We’re back with a USMLE® Step 2 CK Question of the Day! Today’s case involves a 66-year-old man with sharp chest pain. What would be the most appropriate definitive treatment for this patient’s condition?
A 66-year-old man presents to the emergency department with sudden onset sharp chest pain radiating to the back. The patient reports he has a history of long-standing hypertension, but he has not taken his medications in quite some time. His temperature is now 37.0°C (98.6°F), pulse is 120/min, respirations are 23/min, blood pressure is 85/60 mmHg, and oxygen saturation is 94% on room air. Physical examination shows 1+ peripheral pulses in the right upper extremity and 2+ pulses in the left upper extremity. Neurological examination shows 3/5 power in the left upper and lower extremities compared to 5/5 power in the right upper and lower extremities. Cardiovascular examination reveals muffled heart sounds. An ECG is obtained, which shows non-specific T-wave changes as well as electrical alternans. Non-contrast CT-brain is normal. Which of the following is the most appropriate definitive treatment for this patient’s condition?
A. Open vascular repair
B. IV esmolol
C. Thrombolytic therapy
D. Coronary revascularization
E. PericardiocentesisScroll down for the correct answer!
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The correct answer to today’s USMLE® Step 2 CK Question is…
A. Open vascular repair
Before we get to the Main Explanation, let’s see why the answer wasn’t B, C, D or E. Skip to the bottom if you want to see the correct answer right away!
Incorrect answer explanations
Today’s incorrect answers are…
B. IV esmolol
Incorrect: Blood pressure management is the definitive therapy for type B aortic dissections, which occur distal to the ligamentum arteriosum and involve only the descending aorta. The patient in this vignette has concerning features for pericardial tamponade given the muffled heart sounds and the electrical alternans on ECG. Pericardial effusions and subsequent tamponade are uncommon sequelae of type B aortic dissections and more common with type A aortic dissections.
C. Thrombolytic therapy
Incorrect: Thrombolytic therapy may be the treatment for an ischemic stroke or massive PE; however, the definitive treatment for this patient’s condition is endovascular repair of the ascending aorta. While PE is possible, the patient is this vignette is not hypoxic, and no signs of right ventricular strain are noted on his ECG, making the diagnosis of a massive PE less likely. The patient in this vignette is likely suffering a stroke from an aortic dissection; however, administration of thrombolytics in this situation may precipitate uncontrolled bleeding into the dissection and worsen the hemodynamic compromise.
D. Coronary revascularization
Incorrect: While aortic dissections can mimic findings of acute MI due to compression on the coronary vessels, definitive therapy for type A aortic dissection involves endovascular repair of the ascending aorta. Patients with a true MI usually present with dull, pressure-like pain, worsened on exertion, and relieved with rest or nitroglycerin. Neurologic deficits are an uncommon feature of isolated myocardial infarctions.
E. Pericardiocentesis
Incorrect: The patient in this vignette does have exam features concerning for pericardial tamponade, including electrical alternans, muffled heart sounds, hypotension and tachycardia. While pericardiocentesis may improve this patient’s hemodynamic instability, the definitive treatment for this patient’s condition involves repair of the aorta to prevent further pericardial tamponade.
Main Explanation
The patient in this vignette has concerning features for an aortic dissection including sudden onset, sharp chest pain radiating to the back, with associated findings of hypotension, pericardial tamponade, myocardial infarction, and focal neurologic deficits.
Aortic dissections are caused by longitudinal cleavage of the aortic media created by a dissecting column of blood. They are a potentially catastrophic vascular complication that can cause end organ ischemia to a variety of organs – namely the brain and the heart. Aortic dissections are divided into two categories: Stanford type A and Stanford type B. Stanford type A dissection involves the ascending aorta and more commonly leads to hypotension, pericardial tamponade, stroke, and myocardial infarction (MI). The definitive management of Type A dissection is surgical repair.
Stanford type B dissections occur distal to the ligamentum arteriosum and involve only the descending aorta. Type B dissections can also present with stroke-like symptoms, if for example the dissection were to progress retrograde and involve the left common carotid artery; however, this would produce right sided weakness, as opposed to left sided weakness seen in this patient. Type B dissections rarely dissect retrograde to yield tamponade, but they can progress anterograde to compromise blood flow to the renal arteries, resulting in acute renal failure. The definitive therapy for Stanford type B dissections is blood pressure control with either beta blockers, like esmolol, or vasodilators.vasodilators.
Major Takeaway
Stanford type A aortic dissections involve the proximal aorta and are treated with emergent surgical repair. Stanford type B aortic dissections occur distal to the ligamentum arteriosum and are treated by strict blood pressure control.
References
Cambria RP. Surgical treatment of complicated distal aortic dissection. Semin Vasc Surg. 2002;15(2):97‐107. doi:10.1053/svas.2002.33439
Kumar, V., Abbas, A. K., Aster, J. C., & Robbins, S. L. (2013). Robbins Basic Pathology Philadelphia: Elsevier/Saunders
Curry, M. (2017, May 18). Rosen’s Emergency Medicine: Concepts and Clinical Practice. Retrieved from https://www.us.elsevierhealth.com/rosens-emergency-medicine-concepts-and-clinical-practice-9780323354790.html.
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