Peripheral artery occlusive disease
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In medicine (vascular surgery), Peripheral artery occlusive disease (PAOD) is a collator for all disease caused by the obstruction of large peripheral arteries, which can result from atherosclerosis, inflammatory processes leading to stenosis, an embolism or thrombus formation. It causes either acute or chronic ischemia.
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Classification
Peripheral artery occlusive disease is commonly divided in the four Fontaine stages:
- I: mild pain on walking ("intermittent claudication")
- II: severe pain on walking a short distance
- III: pain while resting
- IV: tissue loss (gangrene)
Causes
All causes of atherosclerosis are also causes of PAOD. There is, however, a strong preponderance of diabetic people who smoke. A known diabetic who smokes runs an approximately 30% risk of amputation within 5 years.
Diagnosis
Upon suspicion of PAOD, the first-line test is the ankle-brachial pressure index (ABPI).
The pressures in the posterior tibial artery and the brachial artery are estimated. An ultrasound probe is used to monitor the pulse while a sphygmomanometer cuff is inflated above the artery. The cuff is deflated and the pressure at which the pulse returns is recorded. The ABPI is the ratio of the posterior tibial pressure to the brachial pressure. A reduced ABPI (less than 0.7) is consistent with PAOD.
The next step is generally a form of angiography, where a catheter is used to inject radiodense contrast agent into the aorta or femoral artery. Stenosis of the arteries can be identified, and generally correlates with the patient's symptoms.
Therapy
Dependent on the severity of the disease, the following steps can be taken:
- Conservative measures include medication with aspirin and statins, which reduce clot formation and cholesterol levels, respectively.
- Angioplasty (PTA or percutaneous transluminal angioplasty) can be done on solitary lesions in large arteries, such as the femoral artery.
- Occasionally, bypass grafting is needed to circumvent a seriously stenosed area of the arterial vasculature. Generally, the saphenous vein is used, although artificial (Gore-Tex) material is often used for large tracts when the veins are of lesser quality.
- Rarely, sympathectomy is used - removing the nerves that make arteries contract, effectively leading to vasodilatation.
- When gangrene of toes has set in, amputation is often a last resort to stop infected dying tissues from causing septicemia.
Arterial thrombosis or embolism has a dismal prognosis, but is occasionally treated successfully with thrombolysis.
Associations
Many PAOD patients also have angina pectoris or have had myocardial infarction. There is also an increased risk for stroke.
External links
- Peripheral arterial occlusion (http://www.cvphysiology.com/Peripheral%20Vascular%20Disease/PVD001.htm)
- Merck Manual (http://www.merck.com/mrkshared/mmanual/home.jsp): Peripheral arterial occlusion (http://www.merck.com/mrkshared/mmanual/section16/chapter212/212b.jsp)