Aortic dissection, intramural hematoma, and penetrating athero- sclerotic ulcer are parts of a spectrum of acute aortic syndromes that represent uncommon - but potentially deadly - diagnoses seen in the emergency department. The differential for acute aortic syndromes is large, as many conditions (including the much more common conditions of acute coronary syndromes and pulmonary embolism) present with many of the same chief complaints. This review looks at the features and classifications of acute aortic syndromes and presents evidence regarding the risk factors and chief complaints that can assist emergency clinicians in identifying the patients who require further investigation. Although no set of clinical factors has been shown to rule out aortic dissection, elements of a complete history and physical examination are critical in identifying patients who may be at risk for these diseases. In addition, the advantages and disadvantages of the various available advanced imaging strategies, the evidence regarding efficacy of laboratory testing (including D-dimer), as well as surgical and nonsurgical treatment options are reviewed.
Key words: aortic dissection, acute aortic syndromes, intramural hematoma, penetrating atherosclerotic ulcer, Marfan syndrome, connective tissue disorders, TEVAR
You are working an overnight shift when EMS arrives with a 55-year-old male with severe substernal chest pain and shortness of breath for the past 2 hours. The patient has a history of hypertension and type II diabetes. His blood pressure is 200/110 mm Hg, and his heart rate is 110 beats/min. A prehospital ECG was performed, which shows ST elevation in leads II and III as well as a VF consistent with an acute myocardial infarction, and you call a STEMI alert. The cardiologist calls back from your STEMI alert and states that she is coming in from home to see the patient. To save time, she wants to meet the patient directly in the heart catheterization lab on the second floor. After you get off the phone, you quickly look at the chest radiograph and notice that the mediastinum appears widened. You wonder if it’s a good idea to start anticoagulation and send the patient to the catheterization lab right away…
The next week, you are working at a free-standing ED where the patients are checking in at record volume. You are getting pressure to see and discharge patients as fast as possible when you see a 21-year-old male presenting with chest pain radiating to his back, along with some shortness of breath. The patient reports no improvement in symptoms with over-the-counter analgesics. The patient plays on the local varsity basketball team. He has no known medical history, and his social history is negative for tobacco, alcohol, or illicit drugs. He appears slightly anxious and has a blood pressure of 155/90 mm Hg and a heart rate of 95 beats/min. He is tall and thin and has reproducible chest tenderness. Your CT scanner has unexpectedly gone down and is unavailable for the rest of the night. ECG shows a normal sinus rhythm without evidence of ischemia and a plain chest radiograph appears normal. As you start to watch your department getting backed up, the nurse states that he is concerned about this patient. You assess the patient as low risk for pulmonary embolism, so you decide to get a D-dimer, which comes back negative. You wonder if this patient has something more significant and what your diagnostic options are…
Over 250 years ago, the first description of aortic dissection was made during an autopsy of King George II after he suddenly died “while straining on the toilet.” Over 60 years later, the term “dissecting aneurysm” was coined by René Laennec, which brought both recognition and confusion to this disease, confusion that persists to the present day.1 In 1955, Dr. Michael DeBakey and his team were the first to successfully repair a dissecting aortic aneurysm; ironically, many years later, Dr. DeBakey himself suffered an acute aortic dissection.1
While the term “dissecting aneurysm” is still used, aortic dissection and aortic aneurysm are 2 distinct disease processes. Acute aortic dissection is part of a spectrum often referred to as acute aortic syndrome. This encompasses not only aortic dissection but also its variants, including aortic intramural hematoma and penetrating atherosclerotic ulcer.1 While aortic dissection usually presents with severe pain, its presentation can be more subtle and should be considered in anyone with chest pain and pain with either syncope or focal neurological deficits.
Aortic dissection is a potentially life-threatening diagnosis, and it requires a heightened suspicion. Unfortunately, the diagnosis of aortic dissection in the emergency department (ED) is missed 16% to 38% of the time.2,3 Litigation surrounding missed aortic dissection has also become more common.4 Morbidity and mortality of aortic dissection is high, and it requires aggressive management to prevent poor outcomes. Mortality for an untreated type A dissection is thought to be approximately 1% to 2% per hour in the first 48 hours, 50% by day 3, and 80% by 2 weeks.1,5 Type B dissection has a mortality of approximately 10% at 30 days for lower-risk patients and up to 70% in high-risk groups.1,6 However, recent advances in surgical repair have greatly improved outcomes in these patients. This issue of Emergency Medicine Practice will discuss nontraumatic aortic dissection and its anatomic variants, intramural hematoma and penetrating atherosclerotic ulcer. A review of the pathophysiology, risk factors, and appropriate imaging for aortic dissection will be discussed. Treatment options, both surgical and nonsurgical, will also be reviewed, including new noninvasive management techniques.
A literature search of Ovid MEDLINE®, PubMed, and the Cochrane Database of Systemic Reviews was performed using the search term aortic dissection. The search was limited to the English language, humans, and adults, from 1993 through July 2013. Abstracts and articles were reviewed for applicability related to the acute management and diagnosis of aortic dissection. Policy statements from the American College of Cardiology Foundation/American Heart Association (ACCF/AHA) (including 8 other societies), the European Society of Cardiology, the Japanese Circulation Society, and the American College of Radiology (ACR) were also reviewed.7-10 Currently, the American College of Emergency Physicians (ACEP) is developing a clinical policy for aortic dissection, but it was not available at the time of writing of this article.
Because of the low incidence of aortic dissection, the majority of literature on this topic comes from registry data such as the International Registry of Acute Aortic Dissection (IRAD). IRAD was established in 1996 and now consists of 30 large referral centers in 11 different countries, and it assesses clinical features, treatment, and outcomes for patients with an acute aortic dissection from this large retrospective database.11 While the IRAD database is one of the most important sources of data on aortic dissection, it is important to understand the limitations of registry data, which include the lack of controls as well as the heterogeneity in data from protocol revisions over time. Other registry data also exist, such as the German Registry for Acute Aortic Dissection Type A (GERAADA), which consists of 50 cardiac centers and includes data for new treatment strategies.12 Very few prospective studies exist in regard to acute aortic dissection, and these studies are generally observational in design. The remaining literature consists of case reports and series.
Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.
To help the reader judge the strength of each reference, pertinent information about the study will be included in bold type following the reference, where available.
Bruce M. Lo, MD, CPE, RDMS, FACEP
December 2, 2013