as
methyldopa, guanethidine, and phenoxybenzamine, may be useful in some patients.
Surgical sympathectomy is helpful in some patients who are unresponsive to
medical therapy, but benefit is often transient.
Acrocyanosis
In
this condition, there is arterial vasoconstriction and secondary dilation of
the capillaries and venules with resulting persistent cyanosis of the hands
and, less frequently, the feet. Cyanosis may be intensified by exposure to a
cold environment. Women are affected much more frequently than men, and the age
of onset is usually less than 30 years. Generally, patients are asymptomatic
but seek medical attention because of the discoloration. Examination reveals
normal pulses, peripheral cyanosis, and moist palms. Trophic skin changes and
ulcerations do not occur. The disorder can be distinguished from
Raynaud's phenomenon because it is persistent and not episodic, the
discoloration extends proximally from the digits, and blanching does not occur.
Ischemia secondary to arterial occlusive disease can usually be excluded by the
presence of normal pulses. Central cyanosis and decreased arterial oxygen
saturation are not present. Patients should be reassured and advised to dress
warmly and avoid cold exposure. Pharmacologic intervention is not indicated.
Livedo Reticularis
In
this condition, localized areas of the extremities develop a mottled or netlike
appearance of reddish to blue discoloration. The mottled appearance may be more
prominent following cold exposure. The idiopathic form of this disorder occurs
equally in men and women, and the most common age of onset is in the third decade.
Patients with the idiopathic form are usually asymptomatic and seek attention
for cosmetic reasons. Livedo reticularis can also occur following
atheroembolism (see above). Rarely, skin ulcerations develop. Patients should
be reassured and advised to avoid cold environments. No drug treatment is
indicated.
Pernio (Chilblains)
This
is a vasculitic disorder associated with exposure to cold; acute forms have
been described. Raised erythematous lesions develop on the lower part of the
legs and feet in cold weather. These are associated with pruritus and a burning
sensation, and they may blister and ulcerate. Pathologic examination
demonstrates angiitis characterized by intimal proliferation and perivascular
infiltration of mononuclear and polymorphonuclear leukocytes. Giant cells may
be present in the subcutaneous tissue. Patients should avoid exposure to cold,
and ulcers should be kept clean and protected with sterile dressings.
Sympatholytic drugs may be effective in some patients.
Erythromelalgia (Erythermalgia)
This
disorder is characterized by burning pain and erythema of the extremities. The
feet are involved more frequently than the hands, and males are affected more
frequently than females. Erythromelalgia may occur at any age but is most
common in middle age. It may be primary or secondary to myeloproliferative
disorders such as polycythemia vera and essential thrombocytosis, or it may
occur as an adverse effect of drugs such as nifedipine or bromocriptine.
Patients complain of burning in the extremities that is precipitated by
exposure to a warm environment and aggravated by a dependent position. The
symptoms are relieved by exposing the affected area to cool air or water or by
elevation. Erythromelalgia can be distinguished from ischemia secondary to peripheral
arterial disorders and peripheral neuropathy because the peripheral pulses are
present and the neurologic examination is normal. There is no specific
treatment; aspirin may produce relief in patients with erythromelalgia
secondary to myeloproliferative disease. Treatment of associated disorders in
secondary erythromelalgia may be helpful.
Frostbite
In
this condition, tissue damage results from severe environmental cold exposure
or from direct contact with a very cold object. Tissue injury results from both
freezing and vasoconstriction. Frostbite usually affects the distal aspects of
the extremities or exposed parts of the face, such as the ears, nose, chin, and
cheeks. Superficial frostbite involves the skin and subcutaneous tissue.
Patients experience pain or paresthesia, and the skin appears white and waxy.
After rewarming, there is cyanosis and erythema, wheal- and-flare formation,
edema, and superficial blisters. Deep frostbite involves muscle, nerves, and
deeper blood vessels. It may result in edema of the hand or foot, vesicles and
bullae, tissue necrosis, and gangrene.
Initial
treatment is rewarming, performed in an environment where reexposure to
freezing conditions will not occur. Rewarming is accomplished by immersion of
the affected part in a water bath at temperatures of 40 to 44°C (104 to 111°F).
Massage, application of ice water, and extreme heat are contraindicated. The
injured area should be cleansed with soap or antiseptic and sterile dressings
applied. Analgesics are often required during rewarming. Antibiotics are used
if there is evidence of infection. The efficacy of sympathetic blocking drugs
is not established. Following recovery, the affected extremity may exhibit
increased sensitivity to cold.
Venous Disorders
Veins
in the extremities can be broadly classified as either superficial or deep. In
the lower extremity, the superficial venous system includes the greater and
lesser saphenous veins and their tributaries. The deep veins of the leg
accompany the major arteries. Perforating veins connect the superficial and
deep systems at multiple locations. Bicuspid valves are present throughout the
venous system to direct the flow of venous blood centrally.
Venous Thrombosis
The
presence of thrombus within a superficial or deep vein and the accompanying
inflammatory response in the vessel wall is termed venous thrombosis or thrombophlebitis.
Initially, the thrombus is composed principally of platelets and fibrin. Red
cells become interspersed with fibrin, and the thrombus tends to propagate in
the direction of blood flow. The inflammatory response in the vessel wall may
be minimal or characterized by granulocyte infiltration, loss of endothelium,
and edema.
The
factors that predispose to venous thrombosis were initially described by
Virchow in 1856 and include stasis, vascular damage, and hypercoagulability.
Accordingly, a variety of clinical situations are associated with increased
risk of venous thrombosis (Table 248-2). Venous thrombosis may occur in more
than 50% of patients having orthopedic surgical procedures, particularly those
involving the hip or knee, and in 10 to 40% of patients who undergo abdominal
or thoracic operations. The prevalence of venous thrombosis is particularly
high in patients with cancer of the pancreas, lungs, genitourinary tract,
stomach, and breast. Approximately 10 to 20% of patients with idiopathic deep
vein thrombosis have or develop clinically overt cancer; there is no consensus
on whether these individuals should be subjected to intensive diagnostic workup
to search for occult malignancy. Risk of thrombosis is increased following
trauma, such as fractures of the spine, pelvis, femur, and tibia.
Immobilization, regardless of the underlying disease, is a major predisposing
cause of venous thrombosis. This fact may account for the relatively high
incidence in patients with acute myocardial infarction or congestive heart
failure. The incidence of venous thrombosis is increased during pregnancy,
particularly in the third trimester and in the first month postpartum, and in
individuals who use oral contraceptives or receive postmenopausal hormone
replacement therapy. A variety of clinical disorders that produce systemic
hypercoagulability, including resistance to activated protein C (factor V
Leiden); antithrombin III, protein C, and protein S deficiencies;
antiphospholipid syndrome; SLE; myeloproliferative diseases; dysfibrinogenemia;
and disseminated intravascular coagulation, are associated with venous
thrombosis. Venulitis occurring in thromboangiitis obliterans, Behçet's
disease, and homocysteinuria may also cause venous thrombosis.
Table 248-2: Conditions Associated with an
Increased Risk for Development of Venous Thrombosis
|
Deep Venous Thrombosis
The
most important consequences of this disorder are pulmonary embolism (Chap. 261)
and the syndrome of chronic venous insufficiency. Deep venous thrombosis of the
iliac, femoral, or popliteal veins is suggested by unilateral leg swelling,
warmth, and erythema. Tenderness may be present along the course of the
involved veins, and a cord may be palpable. There may be increased tissue
turgor, distention of superficial veins, and the appearance of prominent venous
collaterals. In some patients, deoxygenated hemoglobin in stagnant veins
imparts a cyanotic hue to the limb, a condition called phlegmasia cerulea
dolens. In markedly edematous legs, the interstitial tissue pressure may
exceed the capillary perfusion pressure, causing pallor, a condition designated
phlegmasia alba dolens.
The
diagnosis of deep venous thrombosis of the calf is often difficult to make at
the bedside. This is so because only one of multiple veins may be involved,
allowing adequate venous return through the remaining patent vessels. The most
common complaint is calf pain. Examination may reveal posterior calf tenderness,
warmth, increased tissue turgor or modest swelling, and, rarely, a cord.
Increased resistance or pain during dorsiflexion of the foot (Homans' sign) is
an unreliable diagnostic sign.
Deep
venous thrombosis occurs less frequently in the upper extremity than in the
lower extremity, but the incidence is increasing because of greater utilization
of indwelling central venous catheters. The clinical features and complications
are similar to those described for the leg.
Diagnosis
The
noninvasive test used most often to diagnose deep venous thrombosis is duplex
venous ultrasonography (B-mode, i.e., two-dimensional, imaging, and pulse-wave
Doppler interrogation). By imaging the deep veins, thrombus can be detected
either by direct visualization or by inference when the vein does not collapse
on compressive maneuvers. The Doppler ultrasound measures the velocity of blood
flow in veins. This velocity is normally affected by respiration and by manual
compression of the foot or calf. Flow abnormalities occur when deep venous
obstruction is present. The positive predictive value of duplex venous
ultrasonography approaches 95% for proximal deep vein thrombosis. In the calf,
because calf veins are more difficult to visualize than proximal veins, the
sensitivity of this technique is only 50 to 75%, although its specificity is
95%.
Impedance
plethysmography measures changes in venous capacitance during physiologic
maneuvers. Venous obstruction blunts the normal changes in venous capacitance
that occur following inflation and deflation of a thigh cuff. The predictive
value of this test for detecting occlusive thrombi in proximal veins is
approximately 90%. However, it is much less sensitive for diagnosing deep
venous thrombosis of the calves.
Magnetic
resonance imaging (MRI) is another noninvasive means to detect deep vein
thrombosis. Its diagnostic accuracy for assessing proximal deep vein thrombosis
is similar to that of duplex ultrasonography. It is useful in patients with
suspected thrombosis of the superior and inferior venae cavae or pelvic veins.
Deep
venous thrombosis can also be diagnosed by venography. Contrast medium is
injected into a superficial vein of the foot and directed to the deep system by
the application of tourniquets. The presence of a filling defect or absence of
filling of the deep veins is required to make the diagnosis.
Deep
vein thrombosis must be differentiated from a variety of disorders that cause
unilateral leg pain or swelling, including muscle rupture, trauma, or
hemorrhage; a ruptured popliteal cyst; and lymphedema. It may be difficult to
distinguish swelling caused by the postphlebitic syndrome from that due to
acute recurrent deep venous thrombosis. Leg pain may also result from nerve
compression, arthritis, tendinitis, fractures, and arterial occlusive
disorders. A careful history and physical examination can usually determine the
cause of these symptoms.
Treatment
Anticoagulants
Prevention
of pulmonary embolism is the most important reason for treating patients with
deep vein thrombosis, since in the early stages the thrombus may be loose and
poorly adherent to the vessel wall. Patients should be placed in bed, and the
affected extremity should be elevated above the level of the heart until the
edema and tenderness subside. Anticoagulants prevent thrombus propagation and
allow the endogenous lytic system to operate. Initial therapy should include
either unfractionated heparin or low-molecular-weight heparin. Unfractionated
heparin should be administered intravenously as an initial bolus of 7500 to
10,000 IU, followed by a continuous infusion of 1000 to 1500 IU/h. The rate of
the heparin infusion should be adjusted so that the activated partial
thromboplastin time (aPTT) is approximately twice the control value.
Subcutaneous injection of heparin has been used as an alternative form of
therapy. In fewer than 5% of patients, heparin therapy may cause
thrombocytopenia. Infrequently, these patients develop arterial thrombosis and
ischemia. Low-molecular-weight (4000 to 6000 Da) heparins are reported to be as
effective as or better than conventional, unfractionated heparin in preventing
extension or recurrence of venous thrombosis. Depending on the specific
preparation, low-molecular-weight heparin is administered subcutaneously, in
fixed doses, once or twice daily; for example, the dose of enoxaparin is 1
mg/kg subcutaneously bid. The incidence of thrombocytopenia is less with
low-molecular-weight heparin than with conventional preparations. Hirudin, a
direct thrombin inhibitor, may be used as initial anticoagulant therapy for
patients in whom heparin is contraindicated because of heparin-induced
thrombocytopenia. Warfarin is administered during the first week of treatment
with heparin and may be started as early as the first day of heparin treatment
if the aPTT is therapeutic. It is important to overlap heparin treatment with
oral anticoagulant therapy for at least 4 to 5 days because the full
anticoagulant effect of warfarin is delayed. The dose of warfarin should be
adjusted to maintain the prothrombin time at an international normalized ratio
(INR) of 2.0 to 3.0.
Anticoagulant
treatment is indicated for patients with proximal deep vein thrombosis, since
pulmonary embolism may occur in approximately 50% of untreated individuals. The
use of anticoagulants for isolated deep vein thrombosis of the calf is
controversial. However, approximately 20 to 30% of calf thrombi propagate to
the thigh, thereby increasing the risk of pulmonary embolism. The overall
incidence of pulmonary embolism in patients presenting initially with deep calf
vein thrombosis is 5 to 20%. Also, isolated calf vein thrombosis has been
identified as a cause of embolic stroke via a patent foramen ovale. Therefore,
patients with calf vein thrombosis should either receive anticoagulants or be
followed with serial noninvasive tests to determine whether proximal
propagation has occurred. Anticoagulant treatment should be continued for at
least 3 to 6 months for patients with acute idiopathic deep vein thrombosis and
for those with a temporary risk factor for venous thrombosis to decrease the
chance of recurrence. The duration of treatment is indefinite for patients with
recurrent deep vein thrombosis and for those in whom associated causes, such as
malignancy or hypercoagulability, have not been eliminated. If treatment with
anticoagulants is contraindicated because of a bleeding diathesis or risk of
hemorrhage, protection from pulmonary embolism can be achieved by mechanically
interrupting the flow of blood through the inferior vena cava. Inferior vena
cava plication generally has been replaced by percutaneous insertion of a
filter.
Thrombolytics
Thrombolytic
drugs such as streptokinase, urokinase, and tPA may also be used, but there is
no evidence that thrombolytic therapy is more effective than anticoagulants in
preventing pulmonary embolism. However, early administration of thrombolytic
drugs may accelerate clot lysis, preserve venous valves, and decrease the
potential for developing postphlebitic syndrome.
Prophylaxis
Prophylaxis
should be considered in clinical situations where the risk of deep vein
thrombosis is high. Low-dose unfractionated heparin (5000 units 2 h prior to
surgery and then 5000 units every 8 to 12 h postoperatively), warfarin, and
external pneumatic compression are all useful. Low-dose heparin reduces the
risk of deep vein thrombosis associated with thoracic and abdominal surgery and
with prolonged bed rest. Low-molecular-weight heparins have been shown to
prevent deep vein thrombosis in patients undergoing general or orthopedic
surgery and in acutely ill medical patients. They are said to be more effective
than conventional heparin and to cause an equal or lower incidence of bleeding.
Danaparoid, a low-molecular-weight heparinoid, may be used for prophylaxis in
patients undergoing hip surgery. Warfarin in a dose that yields a prothrombin
time equivalent to an INR of 2.0 to 3.0 is effective in preventing deep vein thrombosis
associated with bone fractures and orthopedic surgery. Warfarin is started the
night before surgery and continued throughout the convalescent period. External
pneumatic compression devices applied to the legs are used to prevent deep vein
thrombosis when even low doses of heparin or warfarin might cause serious
bleeding, as during neurosurgery or transurethral resection of the prostate.
Superficial Vein Thrombosis
Thrombosis
of the greater or lesser saphenous veins or their tributaries-i.e., superficial
vein thrombosis-does not result in pulmonary embolism. It is associated with
intravenous catheters and infusions, occurs in varicose veins, and may develop
in association with deep vein thrombosis. Migrating superficial vein thrombosis
is often a marker for a carcinoma and may also occur in patients with
vasculitides, such as thromboangiitis obliterans. The clinical features of
superficial vein thrombosis are easily distinguished from those of deep vein
thrombosis. Patients complain of pain localized to the site of the thrombus.
Examination reveals a reddened, warm, and tender cord extending along a
superficial vein. The surrounding area may be red and edematous.
Treatment
Treatment
is primarily supportive. Initially, patients can be placed at bed rest with leg
elevation and application of warm compresses. Nonsteroidal antiinflammatory
drugs may provide analgesia but may also obscure clinical evidence of thrombus
propagation. If a thrombosis of the greater saphenous vein develops in the
thigh and extends toward the saphenofemoral vein junction, it is reasonable to
consider anticoagulant therapy to prevent extension of the thrombus into the
deep system and a possible pulmonary embolism
Varicose Veins
Varicose
veins are dilated, tortuous superficial veins that result from defective
structure and function of the valves of the saphenous veins, from intrinsic
weakness of the vein wall, from high intraluminal pressure, or, rarely, from
arteriovenous fistulas. Varicose veins can be categorized as primary or
secondary. Primary varicose veins originate in the superficial system and occur
two to three times as frequently in women as in men. Approximately half of
patients have a family history of varicose veins. Secondary varicose veins
result from deep venous insufficiency and incompetent perforating veins or from
deep venous occlusion causing enlargement of superficial veins that are serving
as collaterals.
Patients
with venous varicosities are often concerned about the cosmetic appearance of
their legs. Symptoms consist of a dull ache or pressure sensation in the legs
after prolonged standing; it is relieved with leg elevation. The legs feel
heavy, and mild ankle edema develops occasionally. Extensive venous
varicosities may cause skin ulcerations near the ankle. Superficial venous
thrombosis may be a recurring problem, and, rarely, a varicosity ruptures and
bleeds. Visual inspection of the legs in the dependent position usually
confirms the presence of varicose veins.
Varicose
veins can usually be treated with conservative measures. Symptoms often
decrease when the legs are elevated periodically, when prolonged standing is
avoided, and when elastic support hose are worn. External compression stockings
provide a counterbalance to the hydrostatic pressure in the veins. Small
symptomatic varicose veins can be treated with sclerotherapy, in which a sclerosing
solution is injected into the involved varicose vein and a compression bandage
is applied. Surgical therapy usually involves extensive ligation and stripping
of the greater and lesser saphenous veins and should be reserved for patients
who are very symptomatic, suffer recurrent superficial vein thrombosis, and/or
develop skin ulceration. Surgical therapy may also be indicated for cosmetic
reasons.
Chronic Venous Insufficiency
Chronic
venous insufficiency may result from deep vein thrombosis and/or valvular
incompetence. Following deep vein thrombosis, the delicate valve leaflets
become thickened and contracted so that they cannot prevent retrograde flow of
blood; the vein becomes rigid and thick-walled. Although most veins recanalize
after an episode of thrombosis, the large proximal veins may remain occluded.
Secondary incompetence develops in distal valves because high pressures distend
the vein and separate the leaflets. Primary deep venous valvular dysfunction
may also occur without previous thrombosis. Patients with venous insufficiency
often complain of a dull ache in the leg that worsens with prolonged standing
and resolves with leg elevation. Examination demonstrates increased leg
circumference, edema, and superficial varicose veins. Erythema, dermatitis, and
hyperpigmentation develop along the distal aspect of the leg, and skin
ulceration may occur near the medial and lateral malleoli. Cellulitis may be a
recurring problem. Patients should be advised to avoid prolonged standing or
sitting; frequent leg elevation is helpful. Graduated compression stockings
should be worn during the day. These efforts should be intensified if skin
ulcers develop. Ulcers should be treated with applications of wet to dry
dressings and, occasionally, dilute topical antibiotic solutions. Commercially
available dressings comprising antiseptic solutions and compressive bandages
may be applied and should be changed weekly until healing occurs. Recurrent
ulceration and severe edema may be treated by surgical interruption of
incompetent communicating veins. Rarely, surgical valvuloplasty and bypass of
venous occlusions are employed.
Lymphatic Disorders
Lymphatic
capillaries are blind-ended tubes formed by a single layer of endothelial
cells. The absent or widely fenestrated basement membrane of lymphatic
capillaries allows access to interstitial proteins and particles. Lymphatic
capillaries merge to form larger vessels which contain smooth muscle and are
capable of vasomotion. Small and medium-sized lymphatic vessels empty into
progressively larger channels, most of which drain into the thoracic duct. The
lymphatic circulation is involved in the absorption of interstitial fluid and
in the response to infection.
Lymphedema
Lymphedema
may be categorized as primary or secondary (Table 248-3). The prevalence of
primary lymphedema is approximately 1 per 10,000 individuals. Primary
lymphedema may be secondary to agenesis, hypoplasia, or obstruction of the
lymphatic vessels. It may be associated with Turner syndrome, Klinefelter syndrome,
Noonan syndrome, the yellow nail syndrome, the intestinal lymphangiectasia
syndrome, and lymphangiomyomatosis. Women are affected more frequently than
men. There are three clinical subtypes: congenital lymphedema, which appears
shortly after birth; lymphedema praecox, which has its onset at the time of
puberty; and lymphedema tarda, which usually begins after age 35. Familial
forms of congenital lymphedema (Milroy's disease) and lymphedema praecox
(Meige's disease) may be inherited in an autosomal dominant manner with
variable penetrance; autosomal or sex-linked recessive forms are less common.
Table 248-3: Causes of Lymphedema
|
Secondary
lymphedema is an acquired condition resulting from damage to or obstruction of
previously normal lymphatic channels (Table 248-3). Recurrent episodes of
bacterial lymphangitis, usually caused by streptococci, are a very common cause
of lymphedema. The most common cause of secondary lymphedema worldwide is
filariasis (Chap. 221). Tumors, such as prostate cancer and lymphoma, can also
obstruct lymphatic vessels. Both surgery and radiation therapy for breast
carcinoma may cause lymphedema of the upper extremity. Less common causes
include tuberculosis, contact dermatitis, lymphogranuloma venereum, rheumatoid
arthritis, pregnancy, and self-induced or factitious lymphedema following
application of tourniquets.
Lymphedema
is generally a painless condition, but patients may experience a chronic dull,
heavy sensation in the leg, and most often they are concerned about the
appearance of the leg. Lymphedema of the lower extremity, initially involving
the foot, gradually progresses up the leg so that the entire limb becomes
edematous. In the early stages, the edema is soft and pits easily with
pressure. In the chronic stages, the limb has a woody texture, and the tissues
become indurated and fibrotic. At this point the edema may no longer be
pitting. The limb loses its normal contour, and the toes appear square.
Lymphedema should be distinguished from other disorders that cause unilateral
leg swelling, such as deep vein thrombosis and chronic venous insufficiency. In
the latter condition, the edema is softer, and there is often evidence of a
stasis dermatitis, hyperpigmentation, and superficial venous varicosities.
The
evaluation of patients with lymphedema should include diagnostic studies to
clarify the cause. Abdominal and pelvic ultrasound and computed tomography can
be used to detect obstructing lesions such as neoplasms. MRI may reveal edema
in the epifascial compartment and identify lymph nodes and enlarged lymphatic
channels. Lymphoscintigraphy and lymphangiography are rarely indicated, but
either can be used to confirm the diagnosis or to differentiate primary from
secondary lymphedema. Lymphoscintigraphy involves the injection of
radioactively labeled technetium-containing colloid into the distal
subcutaneous tissue of the affected extremity. In lymphangiography, contrast
material is injected into a distal lymphatic vessel that has been isolated and
cannulated. In primary lymphedema, lymphatic channels are absent, hypoplastic,
or ectatic. In secondary lymphedema, lymphatic channels are usually dilated,
and it may be possible to determine the level of obstruction.
Treatment
Patients
with lymphedema of the lower extremities must be instructed to take meticulous
care of their feet to prevent recurrent lymphangitis. Skin hygiene is
important, and emollients can be used to prevent drying. Prophylactic
antibiotics are often helpful, and fungal infection should be treated
aggressively. Patients should be encouraged to participate in physical
activity; frequent leg elevation can reduce the amount of edema. Physical
therapy, including massage to facilitate lymphatic drainage, may be helpful. Patients
can be fitted with graduated compression hose to reduce the amount of
lymphedema that develops with upright posture. Occasionally, intermittent
pneumatic compression devices can be applied at home to facilitate reduction of
the edema. Diuretics are contraindicated and may cause depletion of
intravascular volume and metabolic abnormalities. Recently, microsurgical
lymphatico-venous anastomotic procedures have been performed to rechannel lymph
flow from obstructed lymphatic vessels into the venous system.