statdx/docs_md/articles/dilated-aorta_9daee273-f1e9-4cf9-a979-8990a9b82e40.md

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Dilated Aorta	9daee273-f1e9-4cf9-a979-8990a9b82e40	key value df804626-c042-4296-96e3-836a6da50fd6 Gregory Kicska, MD, PhD	name slug treeNodeId Cardiac cardiac fa90100b-619c-430e-8074-b5b9789bab39 name slug treeNodeId Differential Diagnosis differential-diagnosis 952326a0-b3ea-4a21-aa7a-d796cc9325ed name slug treeNodeId Dilated Aorta dilated-aorta null	Cardiac	a4834ace-8f60-4350-a339-72988d153f26	15	03/17/22	Dilated Aorta	Cardiac, Differential Diagnosis, Dilated Aorta	Dilated Aorta | STATdx	Dilated Aorta	DDX	Cardiac Differential Diagnosis Dilated Aorta

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title: "Dilated Aorta" docid: "9daee273-f1e9-4cf9-a979-8990a9b82e40" authors:

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ESSENTIAL INFORMATION

• Key Differential Diagnosis Issues

  • Pathology indicated by outer diameter measurements - Measurements providing high specificity for pathology - Ascending > 4.5 cm - Proximal descending > 3.2 cm - Ascending:descending ratio > 1.5:1 - Isthmus:hiatus ratio > 1.4:1 - Aorta should taper throughout course; focal distal diameter increase of > 50% is abnormal
  • Morphology - Saccular (false aneurysm): Dissection, mycotic, posttraumatic, penetrating atherosclerotic ulcer (PAU) - Fusiform (true aneurysm): Atherosclerosis, valvular disease
  • Location - Ascending aorta: Valvular pathology, dissection, connective tissue disease, syphilis - Descending aorta: Dissection, PAU, atherosclerotic, mycotic, posttraumatic
  • Distance of aneurysm from major branch vessels determines feasibility of stent placement
  • Tortuosity, calcification, and minimum luminal diameter of iliac arteries determine vascular access strategy
  • Diameter of proximal and distal aneurysm determines selection of stent size
  • Etiology of aneurysm (mycotic, inflammatory, or atherosclerotic) influences decision to treat surgically or endovascular

• Helpful Clues for Common Diagnoses

  • Atherosclerotic - Descending aorta: Tortuous, diffuse intimal calcifications, mural thrombus, focal dilation - Caused by intimal disease with fibrous replacement of underlying media - Coexistent small and medium vessel atherosclerosis
  • Degenerative - Systemic hypertension: Leads to accelerated elastic fiber fragmentation and smooth muscle degeneration - Ascending aortic dilation with relative preservation of root diameter - Older patients
  • Aortic Stenosis - Dense calcifications of aortic valve - Grade of stenosis related to valve area - > 2.0 cm²: No hemodynamically significant stenosis - 2-1.5 cm²: Mild stenosis - 1.5-1 cm²: Moderate stenosis - < 1 cm²: Severe stenosis - Aortic bicuspid-related stenosis - Young patient with calcified valve despite paucity of vascular calcifications elsewhere - Prevalence of 1:1,000: Men more commonly affected - Associated with aortic coarctation and patent ductus arteriosus - Prone to dissection

• Helpful Clues for Less Common Diagnoses

  • Aortic Dissection - Intimal calcifications displaced toward aortic lumen: Can be appreciated on unenhanced study - False lumen expands, leading to aortic dilation - Majority of patients present with systemic hypertension - Intimal flap seen on enhanced CT, 3D MRA, or black-blood MR - May occur in areas of prior intramural hematoma or penetrating atherosclerotic ulcer
  • Pseudoaneurysm - Mycotic Aneurysm - Saccular configuration, irregular lumen, larger than PAU - Adjacent abscess or inflammation - More common etiology in young patients with thoracic aortic aneurysms - Most commonly caused by bacterial infection (Staphylococcus and Salmonella) at site of prior aortic defect - Patients will have prior history of sepsis, IV drug use, endocarditis - Penetrating Atherosclerotic Ulcer - Diffuse atherosclerotic disease present - Penetration of contrast beyond expected outer aortic wall contour - Adjacent inflammatory stranding and wall thickening present - On MR, slow-flowing blood may make PAU appear thrombosed; phase contrast or MRA will more accurately characterize - New PAU found with adjacent inflammation may indicate cause of symptoms in patients presenting with chest pain - Posttraumatic Pseudoaneurysm - History of high-energy blunt trauma - Aortic contour abnormality at ligamentum arteriosum - Calcifications seen in remote trauma - Can less commonly occur at aortic root or hiatus

• Helpful Clues for Rare Diagnoses

  • Collagen Vascular Diseases - Takayasu/giant cell arteritis - Radiographically indistinguishable; Takayasu suspected in patients < 40 years of age, giant cell suspected in patients > 40 years of age - Wall thickening and enhancement present - Branch vessel involvement present, classically subclavian stenosis - Although most commonly causes stenosis, aneurysms can develop - May also present with pulmonary artery stenoses
  • Connective Tissue Disease - Marfan syndrome, Ehlers-Danlos syndrome - Connective tissue defect of aortic wall - Annuloaortic ectasia present with ascending aorta dilation creates "tulip bulb" appearance - Aortic root dilation often results in aortic regurgitation at presentation
  • Syphilis - Occurs in tertiary syphilis - Frequency in developed world has markedly decreased - Often manifest as descending aortic aneurysm although abdominal aortic aneurysm and sinus of Valsalva aneurysms occur - Chronic inflammation leads to obliterative endarteritis causing ischemia of media and adventitia

Images

Selected Images

Atherosclerotic Frontal radiograph shows a dilated tortuous aorta with diffuse calcifications. Intimal disease further exacerbates medial degeneration by increasing wall stress and restricting blood flow.

Atherosclerotic Frontal radiograph shows a dilated tortuous aorta with diffuse calcifications. Intimal disease further exacerbates medial degeneration by increasing wall stress and restricting blood flow.

Atherosclerotic Axial CECT shows intimal disease with mural thrombus and intimal calcifications . This patient had a diffusely dilated and tortuous aorta.

Atherosclerotic Coronal CECT shows extravasation of contrast from a dilated abdominal aorta. Note extravasated blood , which can easily be detected on unenhanced CT.

Atherosclerotic Axial CECT shows dilated abdominal aorta with extensive mural thrombus . Calcifications occur when the thrombus is chronic and does not represent displaced intimal calcifications.

Degenerative Lateral radiograph shows diffuse aortic calcifications in a patient with longstanding hypertension and a dilated ascending aorta.

Aortic Stenosis Double oblique cine MR shows a bicuspid aortic valve in a young patient with a dilated ascending aorta. This image can be used to calculate valve area to quantify stenosis.

Aortic Stenosis Left ventricular outflow CECT shows calcifications on the aortic cusps in an older patient with an ascending aortic aneurysm.

Aortic Dissection Axial CECT shows ascending aortic false lumen dilation in acute dissection. Note the "bird beak" sign and "cob web" sign , which help identify the false lumen . This patient had a bicuspid valve and was treated with a modified Bentall procedure.

Aortic Dissection Double oblique CECT shows dilation of the ascending aorta in a hypertensive patient presenting with anterior chest pain. Note the intimal flap . This patient was treated with emergent surgery.

Mycotic Aneurysm Coronal CECT shows pseudoaneurysm in the mid descending aorta thought to be a mycotic aneurysm. Aside from this aneurysm, there was a paucity of disease throughout the remaining aorta.

Penetrating Atherosclerotic Ulcer Axial black-blood MR shows an aortic wall defect 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.

Penetrating Atherosclerotic Ulcer Coronal CECT shows a previously diagnosed penetrating atherosclerotic ulcer that progressed to frank rupture. Note the extravasated blood .

Posttraumatic Pseudoaneurysm Volume-rendered image shows focal dilation 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.

Connective Tissue Disease Double oblique coronal left ventricular outflow view shows aortic root dilation and loss of sinotubular junction morphology in a patient with Marfan disease.

Additional Images

Posttraumatic Pseudoaneurysm Sagittal oblique conventional angiographic view shows a traumatic pseudoaneurysm prior to treatment with endovascular stenting. This patient suffered high-speed deceleration trauma.