A 59-year-old man with a history of hypertension presented with sudden onset dizziness and lower back pain. He reported that his pain was radiating to the right buttock and that he was lightheaded. He was a lifelong smoker and denied any known history of coronary artery disease, heart failure, or diabetes. Review of systems was negative for syncope, chest pain, shortness of breath, and abdominal pain.
The patient's vital signs were blood pressure of 95/59 mm Hg, pulse of 60 bpm, respiratory rate of 18 bpm, oxygen saturation of 96%, and temperature 37°C.
His initial physical examination was relatively unremarkable: lungs clear to auscultation, no murmurs, rubs, or gallops, a benign abdomen, well perfused extremities with palpable pulses, and an unremarkable neurologic exam.
His ECG demonstrated sinus bradycardia, and bedside ultrasound showed the results in the photo. What is your initial concern for this patient?
Find the diagnosis and case discussion on p. 14.
Diagnosis: Aortic Dissection
These ultrasound images demonstrate an aortic flap concerning for aortic dissection, and a CT angiogram of the chest and abdomen demonstrated a type A aortic dissection.
Vascular surgery was consulted, and the patient was urgently taken to the operating room, where thoracic endovascular aortic repair (TEVAR) was performed. His recovery was unremarkable, and he was discharged home five days later.
Acute aortic dissections fall within the scope of acute aortic syndromes in which blood enters the medial layer of the aortic wall and results in a false lumen. (Circulation 2003;108:628.) Other acute aortic syndromes include intramural hematomas and penetrating atherosclerotic ulcers.
Aortic dissections are classically categorized into types A and B, according to the Stanford system. Type A dissections involve the ascending aorta and usually warrant surgical treatment, while type B dissections involve the aorta beyond the left subclavian artery and are typically medically managed with antihypertensives. Exceptions to this include branch occlusion, leak, and persistent extension despite medical management. (Eur J Vasc Endovasc Surg 2013;46:175.)
Patients at higher risk of developing an aortic dissection include but are not limited to those with hypertension (including abrupt catecholamine-induced hypertension secondary to stimulant use), patients with a history of aortic surgery or structural abnormalities (such as bicuspid aortic valve, aortic coarctation, or aortic dilatation/aneurysm), those with recent cardiac catheterization, patients with arteritis such as Takayasu or giant cell, and patients with genetic predispositions such as Ehlers-Danlos syndrome type IV, Turner syndrome, or Marfan syndrome. (Circulation 2003;108:628.)
Syncope is a less common but ominous sign in these cases, according to the International Registry of Acute Aortic Dissection (IRAD) study. (JAMA 2000;283:897.) Cardiac tamponade or brachiocephalic vessel involvement is more common in cases where syncope is one of the presenting features. Aortic regurgitation is also a common exam finding for type A dissections. (Eur J Vasc Endovasc Surg 2013;46:175.)
A common misconception is that patients with aortic dissection will be hypertensive; it is seen in up to 70 percent of descending aortic dissections while hypotension at initial presentation is a more common initial presentation in patients with ascending aortic dissection. (JAMA 2000;283:897.) If hypotension is present, also look for isolated limb involvement, tamponade, myocardial infarction (classically inferior distribution from right coronary artery involvement), or aortic rupture. Focal neurologic deficits, which are generally secondary to the dissection extending proximally or distally or as a pulse deficit, are also uncommon findings on initial presentation. (Circulation 2004;109:3014.)
The most expeditious mode of diagnostic testing is a bedside TEE to diagnose the hemodynamically unstable patient with concern for aortic dissection. A chest radiograph can be falsely reassuring in up to 16 percent of cases. A widened mediastinum is present in only 56-63 percent of cases and an abnormal aortic contour in 48 percent of presenting patients.
Management in the ED is primarily focused on hemodynamics. Initial beta blockade for a target heart rate of 60-80 bpm theoretically minimizes increased aortic wall stress from reflexive tachycardia prior to the initiation of vasodilators (systolic blood pressure goal of 100-120 mm Hg).
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