Arterial Diseases of the Extremities¶
Chapter 292 | Part 6: Disorders of the Cardiovascular System
KEY CLINICAL POINTS¶
- Peripheral artery disease (PAD) is defined by atherosclerosis, thrombosis, or embolism causing stenosis/occlusion in aortic or limb arteries, with intermittent claudication as the hallmark symptom.
- Noninvasive testing (ABI, TBI, duplex ultrasound) and imaging (MRA, CTA) are critical for diagnosing PAD, while revascularization (PTA, bypass grafts) is indicated for severe ischemia.
- Raynaud phenomenon is classified as primary (idiopathic) or secondary (associated with autoimmune diseases, vasculitis, or medications), with distinct clinical features and management strategies.
1. DEFINITION & OVERVIEW¶
Peripheral artery disease (PAD) is a clinical disorder characterized by stenosis or occlusion of the aorta or limb arteries. Atherosclerosis is the leading cause in patients >40 years old. Other causes include thrombosis, embolism, vasculitis, and trauma. Acute limb ischemia results from sudden arterial occlusion, while chronic conditions like atheroembolism or fibromuscular dysplasia present with progressive ischemia.
Table 292-1: Classification of Raynaud Phenomenon¶
| Category | Causes |
|---|---|
| Primary/Idiopathic | Isolated vasospasm without underlying disease |
| Secondary | Collagen vascular diseases (scleroderma, SLE), arterial occlusive diseases, pulmonary hypertension, neurologic disorders, blood dyscrasias, trauma, drugs/toxins |
1.1 Key Pathophysiology¶
Atherosclerosis causes segmental lesions in large/medium vessels, with calcium deposition, media thinning, and thrombus formation. Distal vasculature involvement is common in elderly or diabetic patients. Acute thrombosis occurs in situ or from emboli, while chronic conditions like fibromuscular dysplasia involve medial hyperplasia.
1.2 Clinical Spectrum¶
PAD ranges from asymptomatic (ABI 0.91–0.99) to critical limb ischemia (ABI ≤ 0.90). Acute limb ischemia presents with sudden pain, pallor, and pulselessness, while chronic ischemia manifests as intermittent claudication, rest pain, or gangrene.
2. EPIDEMIOLOGY¶
PAD prevalence peaks in 6th–7th decades of life, affecting ~12–20% of adults ≥ 65 years. Risk factors include smoking (15–25% 5-year mortality), diabetes (15–25% mortality), hypertension, hypercholesterolemia, and renal insufficiency. Thromboangiitis obliterans (Buerger’s disease) predominantly affects young male smokers in Asia/Eastern Europe.
2.1 Demographics¶
Black individuals have higher prevalence than non-Hispanic whites. Women are 5× more likely than men to develop primary Raynaud phenomenon, typically between 20–40 years of age.
2.2 Risk Factors¶
Smoking, diabetes, hyperlipidemia, hypertension, and atherosclerosis are major risk factors. Thromboangiitis obliterans is linked to cigarette smoking, while atheroembolism is associated with aortic atheromas.
3. ETIOLOGY & PATHOPHYSIOLOGY¶
Atherosclerosis is the leading cause of PAD, with plaque formation at branch points. Thromboangiitis obliterans involves inflammatory vasculitis, while fibromuscular dysplasia is a hyperplastic disorder of medium/small arteries. Atheroembolism results from embolization of atheromatous debris.
3.1 Atherosclerosis¶
Plaque formation at arterial branch points causes stenosis. Distal vasculature involvement is common in elderly or diabetic patients. Thrombus formation occurs in situ or from emboli.
3.2 Thromboangiitis Obliterans¶
Inflammatory vasculitis affecting small/medium arteries/veins, linked to cigarette smoking. Pathology includes polymorphonuclear leukocyte infiltration, fibrosis, and organized thrombus.
4. CLINICAL FEATURES¶
Intermittent claudication (pain during exercise, relieved by rest) is the most common symptom. Acute limb ischemia presents with sudden pain, pallor, and pulselessness. Chronic ischemia may cause rest pain, gangrene, or 'blue toe' syndrome. Raynaud phenomenon involves episodic digital ischemia with pallor/cyanosis/rubor.
4.1 PAD Presentation¶
Intermittent claudication (distal to occlusion), rest pain, muscle atrophy, and skin changes (thickened nails, pallor). Chronic limb-threatening ischemia may present with ulcers/gangrene.
4.2 Raynaud Phenomenon¶
Episodic digital ischemia with sequential pallor/cyanosis/rubor. Primary form is idiopathic; secondary form is associated with autoimmune diseases or medications.
5. DIFFERENTIAL DIAGNOSIS¶
For PAD: atherosclerosis, thromboangiitis obliterans, fibromuscular dysplasia, atheroembolism. For Raynaud phenomenon: acrocyanosis, livedo reticularis, cold-induced vasospasm. Acute limb ischemia must be differentiated from thrombophlebitis or embolism.
5.1 PAD Mimics¶
Thoracic outlet syndrome (neurogenic/venous/arterial), popliteal artery entrapment, arteriovenous fistula, or vasculitis.
5.2 Raynaud Mimics¶
Acrocyanosis (persistent cyanosis), livedo reticularis (mottled skin), or cold-induced vasospasm without episodic changes.
6. INVESTIGATIONS & DIAGNOSIS¶
Noninvasive testing (ABI, TBI, duplex ultrasound) is first-line. Angiography (CTA/MRA) confirms anatomy. Acute limb ischemia requires immediate imaging (duplex ultrasound, CTA). Raynaud phenomenon is diagnosed clinically with exclusion of secondary causes.
Table 292-1: Classification of Raynaud Phenomenon¶
| Category | Causes |
|---|---|
| Primary/Idiopathic | Isolated vasospasm without underlying disease |
| Secondary | Collagen vascular diseases (scleroderma, SLE), arterial occlusive diseases, pulmonary hypertension, neurologic disorders, blood dyscrasias, trauma, drugs/toxins |
6.1 Noninvasive Testing¶
Ankle-brachial index (ABI) <0.90 indicates PAD. Toe-brachial index (TBI) detects distal ischemia. Duplex ultrasound identifies stenosis/occlusion.
6.2 Imaging¶
CTA/MRA for anatomical detail. Angiography confirms diagnosis pre-revascularization. Doppler ultrasound assesses collateral circulation.
7. MANAGEMENT & TREATMENT¶
Lifestyle modification (smoking cessation, exercise) is foundational. Antiplatelet agents (aspirin, clopidogrel) and statins reduce cardiovascular risk. Revascularization (PTA, bypass grafts) is indicated for critical ischemia. Raynaud phenomenon is managed with sympathectomy or vasodilators.
7.1 Medical Therapy¶
Statins (high-intensity for PAD), antiplatelet agents (aspirin/clopidogrel), and vasodilators (cilostazol, pentoxifylline). Avoid NSAIDs in Raynaud phenomenon.
7.2 Revascularization¶
Endovascular (PTA, stents) or surgical (bypass grafts) for severe ischemia. Hybrid approaches combine endovascular and surgical techniques.
8. PROGNOSIS & COMPLICATIONS¶
PAD has 15–25% 5-year mortality. Chronic limb-threatening ischemia may lead to amputation (25% within 1 year). Atheroembolism causes distal ischemia, while thromboangiitis obliterans has poor outcomes with continued smoking. Raynaud phenomenon may progress to digital ulceration in secondary forms.
8.1 PAD Outcomes¶
11% of symptomatic PAD progress to chronic limb-threatening ischemia. Amputation risk is 25% in critical ischemia without revascularization.
8.2 Complications¶
Acute limb ischemia may lead to gangrene. Atheroembolism causes small-vessel ischemia. Thromboangiitis obliterans has high recurrence with smoking.
9. SPECIAL CONSIDERATIONS¶
Pregnancy: manage PAD with caution due to increased bleeding risk. Elderly: prioritize conservative management. Diabetic patients require strict glycemic control. Smoking cessation is critical for all patients.
9.1 Pregnancy¶
Avoid anticoagulants; manage PAD with lifestyle changes and low-dose aspirin if indicated.
9.2 Diabetic Patients¶
Monitor for neuropathy and microvascular complications. Use strict glycemic control to reduce amputation risk.
10. KEY POINTS & CLINICAL PEARLS¶
- ABI <0.90 confirms PAD; TBI detects distal ischemia. 2. Supervised exercise improves walking distance as effectively as revascularization. 3. Raynaud phenomenon is idiopathic in 50% of cases; secondary forms require treatment of underlying disease. 4. Thromboangiitis obliterans is linked to smoking and requires strict cessation. 5. Atheroembolism is managed with anticoagulation and exclusion of atherosclerotic lesions.