## Investigation of Choice for Embolic Arterial Occlusion ### Clinical Context This patient has acute limb ischemia with a clear predisposing factor (atrial fibrillation). The clinical presentation and duplex findings suggest an **embolic occlusion** rather than thrombotic disease. ### Why Transoesophageal Echocardiography (TEE) is Correct **Key Point:** TEE is the gold standard for detecting the **source of embolism** in acute arterial occlusion, particularly in patients with atrial fibrillation. **High-Yield:** TEE has superior sensitivity (>95%) for detecting: - Cardiac thrombi (left atrial/ventricular) - Atrial fibrillation-related thrombus formation - Paradoxical embolism (PFO, ASD) - Endocarditis vegetations - Aortic atherosclerosis ### Diagnostic Algorithm for Acute Limb Ischemia ```mermaid flowchart TD A[Acute arterial occlusion]:::outcome --> B{Embolic vs Thrombotic?}:::decision B -->|Embolic suspected| C[Identify source]:::action B -->|Thrombotic| D[Assess vessel wall]:::action C --> E[TEE for cardiac source]:::action E --> F[Confirm embolism]:::outcome D --> G[CT/MRA for atherosclerosis]:::action ``` ### Timing and Clinical Relevance **Clinical Pearl:** In acute limb-threatening ischemia, TEE provides **immediate diagnostic confirmation** while the patient is being prepared for **emergency embolectomy** (Fogarty catheter thrombectomy is the definitive treatment for embolic occlusion). **Mnemonic: EMBOLI sources** — **E**ndocarditis, **M**yocardial infarction (mural thrombus), **B**ioprothetic valve, **O**pened foramen ovale (paradoxical), **L**eft atrial appendage (AFib), **I**nfective vegetations. ### Why TEE Over TTE - **Sensitivity:** TEE ~95% vs TTE ~60% for thrombus detection - **Resolution:** Superior imaging of left atrium and appendage - **Urgency:** Can be performed bedside in acute settings [cite:Robbins 10e Ch 4] 
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