A 58-year-old man comes to the emergency department with abrupt-onset, severe chest pain that radiates to his back. His blood pressure is 220/130 mm Hg in the left arm and 180/100 mm Hg in the right. His heart rate is 100/min. Initial laboratory studies show normal serum troponin levels. Electrocardiogram is negative for ST-segment changes. This patient's acute condition was most likely triggered by which of the following events?

Question

A 58-year-old man comes to the emergency department with abrupt-onset, severe chest pain that radiates to his back.  His blood pressure is 220/130 mm Hg in the left arm and 180/100 mm Hg in the right.  His heart rate is 100/min.  Initial laboratory studies show normal serum troponin levels.  Electrocardiogram is negative for ST-segment changes.  This patient's acute condition was most likely triggered by which of the following events?

Quizplus · Accepted Answer

11ec160b_38b4_b21c_9249_8b71c6c6f09a_MD0001_00 This patient's presentation is most consistent with aortic dissection, which is characterized by severe retrosternal chest pain radiating to the mid-to-upper back that can move downward as the dissection progresses. It is initiated by a tear in the aortic intima that typically extends for about 1-5 cm in a transverse or oblique direction. The dissection can progress both proximally and distally as blood is forced through the tear, bisecting through the aortic media. Dissections involving any portion of the ascending aorta are classified as type A; those confined to the descending aorta are classified as type B. As the dissecting intramural hematoma spreads along the aortic wall, it can compress major arterial branches. This patient's brachial blood pressure discrepancy suggests compromise of the brachiocephalic trunk servicing his right arm. Hypertension is the primary risk factor for aortic dissection. In many patients with longstanding hypertension, there is medial hypertrophy of the aortic vasa vasorum and, consequently, reduced blood flow to the aortic media. This can cause medial degeneration with a loss of smooth muscle cells, leading to aortic enlargement and increased wall stiffness. Both of these changes exacerbate aortic wall stress, which is already increased due to the hypertension itself. This synergistic increase in aortic wall stress greatly increases the risk of intimal tearing and subsequent development of aortic dissection. (Choice A) An intimal fatty streak is the initial lesion of atherosclerosis. Some fatty streaks progress to frank atheromas, which can progressively weaken the underlying media of the aortic wall. However, atherosclerosis predisposes more to aortic aneurysm formation than to aortic dissection. (Choice C) Monckeberg sclerosis (medial calcific sclerosis) is a form of arteriosclerosis characterized by calcific deposits in the medial layer of muscular arteries. These lesions generally occur in patients age >50 and are thought to cause isolated systolic hypertension due to arterial hardening. (Choices D and E) Aortitis with medial inflammation can be caused by autoimmune conditions such as Takayasu and giant cell arteritis. Tertiary syphilis can also cause a form of aortitis characterized by obliterative endarteritis of the vasa vasorum. These conditions weaken the aortic wall and can predispose to aortic aneurysms and, rarely, dissections. However, hypertension is a more important risk factor for the development of intimal tearing, the primary triggering event of an aortic dissection. Educational objective: Aortic dissection classically presents with severe retrosternal pain that radiates to the back. This condition develops when overwhelming hemodynamic stress leads to tearing of the aortic intima with blood subsequently dissecting through the aortic media. The resulting intramural hematoma can extend both proximally and distally and can compress major arterial branches and impair blood flow. __________ References: Pathogenesis in acute aortic syndromes: aortic dissection, intramural hematoma, and penetrating atherosclerotic aortic ulcer. (http://www.ncbi.nlm.nih.gov/pubmed/12876003)

A 58-Year-Old Man Comes to the Emergency Department with Abrupt-Onset