A 58-year-old man comes to the emergency department due to sudden onset of severe right leg pain several hours ago; the leg has since become numb. He has never had similar symptoms and has no history of trauma, fever, or chills. The patient recently had an acute anterior wall myocardial infarction that resulted in cardiogenic shock; he is undergoing cardiac rehabilitation. Temperature is 36.7 C (98.1 F), blood pressure is 120/70 mm Hg, pulse is 90/min and regular, and respirations are 16/min. Cardiopulmonary examination is unremarkable. Compared with the left leg, the right leg appears pale and is cool to the touch. In the right lower extremity, the popliteal pulse is normal, but more distal pulses are not palpable. Pulses in the other extremities are normal. Neurologic examination shows loss of sensation over the dorsum of the right foot and mild weakness with dorsiflexion. Which of the following is the most likely cause of this patient's symptoms?

Question

A 58-year-old man comes to the emergency department due to sudden onset of severe right leg pain several hours ago; the leg has since become numb.  He has never had similar symptoms and has no history of trauma, fever, or chills.  The patient recently had an acute anterior wall myocardial infarction that resulted in cardiogenic shock; he is undergoing cardiac rehabilitation.  Temperature is 36.7 C (98.1 F), blood pressure is 120/70 mm Hg, pulse is 90/min and regular, and respirations are 16/min.  Cardiopulmonary examination is unremarkable.  Compared with the left leg, the right leg appears pale and is cool to the touch.  In the right lower extremity, the popliteal pulse is normal, but more distal pulses are not palpable.  Pulses in the other extremities are normal.  Neurologic examination shows loss of sensation over the dorsum of the right foot and mild weakness with dorsiflexion.  Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d870_7bc2_bc81_95ec2b405580_MD0003_00 This patient with sudden onset of severe right leg pain and signs of arterial occlusion (eg, coolness, numbness, pulselessness, weakness) has acute limb ischemia (ALI). Common causes of ALI include: Embolism of a cardiac or intraarterial thrombus Local thrombosis from disruption of a preexisting atherosclerotic plaque (eg, peripheral artery disease [PAD]) Traumatic vessel disruption or dissection (eg, penetrating or blunt trauma, iatrogenic injury) The sudden development of ALI in this previously asymptomatic patient without PAD (eg, normal pulses in unaffected extremities) or vascular trauma is most consistent with embolic occlusion. Most arterial emboli originate from the heart. Potential cardiac sources include left atrial thrombus (eg, atrial fibrillation), left ventricular (LV) thrombus (eg, LV aneurysm), infective endocarditis (ie, septic emboli), and prosthetic valve thrombosis. Given this patient's recent severe (ie, causing cardiogenic shock) anterior myocardial infarction, formation of an LV aneurysm is the most likely cause; when the infarcted muscle fails to contract (or even balloons outward) during systole, stasis of adjacent blood can form an LV thrombus capable of subsequent embolization. (Choice B) Peripheral arterial (eg, popliteal) thrombosis usually develops from disruption of an atherosclerotic plaque in patients with preexisting PAD. This patient has no prior symptoms (eg, claudication) or clinical signs (eg, diminished pulses in unaffected extremities) of PAD. (Choice C) Inflammation from arterial vasculitis (eg, Takayasu arteritis, polyarteritis nodosa, giant cell arteritis) may cause arterial thrombosis, progressive luminal occlusion, or aneurysm (with subsequent thromboembolism) that leads to ALI. However, constitutional symptoms (eg, fever, malaise, weight loss) are typically present, as well as other systemic findings specific to each vasculitic syndrome. (Choice D) Cerebral ischemia (eg, embolic stroke) typically causes focal sensory or motor neurologic deficits, not pulselessness. (Choice E) Nerve compression alone can cause numbness and muscle weakness; however, it does not cause pulselessness. (Choice F) Deep venous thrombosis can cause lower extremity pain. However, the pain is typically dull and aching (rather than severe and sudden), and swelling is typically present. In addition, pulselessness is more consistent with arterial (inflow) rather than venous (outflow) occlusion. Educational objective: Sudden development of limb ischemia in a previously asymptomatic patient is most consistent with embolic arterial occlusion. Most arterial emboli are cardiac in origin. References: Acute limb ischemia: an update on diagnosis and management. (http://www.ncbi.nlm.nih.gov/pubmed/31416204) Acute limb ischemia. (http://www.ncbi.nlm.nih.gov/pubmed/30636997)

A 58-Year-Old Man Comes to the Emergency Department Due to Sudden