Glossary
Acute limb ischemia
A sudden decrease in limb perfusion, usually producing new or worsening symptoms and often threatening limb viability.
Amputation
The removal of a body extremity by trauma or surgery. As a surgical measure, amputation is used to control pain or treat disease in the affected limb.
Angina
Chest pain that occurs due to an inadequate supply of oxygen to the myocardium. It can be brought about by effort or excitement and is described as a heavy or squeezing pain to the midsternal area of the chest.
Angiography
A radiographic technique that involves taking an X-ray picture of the inner opening of blood-filled structures following the injection of a radio-opaque contrast material. The technique can be used to diagnose arterial occlusions and other blood vessel conditions. Digital subtraction angiography (DSA) is commonly used to assess patients with PAD. In this technique a ‘pre-contrast image' is subtracted from the subsequent images that are acquired when the contrast material is present in the occlusive vessel.
Angiotensin II receptor blockers (ARB)Also known as angiotensin II receptor antagonists – a group of compounds that treat hypertension. Angiotensin II receptor blockers block the activation of the angiotensin II receptor, which leads to vasodilation and reduced blood pressure.
Angiotensin-converting enzyme (ACE) inhibitors
A group of compounds used to treat hypertension. Angiotensin II acts on the muscles surrounding blood vessels, causing them to contract (vasoconstriction). Angiotensin-converting enzyme catalyzes the formation of angiotensin II from angiotensin I through the removal of two terminal amino acid residues. The formation of angiotensin II is prevented through the use of ACE inhibitors. This inhibition causes the patient's blood pressure to fall through the promotion of vasodilatation. Angiotensin-converting enzyme inhibitors and thiazides should be used as first-line pharmacological agents to treat PAD patients with concomitant hypertension.
Ankle–brachial index (ABI)
A calculation based on the systolic blood pressure in the ankle divided by the higher of the two systolic blood pressures in the arms. The result of an ABI measurement is used to predict the severity of peripheral artery disease. A patient's ABI can be easily measured using a sphygmomanometer and handheld Doppler device. The diagnostic value of ABI measurements are as follows:
Patients with an ABI of ≤0.9 have a three to sixfold increased risk of cardiovascular mortality.
AortaThe main artery in the body, which arises from the left ventricle of the heart. The aorta branches off to the extremities, the neck, and the major organs.
Apolipoprotein (a-1)
The major protein component of high-density lipoprotein. The transport of cholesterol to the liver is promoted by apolipoprotein (a-1).
Aspirin/acetylsalicylic acid (ASA)
A non-steroidal anti-inflammatory drug that causes the irreversible inactivation of the cyclo-oxygenase (COX) enzyme. Cyclo-oxygenase is required for the synthesis of two types of prostanoid: prostaglandins and thromboxanes. Aspirin/ASA has proven analgesic, antipyretic, anti-inflammatory and antiplatelet properties. The use of aspirin/ASA is recommended in patients with PAD to reduce the risk of cardiovascular morbidity and mortality.
Atherosclerosis
A disease that affects arterial blood vessels. It results from the deposition of lipoproteins in the walls of arteries and subsequently causes a chronic inflammatory response. It is commonly referred to as a 'hardening' or 'furring' of the arteries and is caused by the formation of multiple plaques within the blood vessel.
Autogenous or synthetic bypass
The surgical re-routing of blood flow around an obstructed artery. During the procedure, blood is redirected from above the obstructed portion of the artery to another vessel below the obstruction. The procedure requires the use of either an autogenous or synthetic graft. The ideal autogenous graft in patients with PAD is the saphenous vein, although other suitable conduits include the contralateral long saphenous vein, the short saphenous vein, the femoral vein, and the arm vein. A synthetic graft may be used if the patient's veins are not viable, not long enough or anatomically unsuitable.
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Balloon angioplasty
An endovascular revascularization technique used to restore blood flow in blocked arteries. During this procedure, a vascular specialist inserts a very small balloon attached to a thin catheter into an obstructed blood vessel through a small incision in the patient's skin. The catheter is threaded under X-ray guidance to the site of the blocked vessel. The balloon is then inflated to open the vessel and restore blood flow.
Beta-adrenergic blockers
A class of drugs that inhibit epinephrine-mediated sympathetic actions, thereby reducing the effect of physical exertion on the patient's heart rate and force of contraction. They have various therapeutic indications, including the management of cardiac arrhythmias. These also stimulate the dilation of blood vessels, and as such, the use of these drugs may be considered when treating PAD patients with concomitant hypertension.
Bupropion
An antidepressant that acts as a norepinephrine and dopamine reuptake inhibitor. Norepinephrine acts by increasing heart rate and triggering the release of glucose from energy stores. Dopamine stimulates the sympathetic nervous system, which leads to increases in both heart rate and blood pressure. Bupropion also inhibits the action of nicotinic acetylcholine receptors, thereby reducing the severity of nicotine cravings and withdrawal symptoms. The use of bupropion is, therefore, recommended to assist smoking cessation in patients with PAD.
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C-reactive protein (CRP)
A plasma protein synthesized by hepatocytes and adipocytes. Levels of CRP in the blood rise substantially when inflammatory processes occur in the body. Recent research has suggested that patients with elevated basal levels of CRP have an increased risk of diabetes, hypertension, cardiovascular disease, and PAD.
Carotid artery disease
A disease caused by stenosis of the carotid arteries, the main vessels in the neck that supply blood to the brain. Carotid artery disease is a major risk factor for ischemic stroke.
Cerebral artery disease
Collective term for disorders in which an area of the brain is transiently or permanently affected by ischemia or bleeding, and one or more of the cerebral blood vessels are involved in the pathological process.
Cholesterol
An amphipathic lipid that is an integral constituent of cell membranes. It also plays a central role in many biochemical processes, including the synthesis of many steroid hormones. Cholesterol is transported in the circulatory system bound to one of the types of lipoprotein, predominately low-density and high-density lipoprotein.
Cilostazol
A phosphodiesterase III inhibitor with vasodilatory, metabolic and antiplatelet activity. A 3- to 6-month course of cilostazol should be the first-line pharmacotherapy treatment for patients with intermittent claudication, as evidence shows both an improvement in treadmill exercise performance and in quality of life.
Claudication
A medical condition characterized by muscle discomfort in the lower limb reproducibly produced by exercise and relieved by rest within 10 minutes. The symptoms are most commonly localized to the calf, but may also affect the thigh or buttocks. Patients with intermittent claudication have a normal blood flow at rest and, therefore, have no symptoms. When the patients exercise, occlusive lesions in the arterial supply of the leg muscles limits the blood flow, resulting in a mismatch between oxygen supply and muscle metabolic demand that is associated with claudication (limping).
Clopidogrel
A potent oral antiplatelet agent often used in the treatment of coronary artery disease, PAD and cerebral artery disease. Clopidogrel acts by irreversibly blocking the adenosine diphosphate receptor on the cell membranes of platelets. This receptor plays a significant role in clot formation, through its stimulation of fibrin-dependent platelet aggregation. Clopidogrel is effective in reducing cardiovascular events in symptomatic PAD patients.
Collateral
The side branch of, for example, a blood vessel or nerve.
Compartment syndrome
An acute condition in which increased pressure within the fascial compartment impairs the patient's blood supply. Unless the patient receives prompt treatment, the condition can lead to nerve damage and muscle death. Connective tissue within the fascial compartment does not stretch; therefore, swelling of the muscles or a small amount of bleeding can cause the pressure to rise greatly. Acute compartment syndrome is a medical emergency requiring immediate fasciotomy treatment to allow the pressure to return to normal.
Computed tomographic angiography
A specialized X-ray technique that examines blood flow in arterial and venous vessels when they are filled with a contrast material. The contrast material has a different opacity from soft tissue and is injected into a small peripheral vein using a small needle or catheter. Two-dimensional images are obtained through the use of a rotating X-ray sensing unit and the images are combined by a computer to form detailed three-dimensional images.
Coronary artery disease (CAD)
The end result of the accumulation of atheromatous plaques within the walls of the arteries that supply the myocardium with oxygen and nutrients. CAD is the most common cause of global mortality in men and women over 20 years of age.
Critical limb ischemia (CLI)
A severe obstruction of the arteries which seriously decreases blood flow to the extremities (hands, feet and legs) and has progressed to the point of severe pain and with skin ulcers or sores. The term 'critical limb ischemia' implies chronicity and is, therefore, distinguished from acute limb ischemia.
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Diabetes mellitus
A metabolic disorder characterized by hyperglycemia resulting from low levels of the hormone insulin or resistance to insulin's effects. The characteristic symptoms are polyuria, polydipsia and blurred vision; these symptoms may be absent if the blood sugar is only mildly elevated.
Doppler ultrasonography
A noninvasive diagnostic procedure that uses an ultrasound scanner to assess the direction, velocity and turbulence of blood flow. Doppler ultrasonography can be used to detect heart valve problems, evaluate stenosis, diagnose congenital cardiac defects, and assess the damage to the heart caused by myocardial infarction. Doppler devices can also be used to measure a patient's ankle–brachial index, segmental limb pressure or velocity wave form.
Duplex ultrasonography
A noninvasive test that can be used to evaluate blood flow and pressure by bouncing ultrasound waves off red blood cells. The technique is very similar to Doppler ultrasonography, but it also involves rapid movement of the ultrasound beam to acquire real-time images. Duplex ultrasound may help diagnose a number of conditions:
- Blood clots
- Venous insufficiency
- Heart valve defects and congenital heart disease
- Arterial occlusion
- Arterial stenosis
Dyslipidemia
A term used to describe disorders of lipoprotein metabolism, including lipoprotein overproduction or deficiency. These disorders may manifest as one or more of the following conditions:
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An increase in total serum cholesterol
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An increase in low-density lipoprotein (LDL) cholesterol
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An increase in triglyceride concentration
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A decrease in high-density lipoprotein (HDL) cholesterol
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Embolus
Material, such as a blood clot, fat or bone fragment that travels through the circulation and eventually blocks the blood flow (plural: emboli).
Endarterectomy
The surgical removal of plaque from the affected arteries of patients with PAD.
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Fasciotomy
A surgical procedure that involves cutting the fascia to relieve tension or pressure, which results in loss of circulation to an area of tissue or muscle. Fasciotomy is a limb-saving procedure when used to treat acute compartment syndrome. The fascia is the soft tissue component of the connective tissue system that permeates the human body.
Fibrates
A class of amphipathic molecules used to treat a range of metabolic disorders, particularly dyslipidemia. Fibrates can be used to raise high-density lipoprotein cholesterol levels and reduce triglyceride levels in patients with PAD.
Folate
An anionic, water-soluble form of vitamin B9 that occurs naturally in food. Folate has numerous biological roles, including the production and maintenance of new cells and the enzymatic conversion of homocysteine to methionine or cysteine. Folate deficiency can lead to a high level of blood serum homocysteine, which is a strong predictive factor for cardiovascular disease. However, two clinical studies have demonstrated that the use of folate supplements does not result in any clinical benefit in patients with coronary artery disease. Therefore, the TASC II Working Group does not recommend the administration of folate supplements in patients with PAD.
Framingham risk score
A scoring system developed from the results of the Framingham Heart Study, which was initiated in 1948 to identify the common factors or characteristics that contribute to cardiovascular disease. In order to achieve this aim, the development of cardiovascular disease was examined over a long period of time in a large group of participants who did not have overt symptoms of cardiovascular disease when the study was initiated. The Framingham risk score can be used to predict a patient's 10-year total cardiovascular risk. Separate score sheets are used for men and women and the factors used to estimate risk, which include age, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, blood pressure, cigarette smoking, and diabetes mellitus. A patient's relative risk score is estimated by comparison with low-risk Framingham participants.
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Glycosylated hemoglobin (HbA1c)
A form of hemoglobin produced as a result of a nonenzymatic reaction that occurs when hemoglobin is exposed to high plasma levels of glucose. It is primarily used to ascertain a patient's average plasma glucose concentration over a prolonged period of time. High concentrations of HbA1c are observed in patients with poorly controlled diabetes. Patients with diabetes and PAD should receive aggressive treatment to reduce their high blood glucose levels. The aim of the treatment is to reduce the patients' HbA1c level to <7.0% or as close to 6% as possible.
Greater saphenous vein
The principal superficial vein in the leg and the thigh. The vein runs from the large toe to the saphenous opening on the anterior surface of the thigh. The saphenous vein is the optimal conduit to use in femoral below-knee popliteal and distal bypass revascularization surgery.
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Heparin
A highly sulfated glycosaminoglycan that acts by binding to antithrombin and converts it from a slow, progressive inhibitor to a very rapid inhibitor of thrombin and other proteases involved in blood clotting. Immediate anticoagulation with heparin is indicated for patients with acute limb ischemia in order to prevent thrombus propagation.
High-density lipoprotein (HDL)
A class of lipoprotein that is involved in transporting cholesterol from the body's tissues to the liver. Approximately 30% of blood cholesterol is carried by HDL. Clinical studies have shown that elevated HDL-cholesterol is a protective factor for the development of PAD and a low HDL-cholesterol level (<40 mg/dL) is associated with an increased risk of coronary artery disease.
Hyperhomocysteinemia
A medical condition characterized by an abnormally high levels of homocysteine in the blood. Deficiencies of the vitamins folic acid, pyridoxine or B12 can lead to high homocysteine levels, due to the biochemical reactions in which the compound is involved. Supplementation with pyridoxine, folic acid, B12 or trimethylglycine (betaine) reduces the concentration of homocysteine in the bloodstream.
Hyperlipidemia
An elevation of lipids in the bloodstream. These lipids include cholesterol, cholesterol esters, phospholipids, and triglycerides. They are transported in the blood as part of one of the five major families of plasma lipoproteins: chylomicrons; very low-density lipoproteins (VLDL); intermediate-density lipoproteins (IDL); low-density lipoproteins (LDL); and high-density lipoproteins (HDL). When hyperlipidemia is defined in terms of a class or classes of elevated lipoproteins in the blood, the term hyperlipoproteinemia is used. Hypercholesterolemia is the term for high cholesterol levels in the blood. Hypertriglyceridemia refers to high triglyceride levels in the blood.
Hypertension
A medical condition in which the blood pressure is chronically elevated. Hypertension can be classified as either essential (primary) or secondary. Essential hypertension indicates that no specific medical cause can be found to explain a patient's condition. Secondary hypertension indicates that the high blood pressure is a result of another condition, such as kidney disease or certain tumors. Persistent hypertension is one of the risk factors for cerebral artery disease, myocardial infarction and arterial aneurysm, and is a leading cause of chronic renal failure.
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Iloprost
A prostanoid drug used in the treatment of PAD. Clinical studies have also shown that administration of iloprost may reduce ischemic pain and facilitate ulcer healing, and therefore, could be used to treat patients with critical limb ischemia. Unfortunately, although approximately 40% of critical limb ischemia patients may benefit from iloprost administration, it is difficult to predict which patients will respond favorably to this kind of treatment.
Intermittent claudication
A medical condition characterized by muscle discomfort in the lower limb reproducibly produced by exercise and relieved by rest within 10 minutes. The symptoms are most commonly localized to the calf, but may also affect the thigh or buttocks. Patients with intermittent claudication have a normal blood flow at rest and, therefore, have no symptoms. When the patients exercise, occlusive lesions in the arterial supply of the leg muscles limits the blood flow, resulting in a mismatch between oxygen supply and muscle metabolic demand that is associated with claudication (limping).
Intra-operative hybrid procedures
The practice of using both surgical and endovascular revascularization procedures to treat patients with PAD.
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Lipo-ecraprost
A lipid-encapsulated prostaglandin E1 prodrug. The drug was developed to treat patients with critical limb ischemia, with the aim of delivering active prostaglandin directly to the affected area. However, a clinical trial conducted in 2006 found that the prostanoid failed to reduce death and amputation when compared with placebo.
Lipoprotein(a)
A lipoprotein subclass that is involved in the recruitment of inflammatory cells. Lipoprotein(a) is assembled in the blood from low-density lipoprotein molecules and glycoprotein molecules called apolipoprotein-a. High serum lipoprotein(a) levels are a risk factor for various cardiovascular conditions, including atherosclerosis, cerebral artery disease, and PAD.
Low-density lipoprotein (LDL)
A member of the lipoprotein particle family. Its major role involves transporting cholesterol and triglycerides from the liver to peripheral tissues. Low-density lipoprotein cholesterol can be retained in blood vessels by arterial proteoglycans, which leads to the formation of atherosclerotic plaques. Increased levels of LDL are, therefore, associated with coronary artery disease, cerebral artery disease and PAD. All symptomatic PAD patients should have their LDL-cholesterol levels lowered to <2.59 mmol/L (<100 mg/dL).
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Magnetic resonance angiography (MRA)
A technique that uses magnetic fields and radio waves to produce two or three-dimensional images of blood vessels. Magnetic resonance angiography can be employed to help diagnose the following conditions:
- Aortic aneurysms
- Aortic dissections
- Peripheral artery disease
- Congenital heart disorders
- Renal arterial stenosis
- Carotid arterial disease
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Naftidrofuryl
A 5-hydroxytryptamine type 2 antagonist that ameliorates the symptoms of PAD through vasodilatation and improved aerobic metabolism. Naftidrofuryl can be considered as a potential pharmacological therapy for the treatment of claudication symptoms.
Niacin
A water-soluble vitamin (also known as nicotinic acid or vitamin B3) that blocks the breakdown of fats stored within adipose tissue. This decreases the levels of free fatty acids in the bloodstream, which reduces the secretion of very low-density lipoprotein by the liver. By lowering very low-density lipoprotein levels, niacin also increases the level of high-density lipoprotein found in the blood. In patients with PAD, niacin has been associated with femoral atherosclerotic regression and reduced progression of coronary atherosclerosis.
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Pentoxifylline
A hemorheologic agent that has been developed to treat patients with intermittent claudication. The drug decreases blood and plasma viscosity, increases erythrocyte and leukocyte deformability and inhibits neutrophil adhesion. Clinical trials have not consistently demonstrated that the use of pentoxifylline can significantly improve the health of patients with intermittent claudication. Despite these ambiguous results, the American College of Cardiology/American Heart Association (ACC/AHA) recommend that pentoxifylline may be considered as a potential therapy to improve walking distance in patients with intermittent claudication.
Percutaneous thrombectomy
An endovascular revascularization technique used to treat patients with acute limb ischemia. The two main techniques used are percutaneous aspiration thrombectomy (PAT) and percutaneous mechanical thrombectomy (PMT). Percutaneous thrombectomy involves the use of a thin-walled, large-lumen catheter and a 50 mL syringe, which provides the required suction to remove the embolus or thrombus from the patient's blood vessels. The majority of PMT devices operate on the basis of hydrodynamic recirculation. In this technique, a rapid stream of fluid is used to extract the thrombotic material from the lumen of the patient's arteries.
Peripheral artery disease (PAD)
A common circulatory problem in which limb blood flow is reduced by the narrowing of arteries. Patients diagnosed with PAD have an increased risk of mortality, myocardial infarction and cerebrovascular disease.
Plaque debulking
An endovascular revascularization technique for the eradication of plaques from occluded blood vessels, using either an excimer laser or rotational atherectomy. An excimer laser utilizes flexible fiber optic catheters to deliver intense bursts of ultraviolet energy to ablate the relevant section of tissue. Rotational atherectomy involves the use of a flexible catheter-based device that has a high-speed rotating burr covered with microscopic diamond crystals. The rotational burr abrades inelastic plaque material, whilst soft tissue and the vessel wall are forced aside.
Plethysmograph
An instrument that detects and graphically records changes in volume within an organ or the whole body. The plethysmograph measures fluctuations in the amount of air or blood that the organ contains. Some plethysmograph devices are attached to arms, legs or other extremities and used to determine circulatory capacity. A patient's pulse volume recording and toe–brachial index can be measured through the use of a plethysmograph.
Popliteal
Relating to the posterior surface of the knee joint.
Prostaglandin E1 (PGE1)
A prostanoid that has vasodilatory properties and is a potent inhibitor of platelet aggregation. Clinical studies have been conducted to examine the potential of PGE1 to treat patients with both intermittent claudication and critical limb ischemia. Despite the fact that modest benefits have been achieved through the intravenous administration of PGE1, the overall evidence obtained does not support the use of the drug for claudication treatment. Three studies conducted with PGE1 have shown that ulcer size can be reduced in patients with critical limb ischemia. However, favorable outcomes on other critical limb ischemia endpoints were not achieved in these investigations.
Prostanoids
A term used to describe a subclass of eicosanoids consisting of the prostaglandins, the thromboxanes, and the prostacyclins. Prostanoids protect the vascular endothelium and prevent platelet and leukocyte activation, and, therefore, could play a role in the management of critical limb ischemia. Some studies with prostanoids in critical limb ischemia have suggested an improvement in healing of ischemic ulcers and a reduction in amputations. However, recent trials do not support the benefit of prostanoids in promoting amputation-free survival.
Pulse volume recording (PVR)
A noninvasive test that measures blood flow within the arteries of the legs or arms. The technique involves the use of a single, large thigh cuff with calf and ankle cuffs and a brachial cuff, which are connected to a plethysmograph. Patients with poor cardiac function have low-amplitude tracings. To obtain accurate PVR waveforms, the brachial cuff is inflated to 60–65 mmHg, which is sufficient to detect blood volume changes without resulting in arterial occlusion.
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Renal artery disease
A disease characterized by narrowing of the arterial vessels that supply blood to the kidneys. The disease is a component of PAD; however, some patients with renal artery disease have no symptoms or mild symptoms, whilst in others the disease can lead to very high blood pressure (renal vascular hypertension), poor kidney function, and possible kidney failure.
Revascularization
The process of restoring the vasculature of a particular organ or tissue. Revascularization techniques are primarily used to treat patients with critical or acute limb ischemia. Either endovascular or surgical revascularization techniques are used to treat the patients.
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Segmental limb pressure (SLP)
A measurement used to detect and localize occlusive lesions in the major arteries of the lower extremities. To obtain an SLP measurement, a sphygmomanometer cuff is placed at a specified position and a Doppler probe is positioned over one of the pedal arteries. The systolic pressure in the major arteries under the cuff is then measured and recorded. The location of the occlusive lesion is ascertained from the pressure gradients between the different cuffs.
Statins
A class of hypolipidemic agents used to lower cholesterol levels in people with, or at risk of cardiovascular disease. Statins reduce serum levels of cholesterol by inhibiting the enzyme HMG-CoA reductase, which is the rate-limiting enzyme of the cholesterol synthesis pathway. Inhibition of this enzyme stimulates low-density lipoprotein receptors in the liver, which results in an increased clearance of the lipoprotein from the bloodstream. The use of statins is recommended to reduce low-density lipoprotein cholesterol levels in symptomatic PAD patients.
Stenosis
The abnormal narrowing of a duct or canal.
Stent
A wire metal mesh tube that is used to prop open an artery. Stents are used for the endovascular revascularization of patients with PAD. To insert the stent, it is collapsed to a small diameter, put over a balloon catheter and moved into the required position within the occluded vessel. When the balloon is inflated, the stent expands, locks in place and forms a scaffold. The stent stays in the artery permanently, holds it open and improves the patient's blood flow.
Stent graft
A tube composed of fabric supported by a metal mesh called a stent. Endovascular revascularization can involve the use of stent grafts to treat patients with PAD. Over time, blood pressure and other factors can cause weak areas of the patient's vessels to bulge and eventually enlarge and rupture. The stent graft is designed to seal the artery tightly above and below the weak area, thereby preventing the artery from enlarging and subsequently rupturing. The stent graft is inserted over a catheter guidewire under X-ray guidance. The catheter carries a compressed form of the graft so that it can move through the patient's blood vessels. When the graft has reached the required position, the catheter is withdrawn, leaving the graft in place. Stent grafts are generally used to treat aneurysms, most commonly abdominal aortic aneurysms.
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TASC
The acronym for the TransAtlantic InterSociety Consensus. The TASC guidelines have been designed to provide an international consensus on the diagnosis and treatment of PAD.
Thiazides
A class of diuretic drugs used in the treatment of hypertension, most of which are derived from benzothiadiazine. The thiazides stimulate vasodilatation by desensitizing vascular smooth muscle cells to norepinephrine-stimulated calcium release. Thiazides and angiotensin-converting enzyme inhibitors should be used as first-line pharmacologic agents to treat PAD patients with concomitant hypertension.
Thrombolysis
The breakdown of blood clots by pharmacologic means. Three randomized studies have confirmed the importance of catheter-directed thrombolytic therapy for the treatment of acute limb ischemia. Catheter-directed thrombolysis involves the dissolution of atherosclerotic plaques through the administration of various lytic agents, via a catheter directly inserted into a patient's blood vessel. All thrombolytic agents work by activating the enzyme plasminogen, which clears the cross-linked fibrin mesh. This makes the clot soluble and subject to further proteolysis by other enzymes, thereby restoring the blood flow in the occluded blood vessel. The most readily used thrombolytic agents are streptokinase, urokinase and tissue plasminogen activator. Thrombolytic therapy is the initial treatment of choice in patients with less severe acute limb ischemia.
Toe–brachial index (TBI)
A calculation based on the systolic blood pressures of the arm and toes. For patients with rigid ankle blood vessels, the TBI may be measured as an alternative to the ankle-brachial index (ABI), as the TBI relies on the fact that toe arteries are not usually noncompressible. The examination is similar to the ABI except that it is performed with a plethysmograph infrared light sensor and a very small blood pressure cuff placed around the first or second toe. A TBI of <0.7 is considered to be abnormal.
Transcutaneous oxygen tension (tcPO2)
A measurement of the oxygen perfusion of the skin. A patient's tcPO2 is measured using an oxygen sensor consisting of two parts. The first part consists of a modified polarographic sensor, a silver anode, a suitable electrolyte and an oxygen permeable membrane. A heating section with two precision thermistors for measuring and controlling the sensor temperature makes up the second part. When the sensor is exposed to oxygen, there is an electrochemical reaction that allows current to flow through the cathode. An amplifier connected to the cathode measures the flow of the current and converts it to a value proportional to the oxygen tension at the sensor/membrane interface. A tcPO2 measurement of <30 mmHg is indicative of critical limb ischemia.
Triglycerides
Glycerides that are composed of three fatty acid chains esterified to a glycerol backbone, and which are the main constituents of adipose tissue. High serum levels of triglycerides are an independent risk factor for the development of PAD.
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Vasculitis
Inflammation of a blood vessel or lymph vessel.
Velocity wave form
A technique that uses a Doppler device for analyzing arterial blood flow at multiple sites in the peripheral circulation. Velocity wave form analysis provides physicians with another means to detect PAD in patients. A triphasic Doppler wave form is observed in patients that have a normal blood flow, whereas in patients with PAD, the wave form deteriorates significantly to produce a monophasic pattern. Peripheral artery disease diagnosis can be confirmed if a reduced or absent forward flow velocity is observed in the posterior tibial artery.
Very low-density lipoprotein (VLDL)
A lipoprotein subclass that is assembled in the liver from cholesterol and apolipoproteins, and is subsequently converted to low-density lipoprotein in the bloodstream. The main function of VLDL is to transport endogenous triglycerides, phospholipids, cholesterol, and cholesteryl esters throughout the body. Clinical studies have demonstrated that patients with PAD have significantly higher levels of VLDL cholesterol, VLDL triglycerides and VLDL proteins.
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Warfarin
An orally administered anticoagulant that is used as a prophylactic agent to prevent thrombus formation in many disorders. The anticoagulant works by inhibiting the synthesis of vitamin K-dependent proteins that are involved in blood coagulation. Warfarin is recommended as a postoperative anticoagulation agent in patients with acute limb ischemia. However, the prescription of warfarin treatment must be assessed on an individual basis due to the increased risk of bleeding and hemorrhage.
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