Peripheral Vascular Disease

Peripheral Vascular Disease (PVD)

(1) Arteriosclerosis Obliterans (Peripheral Artery Occlusive Disease (PAOD))

Characteristics: chronic occlusive disease resulting from athrosclerotic plaques

Epidemiology: most prevalent vascular disorder; (95% of PVD); 0.3% of population; 5.2% of people over 70

Distribution: large and medium sized vessels; commonly aortic bifurcation and lower extremities

Pathogenesis: same as atherosclerotic coronary artery disease; Risk factors Þ smoking, dyslipidemia, DM, HTN; results in ischemia to affected organs

Symptoms: claudication (fatigue and pain due to intermittent ischemia); ß pulses, bruits, cyanosis

(2) Giant Cell (Temporal) Arteritis

Characteristics: acute&chronic, often granulomatous inflammation of medium and small arteries; may lead to blindness

Epidemiology: occurs most often in people older than 55 and 65% of patients are female; relatively common

Distribution: principally arteries of head including temporal, vertebral and opthalmic arteries; may also affect arteries throughout the body including aortic arch Þ giant cell aortitis; renal, hepatic and coronary arteries are usually spared

Pathogenesis: possible immunologic reaction against a component of the arterial wall

Morphology: short segments of one or more affected arteries develop nodular thickening with reduction of the lumen

Histology: lymphocyte infiltration, intimal fibrosis, focal necrosis, granuloma formation with multinucleated giant cells

Symptoms: relate to discomfort of affected arteries Þ headache, facial pain, claudication of the jaw while chewing; 50% of people suffer visual impairment due to opthalmic artery involvement

Diagnosis + Treatment: biopsy of 2-3 cm of artery due to segmental nature of disease; high dose steroids very effective; self limited course of 1-5 years

(3) Takayasu Arteritis "Pulseless Disease"

Characteristics: large vessels

Epidemiology: mostly women younger than 40; majority of cases in Asia and Africa, but occurs worldwide

Distribution: aortic arch and major branches

Pathogenesis: unknown

Histology: infiltration of plasma cells and lymphocytes into the media and adventitia, giant cells, intimal proliferation, disruption of the elastic lamina and fibrosis

Symptoms: malaise and fever; symptoms related to vascular inflammation Þ cerebrovascular ischemia, myocardial ischemia, arm claudication; ocular distrubances; carotid and limb pulses diminished or absent in 85% of patients;

Diagnosis + Treatment: Steroid and cytotoxic drugs may alleviate symptoms; surgery

(4) Polyarteritis nodosa (PAN)

Characteristics: transmural necrotizing immune complex inflammation of the small and medium sized arteries; nodules are; focal, random and episodic; may form aneurysmal dilatation

Epidemiology: 6 per 100,000 and male to female (1.6:1); lesions of varying ages

Distribution: systemic; typically renal and visceral vessels and usually spares the pulmonary circulation

Pathogenesis: associated with Hep B in 30% of cases

Histology: polymorphonuclear infiltration in all three vessel layers, intimal proliferation and degeneration, and fibrinoid necrosis with occlusion of the lumen; nodules found on the vessels; extensive perarterial inflammation

Symptoms: malaise, fever, weight loss, rapid development of HTN, abdominal pain and melena (due to vascular lesions), diffuse muscular aches and pains, and peripheral neuritis; renal involvement common but no glomerulonephritis because small vessels are not involved

Diagnosis + Treatment:antineutrophil cytoplasmic antibodies (ANCAs) highly suggestive of necrotizing vasculitis, but biopsy of involved vessel necessary for diagnosis; 5 year survival 15% for untreated, 80% for treated (prednisone)

(5) Thromboangiitis obliterans (Buerger’s disease) Þ thrombosis with microabscesses

Characteristics: inflammatory disease of medium sized arteries

Epidemiology: primarily young men

Distribution: distal upper and lower extremities veins and arteries

Pathogenesis: Hep B present 30% of cases; little association with ANCA; strong association with cigarette smoking

Morphology: sharply segmental acute and chronic vasculities with spread to contiguous veins and nerves

Histology: neutrophil infiltration without necrosis and the internal elastic lamina is preserved

Symptoms: superficial nodular phlebitis, cold sensitivity similar to Raynaud’s, and pain in the instep of the foot induced by exercise

Diagnosis + Treatment: biopsy; corticosteroids

(6) Microscopic Polyangiitis

Characteristics: affects arterioles, capillaries and venules

Pathogenesis: may be hypersensitivity reaction; few or no immune deposits

Symptoms: hemoptysis, hematuria and proteinuria, bowel pain or bleeding, and muscle pain

Diagnosis + Treatment: ANCA are present in majority of cases

(7) Vasospastic

Often associated with collagen diseases such as lupus and scleroderma
Primarily affects digital arteries; usually triggered by cold; may progress to fixed lesions

(8) Fribromuscular dysplasia

Characteristics: overgrowth of fibroblasts and smooth muscle cells causing stenosis of the arteries
turbulent blood flow following areas of stenosis cause dilation forming segmental areas of stenosis interrupted by areas of dilation

Distribution: carotid and renal arteries

Epidemiology: mostly young women

Treatment: angioplasty

(9) Thoracic Outlet Syndromes

Pathophysiology

Stenosis/occlusion – blood flow not reduced until 75% of cross sectional area is obliterated (50% of diameter)

pressure gradient across lesion stimulates collateral circulation to develop
signs and symptoms depend on rapidity and extent of occlusion

Embolization – important cause of cerebral ischemia/infarction; e.g., "blue toe" syndrome

Clinical Syndromes of Vascular Insufficiency

Extremities–intermittent claudication=pain on exercise due toß O₂ to muscles; normal resting blood flowÞ relieved by rest

ischemic rest pain develops when blood flow drops below that needed to supply basal metabolic requirements of nerves; begins in toes extremities, sign of impending gangrene
ischemic ulcer

Viscera

kidneys – renovascular hypertension (Goldblatt), renal insufficiency
mesenteric ischemia/infarction

Brain

extracranial vessels most commonly involved; usually an artery-to-artery embolus

Impotence

Treatment

Eliminate risk factors

Alter blood viscosity

Antiplatelet agents

Anticoagulants

Surgery

Percutaneous transluminal dilation (Gruntzig)

Vasodilating drugs usually not helpful because tissue ischemia is most potent dilator

Other Peripheral Vascular Problems

Aneurysms

true – dilation of all three layers of a vessel, creating a large bulge of the vessel wall Þ false lumen

dissecting – formation of a blood-filled channel dividing the arterial layers; almost always in the aorta

retrograde dissection – travels toward the heart and may interfere with branches of the aorta and cause aortic valve insufficiency, may also cause cardiac tampanade

HTN and atherosclerotic plaques Ý risk of aneurysm; can be caused by trauma

Emboli – commonly occur arise from the heart (2/3), aorta and the carotid

Heart emboli: arise from Þ arrhythmias, hypokinesis and valvular disease

Symptoms: acute, severe, neurologic dysfunction, loss of pulses, coldness, pain and pallor

Cell damage: acidosis, hypokalemia and cell swelling Þ muscle damage and neurologic signs

Treatment: surgical removal of clot and thrombolysis

Cerebrovascular Emboli: usually arise from the bifurcation of the internal and external carotid artery due to turbulent flow Þ damage to intima Þ platelet adhesion Þ plaque formation Þ compression of vaso vasorum Þ damage to vessel wall Þ ulceration Þ more platelet adhesion and rupture Þ emboli formation

Complications of Carotid Emboli:

Transient Ischemic Attack (TIA) – focal neurologic deficit lasting less than 24 hrs
Reversible Ischemic Neurologic Deficit (RIND) – focal neurologic deficit lasting greater than 24 hrs
Cerebral Vascular Accident (CVA) – stroke
Global Ischemia – general findings such as loss of memory and ataxia

treatment of carotid atherosclerosis : < 70% stenosis Þ antiplatelet therapy; > stenosis Þ surgery

Thrombus – progressive lumen narrowing with thrombus formation

Presentation: chronic

Symptoms:

Claudication–fatigue+pain from intermittent ischemia; not limb threatening; Treatment:ß smoking;diet, exercise

Rest Pain – more severe ischemia; color changes – limb threatening; Treatment: aggressive

Ulceration – severe ischemia, occurs at distal sites – limb threatening; Treatment: aggressive

Gangrene – severe limb threatening; Treatment: very aggressive

Evaluation:

Ultrasound –used for screening purposes

Serial blood pressure measurements down an extremity to look for a significant (> 20mmHg) drop

Doppler –measure frequency (proportional to flow velocity); serial studies down extremities to look for changes

normal flow velocity shows three waves representing flow (see figure)

Key to figure:

1. Systole with arterial dilation Þ forward flow

2. Rebound arterial contraction Þ reverse flow

3. Arterial contraction with forward flow

in arteriosclerosis, artery cannot dilate with systole and pressure waves become bimodal with mild disease and unimodal with severe disease

Angiogram to study vessel anatomy