Arterial occlusive disease
Arterial occlusive disease: Excerpt from Professional Guide to Diseases (Eighth Edition)
Arterial occlusive disease is the obstruction or narrowing of the lumen of the aorta and its major branches, causing an interruption of blood flow, usually to the legs and feet. This disorder may affect the carotid, vertebral, innominate, subclavian, mesenteric, and celiac arteries. (See Types of arterial occlusive disease.) Occlusions may be acute or chronic and commonly cause severe ischemia, skin ulceration, and gangrene.
The prognosis depends on the occlusion’s location, the development of collateral circulation to counteract reduced blood flow and, in acute disease, the time elapsed between occlusion and its removal.
Causes and incidence
Arterial occlusive disease is a common complication of atherosclerosis. The occlusive mechanism may be endogenous, due to emboli formation or thrombosis, or exogenous, due to trauma or fracture. Predisposing factors include smoking; aging; such conditions as hypertension, hyperlipidemia, and diabetes; and a family history of vascular disorders, myocardial infarction, or stroke.
Arterial occlusive disease has no racial predilection. Men older than 50 are at increased risk for intermittent claudication, a common sign of arterial occlusive disease.
Diagnosis
Diagnosis of arterial occlusive disease is usually indicated by 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 the collateral circulation. It’s particularly useful in chronic disease or for evaluating candidates for reconstructive surgery.
❑ Doppler ultrasonography and plethysmography are noninvasive tests that show decreased blood flow distal to the occlusion in acute disease.
❑ Ophthalmodynamometry helps determine the degree of obstruction in the internal carotid artery by comparing ophthalmic artery pressure to brachial artery pressure on the affected side. More than a 20% difference between pressures suggests insufficiency.
❑ EEG and computed tomography scan may be necessary to rule out brain lesions.
Treatment
Treatment depends on the obstruction’s cause, location, and size. For mild chronic disease, supportive measures include elimination of smoking, hypertension control, and walking exercise. For carotid artery occlusion, antiplatelet therapy may begin with ticlopidine or clopidogrel and aspirin. For intermittent claudication of chronic occlusive disease, pentoxifylline and cilostazol may improve blood flow through the capillaries, particularly for patients who are poor candidates for surgery.
Acute arterial occlusive disease usually requires surgery to restore circulation to the affected area, for example:
❑ Atherectomy — Excision of plaque using a drill or slicing mechanism.
❑ Balloon angioplasty — Compression of the obstruction using balloon inflation.
❑ Bypass graft — Blood flow is diverted through an anastomosed autogenous or Dacron graft past the thrombosed segment.
❑ Combined therapy — Concomitant use of any of the above treatments.
❑ Embolectomy — A balloon-tipped Fogarty catheter is used to remove thrombotic material from the artery. Embolectomy is used mainly for mesenteric, femoral, or popliteal artery occlusion.
❑ Laser angioplasty — Use of excision and hot tip lasers to vaporize the obstruction.
❑ Lumbar sympathectomy — An adjunct to surgery, depending on the sympathetic nervous system’s condition.
❑ Patch grafting — This procedure involves removal of the thrombosed arterial segment and replacement with an autogenous vein or Dacron graft.
❑ Stents — Insertion of a mesh of wires that stretch and mold to the arterial wall to prevent reocclusion. This new adjunct follows laser angioplasty or atherectomy.
❑ Thromboendarterectomy — Opening of the occluded artery and direct removal of the obstructing thrombus and the medial layer of the arterial wall; usually performed after angiography and commonly used with autogenous vein or Dacron bypass surgery (femoral-popliteal or aortofemoral).
❑ Thrombolytic therapy — Lysis of any clot around or in the plaque by urokinase, streptokinase, or alteplase.
Amputation becomes necessary with failure of arterial reconstructive surgery or with the development of gangrene, persistent infection, or intractable pain.
Other therapy includes heparin to prevent emboli (for embolic occlusion) and bowel resection after restoration of blood flow (for mesenteric artery occlusion).
Special considerations
❑ Provide comprehensive patient teaching, including proper foot care. Explain diagnostic tests and procedures. Advise the patient to stop smoking and to follow the prescribed medical regimen.
Preoperatively, during an acute episode:
❑ 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 ordered. 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 carotid, innominate, vertebral, or subclavian artery occlusion, monitor him for signs of stroke, such as numbness in an arm or leg and intermittent blindness.
Postoperatively:
❑ 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 (tachycardia and hypotension) and check dressings for excessive bleeding.
❑ In carotid, innominate, vertebral, or subclavian artery occlusion, assess neurologic status frequently for changes in level of consciousness or muscle strength and pupil size.
❑ In mesenteric artery occlusion, connect the 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 return of peristalsis. Increasing abdominal distention and tenderness may indicate extension of bowel ischemia with resulting gangrene, necessitating further excision, or it may indicate peritonitis.
❑ In saddle block occlusion, check distal pulses for adequate circulation. Watch for signs of renal failure and mesenteric artery occlusion (severe abdominal pain), and for cardiac arrhythmias, which may precipitate embolus formation.
❑ In 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.
❑ In both femoral and popliteal artery occlusions, 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 as ordered, and administer adequate analgesic medication. Because phantom limb pain is common, explain this phenomenon to the patient.
❑ When preparing the patient for discharge, instruct him to watch for signs of recurrence (pain, pallor, numbness, paralysis, and absence of pulse) that can result from graft occlusion or occlusion at another site. Warn him against wearing constrictive clothing.
Pictures
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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