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Predicting the Biomechanics of the Aorta Using Ultrasound
Published in Ayman El-Baz, Jasjit S. Suri, Cardiovascular Imaging and Image Analysis, 2018
Mansour AlOmran, Alexander Emmott, Richard L. Leask, Kevin Lachapelle
Thoracic aortic disease continues to be associated with a significant burden of morbidity and mortality in the general population. Disease of the thoracic aorta is due to aneurysm and/or dissection. An aneurysm is by definition an aortic diameter twice the normal size. This can lead to frank rupture or dissection then rupture. A dissection is a tearing of the inner lumen of the aorta such that the layers of the media separate and blood flows into a false lumen as well as the true lumen. An aortic rupture and an ascending aortic dissection (Type A) are considered surgical emergencies. The mortality is high and generally over 50% are dead without surgical treatment within two weeks. Despite improvement in diagnostics and advanced surgical techniques, mortality rates following surgery for acute aortic syndromes such as a rupture or type A aortic dissection continue to be associated with an overall mortality of 20–25% and significant morbidity such as stroke [1–5]. This high mortality following acute life-saving surgery is contrasted by the much lower risk of mortality (1.5–2.5%) when the ascending aortic aneurysm is repaired electively [3, 4, 6, 7]. This comparison illustrates the critical importance of early detection of individuals at risk for acute aortic syndromes such as dissection and rupture. Currently, most aortic aneurysms are detected incidentally when undergoing imaging for an unrelated issue, as aortic disease is generally asymptomatic until a first presentation of catastrophic dissection or even sudden death [9].
Aortic and Arterial Mechanics
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
The main pathologies affecting the ascending thoracic aorta are dissections and aneurysms (dilatations). Ascending thoracic aorta aneurysms (ATAAs) represent one-tenth of aortic aneurysms, but the surgical repair of ascending thoracic aortic pathologies, especially ATAA, and type A dissections is very complex. Conversely to AAA, of which 50%–75% (depending on countries) are now treated by endovascular repair (EVAR) interventions, ATAAs are commonly treated by conventional surgery, with open chest, requiring heart–lung machine. Note that, as treated by conventional surgery, ATAA is a large source of excised tissue, providing many biomechanical samples.
Cardiovascular system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The aorta is the largest artery in the human body and transports oxygenated blood from the heart to the rest of the body. The thoracic aorta consists of the ascending, arch and descending aorta. There are three major branches from the thoracic aorta, all from the aortic arch: the brachiocephalic, left common carotid and left subclavian arteries. The aorta passes into the abdomen through the diaphragmatic hiatus at T12. The abdominal aorta has three ventral branches (coeliac axis, superior mesenteric and inferior mesenteric arteries) and two lateral branches (right and left renal arteries).
Bicuspid aortic valve aortopathies: An hemodynamics characterization in dilated aortas
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Diana Oliveira, Sílvia Aguiar Rosa, Jorge Tiago, Rui Cruz Ferreira, Ana Figueiredo Agapito, Adélia Sequeira
Three patient-specific non-calcified and non-regurgitant BAV cases were considered: two cusps without a raphe (BAV 0), right-left fusion (BAV R-L) and right-non-coronary fusion (BAV R-NC), characterized by aortic dilation (aortic diameter > 40 mm). Patients underwent computed tomography angiography of the thoracic aorta, scanned on a 64-slice multislice (slice thickness = 1.25 mm) computed tomography scanner (LightSpeed VCT XT, GE Healthcare, Milwaukee, USA). The contrast-enhanced scan was obtained using VisipaqueTM (iodixanol) injected using automated pump injectors through a peripheral vein followed by saline bolus chase, in accordance with patient’s weight. Three-dimensional surface models of the aortic root (including aortic sinuses), ascending aorta and aortic arch were then created from these images through manual segmentation (3D-Slicer v.4.8.0).
How can flow dynamics predict clinical evolution of residual type B aortic dissection?
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
F. Khannous, M. Gaudry, C. Guivier-Curien, P. Piquet, V. Deplano
The thoracic aorta can be prone to different vascular pathologies including aortic dissection (AD). AD results in a tearing of the aortic wall layers leading to dissection and creation of a false lumen (FL), adjacent to the true arterial lumen (TL). TL and FL are separated by a part of the dissected wall that is called the neointimal flap. Blood infiltration is then observed into the aortic wall layers. TL and FL can communicate through more than the only primary entry tear (E). According to Stanford classification, if the primary entry tear is localized in the ascending aorta, dissection is a type A dissection (TAAD) otherwise, it is a type B (TBAD). AD can evolve with complications on the long term, the most feared one being the rupture. Surgical intervention is required to replace the dissected segment of the ascending aorta in TAAD whereas a medical surveillance to stabilize pressure is required for TBAD and complemented later with TEVAR (Thoracic EndoVascular Aortic Repair) procedure if needed. The present work focuses more specifically on patients treated for TAAD and who still suffer from a residual TBAD in the descending thoracic aorta. Although the clinical situation may remain unchanged in several of these cases, an unfavorable evolution may lead to a TEVAR procedure on the descending aorta. This evolution, however, remains difficult to predict, which makes patient monitoring very challenging. Few biomechanical numerical studies have partially addressed the TBAD evolution questioning, however either only one patient was considered (Xu et al. 2018) or the patient-specific physiological conditions were not met (Cheng et al. 2015). The major concern of the present work is therefore to predict the long-term evolution at an early stage of patient monitoring. To tackle this question, 3 D numerical modeling including patient-specific geometries and boundary conditions, unsteady flow and a non-Newtonian fluid behavior was carried out. The aim was to correlate flow behavior and its related physical parameters assessed in early patient monitoring (T0) and clinical evolutions observed about one year later (T1).