A 55-year-old man with a 12-year history of type 2 diabetes mellitus and hypertension presents to the emergency department with sudden onset of left lower limb pain and coldness. On examination, the left foot is pale and pulseless distal to the femoral artery. Digital subtraction angiography (DSA) is performed and reveals a focal, eccentric, irregular narrowing of the superficial femoral artery with overhanging edges and a contrast-filled ulceration. Which of the following angiographic findings is MOST specific for the underlying pathology?

Explanation

## Angiographic Diagnosis of Atherosclerotic Plaque Rupture and Ulceration ### Pathologic Basis The patient presents with acute limb ischemia secondary to rupture of an atherosclerotic plaque in the superficial femoral artery. The angiographic hallmark of a ruptured atherosclerotic lesion is the **eccentric, irregular narrowing with an overhanging edge and contrast-filled ulceration crater**. ### Key Angiographic Features of Atherosclerotic Ulceration **High-Yield:** The ulceration crater is pathognomonic for atherosclerotic plaque rupture. This occurs when the fibrous cap of a lipid-rich plaque fractures, exposing the thrombogenic core to the bloodstream. The overhanging edge represents the intact fibrous cap margin overhanging the crater. | Angiographic Feature | Pathologic Correlate | Clinical Significance | |---|---|---| | Eccentric, irregular narrowing | Plaque asymmetry and heterogeneous composition | Indicates vulnerable plaque | | Overhanging edge | Fibrous cap margin | Defines the ulceration boundary | | Contrast-filled crater | Ulcerated plaque core | Thrombogenic surface; source of emboli | | Acute luminal narrowing | Superimposed thrombosis | Explains acute presentation | ### Distinction from Other Angiographic Patterns **Option 0 (Smooth, concentric narrowing):** This is the classic appearance of **chronic, stable atherosclerotic stenosis**. The smooth, tapered narrowing reflects gradual plaque accumulation with compensatory remodeling. This pattern is NOT associated with acute rupture and does not explain the acute presentation with pulselessness and limb-threatening ischemia. **Option 2 (String-like, multiple focal narrowings):** This pattern is characteristic of **vasculitis** (e.g., Takayasu arteritis, polyarteritis nodosa, or giant cell arteritis). The diffuse, segmental narrowings with a "string of beads" or string-like appearance reflect inflammatory destruction of the arterial wall. The absence of an ulceration crater and the clinical context (diabetes, hypertension, not systemic inflammatory symptoms) make vasculitis unlikely. **Option 3 (Abrupt termination with meniscus sign):** This is the classic angiographic sign of **acute thromboembolism**. The "meniscus sign" (a concave meniscus-shaped contrast level) indicates an acute thrombus lodging in the artery. However, this patient has underlying atherosclerotic disease (diabetes, hypertension), and the presence of an ulceration crater indicates in-situ thrombosis on a ruptured plaque rather than embolic occlusion from a proximal source. ### Clinical Pearl **Key Point:** The **ulceration crater with overhanging edges** is the most specific angiographic sign of atherosclerotic plaque rupture. This finding indicates a vulnerable, ruptured plaque with exposed thrombogenic material, explaining the acute limb-threatening ischemia and the need for urgent revascularization (thromboaspiration, mechanical thrombectomy, or bypass). ### Mechanism of Acute Presentation The rupture of the atherosclerotic plaque exposes the lipid-rich core, triggering platelet aggregation and thrombus formation. The superimposed thrombosis causes acute luminal narrowing or occlusion, leading to sudden ischemia of the distal limb. ### High-Yield Takeaway In a patient with acute limb ischemia and angiographic evidence of an **eccentric, irregular narrowing with an ulceration crater and overhanging edge**, the diagnosis is **ruptured atherosclerotic plaque with superimposed thrombosis**. This is distinct from chronic stable stenosis (smooth narrowing), vasculitis (string-like pattern), or embolic occlusion (abrupt termination with meniscus sign).