AUTHORS: Cristina Font, MD and Philip Stockwell, MD
Acute aortic syndromes are a spectrum of aortic pathologies that include aortic dissection, intramural hematomas (IMHs), and penetrating atherosclerotic ulcers.1 Aortic dissections are the most common and occur when blood passes through an intimal tear, separating the intima from the medial layers and creating a false lumen.1 IMH and penetrating aortic ulcer are variants of the classically described aortic dissection. Fig. 1 illustrates acute aortic syndromes.
Figure 1 Acute aortic syndromes.
A, Classic aortic dissection. There is a tear in the intima with blood entering the media and a dissecting cleavage plane propagating for variable distances anterograde (and occasionally retrograde) throughout the aortic wall. B, Aortic intramural hematoma (IMH). A spontaneous hemorrhage of the vasa vasorum leads to bleeding within the media in the absence of an intimal tear or intimal flap. C, Penetrating atherosclerotic aortic ulcer (PAU). An ulcerated aortic plaque ruptures into the media, leading to an outpouching or ulceration in the aortic wall. This may be associated with IMH formation; pseudoaneurysm; or a focal, thick-walled aortic dissection. (From Zipes DP: Braunwalds heart disease: a textbook of cardiovascular medicine, ed 11, Philadelphia, 2019, Elsevier.)
Aortic dissection is generally classified according to anatomic location (Fig. 2). Table 1 summarizes classification schemes of acute aortic dissection.
TABLE 1 Classification Schemes of Acute Aortic Dissection
| DeBakey Classification | |||
| Type I | Originates in the ascending aorta and extends at least to the aortic arch and often to the descending aorta (and beyond) | ||
| Type II | Originates in the ascending aorta and confined to this segment | ||
| Type III | Originates in the descending aorta, usually just distal to the left subclavian artery, and extends distally | ||
| Stanford Classification | |||
| Type A | Dissections involving the ascending aorta (with or without extension into the descending aorta) | ||
| Type B | Dissections not involving the ascending aorta | ||
From Mann DL et al: Braunwalds heart disease, ed 10, Philadelphia, 2015, Elsevier.
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2.6 to 3.5 per 100,000 person-yr; more frequent in winter as compared to other seasons, although no clear reason has been identified.3,4
TABLE 3 Genetically Triggered Conditions Associated with Aortic Dissection
| Marfan syndrome (MFS) | Autosomal dominant disorder of connective tissue caused by FBN1 mutation; incidence of 1 in ≈5000 individuals; multisystem manifestations, including ectopia lentis; mitral valve prolapse, aortic root aneurysm, aortic dissection; skeletal features (pectus deformities, scoliosis, arachnodactyly, hyperflexibility, tall stature, elongated fingers and toes); dural ectasia; spontaneous pneumothorax | ||
| Loeys-Dietz syndrome (LDS) | Autosomal dominant disorder caused by mutations in TGFBR1 and TGFBR2, associated with aneurysms and dissections involving the aorta and branch vessels, often at relatively small diameters and young age; manifestations include craniofacial features (hypertelorism, craniosynostosis, cleft palate, bifid or broad uvula), bluish sclera, arterial tortuosity, velvety and hyperlucent skin, easily visible veins, clubfeet, skeletal abnormalities; phenotypes may vary, including those with more pronounced craniofacial features and those with more cutaneous features; ectopia lentis has not been described in LDS; mutations in TGFB2 lead to a syndrome with an overlap in clinical features of LDS and MFS | ||
| Familial thoracic aortic aneurysm (FTAA) syndromes | Autosomal dominant disorders with variable expression and penetrance leading to thoracic aortic aneurysms (TAAs) and dissections at variable ages in families; ACTA2 mutations occur in 10%-15% of cases of FTAA and are associated with bicuspid aortic valve (BAV) disease, cerebral aneurysms, livedo reticularis, iris flocculi, PDA, moyamoya, and premature coronary artery disease; gene mutations causing familial thoracic aortic aneurysm and dissection (TAAD) include ACTA2, TGFBR1, TGFBR2, FBN1, MYH11, MYLK, TGFB2, SMAD3 | ||
| Vascular Ehlers-Danlos syndrome (vEDS) | Autosomal dominant disorder of collagen synthesis caused by a gene mutation in COL3A1 leading to rupture and dissection of the aorta (usually the descending and abdominal aorta) and branch vessels; manifestations include flexible digits, hyperlucent skin with visible veins, varicose veins, typical facial appearance, and spontaneous rupture of the uterus or bowel | ||
| Bicuspid aortic valve (BAV) | Congenital condition affecting ≈1% of the population, familial in ≈9% of cases; often associated with dilation of the ascending aorta and carries increased risk for aortic dissection; gene mutations include NOTCH1 and loci at 15q, 18q, 5q, and 13q; may be associated with FTAA | ||
| Turner syndrome (TS) | Genetic disorder affecting 1 in 2000 live-born girls and caused by complete or partial loss of the second sex chromosome (XO, Xp); women with TS often have BAV and aortic coarctation; associated with ascending aortic dilation for body size and increased risk for aortic dissection, especially when associated with BAV, hypertension, and coarctation | ||
| Aneurysms-osteoarthritis syndrome | Autosomal dominant genetic disorder resulting from mutations in the SMAD3 gene and associated with premature osteoarthritis, osteochondritis dissecans, skeletal features, aortic aneurysms, branch vessel aneurysms, and arterial tortuosity; overlap with LDS phenotype |
From Mann DL et al: Braunwalds heart disease, ed 10, Philadelphia, 2015, Elsevier.
TABLE 2 Risk Factors for Aortic Dissection
TAVR, Transcatheter aortic valve replacement.
From Zipes DP: Braunwalds heart disease: a textbook of cardiovascular medicine, ed 11, Philadelphia, 2019, Elsevier.
Genetics, in addition to other risk factors (Tables 4, 5, 6, and 7), contribute to the development of aortic aneurysms and dissection.
TABLE 7 Crawford Classification of Thoracoabdominal Aneurysms
| I | Descending thoracic aorta to suprarenal aorta | ||
| II | Proximal descending thoracic aorta to infrarenal aorta (below the diaphragm) | ||
| III | Mid descending thoracic aorta to infrarenal aorta | ||
| IV | Supravisceral aorta to infrarenal aorta |
From Soto JA, Lucey BC: Emergency radiology: the requisites, ed 2, Philadelphia, 2017, Elsevier.
TABLE 6 Descending Thoracic Aortic Aneurysm
| Degenerative | Resulting from atherosclerosis | ||
|---|---|---|---|
| Focal pseudoaneurysm resulting from a penetrating aortic ulcer | |||
| Arteritis | Giant cell | ||
| Takayasu | |||
| Behçet disease | |||
| Inherited/connective tissue | Marfan syndrome | ||
| Ductus aneurysm | |||
| Loeys-Dietz syndrome | |||
| Infectious | Mycotic aneurysms | ||
| Traumatic | Posttraumatic pseudoaneurysms | ||
| Chronic aortic transection |
From Soto JA, Lucey BC: Emergency radiology: the requisites, ed 2, Philadelphia, 2017, Elsevier.
| Degenerative | Resulting from Atherosclerosis | ||
|---|---|---|---|
| Arteritis | Giant cell | ||
| Takayasu | |||
| Behçet disease | |||
| Infectious | Syphilis |
From Soto JA, Lucey BC: Emergency radiology: the requisites, ed 2, Philadelphia, 2017, Elsevier.
TABLE 4 Ascending Thoracic Aortic Aneurysms
| Degenerative | Associated with Atherosclerosis | ||
|---|---|---|---|
| Inheritable/connective tissue | Marfan syndrome | ||
| Ehlers-Danlos syndrome | |||
| Loeys-Dietz syndrome | |||
| Turner syndrome | |||
| Osteogenesis imperfecta | |||
| Rheumatoid arthritis | |||
| Bicuspid aortic valve | |||
| Aneurysm of sinus of Valsalva | |||
| Arteritis | Giant cell | ||
| Takayasu | |||
| Behçet disease | |||
| Relapsing polychondritis | |||
| Infectious | Syphilis | ||
| Mycotic aneurysms |
From Soto JA, Lucey BC: Emergency radiology: the requisites, ed 2, Philadelphia, 2017, Elsevier.
TABLE 8 Aortic Dissection Detection Risk Score (ADD-RS)
| Clinical Risk Markers∗ | Score | ||
|---|---|---|---|
| High-risk condition such as Marfan syndrome, family history of aortic disease, known aortic valve disease, known thoracic aortic aneurysm, or previous aortic manipulation, including cardiac surgery | 1 | ||
| Pain in the chest, back, or abdomen described as abrupt, of severe intensity, or a ripping/tearing sensation | 1 | ||
| Physical examination findings of perfusion deficit, including pulse deficit, systolic blood pressure difference, or focal neurologic deficit, or with aortic diastolic murmur and hypotension/shock | 1 |
∗Presence of ≥1 marker within each of these groups is given a score of 1 with a maximum cumulative score of 3 if all three are present.
Modified from Erbel R et al: 2014 ESC guidelines on the diagnosis and treatment of aortic diseases: document covering acute and chronic aortic diseases of the thoracic and abdominal aorta of the adult. The Task Force for the Diagnosis and Treatment of Aortic Diseases of the European Society of Cardiology (ESC), Eur Heart J 35:2873-2926, 2014; Hiratzka LF et al: 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients with thoracic aortic disease, Circulation 121:e266-369, 2010; and Hiratzka et al: Surgery for aortic dilatation in patients with bicuspid aortic valves: a statement of clarification from the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines, J Am Coll Cardiol 67:724-731, 2016.
ECG: Helpful to rule out myocardial infarction, although dissection can lead to coronary ischemia.1,3,5
Both the True Lumen (Tl) and the False Lumen are Opacified with Contrast Material in This Example.
From Mann DL et al: Braunwalds heart disease, ed 10, Philadelphia, 2015, Elsevier.
TABLE 10 Indications for Thoracic Endovascular Aortic Repair for Type B Aortic Dissection∗
∗Or open surgical repair if anatomy is unsuitable for TEVAR.
From Zipes DP: Braunwalds heart disease: a textbook of cardiovascular medicine, ed 11, Philadelphia, 2019, Elsevier.
TABLE 9 Size Threshold for Prophylactic Aortic Root or Ascending Aortic Aneurysm Resection for Various Conditions
| Condition | Size Threshold∗ | ||
|---|---|---|---|
| Degenerative aneurysm | ≥5.5 cm | ||
| Bicuspid aortic valve | ≥5.5 cm | ||
| Bicuspid aortic valve with risk factors or low surgical risk | ≥5.0 cm | ||
| Bicuspid aortic valve requiring aortic valve replacement | >4.5 cm | ||
| Marfan syndrome | ≥5.0 cm | ||
| Marfan syndrome with risk factors | >4.5 cm | ||
| Loeys-Dietz syndrome§ | 4.0-4.5 cm | ||
| Familial thoracic aortic aneurysm syndromes¶ | 4.5-5.0 cm | ||
| Turner syndrome | >2.5 cm/m2 |
∗Lower thresholds for intervention may be considered according to body surface area in patients of small stature or in the case of rapid growth of the aorta. Age, body size, rapid growth, family history, risk of surgery, and patient and physician wishes may influence aortic size threshold.
Family history of aortic dissection or aortic growth rate of ≥0.5 cm/yr or if the patient is at low surgical risk (<4%) and the surgery is performed by an experienced aortic surgical team in a center with established expertise in these procedures. Other risk factors for aortic dissection include coarctation of the aorta, hypertension, and the root phenotype of bicuspid aortic valve.
Family history of aortic dissection or rapid aortic growth (>3 mm/yr), or severe aortic or mitral regurgitation. If pregnancy desired, consider prophylactic aortic surgery for aortic diameter of 4.0-4.5 cm.
§ It is reasonable to consider surgical repair of the aorta in adults with Loeys-Dietz syndrome or a confirmed TGFBR1 or TGFBR2 mutation with aortic diameter of 4.2 cm or more by transesophageal echocardiogram or 4.4-4.6 or more by CT or MRI. Aortic surgery at smaller diameters may be recommended when there are severe craniofacial features, rapid growth, or a family history of aortic dissection.
¶ Surgical thresholds vary depending on the specific gene mutation involved. TAA caused by ACTA2, SMAD3, and MYLK may lead to aortic dissection at relatively small aortic diameters.
From Zipes DP: Braunwalds heart disease: a textbook of cardiovascular medicine, ed 11, Philadelphia, 2019, Elsevier.
TABLE 11 Suggested Imaging Surveillance of Asymptomatic Thoracic Aortic Aneurysms∗
| Initial Discovery of Aneurysm | Repeated Imaging at 6 mo to Document Stability | ||
|---|---|---|---|
| Degenerative Aneurysm | |||
| 3.5-4.4 cm | Annual imaging | ||
| 4.5-5.4 cm | Annual to biannual imaging | ||
| MFS, BAV with TAA, and Familial TAA | |||
| 3.5-4.4 cm | Annual imaging | ||
| 4.5-5.0 cm | Biannual imaging | ||
| LDS | |||
| <4 cm | At least annual imaging | ||
| >4 cm | Biannual imaging | ||
BAV, Bicuspid aortic valve; LDS, Loeys-Dietz syndrome; MFS, Marfan syndrome; TAA, thoracic aortic aneurysm.
∗For aneurysms growing rapidly, more frequent imaging is recommended. Management of TAA must take into account the family history, age, body size, sex, rate of aneurysm growth, and underlying disease.
For relatively small degenerative aneurysms found by imaging to be stable from year to year, imaging may be performed every 2-3 yr (Hiratzka et al).
Some recommend surgery for aortic root dimensions larger than 4 cm in adults with LDS, whereas the American College of Cardiology/American Heart Association guidelines for thoracic aortic disease recommend prophylactic surgery at 4.2 cm by TEE and 4.4-4.6 cm by CT or MRI (Hiratzka et al).
From Hiratzka LF et al: 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 Foundation/American Heart Association Task Force on Practice Guidelines, American Association for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic Surgeons, and Society for Vascular Medicine, Circulation 121:e266, 2010; Mann DL et al: Braunwalds heart disease, ed 10, Philadelphia, 2015, Elsevier.
The general principles of the treatment of acute IMHs and penetrating atherosclerotic ulcers are similar to acute aortic dissection.8