CLINICIAN UPDATE

Acute Aortic Dissection

Clinician Update
Alan C. Braverman, MD

A 27-year-old previously healthy woman presented to the emer- gency room after the sudden onset of severe chest
pain and shortness of breath during the 37th week of preg- nancy. Her examination was remark- able for a blood
pressure of 118/
70 mm Hg, heart rate of 100 bpm, and respiratory rate of 24 breaths per minute. The cardiovascular examina- tion was notable for
a soft systolic ejection murmur, and the pulmonary and general examinations were unre- markable. ECG demonstrated sinus
tachycardia, and her chest x-ray was normal. A D-dimer level was elevated. She underwent a spiral computed to- mography scan to
evaluate for pulmo- nary embolism, which instead demon- strated an acute type A aortic dissection and a very small patent duc-
tus arteriosus. The patient underwent emergency cesarean section, which de- livered a viable baby, and repair of the type A dissection.
Her aortic valve was trileaflet. She had no features on ex- amination to suggest Marfan syndrome or Loeys-Dietz aneurysm syndrome.
Her father had died suddenly at 31 years of age of a presumed heart
attack, and her paternal uncle had undergone ascending aortic aneurysm resection at 42 years of age. Mutation analysis in this woman
detected a het- erozygous mutation in MYH11, con- firming familial thoracic aortic aneu- rysm/dissection (TAA/D).
Acute aortic dissection is the most common life-threatening disorder af- fecting the aorta.1 The immediate mor- tality rate in aortic
dissection is as high as 1% per hour over the first several hours, making early diagnosis and treatment critical for survival. Classi-
fication schemes for aortic dissection are based on anatomic involvement of the aortic dissection (Figure 1). 2 In the DeBakey
classification, type I dissec- tions originate in the ascending aorta and extend to at least the aortic arch; type II dissections involve the
ascend- ing aorta only; and type III dissections begin in the descending aorta, usually just distal to the left subclavian artery. In the
Stanford classification, type A dissections involve the ascending aorta, and type B dissections are those that do not involve the
ascending aorta. Ascending dissections require emer- gency surgical repair, whereas medical
 therapy is usually the initial strategy for acute type B dissections. Ascend- ing aortic dissection is most common in the 50- to
60-year age range, whereas descending dissections occur more commonly in older individuals. Because acute aortic dissection is
much less common than other condi- tions associated with chest or back pain, a high index of suspicion is important in making this
diagnosis.
Many conditions are associated with aortic dissection (the Table).2 Hyper- tension is present in 75% of individ- uals with
aortic dissection. Genetically triggered disorders affecting the aorta are an important and often underrecog- nized cause of aortic
dissection. Marfan syndrome, Loeys-Dietz aneu- rysm syndrome, vascular Ehlers- Danlos syndrome, bicuspid aortic valve,
Turner syndrome, and familial TAA/D syndrome are all genetic con- ditions associated with thoracic aortic aneurysm and/or
dissection. Prior car- diac surgery, especially aortic valve replacement and aortic manipulation (including angiography and stenting),
are risk factors for aortic dissection. Acute hemodynamic stress such as that

From the Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St Louis, Mo.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/cgi/content/full/122/2/184/DC1.
Correspondence to Alan C. Braverman, MD, FACC, Alumni Endowed Professor of Cardiovascular Diseases, Cardiovascular Division, Department of
Medicine, Washington University School of Medicine, 660 S Euclid Ave, Box 8086, St. Louis, MO 63110. E-mail abraverm@dom.wustl.edu
(Circulation. 2010;122:184-188.)
2010 American Heart Association, Inc.
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Circulation is available at http://circ.ahajournals.org DOI: 10.1161/CIRCULATIONAHA.110.958975

184
185 Circulation July 13, 2010 Braverman Acute Aortic Dissection 185

Figure 1. Classification schemes of acute aortic dissection. Reprinted with permission from Braverman et al.2 Elsevier. In press.
 186 Circulation July 13, 2010 Braverman Acute Aortic Dissection 186

Table. Risk Factors for Aortic

Dissection
Hypertension
Genetically triggered thoracic aortic disease
Marfan syndrome Bicuspid aortic valve Loeys-Dietz syndrome Hereditary TAA/D
Vascular Ehlers-Danlos syndrome
Congenital diseases/syndromes Coarctation of the aorta Turner syndrome
Tetralogy of Fallot
Atherosclerosis
Penetrating atherosclerotic ulcer
Trauma, blunt, or iatrogenic
Catheter/stent
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Intraaortic balloon pump Aortic/vascular surgery Motor vehicle accident

Coronary artery bypass surgery/aortic valve replacement
Cocaine use
Inflammatory/infectious diseases
Giant cell arteritis
encountered with cocaine use, pheo-
chromocytoma, and heavy weightlift- ing has been associated with aortic dissection. Aortic dissection may com- plicate aortitis, most
commonly giant cell arteritis.
Acute aortic dissection complicating pregnancy is uncommon. It usually occurs during labor and delivery or in the early postpartum
period. Although hormonal changes in the aortic wall have been theorized as potentially playing a role, an underlying genetic
disorder associated with abnormalities of the aortic wall such as that present in familial TAA/D, Marfan syndrome, Loeys-Dietz
aneurysm syndrome, vas- cular Ehlers-Danlos syndrome, bicus- pid aortic valve, Turner syndrome, or other genetic disorder is the
most likely underlying cause for aortic dis- section complicating pregnancy.
Cystic medial degeneration is the pathology underlying many thoracic aortic aneurysms and dissections. Ab- normalities in the
transforming growth factor- pathway and abnormalities in
 187 Circulation July 13, 2010 Braverman Acute Aortic Dissection 187

smooth muscle cell contractile element function may underlie certain aortic dissections.3 Patients with thoracic aortic aneurysms from
any cause are at risk for aortic dissection, with absolute size (especially 5 to 6 cm), age, body surface area, sex, rate of growth, and
specific genetic disorder all modulat- ing risk of dissection.

Clinical Manifestations
The symptoms of aortic dissection
may be highly variable and may mimic much more common conditions. Thus, a high index of suspicion must be maintained, especially
when risk fac- tors for dissection are present or signs and symptoms suggest this possibility. The vast majority of patients with
acute dissection have sudden, severe chest, back, or abdominal pain, which may be maximal at its onset. The pain may be migratory
or may radiate from chest or back to the abdomen or to the lower extremities. However, in some instances, the pain resolves and symp-
toms may be referable to other com-
 188 Circulation July 13, 2010 Braverman Acute Aortic Dissection 188

Takayasu arteritis Behet disease Aortitis

Syphilis
Pregnancy Reprinted with permission from Braverman et
al.2 Elsevier. In press.

plications such as heart failure from acute aortic regurgitation, neurological deficits, syncope, or vascular insufficiency.
Although most patients with type B dissections are hypertensive, many pa- tients with type A dissections are nor- motensive or
hypotensive on presenta- tion.1 Hypotension complicating acute aortic dissection is usually related to cardiac tamponade, aortic
rupture, or heart failure associated with severe aortic regurgitation. Sudden chest or back pain accompanied by pulse defi- cits, aortic
regurgitation, or neurologi- cal manifestations should alert the cli- nician to the diagnosis of acute aortic dissection. However, pulse
deficits were present in only 19% of type A
 189 Circulation July 13, 2010 Braverman Acute Aortic Dissection 189

dissection and 9% of type B dissec- tion.1 The murmur of aortic regurgita- tion was present in 44% of type A dissections and 12%
of type B dissec- tions in the International Registry of Acute Aortic Dissection series. 1 There are several mechanisms for acute aor-
tic regurgitation in type A dissection, with aortic leaflet prolapse or distor- tion of leaflet alignment by the dissec- tion flap being
most common.
Neurological complications of dis- section are more common in type A dissections and include stroke, spinal cord ischemia,
ischemic neuropathy, and hypoxic encephalopathy. Syncope occurs in 9% of acute dissection and may be caused by cardiac
tamponade, aortic rupture, cerebral vessel obstruc- tion, or activation of cerebral barore- ceptors. A particularly dangerous com-
plication of dissection is acute myocardial infarction or coronary is- chemia related to the dissection flap obstructing coronary
flow because it may mask the diagnosis of dissection or lead to inadvertent use of anti- platelet and anticoagulant therapy and
delay recognition and treatment of the dissection.
Vascular complications involving branch vessels may lead to malperfu- sion, which may lead to mesenteric or limb ischemia.
Renal ischemia or re- novascular hypertension may be a re- sult of the dissection process. Left- sided pleural effusions are common
with acute dissection and are usually sympathetic effusions, whereas acute hemothorax signals acute aortic rup- ture or leaking
dissection.
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Laboratory Features
The chest x-ray may be the first clue to
the diagnosis of aortic dissection, with abnormal aortic contour or widening of the aortic silhouette being present in
80% of acute dissection.1 However,
12% to 15% of patients with acute aortic dissection will have a normal chest x-ray. Thus, it is important to remember that a normal
chest x-ray cannot exclude the presence of aortic dissection. The ECG changes in aortic dissection are usually nonspecific, but
 190 Circulation July 13, 2010 Braverman Acute Aortic Dissection 190

1% to 2% of patients have acute ST

elevation.
Tremendous interest exists in the development of biomarkers that can reliably diagnose or exclude acute aor- tic dissection. Release
of smooth mus- cle proteins, soluble elastin fragments, myosin heavy chain, and creatine kinase-BB isoform has been reported after
aortic dissection, but none are currently available for clinical use.4 As is the case in pulmonary embolism, D-dimer levels are
elevated in acute aortic dissection.4 Additionally, in pa- tients presenting within the first 24 hours of symptom onset, a D-dimer level
500 ng/mL had a negative like- lihood ratio of 0.07 and a negative predictive value of 95%.4 However, the patency of the true
lumen affects D-dimer levels in acute dissection. Dissection variants such as intramural hematoma and penetrating atheroscle- rotic
ulcer may not have elevated D-dimer levels. More studies are re- quired to determine the accuracy of D-dimer assays in acute
aortic syn- dromes and how to best use D-dimer testing in aortic dissection.

Diagnostic Techniques Multidetector computed tomography, transesophageal echocardiogram, and magnetic

resonance imaging are highly accurate in the diagnosis of aortic dissection (Figure 2).2 In addi- tion to making the
diagnosis of aortic dissection or its variants (intramural hematoma and penetrating atheroscle- rotic ulcer), the imaging must
confirm whether the ascending aorta is in- volved. Other useful information in- cludes anatomic features and compli-
cations of the dissection, including entry and reentry sites, extent of dis- section, branch vessel involvement, aortic
regurgitation, pericardial effu- sion or hemopericardium, and any signs of rupture. The selection of a specific imaging
modality is influ- enced by individual patient character- istics and variables and institutional capabilities and expertise.5
Contrast computed tomography is the most commonly used modality in diagnos-
 191 Circulation July 13, 2010 Braverman Acute Aortic Dissection 191

ing aortic dissection and is readily available in most emergency rooms. Because magnetic resonance imaging takes longer for image
acquisition and leaves the patient relatively unmoni- tored, it is usually not the procedure of first choice. Transesophageal echocar-
diogram has an advantage in being portable and able to be performed at the bedside for the unstable patient (Movies I and II in
the online-only Data Supplement). Although aortic dissection may be diagnosed by trans- thoracic echocardiogram, the sensitiv-
ity and specificity are much lower than with the other diagnostic modalities; thus, this technique is not the first choice for diagnosing
dissection.

Management
Immediate management of aortic dis- section includes stabilizing the patient with prompt attention to blood pres- sure reduction. -
Blockers are the first drugs of choice because of their mech- anism of lowering the rate of rise of ventricular force (dP/dt) and stress
on the aorta. Intravenous agents are cho- sen for rapid onset. In many instances, multiple blood pressure agents are re- quired. In
patients in whom refractory hypertension exists, renovascular hy- pertension related to the dissection flap must be considered. All
patients with acute aortic dissection should undergo multidisciplinary evaluation that in- cludes cardiothoracic and/or vascular
surgical consultation. Emergency sur- gery is recommended for acute type A dissection; initial medical management is recommended
for uncomplicated type B dissection. In the International Registry of Acute Aortic Dissection, the mortality rate of patients undergo-
ing surgery for type A dissection was
26% and for those treated medically was 58%.1 Patients with low-risk fea- tures have a significantly lower mor- tality rate than those
with malperfu- sion, shock, or cardiac tamponade. Uncomplicated type B dissection has an in-hospital mortality rate of 10%. Most
series of acute type B dissection have reported a mortality rate between
192 Circulation July 13, 2010 Braverman Acute Aortic Dissection 192

Figure 2. Contrast computed tomography scan demonstrating acute type A aortic dissection with enlargement of the ascending
aorta and intimal flap (arrow) in the ascending and descending aorta. Both the true lumen (TL) and false lumen are opacified with
contrast in this example. Reprinted with permission from Braverman et al.2 Elsevier. In press.
 193 Circulation July 13, 2010 Braverman Acute Aortic Dissection 193

triggered disorders. Bicuspid aortic valve is associated with ascending thoracic aortic aneurysm and risk of aortic dissection
and may be familial in 10% of cases. 8
As detailed in the case presentation above, familial thoracic aortic aneu- rysm syndromes are an ever- expanding cause of aortic
dissection. Comprehensive family studies have recognized that 20% of individuals with a thoracic aortic aneurysm or dissection
will have another first- degree relative with thoracic aortic dis- ease.9 Screening first-degree relatives of the patient with acute aortic
dissec- tion for thoracic aortic disease is im- portant. This involves a clinical his- tory, physical examination, and imaging for
appropriate candidates.
In most patients with familial
TAA/D, the disorder is autosomal
25% and 50% for those requiring
emergency surgery.
Surgical management of type A dis- section involves excision of the intimal tear when possible, obliteration of en- try into the
false lumen proximally and distally, and interposition graft re- placement of the ascending aorta. The aortic valve may need to be
replaced, depending on the underlying pathol- ogy of the valve and aortic root. Com- plicated type B dissections may re- quire repair
of conditions such as aortic rupture, visceral, or branch ves- sel ischemia. Endovascular grafts have the potential to treat many
complica- tions of type B dissections with rela- tively low short-term morbidity and mortality rates. Trials are underway to
prospectively evaluate endovascular graft therapy in acute complicated type B dissection.
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Long-Term Management Short- and long-term survival in acute type A dissection has ranged between
52% and 94% at 1 year and 45% and
88% at 5 years.6 The 10-year actuarial survival rate of patients with acute dissection who survive initial hospital- ization is reported
as 30% to 60% in various studies. One recent study re- ported a 10-year survival of 55% and
 194 Circulation July 13, 2010 Braverman Acute Aortic Dissection 194

20-year survival of 30% after type A

dissection.7 -Blocker based therapy is the foundation of long-term medical management. Drugs such as angioten- sin receptor
blockers, by antagonizing transforming growth factor- , may be beneficial in certain genetically trig- gered disorders, but prospective
data after aortic dissection are lacking. Lifelong imaging of the entire aorta at regular intervals is important to survey for aneurysmal
enlargement or other complications. Lifestyle modifica- tions, including limitations on physical activity and certain types of employ-
ment, are important tenets of management.
Although most patients with dissec- tion have underlying hypertension, only a tiny fraction of all hyperten- sive individuals
ever have a dissec- tion. It is imperative that one consider an underlying genetic disorder in the individual with acute aortic dissection
and that a comprehensive family his- tory be obtained. Some patients will have syndromic features such as those characteristic of
Marfan syndrome or Loeys-Dietz syndrome. The presence of dural ectasia in the lumbosacral spine on the computed tomography
or magnetic resonance imaging will of- ten provide a clue to such genetically
 195 Circulation July 13, 2010 Braverman Acute Aortic Dissection 195

dominant with decreased penetrance and variable expression. 3 Several genes have been identified in families with thoracic aortic
disease, including FBN1, TGFBR1 and 2, ACTA2, and MYH11. ACTA2 mutations have been identified in 14% of TAA/D and
have been associated with livedo re- ticularis, patent ductus arteriosus, and bicuspid aortic valve.3 If a specific gene mutation is
determined in a fam- ily, all first-degree relatives may be screened for the same mutation. Rec- ognition of individuals at risk for
tho- racic aortic disease allows prophylac- tic surgery and lessens risk of aortic dissection.
One year has passed since the acute dissection in the patient presented above. Imaging studies have demon- strated no change in
the residual aortic dissection. She has been maintained on
-blocker and angiotensin receptor blocker therapy. It is likely that her late fathers death was related to an acute aortic dissection
instead of a myocar- dial infarction. The patients 5 chil- dren have undergone evaluation; two, including the one born during the
acute aortic dissection, harbor the same mu- tation in MYH11. It is important to consider genetically triggered disor- ders in patients
with aortic dissection
 196 Circulation July 13, 2010 Braverman Acute Aortic Dissection 196

and to evaluate their first-degree rela- tives for thoracic aortic disease.

Disclosures
Dr Braverman is a member of the Profes- sional Advisory Board of the National Marfan Foundation. Dr Braverman has served as an expert
witness in cases of aortic dissection with a modest relationship.

1. Hagan PG, Nienaber CA, Isselbacher EM, Bruckman D, Karavite DJ, Russman PL, Evangelista A, Fattori R, Suzuki T, Oh JK, Moore AG, Malouf JF, Pape
LA, Gaca C, Sechtem U, Lenferink S, Deutsch HJ, Diedrichs H, Marcos y Robles J, Llovet A, Gilon D, Das SK, Armstrong WF, Deeb GM, Eagle KA.
International Registry of Acute Aortic Dissection (IRAD): new insights from an old disease. JAMA. 2000;283:897903.
2. Braverman AC, Thompson R, Sanchez L.
Diseases of the aorta. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwalds Heart Disease. 9th ed. Philadelphia, Pa: Elsevier. In press.
3. Milewicz DM, Guo DC, Tran-Fadulu V, Lafont AL, Papke CL, Inamoto S, Kwartler CS, Pannu H. Genetic basis of thoracic aortic aneurysms and dissections:
focus on smooth
Downloaded from http://circ.ahajournals.org/ by guest on March 12, 2017
 197 Circulation July 13, 2010 Braverman Acute Aortic Dissection 197

muscle cell contractile dysfunction. Annu

Rev Genomics Hum Genet. 2008;9:283302.
4. Suzuki T, Distante A, Zizza A, Trimarchi S, Villani M, Salerno Uriarte JA, De Luca Tupputi Schinosa L, Renzulli A, Sabino F, Nowak R, Birkhahn R, Hollander JE,
Coun- selman F, Vijayendran R, Bossone E, Eagle K, for the IRAD-Bio Investigators. Diagnosis of acute aortic dissection by D-dimer: the Inter- national Registry of Acute
Aortic Dissection Substudy on Biomarkers (IRAD-bio) expe- rience. Circulation. 2009;119:27022707.
5. Hiratzka LF, Bakris GL, Beckman JA,

KA, Hermann LK, Isselbacher EM, Kazerooni EA, Kouchoukos NT, Lytle BW, Milewicz DM, Reich DL, Sen S, Shinn JA, Svensson LG, Williams DM, for
the American College of Cardiology Founda- tion/American Heart Association Task Force on Practice Guidelines; American Asso- ciation for Thoracic Surgery;
American College of Radiology; American Stroke Association; Society of Cardiovascular Anesthesiologists; Society for Cardio- vascular Angiography and
Interventions; Society of Interventional Radiology; Society of Thoracic Surgeons; Society for Vascular Medicine. 2010 ACCF/AHA/AATS/ACR/
ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients with thoracic aortic disease: a report of the American College of Cardiology
Founda- tion/American Heart Association Task Force
 198 Circulation July 13, 2010 Braverman Acute Aortic Dissection 198

on Practice Guidelines, American Asso- ciation for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of
Cardiovascular Anesthesiologists, Society for Cardio- vascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic
Surgeons, and Society for Vascular Medicine. Circulation. 2010;
121(13):e266 e369.
6. Tsai TT, Fattori R, Trimarchi S, Issel- bacher E, Myrmel T, Evangelista A, Hutchison S, Sechtem U, Cooper JV,

Raghupathy A, Januzzi JL, Eagle KA, Nienaber CA. International Registry of Acute Aortic Dissection. Circulation.
2006;114:2226 2231.
7. Stevens LM, Madsen JC, Isselbacher EM, Khairy P, MacGillivray TE, Hilgenberg AD, Agnihotri AK. Surgical management and long-term outcomes of acute
ascending aortic dissection. J Thorac Cardiovasc Surg.
2009;138:1349 1357.
8. Braverman AC, Beardslee MA. The bicuspid aortic valve. In: Otto C, Bonow R, eds. Valvular Heart Disease: A Companion to Braunwalds Heart Disease.
Philadelphia, Pa: Saunders/Elsevier; 2009;169 186.
9. Albornoz G, Coady MA, Roberts M, Davies RR, Tranquilli M, Rizzo JA, Elefteriades JA. Familial thoracic aortic aneurysms and dis- sections: incidence, modes
of inheritance, and phenotypic patterns. Ann Thorac Surg.
2006;82:1400 1405.
 Acute Aortic Dissection: Clinician Update
Alan C. Braverman

Circulation. 2010;122:184-188
doi: 10.1161/CIRCULATIONAHA.110.958975
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