NURS 6501: MIDTERM EXAM: Please contact Your Favorite Professor for help with   NURS 6501: Midterm Exam or any other assignment. Email: professorrobertphd@gmail.com An elderly patient with a history of atrial fibrillation presents with sudden onset of right-sided weakness and aphasia. Which is the most likely source of the embolus causing this patient's symptoms? Group of answer choices

• Carotid artery atherosclerotic plaque
• Cardiac thrombus from the left atrium
• Thrombus from a deep vein thrombosis
• Right ventricular thrombus post-myocardial infarction

  The correct answer is Cardiac thrombus from the left atrium. Explanation: The patient's symptoms of right-sided weakness and aphasia are suggestive of a stroke affecting the left hemisphere of the brain (since aphasia, which is a language disorder, is typically associated with left-sided brain damage). Given the patient's history of atrial fibrillation (AF), the most likely source of the embolus causing the stroke is a cardiac thrombus from the left atrium. In atrial fibrillation, the irregular heart rhythm leads to poor blood flow and stasis in the left atrium, particularly in the left atrial appendage, where clots are more likely to form. These clots can then be pumped out of the heart and travel through the bloodstream, causing an embolic stroke. If the embolus travels to the right side of the brain, it can result in right-sided weakness and potentially aphasia (if the embolus affects areas controlling language). Why the other options are less likely:

• Carotid artery atherosclerotic plaque: Atherosclerotic plaque in the carotid artery can lead to ischemic stroke, but this typically presents with contralateral weakness (i.e., weakness on the opposite side of the plaque). The symptoms in this patient (right-sided weakness) are more consistent with an embolus from the heart.
• Thrombus from a deep vein thrombosis (DVT): While a thrombus from a DVT can lead to a pulmonary embolism, which causes respiratory symptoms, it is not typically associated with causing ischemic strokes unless it is paradoxically embolized through a patent foramen ovale. However, this is a less common scenario compared to emboli originating from the heart in patients with atrial fibrillation.
• Right ventricular thrombus post-myocardial infarction: A right ventricular thrombus is much less likely to cause a stroke because emboli originating from the right side of the heart typically go to the lungs (causing pulmonary embolism) rather than to the brain.

Conclusion: The most likely source of the embolus in this patient with a history of atrial fibrillation and sudden-onset stroke symptoms is a cardiac thrombus from the left atrium.