Author: Nicole Anthony, MD

Aortic dissections are difficult to diagnose in a timely manner for a variety of reasons, chief among those being the variability in presenting symptoms from one patient to the next: “I have chest pain, and my right side doesn’t work” or “I have abdominal cramping and my foot is cold.” This “vague symptomatology” becomes not so vague or surprising if you familiarize yourself with the anatomy of the aortic dissection and the many malperfusion syndromes that complicate up to 20-30% of all aortic dissections.[1]

There is a common paradigm in emergency medicine regarding aortic dissections known as “chest pain plus…”–that patients with chest pain complicated by another (often seemingly unrelated) complaint, such as chest pain PLUS arm weakness, should raise your index of suspicion for aortic dissection. The following post will elucidate the pathophysiology of the “plus” symptoms one can expect to see in complicated aortic dissections.

 

aortic dissection

Figure 1. Illustration of potential sites of dissection along the aorta and likely dissection morphology predicated on proximity to major branching vessels.[2]

A dissection flap can extend into and occlude any branch of the aorta with dramatically different phenotypes depending on the vessels involved. Further, dissections can be classified as static or dynamic, as determined by dissection flap morphology. The dissection is termed static if it completely occludes the branch ostium leading to secondary thrombus formation (Figure 2A below). Static dissections tend to cause continuous symptoms with little to no variation. A dynamic dissection is one in which the flap intermittently occludes the branching vessel, usually coinciding with increased shear forces, such as seen during cardiac systole or higher blood pressures (Figure 2B). Symptoms caused by a dynamic dissection can wax and wane and should, theoretically, improve with reduced heart rate and blood pressure.
Williams et al used aortography to evaluate the mechanism of dissections with malperfusion syndromes and found that the vast majority of dissection flaps were dynamic with intermittent prolapse of the flap into the vessel branch ostium.[3] Simply put, we should expect that the hard signs we rely so heavily on to help us make this diagnosis (such as pulse deficits) can wax and wane throughout the patient’s visit.

 

aortic dissection

Figure 2. (A) Static prolapse of intimal dissection flap into vessel branch ostium with secondary clot formation. (B) Mobile intimal dissection flap with intermittent prolapse into vessel branch ostium (more common).[4]

Without further ado, let’s discuss the many malperfusion syndromes that you can expect to see as a result of aortic dissection.

Cerebral Malperfusion

Incidence: 6-14% of Type A Aortic Dissections (TAAD)[5]
Mechanism:
– Occlusion of arch vessels (either brachiocephalic artery or left carotid) by dissection flap
– False lumen thrombus embolizing to the brain
– Hypoperfusion event as a result of profound hypotension or cardiac tamponade

 

aortic dissection

Figure 3. Evolution of ischemic stroke in a patient with occlusion of left carotid by an aortic dissection flap. (A) Dissection flap visualized in all vessels of the aortic arch. (B) Dissection flap involving the left carotid with partial occlusion. (C) Subacute ischemia pre-extra-anatomic bypass. (D) Ischemic stroke with hemorrhagic conversion post-intervention.[6]

 

Myocardial Malperfusion Syndrome

Incidence: 10-15% of TAAD[5]
Mechanism:
– Coronary artery occlusion by dissection flap or extension

– Coronary artery disruption

Right Coronary Artery Involvement

There are three mechanisms by which coronary artery involvement can result in coronary malperfusion: obstruction of the coronary artery by the dissection flap, extension of the dissection into the coronary artery (as pictured below), and coronary artery disruption (or rupture).

In a retrospective study at a single, tertiary care hospital, only five patients out of 159 patients (3.1%) with acute type A aortic dissections were found to have involvement of the RCA. All five of those patients, however, followed the predictable pattern of RCA malperfusion/occlusion with ST-segment elevations in II, III, and aVF, making it easily mistakable for an OMI.[7] Although the sample size was quite small, this ECG pattern has been observed in numerous other case reports of aortic dissections with RCA involvement.[8-11]

 

aortic dissection

Figure 4a. Dissection into valve with flap occluding right coronary artery. [12]

Figure 4b. ECG notable for ST-elevations in leads II, III, aVF. Patient found to have a type A aortic dissection with disruption of the right coronary artery.[7]

 

 

 

 

Left Coronary Artery Involvement

Dissections with left coronary involvement are less likely, and although they also tend to show ST-elevations on ECG, they are less predictable than RCA occlusions in their pattern.[7,13]

 

Figure 5. ECG of a patient with aortic dissection into the left coronary artery with ST-elevations in aVL, aVR, V2, and V6 and depressions in II, III, and avF.[13]

Special Cases

Cardiac tamponade

Incidence: 20-36% of TAAD[14]
Mechanism:
– Rupture of adventitia in the ascending aortic artery
– Cardiac rupture

 

aortic dissection

Figure 6. Rupture of the adventitia creating a contiguous space between the pericardium and the false lumen of the ascending aorta.[15] Small-volume, controlled pericardiocentesis can be used to improve hemodynamics, but one should expect the hemopericardium to reaccumulate.

Aortic Regurgitation
Incidence: 50%-66 of TAAD[16]
Mechanism: Dilation of the aortic root
Aortic insufficiency in aortic dissection can present as a new early diastolic murmur (sensitivity 20.6%, specificity 97.8%, LR- 0.81, LR+ 9.41) and a narrowed pulse pressure.[17] Although aortic insufficiency in this context is a cause for concern insofar as it is a marker of aortic aneurysm versus dissection, it is the only complication that does not have an association with long-term morbidity or mortality in aortic dissection.

Renal Malperfusion

Incidence: Approximately 8% of all aortic dissections[18,19]
Mechanism:
– Dissection into the renal artery
– Occlusion of vessel by dissection flap
– Thrombus
– Compression of the left renal vein by the enlarged aorta (“Nutcracker Syndrome”)

Symptoms and signs of renal artery involvement include flank pain and hematuria. In a patient with known renal artery involvement, keep a high index of suspicion for renal malperfusion, especially in the context of worsening kidney function or progressively uncontrolled hypertension.

 

aortic dissection

Figure 7. Left renal artery arising from the false lumen with subsequent poor perfusion of the left kidney as evidenced by non-enhancement.[20]

Mesenteric Malperfusion

Incidence: 4-6% of all aortic dissections[5,21]
Mechanism:
– Occlusion of Celiac and Mesenteric Arteries by the dissection flap[22]
– Thrombus in false lumen
– Dissection into the Celiac and/or Mesenteric Arteries

The most common symptoms of malperfusion due to aortic dissection include abdominal pain, nausea, vomiting, and diarrhea; however, up to 40% of patients with this malperfusion syndrome do not have any abdominal pain. This is especially concerning when considering that mesenteric malperfusion is a strong predictor of mortality with up to two-thirds of patients dying during hospitalization.[5]

 

 

aortic dissection

Figure 8. Total collapse of the true lumen with malperfusion of the celiac and superior mesenteric arteries.[5]

 

Spinal Malperfusion 

Incidence: 4% of all aortic dissections[23]
Mechanism:
– Radiculolumbar arteries originating in the false lumen. The anterior cord at the T10-T12 level (Artery of Adamkiewisz) is a watershed area and most often involved[24]
– Thrombosis
– Hypoperfusion event as a result of profound hypotension

 

Figure 9. Illustration of the territory supplied by the Artery of Adamkiewicz and subsequent tracts that might be involved in spinal cord ischemia.[25]

Spinal malperfusion is one of the least common malperfusion syndromes that complicates aortic dissection and can present with varying severity, ranging from decreased motor strength to complete limb paralysis, urinary retention, and paresthesias. Painless motor deficits occur in less than 1% of aortic dissections.[26] The spinal cord is more sensitive to sudden changes in perfusion pressures and thus, neurological symptoms may precede “typical” symptoms of aortic dissection.
aortic dissection

Figure 10a. CTA shows thrombus in the thoracic aorta in a patient who presents with mild neck pain, bilateral lower extremity numbness & flaccid paralysis, poor rectal tone, and urinary retention.[27]

aortic dissection

Figure 10b. MR is notable for abnormal signal in the conus medullaris, likely indicative of spinal ischemia.[27]

Limb Malperfusion

Limb ischemia secondary to aortic dissection typically presents with pain, signs of decreased perfusion, paresthesias, and/or weakness. The lower extremities are more often involved than the upper extremities.[28] In over half of cases with lower limb ischemia due to aortic dissection, both lower extremities are involved.[29] Pulse deficits are only 30% sensitive in detecting thoracic aortic dissection and should not be used to rule out dissection.[30]

Upper Limb Ischemia

Incidence: 1-4% of TAAD and more likely to involve the right rather than the left upper extremity[28]
Mechanism:
– Obstruction of vessel by flap
– Thrombosis
– Decreased flow due to blood supply from false lumen

 

aortic dissection

Figure 11. Absent filling of the brachiocephalic trunk in a patient with a proximal aortic dissection.[31]

Lower Limb Ischemia

Incidence: 4-23% of TAAD[19,28] and 6% of Type B dissections[32]
Mechanism:
– Obstruction of iliac artery or aortic obstruction by dissection flap
– Thrombosis
– Decreased flow due to origination of artery in false lumen

 

aortic dissection

Figure 12. A patient presenting with right leg pain found to have a type A dissection and right common iliac artery thrombosis with complete occlusion.[33]

Final Words

– Consider aortic dissection in “chest pain + ____” patients.
– Physical exam findings (such as weakness and pulse deficits) can be waxing and waning.
– Malperfusion syndromes complicate 25-30% of all aortic dissections.
– Symptoms of malperfusion syndromes can overlap and more than one major vascular bed can be involved.
– Although type B dissections are typically managed non-operatively, the presence of a concurrent malperfusion syndrome warrants evaluation for operative management.

Extra

– EM:RAP’s March 2021 Aortic Dissection Update
– Features of acute vs chronic dissection on CT
Hounsfield units as a means to spot extravasation on CT
Case-based learning from presentation to management
– The utility of d-dimers in the diagnosis of aortic dissection

References

​​1. Hagan PG, Nienaber CA, Isselbacher EM, et al. The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease. JAMA. 2000;283(7):897-903. doi:10.1001/jama.283.7.897

2. Patel HJ, Williams DM. Endovascular Therapy for Malperfusion in Acute Type B Aortic Dissection. Operative Techniques in Thoracic and Cardiovascular Surgery. 2009;14(1):2-11. doi:10.1053/j.optechstcvs.2007.10.001

3. Williams DM, Lee DY, Hamilton BH, et al. The dissected aorta: percutaneous treatment of ischemic complications–principles and results. J Vasc Interv Radiol. 1997;8(4):605-625. doi:10.1016/s1051-0443(97)70619-5

4. Crawford TC, Beaulieu RJ, Ehlert BA, Ratchford EV, Black JH 3rd. Malperfusion syndromes in aortic dissections. Vasc Med. 2016;21(3):264-273. doi:10.1177/1358863X15625371

5. Berretta P, Trimarchi S, Patel HJ, Gleason TG, Eagle KA, Di Eusanio M. Malperfusion syndromes in type A aortic dissection: what we have learned from IRAD. J Vis Surg. 2018;4:65. Published 2018 Mar 31. doi:10.21037/jovs.2018.03.13

6. Luehr M, Etz CD, Nozdrzykowski M, et al. Extra-anatomic revascularization for preoperative cerebral malperfusion due to distal carotid artery occlusion in acute type A aortic dissection. Eur J Cardiothorac Surg. 2016;49(2):652-659. doi:10.1093/ejcts/ezv064

7. Hirata K, Wake M, Kyushima M, et al. Electrocardiographic changes in patients with type A acute aortic dissection. Incidence, patterns and underlying mechanisms in 159 cases. J Cardiol. 2010;56(2):147-153. doi:10.1016/j.jjcc.2010.03.007

8. Wu BT, Li CY, Chen YT. Type A Aortic Dissection Presenting with Inferior ST-Elevation Myocardial Infarction. Acta Cardiol Sin. 2014;30(3):248-252

9. Chen A, Ren X. Aortic Dissection Manifesting as ST-Segment-Elevation Myocardial Infarction. Circulation. 2015;131(21):e503-e504. doi:10.1161/CIRCULATIONAHA.114.015200

10. Tarver K, Kindler H, Lythall D. Extensive aortic dissection presenting as acute inferior myocardial infarction. Heart. 2007;93(10):1225. doi:10.1136/hrt.2006.097444

11. Horszczaruk GJ, Roik MF, Kochman J, et al. Aortic dissection involving ostium of right coronary artery as the reason of myocardial infarction. Eur Heart J. 2006;27(5):518. doi:10.1093/eurheartj/ehi525

12. Braverman AC. Aortic dissection: prompt diagnosis and emergency treatment are critical. Cleve Clin J Med. 2011;78(10):685-696. doi:10.3949/ccjm.78a.11053

13. Hema B, Thomas W. A Misleading Diagnosis: Anterolateral STEMI Disguising Type A Aortic Dissection in Postpartum. International Journal of Clinical Cardiology. 2020;7(3). doi:10.23937/2378-2951/1410177

14. Hirata K. Acute Aortic Dissection: A Rare but Important Cause of Acute Pericarditis. American College of Cardiology. https://www.acc.org/latest-in-cardiology/articles/2020/09/14/09/08/acute-aortic-dissection. Published September 14, 2020. Accessed July 20, 2021.

15. Nallamothu BK, Saint S, Kolias TJ, Eagle KA. Clinical problem-solving. Of nicks and time. N Engl J Med. 2001;345(5):359-363. doi:10.1056/NEJM200108023450508

16. Doroghazi RM, Slater EE, DeSanctis RW, Buckley MJ, Austen WG, Rosenthal S. Long-term survival of patients with treated aortic dissection. J Am Coll Cardiol. 1984;3(4):1026-1034. doi:10.1016/s0735-1097(84)80363-0

17. Ohle R, Um J, Anjum O, et al. High Risk Clinical Features for Acute Aortic Dissection: A Case-Control Study. Acad Emerg Med. 2018;25(4):378-387. doi:10.1111/acem.13356

18. Jain A, Tracci MC, Coleman DM, Cherry KJ, Upchurch GR Jr. Renal malperfusion: spontaneous renal artery dissection and with aortic dissection. Semin Vasc Surg. 2013;26(4):178-188. doi:10.1053/j.semvascsurg.2014.06.004

19. Norton EL, Khaja MS, Williams DM, Yang B. Type A aortic dissection complicated by malperfusion syndrome. Curr Opin Cardiol. 2019;34(6):610-615. doi:10.1097/HCO.0000000000000667

20. Tweet M, Waymack JR. Renal Infarction from Type B Aortic Dissection. Journal of Education & Teaching in Emergency Medicine. 2017;2(3). doi:https://doi.org/10.21980/J8HG9G

21. Jonker FH, Patel HJ, Upchurch GR, et al. Acute type B aortic dissection complicated by visceral ischemia. J Thorac Cardiovasc Surg. 2015;149(4):1081-6.e1. doi:10.1016/j.jtcvs.2014.11.012

22. Afifi RO, Zhu Y, Leake SS, et al. Complicated type B aortic dissection causing ischemia in the celiac and inferior mesenteric artery distribution despite patent superior mesenteric artery bypass. Vascular. 2015;23(4):422-426. doi:10.1177/1708538114548262

23. Killen DA, Weinstein CL, Reed WA. Reversal of spinal cord ischemia resulting from aortic dissection. J Thorac Cardiovasc Surg. 2000;119(5):1049-1052. doi:10.1016/S0022-5223(00)70105-X

24. Sui RB, Zhang L, Liu K. Aortic dissection presenting primarily as acute spinal cord damage: a case report and literature review. J Int Med Res. 2012;40(5):2014-2020. doi:10.1177/030006051204000544

25. Moore DW. Spinal Cord Monitoring. Orthobullets. https://www.orthobullets.com/spine/9023/spinal-cord-monitoring. Published June 23, 2021. Accessed July 20, 2021.

26. Agarwal M, How L, Chattopadhyay S, Kardos A. Leg weakness and paraesthesia provide a clue to sudden death due to aortic dissection. Lancet. 2021;397(10269):128. doi:10.1016/S0140-6736(20)32724-0

27. Kawabata A, Tomori M, Arai Y. Spinal Cord Infarction with Aortic Dissection. Case Rep Orthop. 2018;2018:7042829. Published 2018 Jun 28. doi:10.1155/2018/7042829

28. Charlton-Ouw KM, Sritharan K, Leake SS, et al. Management of limb ischemia in acute proximal aortic dissection. J Vasc Surg. 2013;57(4):1023-1029. doi:10.1016/j.jvs.2012.10.079

29. Gargiulo M, Bianchini Massoni C, Gallitto E, et al. Lower limb malperfusion in type B aortic dissection: a systematic review. Ann Cardiothorac Surg. 2014;3(4):351-367. doi:10.3978/j.issn.2225-319X.2014.07.05

30. Teece S, Hogg K. Best evidence topic report. Peripheral pulses to exclude thoracic aortic dissection. Emerg Med J. 2004;21(5):589. doi:10.1136/emj.2004.017954

31. Liu KT, Chan HM, Lin TJ. Painless aortic dissection with initial symptom of right upper extremity weakness: a case report. Kaohsiung J Med Sci. 2007;23(1):45-49. doi:10.1016/S1607-551X(09)70374-2

32. Henke PK, Williams DM, Upchurch GR Jr, et al. Acute limb ischemia associated with type B aortic dissection: clinical relevance and therapy. Surgery. 2006;140(4):532-540. doi:10.1016/j.surg.2006.06.019

33. George N, Ganti L, Falgiani M, Desai B. Aortic Dissection Presenting as Leg Pain. Cureus. 2020;12(6):e8389. Published 2020 Jun 1. doi:10.7759/cureus.8389

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nicanthony

Associate Editor at County EM Blog
Nicole Anthony is a Kings County/SUNY Downstate EM Resident in the Class of 2023 whose prior life included EMS, a failed app, and a Creative Writing minor. Most of her heart is in Prague, but you can also find a part of it in the 2 Hallway column.

Latest posts by nicanthony (see all)


nicanthony

Nicole Anthony is a Kings County/SUNY Downstate EM Resident in the Class of 2023 whose prior life included EMS, a failed app, and a Creative Writing minor. Most of her heart is in Prague, but you can also find a part of it in the 2 Hallway column.

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