1. Aortic Dissection By Hari Bhatt

2. Definition Aortic dissection is an acute event where blood enters the aortic wall through a tear of the intima followed by extravasation of blood into the media. Currently believed the process begins with an intramural hematoma

3. etiology Degenerative Hypertension Pregnancy Skeletal (scoliosis) Connective tissue (Marfan’s) Mycotic aneurysm Takayasu (giant cell) arteritis Aortic laceration/coarctation

4. Classification DeBakey: I –ascending aorta --> arch +/- descending aorta II –ascending aorta only III –descending aorta --> thoracic aorta

5. Classification (cont.) More commonly used is the Stanford classification, better linked to clinical outcome Type A: involves the ascending aorta acute, 70% mortality Type B: not involving the ascending aorta, chronic tx. conservatively

6. Schematic A/B

7. Type B Dissection a) Increased soft tissue shadow beyond the aortic knuckle, b) one year before

8. Type A dissection A medical emergency Imaging may include –Chest radiograph –TOE best accuracy, in skilled hands, however more invasive –MRI- ok if pt. stable, otherwise not used in acute scenario, good at showing early intramural hematoma –CT- disadvantage restricted to single axial plane, motion artifacts of the aortic root

9. CT/MRI side by side

10. MRI of Type A dissection

11. Which imaging study works?? In a large and well constructed study by Nienaber et. al. TOE, TTE, CT, MRI were compared in pt’s with suspected acute aortic dissection. -the results showed that for sensitivity: TOE (97.7%), TTE (59.3%), CT (93.8%), MRI (98.3%) -as for specificity: TOE (77.0%), TTE(83.0%), CT (87.1%), MRI (97.8%)

12. References Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging, 4th ed., Copyright © 2001 Churchill Livingstone, Inc. CHORUS (Hypertext of Radiology) Nienaber C A, von Kodolitsch Y, Nicolas V et al 1993 The diagnosis of thoracic aortic dissection by noninvasive imaging procedures. N Engl J Med 328: 1–14