A 32-year-old woman is hospitalized with left leg pain and swelling two weeks after an uneventful vaginal delivery of a healthy baby girl. She is diagnosed with a left lower extremity deep venous thrombosis and is started on intravenous heparin. On the second day of her hospitalization, she develops left-sided weakness and a facial droop. A non-contrast CT scan of the head reveals no intracranial bleeding but suggests an ischemic infarction in the territory of the right middle cerebral artery. Which of the following is most likely to reveal the cause of this patient's symptoms?

Question

A 32-year-old woman is hospitalized with left leg pain and swelling two weeks after an uneventful vaginal delivery of a healthy baby girl.  She is diagnosed with a left lower extremity deep venous thrombosis and is started on intravenous heparin.  On the second day of her hospitalization, she develops left-sided weakness and a facial droop.  A non-contrast CT scan of the head reveals no intracranial bleeding but suggests an ischemic infarction in the territory of the right middle cerebral artery.  Which of the following is most likely to reveal the cause of this patient's symptoms?

Quizplus · Accepted Answer

Explanation: This young woman has a new ischemic stroke in the setting of a lower extremity deep venous thrombosis (DVT), suggesting that a paradoxical embolus may be responsible. Typically, embolic strokes occur when a mural thrombus from the left atrium or a plaque from a carotid artery embolizes and lodges in the cerebral circulation. However, patients may develop embolic strokes with origins in the venous system as well. This can occur when an intracardiac communication like a patent foramen ovale or atrial septal defect is present and allows a dislodged venous clot to travel into the arterial circulation. These so-called paradoxical emboli are often responsible for embolic strokes in younger patients. A transthoracic or transesophageal echocardiogram with a bubble study will reveal such an intracardiac shunt. (Choice A) There is no physical exam evidence of a right lower extremity DVT. Moreover, a right lower extremity DVT would not put her at significant risk of an embolic stroke unless she had an intracardiac communication. (Choice B) Venography can be used diagnose lower extremity DVTs when the diagnosis is unclear. As described above, there is little to suggest a right lower extremity DVT and, even if one was present, there would also have to be an intracardiac communication for it to cause a stroke. (Choice C) Carotid artery atherosclerosis increases one's risk of developing a stroke. It is more common in older patients than in young ones, and this patient already has a compelling embolic source. (Choice E) 24-hour cardiac monitoring is used to diagnose arrhythmias. Atrial fibrillation is a leading cause of embolic strokes; however, this young woman who developed a stroke in the setting of a lower extremity DVT is more likely to be suffering from a paradoxical embolus. Educational objective: Paradoxical emboli are those that originate in the venous system and enter the arterial system via an intracardiac shunt. They are a more common cause of stroke in the young than in the elderly. They can be diagnosed with an echocardiogram and bubble study.

A 32-Year-Old Woman Is Hospitalized with Left Leg Pain and Swelling