# Seminar 16: Vascular Surgery ## General Surgery Clerkship - Unit 16 --- ## Learning Objectives By the end of this seminar, students will be able to: 1. Describe the pathophysiology, clinical presentation, and classification of peripheral arterial disease using Fontaine and Rutherford staging 2. Differentiate claudication from critical limb ischemia and select appropriate medical, endovascular, and surgical management strategies 3. Recognize acute limb ischemia as a surgical emergency and apply appropriate diagnostic and therapeutic interventions 4. Evaluate carotid artery disease and apply evidence-based indications for carotid endarterectomy and carotid artery stenting 5. Describe the natural history, screening recommendations, and treatment thresholds for abdominal aortic aneurysm 6. Recognize venous disease including chronic venous insufficiency and deep vein thrombosis and apply appropriate management principles --- ## Seminar Outline ### I. Peripheral Arterial Disease Epidemiology and Pathophysiology Peripheral arterial disease affects approximately twelve percent of the adult population, with prevalence increasing dramatically with age to over twenty percent in those over seventy years. The condition represents a manifestation of systemic atherosclerosis with significant implications for both limb outcomes and cardiovascular mortality, as patients with peripheral arterial disease have markedly elevated risk of myocardial infarction, stroke, and cardiovascular death. Understanding the shared pathophysiology with coronary and cerebrovascular disease emphasizes the importance of comprehensive cardiovascular risk modification in all patients with peripheral arterial disease, regardless of symptom severity. The pathophysiology of peripheral arterial disease involves progressive atherosclerotic narrowing of the arterial lumen, reducing blood flow to distal tissues. The superficial femoral artery within the adductor canal represents the most commonly affected segment, followed by the aortoiliac vessels and infrapopliteal arteries. Plaque formation progresses through fatty streak development, fibrous cap formation, and potential plaque rupture with acute thrombosis. The gradual nature of chronic arterial stenosis allows development of collateral circulation that may maintain tissue perfusion at rest, with symptoms manifesting only when metabolic demands exceed supply during exercise. Risk factors for peripheral arterial disease parallel those for coronary atherosclerosis, with cigarette smoking representing the most important modifiable risk factor and conferring up to fourfold increased risk. Diabetes mellitus increases risk approximately twofold and is associated with more distal disease distribution, accelerated progression, and worse outcomes including higher amputation rates. Hypertension, hyperlipidemia, chronic kidney disease, and elevated homocysteine levels contribute additional risk. The constellation of metabolic syndrome components creates synergistic cardiovascular risk. Family history of premature atherosclerotic disease suggests genetic predisposition requiring earlier and more aggressive risk modification. The ankle-brachial index provides the cornerstone of noninvasive peripheral arterial disease diagnosis, calculated as the ratio of ankle systolic pressure to brachial systolic pressure. Values less than 0.90 indicate hemodynamically significant peripheral arterial disease with sensitivity and specificity exceeding ninety percent. Values between 0.91 and 0.99 are considered borderline, while values above 1.30 suggest non-compressible calcified vessels commonly seen in diabetes and renal failure, requiring alternative assessments such as toe-brachial index or pulse volume recordings. The severity of ankle-brachial index reduction correlates with symptom severity, limb outcomes, and cardiovascular mortality risk. Panel A: Epidemiology graph showing peripheral arterial disease prevalence by age and the association with cardiovascular mortality compared to patients without PAD. Panel B: Anatomical diagram showing common sites of atherosclerotic disease in the lower extremity including aortoiliac, femoropopliteal, and infrapopliteal segments. Panel C: Pathophysiology illustration of progressive atherosclerotic plaque formation with lipid core, fibrous cap, and potential rupture with thrombosis. Panel D: Ankle-brachial index measurement technique demonstrating Doppler assessment, pressure calculation, and interpretation of values from normal through severe disease. --- ### II. Clinical Presentation and Classification of Peripheral Arterial Disease The clinical spectrum of peripheral arterial disease ranges from asymptomatic disease detected by abnormal ankle-brachial index to limb-threatening ischemia requiring urgent intervention. Classification systems stratify disease severity to guide management decisions and communicate prognosis. The Fontaine classification divides peripheral arterial disease into four stages: stage I represents asymptomatic disease, stage II includes intermittent claudication with IIa representing claudication at greater than two hundred meters and IIb at less than two hundred meters, stage III denotes ischemic rest pain, and stage IV encompasses tissue loss with ulceration or gangrene. The Rutherford classification provides more granular categorization from grade zero category zero through grade three category six. Intermittent claudication represents the classic symptomatic presentation, characterized by reproducible muscular discomfort precipitated by walking and relieved by rest. The location of discomfort correlates with the level of arterial obstruction, with calf claudication indicating superficial femoral or popliteal disease, thigh and buttock claudication suggesting aortoiliac disease, and hip claudication associated with hypogastric or internal iliac involvement. The Leriche syndrome of bilateral buttock and thigh claudication with erectile dysfunction results from aortoiliac occlusive disease. Claudication distance, the walking distance at which symptoms develop, provides a functional measure of disease severity and treatment response. Critical limb ischemia represents the most severe manifestation of chronic peripheral arterial disease, defined by the presence of ischemic rest pain, tissue loss with non-healing ulcers or gangrene, or ankle pressure less than fifty millimeters of mercury in patients with rest pain or less than seventy in patients with tissue loss. Rest pain characteristically affects the forefoot and toes, worsens with leg elevation, and is relieved by dependency as gravity assists arterial perfusion. Patients commonly sleep with the affected leg hanging over the bedside. Without revascularization, approximately twenty-five percent of patients with critical limb ischemia will require major amputation within one year, and mortality approaches twenty percent. Physical examination findings in peripheral arterial disease include diminished or absent peripheral pulses, femoral bruit suggesting proximal stenosis, trophic skin changes with hair loss and thin shiny skin, delayed capillary refill, dependent rubor with pallor on elevation, and in advanced disease, ulceration or gangrene. Ischemic ulcers characteristically occur at pressure points including the toes, heel, and malleoli, with painful well-demarcated borders and pale wound base. Gangrene may be dry with mummification or wet with superimposed infection. Careful pulse examination with Doppler enhancement when pulses are not palpable, combined with ankle-brachial index measurement, confirms the clinical diagnosis. Panel A: Fontaine and Rutherford classification systems presented side by side with stage definitions, clinical features, and correlation between the two systems. Panel B: Clinical presentation spectrum from asymptomatic disease through claudication to critical limb ischemia with tissue loss photographs. Panel C: Physical examination findings including pulse assessment locations, trophic changes, dependent rubor, and characteristic ischemic ulcer appearance. Panel D: Differentiation between arterial and venous ulcers showing location, appearance, pain characteristics, and associated examination findings. --- ### III. Medical Management and Claudication Medical management forms the foundation of peripheral arterial disease treatment regardless of revascularization status, targeting both limb outcomes and cardiovascular risk reduction. Smoking cessation represents the single most important intervention, with continued smoking associated with accelerated disease progression, reduced patency following revascularization, and increased amputation and mortality rates. Patients should receive structured cessation counseling, pharmacotherapy including nicotine replacement and bupropion or varenicline, and referral to smoking cessation programs. Even patients with critical limb ischemia benefit from cessation, though urgency of revascularization takes precedence. Antiplatelet therapy with aspirin or clopidogrel reduces cardiovascular events in patients with peripheral arterial disease and should be prescribed for all symptomatic patients without contraindication. The CAPRIE trial demonstrated modest superiority of clopidogrel over aspirin in the peripheral arterial disease subgroup. Dual antiplatelet therapy is not routinely recommended for peripheral arterial disease alone but may be appropriate following lower extremity revascularization, particularly endovascular intervention. High-intensity statin therapy reduces cardiovascular events and may slow peripheral arterial disease progression, with LDL cholesterol target less than seventy milligrams per deciliter recommended. Blood pressure control and glucose management in diabetic patients complete cardiovascular risk factor modification. Supervised exercise therapy represents first-line treatment for claudication, with structured programs demonstrating improvement in walking distance comparable to revascularization in multiple randomized trials. Programs typically involve treadmill walking to near-maximal claudication pain three times weekly for twelve weeks, with subsequent maintenance. Mechanisms of benefit include improved walking efficiency, enhanced oxygen extraction, and potentially collateral development. Coverage for supervised exercise programs has expanded, though access remains limited. Home-based exercise programs provide an alternative when supervised programs are unavailable, though benefits are less well established. Cilostazol, a phosphodiesterase III inhibitor with antiplatelet and vasodilatory properties, is the only medication approved for claudication treatment that improves walking distance. Meta-analyses demonstrate approximately fifty percent improvement in maximal walking distance compared to placebo. Contraindications include heart failure of any severity due to increased mortality with other phosphodiesterase III inhibitors in this population. Side effects include headache, diarrhea, and dizziness. Pentoxifylline, a rheologic agent, is commonly prescribed but has minimal evidence of efficacy and is not recommended in current guidelines. Medical management should be optimized before proceeding to revascularization for claudication. Panel A: Medical management pyramid showing foundational cardiovascular risk modification, exercise therapy, and pharmacotherapy with evidence levels for each intervention. Panel B: Smoking cessation strategies including counseling, pharmacotherapy options, and impact on disease progression and revascularization outcomes. Panel C: Supervised exercise therapy protocol showing treadmill program structure, duration, intensity targets, and expected outcomes compared to revascularization. Panel D: Cilostazol mechanism of action, efficacy data, contraindications, and comparison with other claudication medications. --- ### IV. Revascularization for Peripheral Arterial Disease Revascularization for peripheral arterial disease is indicated when medical management fails to adequately control symptoms affecting quality of life or when critical limb ischemia threatens limb viability. The choice between endovascular and open surgical approaches depends on anatomic considerations, patient comorbidities, and institutional expertise. Endovascular intervention has become first-line therapy for most lesions given lower procedural morbidity and acceptable durability, with open bypass reserved for failed endovascular approaches, complex anatomy not amenable to endovascular treatment, and patients with good operative risk and favorable anatomy for durable reconstruction. Aortoiliac occlusive disease is amenable to both endovascular and open surgical treatment. Endovascular options include angioplasty with or without stenting for focal stenoses and kissing stents at the aortic bifurcation for bilateral iliac disease. Primary patency rates exceed eighty percent at five years for iliac stenting. Aortobifemoral bypass provides excellent durability with five-year patency rates exceeding eighty-five percent but carries higher perioperative morbidity and mortality, making it appropriate for younger patients with diffuse disease and acceptable operative risk. Extra-anatomic bypass through axillofemoral or femorofemoral configurations provides alternatives for patients with prohibitive operative risk or hostile abdominal conditions. Femoropopliteal disease represents the most common pattern of symptomatic peripheral arterial disease. Endovascular treatment options include angioplasty alone, angioplasty with stenting, atherectomy, and drug-coated balloons or stents that have demonstrated improved patency through inhibition of neointimal hyperplasia. Lesion characteristics including length, degree of calcification, and presence of chronic total occlusion influence technical success and durability. Infrainguinal bypass with autogenous saphenous vein provides superior long-term patency compared to prosthetic conduit, particularly for below-knee targets, and remains the gold standard for durable revascularization in appropriate candidates. Critical limb ischemia demands urgent revascularization to prevent limb loss, with endovascular approaches increasingly utilized even for complex multivessel disease. The goal is restoration of inline flow to the foot through at least one tibial vessel. Angiosome-directed revascularization targeting the artery supplying the ischemic territory may improve wound healing outcomes. Even limited improvement in perfusion may promote healing if combined with meticulous wound care and offloading. Primary amputation without revascularization attempt is appropriate only when no revascularization options exist, the patient cannot tolerate any intervention, or the limb is non-salvageable due to extensive tissue loss or infection. Palliative amputation may also align with patient goals when functional recovery is not anticipated. Panel A: Decision algorithm for revascularization showing indications for intervention, choice between endovascular and open approaches based on anatomy and patient factors. Panel B: Endovascular treatment options for iliac and femoropopliteal disease including angioplasty, stenting, atherectomy, and drug-coated technologies with typical patency outcomes. Panel C: Infrainguinal bypass anatomy showing proximal and distal anastomosis options, vein versus prosthetic conduit comparison, and tunneling routes. Panel D: Critical limb ischemia revascularization goals illustrating angiosome concept, tibial targets, and integration with wound care. --- ### V. Acute Limb Ischemia Acute limb ischemia represents a surgical emergency requiring prompt recognition and intervention to prevent irreversible tissue damage and limb loss. The classic presentation includes the six Ps: pain of sudden onset and severity, pallor with waxy white appearance, pulselessness with absent distal pulses, paresthesias from sensory nerve ischemia, paralysis indicating motor nerve involvement, and poikilothermia with cold extremity assuming ambient temperature. The distinction between viable, threatened, and irreversible ischemia guides urgency and type of intervention. The etiology of acute limb ischemia is most commonly embolism or thrombosis in situ. Embolic occlusion typically originates from cardiac sources including atrial fibrillation with left atrial thrombus, ventricular thrombus following myocardial infarction, and valvular disease with vegetations. The onset is typically sudden and severe in a limb without prior ischemic symptoms or signs of chronic arterial disease. Thrombosis in situ occurs on underlying atherosclerotic disease, with less abrupt onset due to pre-existing collateral development. Thrombosed popliteal aneurysm represents an important cause of acute ischemia with distal embolization. Less common etiologies include arterial trauma, graft thrombosis, and aortic dissection with malperfusion. The Rutherford classification of acute limb ischemia stratifies severity to guide management urgency. Class I viable limbs have no immediate threat and allow time for comprehensive evaluation and intervention planning. Class IIa marginally threatened limbs are salvageable with prompt treatment and typically lack motor deficit. Class IIb immediately threatened limbs have motor deficit or rest pain with sensory loss and require emergent revascularization within hours. Class III irreversible ischemia manifests with profound sensory and motor loss, muscle rigidity, and absent Doppler signals, indicating non-viable tissue requiring primary amputation as revascularization would produce only reperfusion injury without functional recovery. Treatment of acute limb ischemia begins with immediate anticoagulation to prevent propagation of thrombus, typically with intravenous unfractionated heparin. Emergent revascularization for threatened limbs may employ surgical thromboembolectomy using Fogarty balloon catheters, which provides rapid restoration of flow and is preferred for embolic occlusion in otherwise healthy vessels. Catheter-directed thrombolysis with tissue plasminogen activator allows dissolution of thrombus over hours to days, is appropriate for thrombosis with underlying disease requiring treatment, and may unmask stenoses amenable to endovascular treatment. Hybrid approaches combining open and endovascular techniques provide flexibility for complex presentations. Following revascularization, vigilance for reperfusion injury and compartment syndrome is essential. Panel A: Six Ps of acute limb ischemia with clinical findings and progression timeline from reversible ischemia through irreversible necrosis. Panel B: Etiology comparison between embolic and thrombotic acute ischemia showing sources, presentation characteristics, and underlying conditions. Panel C: Rutherford classification of acute limb ischemia from Class I viable through Class III irreversible with clinical findings and management urgency for each category. Panel D: Treatment options including surgical thromboembolectomy technique with Fogarty catheter, catheter-directed thrombolysis setup, and hybrid approach integration. --- ### VI. Carotid Artery Disease Carotid artery stenosis accounts for approximately twenty to twenty-five percent of ischemic strokes, with the mechanism typically involving embolization of thrombus or plaque material from the carotid bifurcation rather than hemodynamic insufficiency from flow limitation. The natural history of carotid stenosis depends critically on symptom status, with symptomatic stenosis carrying substantially higher stroke risk than asymptomatic disease. Symptoms attributable to carotid disease include transient ischemic attack with transient neurological deficit resolving within twenty-four hours, amaurosis fugax with transient monocular vision loss from ophthalmic artery embolism, and completed stroke with permanent neurological deficit in the carotid distribution. Duplex ultrasound provides the primary screening and diagnostic modality for carotid stenosis, using velocity criteria to estimate degree of narrowing. Peak systolic velocity greater than 125 centimeters per second suggests greater than fifty percent stenosis, while velocity exceeding 230 centimeters per second indicates greater than seventy percent stenosis. Computed tomographic angiography and magnetic resonance angiography provide complementary anatomic information and are typically performed to confirm stenosis severity and plan intervention. Conventional catheter angiography remains the gold standard but is now rarely required for diagnosis given the accuracy of noninvasive imaging. Treatment decisions for carotid stenosis are based on symptom status, degree of stenosis, and patient operative risk. Symptomatic carotid stenosis of fifty percent or greater benefits from revascularization, with the greatest benefit in stenosis exceeding seventy percent. The benefit of intervention is time-sensitive, with maximum risk reduction when performed within two weeks of symptom onset. Asymptomatic carotid stenosis of seventy percent or greater may benefit from revascularization in appropriately selected patients with low operative risk and reasonable life expectancy, though the absolute benefit is smaller given lower baseline stroke risk. Medical therapy with antiplatelet agents, high-intensity statins, and blood pressure control is essential for all patients regardless of intervention. Carotid endarterectomy involves surgical exposure of the carotid bifurcation, clamping with or without shunt placement to maintain cerebral perfusion, arteriotomy with removal of atherosclerotic plaque, and closure with primary repair or patch angioplasty. The procedure has been performed for over sixty years with well-established efficacy and safety, achieving combined stroke and death rates of less than three percent at high-volume centers. Carotid artery stenting provides an endovascular alternative appropriate for patients with high surgical risk due to anatomic factors such as prior neck radiation or surgery, or medical comorbidities. Embolic protection devices reduce procedural stroke risk during stenting. Outcomes data suggest carotid endarterectomy remains preferred for most patients, particularly those over seventy years and symptomatic patients. Panel A: Carotid stenosis pathophysiology showing plaque at bifurcation, embolic mechanism, and cerebrovascular distribution with watershed areas. Panel B: Duplex ultrasound velocity criteria for stenosis severity with corresponding angiographic images showing fifty percent versus seventy percent stenosis. Panel C: Evidence-based treatment thresholds comparing symptomatic versus asymptomatic disease with timing considerations and patient selection. Panel D: Carotid endarterectomy surgical technique showing exposure, clamping with shunt option, plaque removal, and patch angioplasty closure. --- ### VII. Abdominal Aortic Aneurysm Abdominal aortic aneurysm is defined as focal dilation of the aorta to greater than three centimeters or 1.5 times the normal diameter, with the infrarenal aorta being the most common site due to structural differences in the aortic wall and hemodynamic factors. Aneurysm formation involves degradation of elastin and collagen in the media by matrix metalloproteinases, chronic inflammation, and smooth muscle cell apoptosis, resulting in progressive weakening and dilation. Risk factors parallel those for atherosclerosis and include smoking as the strongest modifiable factor, advanced age, male sex, hypertension, and family history of aneurysm in first-degree relatives. The natural history of abdominal aortic aneurysm involves progressive enlargement with eventual rupture if left untreated. The relationship between aneurysm size and rupture risk follows an exponential curve, with annual rupture risk less than one percent for aneurysms less than four centimeters, one to three percent for four to five centimeters, three to ten percent for five to six centimeters, and exceeding ten percent for aneurysms greater than six centimeters. Average growth rate is approximately three to five millimeters per year, though significant individual variation exists. Rupture carries approximately eighty percent overall mortality, with half of patients dying before reaching the hospital and half of those undergoing emergency repair not surviving. Screening for abdominal aortic aneurysm with one-time abdominal ultrasound is recommended for men aged sixty-five to seventy-five years who have ever smoked, based on randomized trials demonstrating reduced aneurysm-related mortality with screening. Surveillance intervals for detected aneurysms depend on size, with repeat imaging every three years for aneurysms 3.0 to 3.9 centimeters, annually for 4.0 to 4.9 centimeters, and every six months for 5.0 to 5.4 centimeters. Intervention is recommended at 5.5 centimeters in men and potentially 5.0 centimeters in women given higher rupture risk at smaller sizes. Rapid growth exceeding one centimeter per year or symptomatic aneurysm with pain also indicate intervention regardless of absolute size. Medical management of abdominal aortic aneurysm focuses on cardiovascular risk factor modification and potentially slowing aneurysm growth. Smoking cessation is essential, as continued smoking accelerates expansion. Statin therapy, beta-blockers, and blood pressure control may reduce cardiovascular events though impact on aneurysm growth is uncertain. No pharmacotherapy has been definitively shown to reduce growth rate or rupture risk. Surveillance with serial imaging at appropriate intervals monitors growth, with intervention timing based on reaching size threshold, growth rate, or symptoms. Panel A: Abdominal aortic aneurysm pathophysiology showing media degeneration, inflammatory infiltrate, and biomechanical wall stress distribution. Panel B: Rupture risk curve demonstrating exponential relationship between aneurysm diameter and annual rupture risk with mortality statistics. Panel C: Screening and surveillance algorithm showing recommended populations, imaging intervals by size category, and intervention thresholds. Panel D: CT angiography demonstrating infrarenal abdominal aortic aneurysm with measurement technique and anatomic assessment for repair planning. --- ### VIII. Abdominal Aortic Aneurysm Repair Repair of abdominal aortic aneurysm may be accomplished through open surgical or endovascular approaches, with selection based on anatomic suitability, patient risk factors, and operator expertise. Endovascular aneurysm repair has become the dominant approach, accounting for approximately eighty percent of elective repairs, based on reduced perioperative morbidity and mortality compared to open repair. However, endovascular repair requires lifelong imaging surveillance for endoleaks and device complications, and long-term durability may be inferior to open repair in younger patients with favorable anatomy. Open surgical repair involves transperitoneal or retroperitoneal exposure of the aneurysm, proximal and distal aortic control, aneurysmorrhaphy with placement of a prosthetic tube or bifurcated graft, and closure of the aneurysm sac over the graft. Perioperative mortality for elective open repair has declined to three to five percent at experienced centers, though significant cardiopulmonary morbidity and prolonged recovery remain concerns. Open repair provides definitive treatment without need for ongoing surveillance, with late complications including anastomotic aneurysm and graft infection being rare. The operation may be particularly appropriate for younger patients, those with unsuitable anatomy for endovascular repair, and those requiring concomitant aortic branch reconstruction. Endovascular aneurysm repair involves percutaneous or surgical femoral access with deployment of a modular stent graft that excludes the aneurysm from systemic pressure. Anatomic requirements include adequate proximal neck length and diameter for seal, absence of severe angulation, and sufficient iliac caliber for device delivery. Perioperative mortality is approximately one percent for elective procedures, with major advantages of avoiding laparotomy, aortic clamping, and associated cardiopulmonary stress. However, incomplete exclusion of the aneurysm sac may result in endoleak with persistent sac pressurization and continued rupture risk, necessitating lifelong imaging surveillance. Endoleak classification describes the source of persistent blood flow into the aneurysm sac following endovascular repair. Type I endoleak at the proximal or distal attachment site represents treatment failure requiring intervention. Type II endoleak from retrograde flow through branch vessels such as lumbar or inferior mesenteric arteries is most common and frequently benign, with intervention indicated only for sac enlargement. Type III endoleak from graft component separation or fabric defect requires repair. Type IV endoleak from graft porosity is transient. Type V or endotension represents sac enlargement without demonstrable endoleak. Surveillance imaging with CT angiography or duplex ultrasound is performed at one month, twelve months, and annually thereafter to detect endoleaks and monitor sac size. Panel A: Comparison of open surgical versus endovascular repair approaches showing procedural differences, perioperative outcomes, and long-term considerations for each. Panel B: Open repair surgical technique with transperitoneal exposure, aortic clamping, and tube versus bifurcated graft configurations. Panel C: Endovascular stent graft deployment demonstrating femoral access, modular component assembly, and proximal and distal seal zones. Panel D: Endoleak classification from Type I through Type V with anatomic source, clinical significance, and management for each type. --- ### IX. Venous Disease Chronic venous insufficiency results from incompetent venous valves that allow reflux of blood in the dependent position, producing venous hypertension with resultant skin and soft tissue changes. Primary venous insufficiency involves intrinsic valve dysfunction, while secondary insufficiency follows deep venous thrombosis with valve damage during recanalization. The CEAP classification provides systematic categorization: clinical classes range from C0 with no visible disease through C6 with active ulceration, etiologic categories distinguish primary from secondary and congenital causes, anatomic classification specifies superficial, deep, or perforator involvement, and pathophysiologic designation indicates reflux, obstruction, or both. Clinical manifestations of chronic venous insufficiency progress from cosmetically concerning telangiectasias and varicose veins through edema, skin changes including hyperpigmentation and lipodermatosclerosis, and ultimately venous ulceration. Venous ulcers characteristically occur in the gaiter distribution above the medial malleolus, have irregular borders with shallow moist bases, and are associated with surrounding pigmentation and induration. Pain is variable but often less severe than with arterial ulcers. The differential diagnosis includes arterial, neuropathic, and mixed-etiology ulcers, with ankle-brachial index measurement essential to exclude significant arterial disease before initiating compression therapy. Duplex ultrasound provides the primary diagnostic modality for venous insufficiency, documenting the presence and distribution of reflux in superficial, deep, and perforator veins. Reflux is defined as retrograde flow exceeding 0.5 seconds in superficial veins and one second in deep veins. The great and small saphenous veins are most commonly involved in superficial reflux. Deep venous reflux following prior thrombosis indicates post-thrombotic syndrome. Evaluation should precede treatment to identify the source of venous hypertension and guide intervention. Compression therapy forms the foundation of treatment for chronic venous insufficiency and venous ulceration, providing external support to counteract venous hypertension and reduce edema. Graduated compression stockings delivering thirty to forty millimeters of mercury pressure at the ankle improve symptoms and prevent ulcer recurrence. Compression bandaging with multilayer systems accelerates ulcer healing. Ablation of incompetent superficial veins through endovenous laser therapy, radiofrequency ablation, or foam sclerotherapy reduces recurrence when combined with compression. Saphenous vein stripping has largely been replaced by less invasive ablation techniques. Intervention on the deep venous system is technically challenging with variable outcomes and is generally reserved for patients failing conservative and superficial venous management. Panel A: Venous valve function in normal state versus incompetent valve with reflux, demonstrating mechanism of venous hypertension in dependent position. Panel B: CEAP classification clinical stages from C0 through C6 with representative images and progression of disease manifestations. Panel C: Characteristic venous ulcer appearance and location in gaiter distribution with comparison to arterial and neuropathic ulcer features. Panel D: Treatment algorithm from compression therapy through endovenous ablation showing duplex-guided assessment and intervention selection. --- ### X. Deep Vein Thrombosis and Vascular Access Deep vein thrombosis represents clot formation in the deep venous system, most commonly in the lower extremities, with potential for pulmonary embolism and long-term post-thrombotic syndrome. Virchow's triad of stasis, endothelial injury, and hypercoagulability describes the pathophysiologic basis for thrombosis. Risk factors include immobility from surgery, trauma, or medical illness, malignancy, pregnancy and postpartum state, oral contraceptive use, inherited thrombophilias, and indwelling venous catheters. Clinical presentation includes unilateral leg swelling, pain, warmth, and superficial venous dilation, though many cases are asymptomatic or have nonspecific findings. Diagnosis of deep vein thrombosis employs risk stratification with the Wells score combined with D-dimer testing and duplex ultrasound. Low pretest probability with negative D-dimer effectively excludes deep vein thrombosis without need for imaging. Moderate or high pretest probability, or low probability with positive D-dimer, requires compression ultrasound demonstrating non-compressibility of the vein for diagnosis. Treatment involves anticoagulation with direct oral anticoagulants such as rivaroxaban or apixaban preferred for most patients, or low-molecular-weight heparin particularly in malignancy-associated thrombosis. Duration is typically three months for provoked deep vein thrombosis, with extended anticoagulation for unprovoked or recurrent events. Catheter-directed thrombolysis may be considered for acute iliofemoral deep vein thrombosis presenting within fourteen days with severe symptoms and low bleeding risk, as this approach may reduce post-thrombotic syndrome compared to anticoagulation alone. Thrombolysis delivers tissue plasminogen activator directly into the thrombus through a catheter, often combined with mechanical thrombectomy devices for faster thrombus removal. Inferior vena cava filter placement is indicated when anticoagulation is contraindicated due to active bleeding or very high bleeding risk, with retrieval recommended once anticoagulation becomes feasible. Vascular access for hemodialysis represents a growing component of vascular surgery practice given the epidemic of end-stage renal disease. The preferred access is an autogenous arteriovenous fistula, typically radiocephalic at the wrist or brachiocephalic at the elbow, which provides the best long-term patency and lowest infection rate. Fistulas require six to eight weeks of maturation before use and must achieve the rule of sixes: six millimeters diameter, less than six millimeters depth, and six hundred milliliters per minute flow. Arteriovenous grafts using prosthetic conduit provide an alternative when native veins are inadequate, with earlier usability but inferior patency and higher infection rates. Tunneled dialysis catheters serve as temporary access or for patients who have exhausted fistula and graft options, but have the highest complication rates including infection, thrombosis, and central venous stenosis. Panel A: Virchow's triad components with specific risk factors for each element and cumulative effect on thrombosis risk. Panel B: Deep vein thrombosis diagnostic algorithm from Wells score through D-dimer and compression ultrasound with interpretation at each step. Panel C: Treatment options comparing anticoagulation agents, catheter-directed thrombolysis indications, and IVC filter placement criteria. Panel D: Hemodialysis access types showing radiocephalic fistula, brachiocephalic fistula, AV graft configurations, and tunneled catheter with relative advantages and complications of each. --- ## Summary - Peripheral arterial disease affects twelve percent of adults with ankle-brachial index less than 0.90 confirming diagnosis and severity correlating with cardiovascular mortality risk - Claudication is managed with smoking cessation, supervised exercise therapy, antiplatelet agents, statins, and cilostazol, with revascularization reserved for lifestyle-limiting symptoms refractory to medical therapy - Critical limb ischemia with rest pain or tissue loss requires urgent revascularization through endovascular or open surgical approaches to prevent amputation - Acute limb ischemia presents with the six Ps and is classified by Rutherford system to guide urgency, with treatment by surgical thromboembolectomy or catheter-directed thrombolysis - Symptomatic carotid stenosis greater than fifty percent benefits from revascularization within two weeks of symptoms, with carotid endarterectomy preferred for most patients - Abdominal aortic aneurysm screening with ultrasound is recommended for men 65-75 who have smoked, with repair indicated at 5.5 centimeters or for rapid growth - Endovascular aneurysm repair has lower perioperative mortality than open repair but requires lifelong surveillance for endoleaks - Chronic venous insufficiency is managed with compression therapy and endovenous ablation of incompetent superficial veins - Deep vein thrombosis treatment involves anticoagulation typically for three months, with catheter-directed thrombolysis considered for acute iliofemoral thrombosis - Arteriovenous fistula is the preferred hemodialysis access with best long-term patency and lowest infection rates --- ## Key Terms | Term | Definition | |------|------------| | Ankle-brachial index | Ratio of ankle to brachial systolic pressure used to diagnose peripheral arterial disease, with values less than 0.90 indicating disease | | Critical limb ischemia | Severe PAD manifesting as rest pain or tissue loss, requiring urgent revascularization to prevent amputation | | Acute limb ischemia | Sudden decrease in limb perfusion threatening viability, presenting with six Ps and requiring emergent intervention | | Carotid endarterectomy | Surgical removal of atherosclerotic plaque from the carotid bifurcation to prevent stroke | | Abdominal aortic aneurysm | Focal aortic dilation greater than 3 cm with risk of rupture proportional to size | | Endovascular aneurysm repair | Minimally invasive treatment using stent graft to exclude aneurysm from systemic pressure | | Endoleak | Persistent blood flow into aneurysm sac following endovascular repair, classified by source | | Chronic venous insufficiency | Venous valve incompetence causing reflux and venous hypertension with skin changes and ulceration | | Arteriovenous fistula | Surgically created connection between artery and vein for hemodialysis access | | Claudication | Reproducible muscular pain with walking due to arterial insufficiency, relieved by rest | --- *This content is subject to the [MIT License](https://opensource.org/licenses/MIT). © 2024–2026 Hibbert School of Medicine.*