What is the most appropriate initial investigation for a patient with intermittent claudication, decreased sensation, and painful left leg while walking, relieved with rest, and absent distal pulses?

Appropriate Investigation for Intermittent Claudication with Absent Distal Pulses

The most appropriate initial investigation is CT angiography (CTA) of the lower extremities with IV contrast. 1, 2

Clinical Presentation Analysis

This patient presents with classic intermittent claudication—exertional leg pain relieved by rest—combined with:

• Bilateral absent distal pulses (dorsalis pedis and posterior tibial) 1
• Preserved proximal pulses (femoral and popliteal bilaterally) 1
• Decreased sensation, suggesting more severe ischemia 2

The bilateral absence of distal pulses with preserved proximal pulses indicates multilevel infrainguinal disease requiring detailed anatomic mapping for treatment planning. 1, 2

Why CT Angiography is the Answer

CTA is rated 8/9 ("usually appropriate") by the American College of Radiology for patients with intermittent claudication when revascularization is being considered. 1, 2

Key Advantages of CTA:

• Provides comprehensive anatomic detail from aortoiliac vessels through pedal arteries in a single study 1, 2
• Rapid acquisition time with excellent visualization of calcified vessels 1
• Defines the extent and location of disease necessary for determining endovascular versus surgical intervention 1
• Widely available and can be performed urgently if needed 1
• Actually reduces total contrast exposure by facilitating better procedural planning, decreasing contrast needed during subsequent interventions 1

Why Other Options Are Incorrect

B - Vascular Ultrasound (Duplex):

While duplex ultrasound has good accuracy for aortoiliac disease (92% sensitivity, 96% specificity), it has significant limitations: 1

• Operator-dependent and requires significant expertise 3
• Cannot adequately visualize multilevel disease from aorta to pedal arteries in one examination 3
• Poor visualization in patients with heavy calcification 3
• Best used for screening, not for detailed revascularization planning 1

C - Conventional Angiography:

Catheter-directed angiography should only be performed at the time of planned intervention, not as an initial diagnostic test. 1, 2

• Invasive with potential complications (bleeding, arterial injury, contrast nephropathy) 1
• The ACC/AHA guidelines explicitly state that arterial imaging with catheter angiography is reserved for when revascularization is being performed 1

D - MR Angiography:

MRA with contrast is also rated 8/9 by the ACR and is an acceptable alternative, but: 1, 2

• Longer acquisition time compared to CTA 1
• Less widely available, especially for urgent evaluation 1
• More expensive than CTA 1
• Contraindicated in patients with certain implants or severe claustrophobia 2

Clinical Algorithm

Step 1: Confirm peripheral arterial disease with ankle-brachial index (ABI) measurement—should be abnormal at rest or post-exercise. 1

Step 2: If ABI confirms PAD and patient has:

• Significant functional impairment 1
• Failed conservative management (exercise therapy, risk factor modification) 1
• Anatomy likely amenable to revascularization 1

Step 3: Proceed directly to CTA lower extremity with IV contrast for anatomic mapping. 1, 2

Step 4: Use CTA findings to determine if endovascular or surgical revascularization is appropriate. 1

Important Caveats

• Check renal function before contrast-enhanced imaging; if severe chronic kidney disease is present, consider MRA without contrast (though less optimal). 2
• The presence of decreased sensation in this patient suggests more severe ischemia than simple claudication and warrants expedited evaluation. 2
• Do not delay imaging with prolonged trials of conservative therapy if the patient has significant functional impairment and is a revascularization candidate. 1
• CTA findings showing multilevel disease may require both inflow and outflow procedures for optimal results. 1