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title: "Dilated Aorta"
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docid: "9daee273-f1e9-4cf9-a979-8990a9b82e40"
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authors:
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- key: "df804626-c042-4296-96e3-836a6da50fd6"
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value: "Gregory Kicska, MD, PhD"
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breadcrumbs:
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-
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name: "Cardiac"
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slug: "cardiac"
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treeNodeId: "fa90100b-619c-430e-8074-b5b9789bab39"
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-
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name: "Differential Diagnosis"
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slug: "differential-diagnosis"
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treeNodeId: "952326a0-b3ea-4a21-aa7a-d796cc9325ed"
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-
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name: "Dilated Aorta"
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slug: "dilated-aorta"
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treeNodeId: null
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category: "Cardiac"
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documentVersionId: "a4834ace-8f60-4350-a339-72988d153f26"
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imageCount: 15
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lastUpdated: "03/17/22"
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pageDescription: "Dilated Aorta"
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pageKeywords: "Cardiac, Differential Diagnosis, Dilated Aorta"
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pageTitle: "Dilated Aorta | STATdx"
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enhancedTitle: "Dilated Aorta"
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type: "DDX"
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breadcrumbs:
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- "Cardiac"
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- "Differential Diagnosis"
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- "Dilated Aorta"
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---
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# ESSENTIAL INFORMATION
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- ## Key Differential Diagnosis Issues
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- Pathology indicated by outer diameter measurements
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- Measurements providing high specificity for pathology
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- Ascending > 4.5 cm
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- Proximal descending > 3.2 cm
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- Ascending:descending ratio > 1.5:1
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- Isthmus:hiatus ratio > 1.4:1
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- Aorta should taper throughout course; focal distal diameter increase of > 50% is abnormal
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- Morphology
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- Saccular (false aneurysm): Dissection, mycotic, posttraumatic, penetrating atherosclerotic ulcer (PAU)
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- Fusiform (true aneurysm): Atherosclerosis, valvular disease
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- Location
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- Ascending aorta: Valvular pathology, dissection, connective tissue disease, syphilis
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- Descending aorta: Dissection, PAU, atherosclerotic, mycotic, posttraumatic
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- Distance of aneurysm from major branch vessels determines feasibility of stent placement
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- Tortuosity, calcification, and minimum luminal diameter of iliac arteries determine vascular access strategy
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- Diameter of proximal and distal aneurysm determines selection of stent size
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- Etiology of aneurysm (mycotic, inflammatory, or atherosclerotic) influences decision to treat surgically or endovascular
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- ## Helpful Clues for Common Diagnoses
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- **Atherosclerotic**
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- Descending aorta: Tortuous, diffuse intimal calcifications, mural thrombus, focal dilation
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- Caused by intimal disease with fibrous replacement of underlying media
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- Coexistent small and medium vessel atherosclerosis
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- **Degenerative**
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- Systemic hypertension: Leads to accelerated elastic fiber fragmentation and smooth muscle degeneration
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- Ascending aortic dilation with relative preservation of root diameter
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- Older patients
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- **Aortic Stenosis**
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- Dense calcifications of aortic valve
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- Grade of stenosis related to valve area
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- > 2.0 cm²: No hemodynamically significant stenosis
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- 2-1.5 cm²: Mild stenosis
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- 1.5-1 cm²: Moderate stenosis
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- < 1 cm²: Severe stenosis
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- Aortic bicuspid-related stenosis
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- Young patient with calcified valve despite paucity of vascular calcifications elsewhere
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- Prevalence of 1:1,000: Men more commonly affected
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- Associated with aortic coarctation and patent ductus arteriosus
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- Prone to dissection
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- ## Helpful Clues for Less Common Diagnoses
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- **Aortic Dissection**
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- Intimal calcifications displaced toward aortic lumen: Can be appreciated on unenhanced study
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- False lumen expands, leading to aortic dilation
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- Majority of patients present with systemic hypertension
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- Intimal flap seen on enhanced CT, 3D MRA, or black-blood MR
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- May occur in areas of prior intramural hematoma or penetrating atherosclerotic ulcer
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- **Pseudoaneurysm**
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- **Mycotic Aneurysm**
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- Saccular configuration, irregular lumen, larger than PAU
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- Adjacent abscess or inflammation
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- More common etiology in young patients with thoracic aortic aneurysms
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- Most commonly caused by bacterial infection (*Staphylococcus* and *Salmonella*) at site of prior aortic defect
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- Patients will have prior history of sepsis, IV drug use, endocarditis
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- **Penetrating Atherosclerotic Ulcer**
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- Diffuse atherosclerotic disease present
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- Penetration of contrast beyond expected outer aortic wall contour
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- Adjacent inflammatory stranding and wall thickening present
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- On MR, slow-flowing blood may make PAU appear thrombosed; phase contrast or MRA will more accurately characterize
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- New PAU found with adjacent inflammation may indicate cause of symptoms in patients presenting with chest pain
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- **Posttraumatic Pseudoaneurysm**
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- History of high-energy blunt trauma
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- Aortic contour abnormality at ligamentum arteriosum
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- Calcifications seen in remote trauma
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- Can less commonly occur at aortic root or hiatus
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- ## Helpful Clues for Rare Diagnoses
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- **Collagen Vascular Diseases**
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- Takayasu/giant cell arteritis
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- Radiographically indistinguishable; Takayasu suspected in patients < 40 years of age, giant cell suspected in patients > 40 years of age
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- Wall thickening and enhancement present
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- Branch vessel involvement present, classically subclavian stenosis
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- Although most commonly causes stenosis, aneurysms can develop
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- May also present with pulmonary artery stenoses
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- **Connective Tissue Disease**
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- Marfan syndrome, Ehlers-Danlos syndrome
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- Connective tissue defect of aortic wall
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- Annuloaortic ectasia present with ascending aorta dilation creates "tulip bulb" appearance
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- Aortic root dilation often results in aortic regurgitation at presentation
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- **Syphilis**
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- Occurs in tertiary syphilis
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- Frequency in developed world has markedly decreased
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- Often manifest as descending aortic aneurysm although abdominal aortic aneurysm and sinus of Valsalva aneurysms occur
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- Chronic inflammation leads to obliterative endarteritis causing ischemia of media and adventitia
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## Images
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### Selected Images
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**Atherosclerotic**
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*Frontal radiograph shows a dilated tortuous aorta with diffuse calcifications. Intimal disease further exacerbates medial degeneration by increasing wall stress and restricting blood flow.*
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**Atherosclerotic**
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*Frontal radiograph shows a dilated tortuous aorta with diffuse calcifications. Intimal disease further exacerbates medial degeneration by increasing wall stress and restricting blood flow.*
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**Atherosclerotic**
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*Axial CECT shows intimal disease with mural thrombus <img src='img/arrows/WS.png'/> and intimal calcifications <img src='img/arrows/BS.png'/>. This patient had a diffusely dilated and tortuous aorta.*
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**Atherosclerotic**
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*Coronal CECT shows extravasation of contrast <img src='img/arrows/WS.png'/> from a dilated abdominal aorta. Note extravasated blood <img src='img/arrows/WC.png'/>, which can easily be detected on unenhanced CT.*
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**Atherosclerotic**
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*Axial CECT shows dilated abdominal aorta with extensive mural thrombus <img src='img/arrows/WC.png'/>. Calcifications <img src='img/arrows/WS.png'/> occur when the thrombus is chronic and does not represent displaced intimal calcifications.*
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**Degenerative**
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*Lateral radiograph shows diffuse aortic calcifications <img src='img/arrows/WS.png'/> in a patient with longstanding hypertension and a dilated ascending aorta.*
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**Aortic Stenosis**
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*Double oblique cine MR shows a bicuspid aortic valve <img src='img/arrows/WS.png'/> in a young patient with a dilated ascending aorta. This image can be used to calculate valve area to quantify stenosis.*
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**Aortic Stenosis**
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*Left ventricular outflow CECT shows calcifications on the aortic cusps <img src='img/arrows/BS.png'/> in an older patient with an ascending aortic aneurysm.*
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**Aortic Dissection**
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*Axial CECT shows ascending aortic false lumen dilation <img src='img/arrows/WO.png'/> in acute dissection. Note the "bird beak" sign <img src='img/arrows/BS.png'/> and "cob web" sign <img src='img/arrows/WS.png'/>, which help identify the false lumen <img src='img/arrows/WC.png'/>. This patient had a bicuspid valve and was treated with a modified Bentall procedure.*
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**Aortic Dissection**
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*Double oblique CECT shows dilation of the ascending aorta in a hypertensive patient presenting with anterior chest pain. Note the intimal flap <img src='img/arrows/WS.png'/>. This patient was treated with emergent surgery.*
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**Mycotic Aneurysm**
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*Coronal CECT shows pseudoaneurysm in the mid descending aorta <img src='img/arrows/WS.png'/> thought to be a mycotic aneurysm. Aside from this aneurysm, there was a paucity of disease throughout the remaining aorta.*
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**Penetrating Atherosclerotic Ulcer**
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*Axial black-blood MR shows an aortic wall defect <img src='img/arrows/WS.png'/> that extends beyond the expected contour of the aortic lumen. High signal in this penetrating aortic ulcer is due to slow-flowing blood and not thrombosis.*
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**Penetrating Atherosclerotic Ulcer**
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*Coronal CECT shows a previously diagnosed penetrating atherosclerotic ulcer <img src='img/arrows/BS.png'/> that progressed to frank rupture. Note the extravasated blood <img src='img/arrows/WS.png'/>.*
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**Posttraumatic Pseudoaneurysm**
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*Volume-rendered image shows focal dilation <img src='img/arrows/WS.png'/> of the aortic lumen at the level of the ligamentum arteriosum. This patient suffered a high-speed deceleration injury, presented with a traumatic pseudoaneurysm, and was treated with endovascular repair.*
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**Connective Tissue Disease**
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*Double oblique coronal left ventricular outflow view shows aortic root dilation <img src='img/arrows/WS.png'/> and loss of sinotubular junction morphology in a patient with Marfan disease.*
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### Additional Images
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**Posttraumatic Pseudoaneurysm**
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*Sagittal oblique conventional angiographic view shows a traumatic pseudoaneurysm <img src='img/arrows/BS.png'/> prior to treatment with endovascular stenting. This patient suffered high-speed deceleration trauma.*
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