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ECR 2018 / C-1522
Computed Tomography Angiography in Aortic Disease: what the surgeon needs to know.
Congress: ECR 2018
Poster No.: C-1522
Type: Educational Exhibit
Keywords: Cardiovascular system, Arteries / Aorta, Emergency, CT-Angiography, CT, Image manipulation / Reconstruction, Contrast agent-intravenous, Technical aspects, Computer Applications-Detection, diagnosis, Aneurysms, Dissection, Dilatation
Authors: G. Gentile1, V. Carollo2, G. Mamone3, G. Marrone1, G. Raffa1, S. Caruso4, M. Milazzo3, F. Crinò2, R. Miraglia5; 1Palermo/IT, 2Palermo (PA)/IT, 3Palermo, It/IT, 4Palermo (PA), italy/IT, 5Palermo /IT
DOI:10.1594/ecr2018/C-1522

Background

The aorta is the largest artery in the human body, pumping up to 200 million liters of blood through the body in an average lifetime. Thoracic aortic disease presentation ranges from asymptomatic (as in an aneurysm incidentally detected on imaging) to severe acute chest pain (as in acute aortic dissection). The recent increased prevalence of aortic disease in Western countries is a result of increased clinical awareness and longer life spans. Multidetector-row Computed Tomography (MDCT) of the aorta can be used to diagnose various acute and chronic conditions of the aorta. Modern 64 detector-row and newer-generation CT scanners can evaluate the entire aorta, including its smaller branches, with one short breath hold. Endovascular therapies are playing an increasingly important role in the treatment of aortic diseases, while surgery remains necessary in many situations. 

 

The Thoracic Aorta (Fig. 1) extends proximally from the aortic annulus to the diaphragmatic crura distally. The thoracic aorta is subdivided into 3 parts: the ascending aorta, the arch, and the descending aorta. The Ascending Thoracic Aorta comprises the aortic root and the tubular ascending aorta. The Aortic Root lies between the aortic annulus and the sinotubular junction. The Sinuses of Valsalva arise from the aortic root. The tubular ascending aorta extends from the sinotubular junction to the brachiocephalic trunk. Approximately 3 cm of the proximal ascending aorta is within the pericardium. The coronary arteries are the only branches of the ascending aorta. The Aortic Arch extends from the brachiocephalic trunk to the origin of the left subclavian artery. The Isthmus extends from the left subclavian artery to the ligamentum arteriosum. Three branches usually arise from the aortic arch: the brachiocephalic trunk, the left common carotid artery, and the left subclavian artery. The brachiocephalic trunk divides into the right common carotid artery and the right subclavian artery. 

 

Fig. 1: Segments of the ascending and descending aorta. Three-dimensional arrangement of the aortic root, which contains 3 circular “rings” but with the leaflets suspended within the root in crown-like fashion. Green Ring: virtual ring formed by joining basal attachment of aortic valvar leaflets; Yellow Ring: anatomic ventriculo-arterial junction; Blue Ring: sinutubular junction.
References: Piazza N. et al. Circulation: Cardiovascular Interventions. 2008;1:74-81

 

Acute Aortic Syndrome is a group of aortic pathologies that are acute emergencies. Underlying aortic diseases include penetrating atherosclerotic ulcer, intramural hematoma, aortic dissection, rupturing aneurysms and traumatic aortic injury. The aortic wall consists of 3 layers (tunica intima, tunica media, and adventitia). Acute Aortic Dissection is presumed to occur when an intimal tear develops, permitting entry of blood to a diseased underlying media characterized by elastic degeneration and smooth muscle cell loss (Fig. 2). Chronic acquired conditions, such as systemic arterial hypertension, sometimes in combination with atherosclerosis, cause thickening and fibrosis of the intimal layer and degradation and apoptosis of smooth muscle cells in the media. These processes lead to necrosis and fibrosis of the elastic components of the arterial wall, which in turn produce wall stiffness and weakness, from which dissection and rupture may arise. Chronic arterial hypertension has been widely accepted as the most common acquired condition that leads to dissection of the aorta from high shear stress. Nearly 75% of patients with AAD have an history of hypertension. Other acquired conditions that have been associated with AAD include direct blunt trauma, tobacco use, hyperlipidemia, cocaine (including crack cocaine) use, and pregnancy.

 

Fig. 2: A) Intimal Tear permits entry of blood to a diseased underlying media. B) Alternatively, the dissection may originate from the vasa vasorum rupture within the media, developing an Intramural Hematoma. C) Penetrating Atherosclerotic Ulcer consists of the ulceration of an atherosclerotic lesion, penetrating the internal elastic lamina and determining hematoma of the media; atherosclerotic penetrating ulcer leads to late formation of saccular or fusiform aneurysms.
References: Braunwald’s Heart Disease VII Edition – 2007 Elsevier Masson srl.

 

Aortic Dissections can be classified according to involvement of the ascending aorta or arch. This involvement implies a worse prognosis and usually requires surgical management. The DeBakey and Stanford classification systems are the most commonly used systems to categorize aortic dissections and they are based on location (Fig. 3). 

 

Fig. 3: In type I De-Bakey dissections, the intimal flap involves both the ascending and descending thoracic aorta; in type II, the intimal flap involves the ascending aorta only; and in type III, the intimal flap is isolated to the descending thoracic aorta. In Stanford type A dissections, the intimal flap involves the ascending thoracic aorta (with or without extension into the descending aorta), whereas in type B, the flap does not involve the ascending thoracic aorta or arch. An acute aortic dissection means that the dissection has been diagnosed within 2 weeks of the aortic dissection occurring. A chronic aortic dissection refers to an interval of 4 weeks or more from the time when the aortic dissection started.
References: ESC Guidelines on the diagnosis and treatment of aortic diseases - European Heart Journal (2014) 35, 2873–2926

 

 

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