Aortic Dissection Presenting as a STEMI

Abstract

Audience: This scenario was developed to educate emergency medicine residents on the presentation and management of a patient with a Stanford type A aortic dissection.

Introduction: Chest pain is one of the most common chief complaints seen in the emergency department with a deadly differential diagnosis list. A "can't miss" diagnosis, aortic dissection occurs when an intimal tear creates a false lumen in the aorta, with a variably reported incidence of approximately 2.5-5 per 100,000 person-years.1 This amounts to an estimated 8,000-16,000 cases per year in the United States with a mortality likely underestimated due to prehospital death ranging from 20-40% within 24 hours and 30-50% at 5 years.2,3,4 There is a reported increase in mortality by 1% for every hour the diagnosis is delayed, and half of diagnoses are made greater than 24 hours after presentation.5 The symptoms can range from chest pain to back pain, abdominal pain or extremity pain, to syncope or isolated neurologic deficits, even to shock or cardiac arrest.6 Aortic dissection is most commonly categorized into two groups: Stanford type A, involving the ascending aorta, and Stanford type B, involving only the descending aorta, and are generally managed surgically vs. medically respectively based on this paradigm.7,8 Stanford type A can be complicated by severe aortic regurgitation, pericardial tamponade or coronary artery occlusion mimicking ST-segment elevation myocardial infarction (STEMI). These potentials make it important to switch from heuristic to analytical thinking when developing a differential diagnosis.9 A high index of suspicion with early recognition and management is critical in this catastrophic disease state, especially given the propensity for complications and a wide variety of presentations.

Educational objectives: At the conclusion of the simulation session or during the debriefing session, learners will be able to: 1) Verbalize the anatomical differences and management of Stanford type A and type B aortic dissections, 2) Describe physical exam findings that may be found with ascending aortic dissections, 3) Describe the various clinical manifestations of the propagation of aortic dissections, 4) Discuss the management of aortic dissection, including treatment and disposition.

Educational methods: This session was conducted using a simulation scenario with a high-fidelity manikin as the patient and confederate/actor in the nursing role, followed by a post-scenario debriefing session on the presentation, differential diagnosis, potential physical exam findings, and management of patients with aortic dissection. Debriefing methods may be left to the discretion of the educators, but the authors have utilized advocacy-inquiry techniques.10 This scenario may also be run as an oral board examination case.

Research methods: The residents are provided an electronic survey at the completion of the debriefing session to anonymously rate different aspects of the simulation, as well as provide qualitative feedback on the scenario. This survey is specific to the local institution's simulation center.

Results: Twenty learners completed a feedback form. This session received all 6 and 7 scores (consistently effective/very good and extremely effective/outstanding, respectively) other than one isolated 5 score. The lowest average score was 6.5 for, "Before the simulation, the instructor set the stage for an engaging learning experience," and the highest average score was 6.84 for, "The instructor identified what I did well or poorly - and why." Feedback from the residents was overwhelmingly positive (available upon request). All groups initially gave aspirin upon identification of the STEMI and several gave heparin. Debriefing topics included STEMI mimics, physical exam findings for aortic dissection, imaging and laboratory workup for aortic dissection, blood pressure and heart rate goals and pharmacologic management, uncomplicated STEMI management, and Type I versus Type II decision-making.

Discussion: This is an easily reproducible method for reviewing management of patients with aortic dissection. There are multiple potential presentations and complications of aortic dissections to further customize the experience for learners' needs. While it was discussed during debriefing that heparin administration was unlikely to cause immediate cardiopulmonary arrest, this state was included to reflect downstream hemorrhagic complications that may occur in the setting of antiplatelet administration for acute aortic dissection. Facilitators may choose to omit the arrest at their discretion.

Topics: Medical simulation, emergency medicine, aortic dissection, ST-elevation myocardial infarction, cardiovascular emergencies, hypertensive emergencies, STEMI mimics, vascular surgery, cardiothoracic surgery.