A 62-year-old man with a 40-pack-year smoking history and type 2 diabetes presents with a 6-month history of progressive pain in his right calf during walking that resolves with rest. On examination, the right foot is cool to touch, and the dorsalis pedis pulse is absent. The ankle-brachial index (ABI) on the right is 0.65. What is the most appropriate next step in management?

Explanation

## Clinical Diagnosis and Workup **Key Point:** This patient presents with intermittent claudication (pain on exertion, relief at rest) due to peripheral arterial disease (PAD). The ABI of 0.65 confirms significant hemodynamically relevant stenosis (ABI 0.41–0.60 = moderate; 0.61–0.90 = mild-to-moderate). ## Diagnostic Algorithm for PAD ```mermaid flowchart TD A[Claudication + absent pulse]:::outcome --> B[Measure ABI]:::action B --> C{ABI result?}:::decision C -->|0.41-0.90| D[Duplex ultrasound]:::action C -->|< 0.40| E[Consider CTA/MRA]:::action D --> F{Lesion location & length?}:::decision F -->|Short stenosis| G[PTA candidate]:::action F -->|Long occlusion| H[Surgery or hybrid]:::action E --> I[Revascularization planning]:::action ``` **High-Yield:** Duplex ultrasonography is the first-line imaging modality after ABI measurement in stable claudication. It is non-invasive, operator-dependent but highly specific for stenosis >50%, and guides the decision between endovascular and surgical intervention. ## Why Duplex Is Correct 1. **Non-invasive:** No contrast or radiation; safe in diabetics with renal impairment. 2. **Localizes lesion:** Identifies whether stenosis is in the aortoiliac, femoropopliteal, or infrapopliteal segment—critical for choosing PTA vs. surgery. 3. **Assesses feasibility:** Determines lesion length, calcification, and vessel diameter—factors that predict success of endovascular therapy. 4. **Cost-effective:** Cheaper than CTA/MRA; appropriate for initial anatomic assessment. **Clinical Pearl:** PTA is not the immediate next step without anatomic confirmation. Rushing to intervention without duplex risks choosing the wrong approach (e.g., attempting PTA on a long occlusion that requires surgery). ## Management Pathway | Finding | Next Step | |---------|----------| | Short stenosis (<5 cm) on duplex | PTA ± stent | | Long occlusion (>5 cm) | Bypass surgery or hybrid approach | | Infrapopliteal disease | Consider CTA/MRA for better resolution | | Aortoiliac disease | PTA often first-line | **Mnemonic — PAD Workup:** **ABI-DIM** = ABI measurement → Duplex → Imaging (CTA/MRA if needed) → Management (PTA/surgery). [cite:Harrison 21e Ch 243]