Stanford Type B dissections are usually managed medically unless there is aortic rupture, ischemic bowel/extremities, or uncontrollable hypertension. Mortality for Stanford Type B dissections with medical management is 13%. Endovascular stenting is increasingly popular and used in patients previously not considered for open surgery. Preliminary studies with endovascular stenting of Stanford Type B dissections show 5% inhospital mortality, with 11% experiencing life-threatening complications, including aorto-esophageal fistula and transformation into Stanford Type A dissection. Ninety percent survive at 1 year, and 12% require reintervention.2
Explore This IssueACEP News: Vol 28 – No 07 – July 2009
Undifferentiated patients with chest pain presenting to the emergency department ultimately can be diagnosed with MI, PE, or AAD (among many other less serious diagnoses). Although treatment of PE and MI both involve anticoagulation, this therapy given to patients with a missed diagnosis of AAD carries the risk of potentially fatal hemorrhage. Antiplatelet therapy theoretically carries a similar risk, but no studies have demonstrated poor outcomes in AAD patients. While empiric antiplatelet therapy is still indicated in chest pain patients with suspicion for acute coronary syndrome, emergency physicians should withhold thrombolytic and fibrinolytic agents until they sufficiently evaluate the risk of AAD with clinical assessment and, if necessary, advanced imaging.27
d-dimer has been evaluated in several small trials as a specific laboratory marker to rule out aortic dissection without the need for advanced imaging. Limitations of these studies include small size, variable cutoffs, and many false negatives (completely thrombosed dissection lumens, shorter dissection lengths, young subject age). Pooled sensitivity in 11 studies was 94%, with a negative likelihood ratio of 0.15.28 Until larger prospective trials with fixed threshold values have been evaluated, d-dimer cannot be recommended for use in evaluation of AAD.29
Acute aortic dissection is a rapidly fatal disease, necessitating emergent evaluation and management. Patients often present with sudden onset of severe chest pain radiating to the back, but atypical symptoms are common. Clinical suspicion based on history, asymmetric pulses/blood pressure or abnormal CXR warrants advanced imaging with CT or TEE. No single laboratory test, historical feature, or physical finding can safely rule out AAD. Optimal management hinges on aggressive blood pressure and heart rate control, avoidance of anticoagulation, and timely surgical consultation.
Dr. Aldeen is an assistant professor and the assistant residency director in the Department of Emergency Medicine at Northwestern University Feinberg School of Medicine. Dr. Rosiere is a resident physician in the Department of Emergency Medicine at Northwestern University Feinberg School of Medicine. Medical Editor Dr. Robert C. Solomon is an attending emergency physician at Trinity Health System in Steubenville, Ohio, and clinical assistant professor of emergency medicine at the West Virginia School of Osteopathic Medicine.