Review Question - QID 214280

This patient's acute left-sided weakness and evidence of infarction on CT head is concerning for an acute ischemic stroke. She likely has an intracardiac shunt that allowed a clot from the venous system (from her likely deep vein thrombosis given her exam) to enter the arterial system and cause a stroke.

Atrial septal abnormalities, such as a patent foramen ovale (PFO) place patients at risk of developing an acute ischemic stroke. In patients with an atrial septal defect or PFO, they allow for clots in the venous circulation to enter the arterial circulation (paradoxical emboli), leading to a stroke. Risk factors for developing a clot in the venous circulation include oral contraceptive use and prolonged immobilization. An echocardiogram with bubble study is the diagnostic study of choice for evaluating atrial septal abnormalities. The echocardiogram with bubble study (transthoracic or transesophageal) is performed with agitated normal saline in order to detect right-to-left shunting. If atrial septal abnormalities are associated with acute ischemic stroke, treatment options include antithrombotic therapy versus closure of the atrial defect.

Jolobe et. al review paradoxical embolism. They describe the pathophysiology behind this phenomenon and discuss evaluation and management. They recommend evaluation with echocardiography for patients with suspected stroke due to paradoxical emboli.

Incorrect Answers:
Answer 1: Carotid ultrasound would determine if there is evidence for carotid atherosclerosis that could result in stroke. Carotid atherosclerosis is uncommon in patients in their 20s, and this patient's history suggests that her stroke likely stemmed from a deep vein thrombosis.

Answer 2: CT angiography of the head and neck will determine if there is intracranial or extracranial atherosclerosis. Evidence of atherosclerosis is most common in the elderly. CT angiography can evaluate for an occlusion in the proximal circulation which would determine if the patient needs mechanical thrombectomy. Evidence of a clot in the proximal circulation would not elucidate the cause of her stroke.

Answer 4: Electrocardiogram is typically included in the work up of acute stroke, to screen for arrhythmia, such as atrial fibrillation. While this patient would likely have an electrocardiogram obtained as part of her evaluation, her history is not suggestive of atrial fibrillation or other arrhythmia as a cause of her stroke.

Answer 5: Lipid panel is typically included in the work up of acute stroke to screen for underlying hypercholesterolemia or other disorders of lipid metabolism. While this patient would likely have a lipid panel as a part of her evaluation, her history is more suggestive of a deep venous thrombosis as the cause of her stroke.

Bullet Summary:
The presence of a patent foramen ovale or other atrial septal defect may allow for deep venous thromboses to enter the arterial circulation causing stroke, and are best evaluated with echocardiography with a bubble study.