A 63-year-old man comes to the emergency department due to left leg pain. The patient typically has pain in both legs after walking a couple of blocks, but several hours ago, severe left leg pain suddenly developed while he was resting. He reports numbness in the left leg, and he is also experiencing intermittent palpitations. Medical history includes hypertension and hyperlipidemia. The patient has smoked a pack of cigarettes daily for 45 years. Blood pressure is 130/80 mm Hg, and pulse is 116/min and irregular. On examination, hair is sparse on both legs. Distal pulses are absent on the left and diminished on the right. Sensation to light touch is decreased on the dorsum of the left foot and leg, and ankle dorsiflexion is weaker on the left. Which of the following is the best first step in management of this patient?
Acute limb ischemia | |
Etiology |
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Clinical | 6 Ps of acute limb ischemia
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Management |
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AF = atrial fibrillation; IE = infective endocarditis; LV = left ventricular; PAD = peripheral artery disease. | |
This patient has a classic presentation of arterial occlusion leading to acute limb ischemia (ALI): Pain, Pallor, Paresthesia, Pulselessness, Poikilothermia (cool extremity), and Paralysis (6 Ps). His occlusion may be due to either embolism of a left atrial thrombus in the setting of atrial fibrillation (eg, palpitations, irregular pulse) or thrombosis following atherosclerotic plaque rupture in the setting of peripheral artery disease (PAD) (eg, claudication).
Patients with ALI diagnosed via clinical examination should be immediately given anticoagulation (eg, intravenous heparin infusion). Anticoagulation prevents further arterial thrombus propagation, as well as distal arterial and venous thrombosis (from stasis), while the patient undergoes further diagnostic imaging or awaits surgical intervention.
For some patients, anticoagulation may result in clinical improvement. However, many patients require percutaneous thrombolysis (eg, alteplase) or surgical thrombectomy to restore perfusion to the threatened limb.
(Choices A and E) The ankle-brachial index (ABI), the ratio of systolic blood pressure in the ankle compared with that in the arm, can help confirm suspected PAD, and transthoracic echocardiography (TTE) can help identify cardiac sources of emboli (eg, left atrial thrombus due to atrial fibrillation). This patient may eventually benefit from nonurgent ABI evaluation of the right leg, given his history of claudication, and from TTE prior to hospital discharge, given his likely atrial fibrillation. However, these tests should be performed only after his emergent ALI has been treated with intravenous heparin infusion followed by thrombolysis or surgery.
(Choice B) CT angiography of the lower extremities can provide anatomic information about the location of the arterial occlusion and help guide decisions about invasive interventions. However, initiation of systemic anticoagulation (eg, intravenous heparin infusion) should occur first, as soon as the clinical diagnosis of ALI (eg, pulselessness) is made, to prevent further clot propagation while imaging is ongoing.
(Choice D) Surgical bypass grafting is typically used in the setting of chronic PAD to improve distal perfusion past an area of severe or complete atherosclerotic luminal stenosis. In this patient with acute occlusion due to embolus or thrombus, surgical thrombectomy would be more appropriate. Regardless, anticoagulation should be initiated first.
Educational objective:
As soon as acute limb ischemia is clinically diagnosed (eg, pallor, pulselessness), anticoagulation (eg, intravenous heparin infusion) should be initiated. This prevents thrombus propagation and distal thrombosis while the patient undergoes further diagnostic procedures or awaits surgical intervention.