A 55-year-old man with hyperthyroidism develops absent pulses in the left leg. Which is the most likely cause of his acute limb ischemia?

A 55-year-old man with hyperthyroidism develops absent pulses in the left leg. Which is the most likely cause of his acute limb ischemia?

• A. DVT with venous thrombus
• B. Aortic dissection
• C. Popliteal aneurysm
• D. Left atrial mural thrombus

Answer: (D)

Hyperthyroidism often leads to atrial fibrillation, which causes rapid, irregular atrial contraction and blood stasis in the left atrium. This stasis favors the formation of a thrombus in the left atrium (especially the left atrial appendage). If a fragment breaks off, it can travel through the arterial system and lodge in a distal leg artery, abruptly cutting off blood flow and producing acute limb ischemia with sudden onset pain and a nonpalpable pulse. Thus, the most likely cause of the leg ischemia in this setting is a thrombus formed in the left atrium due to atrial fibrillation from hyperthyroidism, which embolizes to the leg. DVT would cause venous symptoms like swelling rather than arterial occlusion; aortic dissection would present with chest or back pain and potential limb differences but not the typical presentation here; a popliteal aneurysm could cause limb ischemia through embolization but is less directly tied to the hyperthyroidism-associated atrial fibrillation pattern.

Hyperthyroidism often leads to atrial fibrillation, which causes rapid, irregular atrial contraction and blood stasis in the left atrium. This stasis favors the formation of a thrombus in the left atrium (especially the left atrial appendage). If a fragment breaks off, it can travel through the arterial system and lodge in a distal leg artery, abruptly cutting off blood flow and producing acute limb ischemia with sudden onset pain and a nonpalpable pulse.

Thus, the most likely cause of the leg ischemia in this setting is a thrombus formed in the left atrium due to atrial fibrillation from hyperthyroidism, which embolizes to the leg. DVT would cause venous symptoms like swelling rather than arterial occlusion; aortic dissection would present with chest or back pain and potential limb differences but not the typical presentation here; a popliteal aneurysm could cause limb ischemia through embolization but is less directly tied to the hyperthyroidism-associated atrial fibrillation pattern.