Arterial occlusive disease
Arterial occlusive disease: Excerpt from Handbook of Diseases
With arterial occlusive disease, the obstruction or narrowing of the lumen of the aorta and its major branches causes an interruption of blood flow, usually to the legs and feet. Arterial occlusive disease may affect the carotid, vertebral, innominate, subclavian, mesenteric, or celiac artery. Occlusions, which may be acute or chronic, often cause severe ischemia, skin ulceration, and gangrene.
Arterial occlusive disease is more common in males than in females. The prognosis depends on the location of the occlusion, the development of collateral circulation to counteract reduced blood flow and, if the patient has acute disease, the time elapsed between occlusion and its removal.
Causes
Arterial occlusive disease is a common complication of atherosclerosis. The occlusive mechanism may be endogenous, due to embolus formation or thrombosis, or exogenous, due to trauma or fracture. Predisposing factors include smoking; aging; conditions such as hypertension, hyperlipidemia, and diabetes; and a family history of vascular disorders, myocardial infarction, or stroke.
Signs and symptoms
Evidence of this disease varies widely, according to the occlusion site. (See Clinical features of arterial occlusive disease.)
Diagnosis
With arterial occlusive disease, the diagnosis is usually based on patient history and physical examination.
Pertinent supportive diagnostic tests include the following:
Arteriography demonstrates the type (thrombus or embolus), location, and degree of obstruction and collateral circulation. Arteriography is particularly useful in patients with chronic disease or for evaluating candidates for reconstructive surgery.
Doppler ultrasonography and plethysmography are noninvasive tests that, in acute disease, show decreased blood flow distal to the occlusion.
Ophthalmodynamometry helps determine the degree of obstruction in the internal carotid artery by comparing ophthalmic artery pressure with brachial artery pressure on the affected side. A more than 20% difference between pressures suggests insufficiency.
EEG and a computed tomography scan may be necessary to rule out brain lesions.
Treatment
Effective treatment depends on the cause, location, and size of the obstruction. The goal of medical management is to impede progression of peripheral arterial occlusive disease. For mild chronic disease, supportive measures include elimination of smoking, control of hypertension, and initiation of a walking program. For carotid artery occlusion, antiplatelet therapy may begin with aspirin. For intermittent claudication of chronic occlusive disease, pentoxifylline may improve blood flow through the capillaries, particularly in patients who are poor candidates for surgery. Exercise also plays a vital role in treatment for claudication.
Acute arterial occlusive disease usually requires surgery to restore circulation to the affected area. Possible procedures include the following:
Embolectomy — A balloon-tipped catheter is used to remove thrombotic material from the artery. Embolectomy is used mainly for mesenteric, femoral, or popliteal artery occlusion.
Thromboendarterectomy — The occluded artery is opened and the obstructing thrombus and the medial layer of the arterial wall removed. This procedure is usually performed after angiography and is commonly used with autogenous vein or Dacron bypass surgery (femoral-popliteal or aortofemoral).
Patch grafting — This procedure involves removal of the thrombosed arterial segment and replacement with an autogenous vein or Dacron graft.
Bypass graft — Blood flow is diverted through an anastomosed autogenous or Dacron graft past the thrombosed segment.
Thrombolytic therapy — Any clot around or in the plaque is lysed by urokinase, streptokinase, or alteplase.
Atherectomy — Plaque is excised using a drill or slicing mechanism.
Balloon angioplasty — The obstruction is compressed using balloon inflation.
Laser angioplasty — Excision and hot-tip lasers are used to vaporize the obstruction.
Stents — A mesh of wires that stretch and mold to the arterial wall are inserted to prevent reocclusion.
Combined therapy — Any of the above treatments are used concomitantly.
Lumbar sympathectomy — The procedure is an adjunct to surgery, depending on the condition of the sympathetic nervous system.
Amputation becomes necessary with failure of arterial reconstructive surgery or with the development of gangrene, persistent infection, or intractable pain.
Other treatments include heparin to prevent embolus formation (for embolic occlusion) and bowel resection after restoration of blood flow (for mesenteric artery occlusion).
Special considerations
Provide comprehensive patient teaching, such as proper foot care. Explain all diagnostic tests and procedures. Advise the patient to stop smoking and to follow the prescribed medical regimen.
Preoperatively (during an acute episode), perform the following:
Assess the patient’s circulatory status by checking for the most distal pulses and by inspecting his skin color and temperature.
Provide pain relief as needed.
Administer heparin by continuous I.V. drip as needed. Use an infusion monitor or pump to ensure the proper flow rate.
Wrap the patient’s affected foot in soft cotton batting, and reposition it frequently to prevent pressure on any one area. Strictly avoid elevating or applying heat to the affected leg.
Watch for signs of fluid and electrolyte imbalance, and monitor intake and output for signs of renal failure (urine output less than 30 ml/hour).
If the patient has a carotid, innominate, vertebral, or subclavian artery occlusion, monitor him for signs and symptoms of stroke, such as numbness in an arm or a leg and intermittent blindness.
Postoperatively, perform the following:
Monitor the patient’s vital signs. Continuously assess his circulatory function by inspecting skin color and temperature and by checking for distal pulses. In charting, compare earlier assessments and observations. Watch closely for signs of hemorrhage (including tachycardia and hypotension), and check dressings for excessive bleeding.
If the patient has a carotid, innominate, vertebral, or subclavian artery occlusion, assess neurologic status frequently for changes in level of consciousness, muscle strength, and pupil size.
If the patient has mesenteric artery occlusion, connect a nasogastric tube to low intermittent suction. Monitor intake and output (low urine output may indicate damage to renal arteries during surgery). Check bowel sounds for the return of peristalsis. Increasing abdominal distention and tenderness may indicate extension of bowel ischemia with resulting gangrene, necessitating further excision, or they may indicate peritonitis.
If the patient has aortic bifurcation, also known as saddle-block occlusion, check distal pulses for adequate circulation. Watch for indications of renal failure and mesenteric artery occlusion (such as severe abdominal pain) and for cardiac arrhythmias, which may precipitate embolus formation.
If the patient has iliac artery occlusion, monitor urine output for signs of renal failure from decreased perfusion to the kidneys as a result of surgery. Provide meticulous catheter care.
If the patient has femoral or popliteal artery occlusion, assist with early ambulation, but discourage prolonged sitting.
After amputation, check the patient’s stump carefully for drainage, and record its color and amount and the time. Elevate the stump and administer an analgesic. Because phantom limb pain is common, explain this phenomenon to the patient.
When preparing the patient for discharge, instruct him to watch for signs and symptoms of recurrence (such as pain, pallor, numbness, paralysis, and absence of pulse), which can result from graft occlusion or occlusion at another site. Warn him against wearing constrictive clothing. Pictures
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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