A 42-year-old man comes to the emergency department due to severe chest pain that started abruptly 2 hours ago. The pain is midline, constant, and 10/10 in intensity. He has had no fever, cough, or shortness of breath. His only medical condition is hypertension. On examination, the patient is diaphoretic and is in severe distress due to pain. Temperature is 37 C (98.6 F), pulse is 116/min, and respirations are 24/min. Systolic blood pressure is 82 mm Hg in the right arm and 60 mm Hg in the left arm. Jugular veins are distended with an estimated pressure of 13 cm H₂O. The lungs are clear to auscultation. The point of maximal impulse is not palpable. The extremities are cold with no peripheral edema. The patient develops cardiac arrest and dies soon after arrival. Autopsy would most likely reveal which of the following findings?

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11ec160b_38b6_d4ff_9249_c9dfd7178b01_MD0001_00 This patient's presentation is most consistent with an ascending aortic dissection complicated by cardiac tamponade. Dissections can affect the ascending aorta (type A) or may involve only the descending aorta (type B). The most common symptom is sharp or tearing chest and back pain that is severe and sudden. If an ascending dissection extends proximally to the aortic root, it can affect the coronary ostia or aortic valve, resulting in myocardial ischemia or aortic regurgitation, respectively. Other signs and symptoms include blood pressure asymmetry, stroke, or paraplegia, depending on the vessels and structures involved (eg, subclavian artery, carotid artery, spinal arteries). In addition, a dissection may extend proximally into the pericardium, causing blood to fill the pericardial space and leading to acute tamponade. As blood accumulates, the rising pericardial pressure can rapidly supersede right-sided filling pressures and restrict venous return, resulting in a precipitous drop in cardiac output and obstructive shock that can lead to cardiac arrest. Signs of tamponade include jugular venous distension, muffled heart sounds, and hypotension (Beck triad), as well as reduced point of maximal impulse, cool extremities, and clear lungs. (Choice A) Air in the pleural space is expected with tension pneumothorax, which can cause obstructive shock due to mediastinal shifting with vena cava collapse and impaired venous return to the heart. Although sudden-onset chest pain is common, shortness of breath and unilaterally absent breath sounds are expected. (Choice C) A ruptured posteromedial papillary muscle causes acute mitral regurgitation, which can abruptly lead to cardiogenic shock. Patients are expected to have shortness of breath and lung crackles due to acute pulmonary edema. (Choice D) A saddle pulmonary thromboembolism can cause obstructive shock with right ventricular failure and jugular venous distension. However, it would not account for upper extremity blood pressure asymmetry or distant heart sounds. (Choice E) Transmural necrosis of the anterolateral myocardium can cause left ventricular free wall rupture with patients developing acute tamponade as blood rapidly fills the pericardium. This etiology of tamponade would not explain upper extremity blood pressure asymmetry. Educational objective: Acute aortic dissection typically presents with sudden-onset, severe chest pain that is sharp or tearing in nature. Upper extremity blood pressure asymmetry can result from extension of the dissection plane into the subclavian artery, and additional complications (eg, stroke, myocardial ischemia) can result from extension into other vessels. Extension into the pericardium can cause acute tamponade with reduced cardiac output and shock. __________ References: Screening, evaluation, and early management of acute aortic dissection in the ED. (http://www.ncbi.nlm.nih.gov/pubmed/22708909)

A 42-Year-Old Man Comes to the Emergency Department Due to Severe