scholarly journals Prefailure and Failure Mechanics of the Porcine Ascending Thoracic Aorta: Experiments and a Multiscale Model

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Sachin B. Shah ◽  
Colleen Witzenburg ◽  
Mohammad F. Hadi ◽  
Hallie P. Wagner ◽  
Janna M. Goodrich ◽  
...  
Keyword(s):  
Thoracic Aorta ◽  
Axial Direction ◽  
Multiscale Model ◽  
Aortic Aneurysms ◽  
Critical Threshold ◽  
Fiber Network ◽  
Thoracic Aortic Aneurysms ◽  
Aortic Media ◽  
The Media ◽  
Complex Architecture

Ascending thoracic aortic aneurysms (ATAA) have a high propensity for dissection, which occurs when the hemodynamic load exceeds the mechanical strength of the aortic media. Despite our recognition of this essential fact, the complex architecture of the media has made a predictive model of medial failure—even in the relatively simple case of the healthy vessel—difficult to achieve. As a first step towards a general model of ATAA failure, we characterized the mechanical behavior of healthy ascending thoracic aorta (ATA) media using uniaxial stretch-to-failure in both circumferential (n = 11) and axial (n = 11) orientations and equibiaxial extensions (n = 9). Both experiments demonstrated anisotropy, with higher tensile strength in the circumferential direction (2510 ± 439.3 kPa) compared to the axial direction (750 ± 102.6 kPa) for the uniaxial tests, and a ratio of 1.44 between the peak circumferential and axial loads in equibiaxial extension. Uniaxial tests for both orientations showed macroscopic tissue failure at a stretch of 1.9. A multiscale computational model, consisting of a realistically aligned interconnected fiber network in parallel with a neo-Hookean solid, was used to describe the data; failure was modeled at the fiber level, with an individual fiber failing when stretched beyond a critical threshold. The best-fit model results were within the 95% confidence intervals for uniaxial and biaxial experiments, including both prefailure and failure, and were consistent with properties of the components of the ATA media.

scholarly journals Quantitative not qualitative histology differentiates aneurysmal from nondilated ascending aortas and reveals a net gain of medial components

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sameh Yousef ◽  
Nana Matsumoto ◽  
Issam Dabe ◽  
Makoto Mori ◽  
Alden B. Landry ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Quantitative Assessment ◽  
Cell Number ◽  
Aortic Aneurysms ◽  
Aortic Dilatation ◽  
Adaptive Responses ◽  
Cross Sectional ◽  
Thoracic Aortic Aneurysms ◽  
Medial Degeneration ◽  
The Media

AbstractMedial degeneration is a common histopathological finding in aortopathy and is considered a mechanism for dilatation. We investigated if medial degeneration is specific for sporadic thoracic aortic aneurysms versus nondilated aortas. Specimens were graded by pathologists, blinded to the clinical diagnosis, according to consensus histopathological criteria. The extent of medial degeneration by qualitative (semi-quantitative) assessment was not specific for aneurysmal compared to nondilated aortas. In contrast, blinded quantitative assessment of elastin amount and medial cell number distinguished aortic aneurysms and referent specimens, albeit with marked overlap in results. Specifically, the medial fraction of elastin decreased from dilution rather than loss of protein as cross-sectional amount was maintained while the cross-sectional number, though not density, of smooth muscle cells increased in proportion to expansion of the media. Furthermore, elastic lamellae did not thin and interlamellar distance did not diminish as expected for lumen dilatation, implying a net gain of lamellar elastin and intralamellar cells or extracellular matrix during aneurysmal wall remodeling. These findings support the concepts that: (1) medial degeneration need not induce aortic aneurysms, (2) adaptive responses to altered mechanical stresses increase medial tissue, and (3) greater turnover, not loss, of mural cells and extracellular matrix associates with aortic dilatation.

scholarly journals Arterial hypertension and aortic root dilatation: an unsolved mystery

2013 ◽  
pp. 6-11
Author(s):  
Alberto Milan ◽  
Francesco Tosello ◽  
Sara Abram ◽  
Ambra Fabbri ◽  
Alessandro Vairo ◽  
...  
Keyword(s):  
Arterial Hypertension ◽  
Thoracic Aorta ◽  
Aortic Root ◽  
Aortic Wall ◽  
Aortic Aneurysms ◽  
Published Data ◽  
Thoracic Aortic Aneurysms ◽  
Biological Variables ◽  
Aortic Root Dilatation ◽  
Active Debate

Introduction: Acute and chronic aortic syndromes are associated with substantial morbidity and mortality. Silent risk factors such as arterial hypertension and aortic root dilatation can increase the likelihood of aortic dissection or rupture. The relationship between arterial hypertension and the dimensions of the aortic root dimension is a topic of active debate. Materials and methods: We reviewed the literature on the physiopathology, diagnosis, natural history, and management of thoracic aortic aneurysms. Results: Biological variables influencing the size of the aorta include age, sex, body surface area, pressure values, and stroke volume. Pathologic enlargement of the thoracic aorta can be caused by genetic, degenerative, inflammatory, traumatic, or toxic factors. Studies investigating the correlation between aortic dimensions and arterial pressures (diastolic, systolic, or pulse) have produced discordant results. Discussion: Classically, emphasis has been placed on the importance of hypertension-related degeneration of the medial layer of the aortic wall, which leads to dilatation of the thoracic aorta, reduced aortic wall compliance, and increased pulse pressures. However, there are no published data that demonstrate unequivocally the existence of a pathogenetic correlation between arterial hypertension and aortic root dilatation. Furthermore, there is no evidence that antihypertensive therapy is effective in the management of nonsyndromic forms of aortic root dilatation. An interesting branch of research focuses on the importance of genetic predisposition in the pathogenesis of thoracic aortic aneurysms. Different genetic backgrounds could explain differences in the behaviour of aortic walls exposed to the same hemodynamic stress. Further study is needed to evaluate these focal physiopathological aspects.

Endovascular versus open treatment of degenerative aneurysms of the descending thoracic aorta: a single center experience

Vascular ◽  
2011 ◽  
Vol 19 (1) ◽  
pp. 8-14 ◽  
Author(s):  
Joachim Andrassy ◽  
Rolf Weidenhagen ◽  
Georgios Meimarakis ◽  
M Rentsch ◽  
K-W Jauch ◽  
...  
Keyword(s):  
Endovascular Treatment ◽  
Thoracic Aorta ◽  
Open Surgery ◽  
Aortic Aneurysms ◽  
Descending Thoracic Aorta ◽  
Entire Cohort ◽  
Thoracic Aortic Aneurysms ◽  
Asymptomatic Patients ◽  
Open Treatment ◽  
One Year

Multiple reports could show a reduced risk for thoracic endovascular aortic repair (TEVAR) compared with open treatment. The aim of this study was to evaluate our twelve-year TEVAR experience for thoracic aortic aneurysms and compare these results with open repair. All patients who had received either open or endovascular surgery for a degenerative aortic aneurysm of the descending thoracic aorta in our center were evaluated retrospectively. N = 53 TEVAR patients (1997–2008) were included and their course was compared with an open-surgery group of n = 24 patients (1992–2002). The percentage of symptomatic patients was 43% (TEVAR) and 42% (open surgery). Endovascular treatment resulted in a significantly reduced 30-day (5.7% versus 25% P = 0.02) and one-year mortality (19% versus 42% P = 0.05) in the entire cohort. Symptomatic patients benefited the most from TEVAR (30-day mortality: 9% versus 40%, P = 0.06; one-year mortality: 27% versus 70%, P = 0.049) whereas the survival of our asymptomatic patients was not significantly different (30-day mortality: 3% versus 14%, P = 0.22; one-year mortality: 13% versus 21%, P = 0.65). Lastly, Kaplan–Meier analysis showed a significantly improved survival after TEVAR ( P = 0.05) and in particular for the symptomatic patients ( P = 0.003). In conclusion, endovascular treatment for patients with degenerative thoracic aortic aneurysms has significant advantages over open surgery.

Ascending Thoracic Aorta Exhibits Anisotropic Failure Behavior in Shear Lap Testing

2013 ◽  
Author(s):  
Colleen Witzenburg ◽  
Sachin Shah ◽  
Hallie P. Wagner ◽  
Janna Goodrich ◽  
Victor H. Barocas
Keyword(s):  
Arterial Pressure ◽  
Mechanical Behavior ◽  
Thoracic Aorta ◽  
Ascending Aorta ◽  
Aortic Aneurysms ◽  
Failure Behavior ◽  
Thoracic Aortic Aneurysms ◽  
Wall Strength ◽  
Imminent Death ◽  
Aneurysm Dissection

Aneurysm dissection and rupture, resulting in imminent death, is the primary risk associated with thoracic aortic aneurysms (TAA). Nearly 60% of TAA involves the ascending aorta [1]. Dissection and rupture occur when the remodeled tissue is no longer able to withstand the stresses generated by the arterial pressure. As the ascending TAA grows, however, changes in its mechanical behavior, particularly wall strength, are unknown.

scholarly journals Angiotensin II infusion promotes ascending aortic aneurysms: attenuation by CCR2 deficiency in apoE−/− mice

2010 ◽  
Vol 118 (11) ◽  
pp. 681-689 ◽  
Author(s):  
Alan Daugherty ◽  
Debra L. Rateri ◽  
Israel F. Charo ◽  
A. Phillip Owens ◽  
Deborah A. Howatt ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Chemokine Receptor ◽  
Plasma Cholesterol ◽  
Ascending Aorta ◽  
Aortic Aneurysms ◽  
Whole Body ◽  
Abdominal Aortic ◽  
Aortic Media ◽  
The Media ◽  
Medial Thickening

AngII (angiotensin II) induces atherosclerosis and AAAs (abdominal aortic aneurysms) through multiple proposed mechanisms, including chemotaxis. Therefore, we determined the effects of whole-body deficiency of the chemokine receptor CCR2 (CC chemokine receptor 2) on these diseases. To meet this objective, apoE (apolipoprotein E)−/− mice that were either CCR2+/+ or CCR2−/−, were infused with either saline or AngII (1000 ng·kg−1 of body weight·min−1) for 28 days via mini-osmotic pumps. Deficiency of CCR2 markedly attenuated both atherosclerosis and AAAs, unrelated to systolic blood pressure or plasma cholesterol concentrations. During the course of the present study, we also observed that AngII infusion led to large dilatations that were restricted to the ascending aortic region of apoE−/− mice. The aortic media in most of the dilated area was thickened. In regions of medial thickening, distinct elastin layers were discernable. There was an expansion of the distance between elastin layers in a gradient from the intimal to the adventitial aspect of the media. This pathology differed in a circumscribed area of the anterior region of ascending aortas in which elastin breaks were focal and almost transmural. All regions of the ascending aorta of AngII-infused mice had diffuse medial macrophage accumulation. Deficiency of CCR2 greatly attenuated the AngII-induced lumen dilatation in the ascending aorta. This new model of ascending aortic aneurysms has pathology that differs markedly from AngII-induced atherosclerosis or AAAs, but all vascular pathologies were attenuated by CCR2 deficiency.

Proteomic Study of the Microdissected Aortic Media in Human Thoracic Aortic Aneurysms

2014 ◽  
Vol 13 (11) ◽  
pp. 5071-5080 ◽  
Author(s):  
Muge Serhatli ◽  
Kemal Baysal ◽  
Ceyda Acilan ◽  
Eylem Tuncer ◽  
Seldag Bekpinar ◽  
...  
Keyword(s):  
Aortic Aneurysms ◽  
Thoracic Aortic Aneurysms ◽  
Proteomic Study ◽  
Aortic Media

Robotic Replacement of the Descending Thoracic Aorta: An Alternative to Endovascular Therapy?

2006 ◽  
Vol 1 (3) ◽  
pp. 115-118
Author(s):  
Eyal E. Porat ◽  
Peter D. Herrera ◽  
Roy Sheinbaum ◽  
Anthony L. Estrera ◽  
Tam T.T. Huynh ◽  
...  
Keyword(s):  
Endovascular Treatment ◽  
Thoracic Aorta ◽  
Lung Ventilation ◽  
Aortic Aneurysms ◽  
Added Value ◽  
Long Term Results ◽  
Dacron Graft ◽  
Descending Thoracic Aorta ◽  
Thoracic Aortic Aneurysms

Background Replacement of the descending thoracic aorta is traditionally performed via a left thoracotomy. Endovascular treatment of descending thoracic aortic aneurysms has recently evolved as an alternative treatment for selected patients, yet no long-term results are available. The authors replaced the descending thoracic aorta in a group of pigs with an interposition Dacron graft using a closed-chest, totally robotic technique. Methods Ten pigs, weighing 25 to 45 kg, underwent surgery using the DaVinci robotic surgical system. Under single-lung ventilation and CO2 insufflation, the descending thoracic aorta was completely mobilized. Proximal and distal cross-clamps were applied through separate accessory stab wounds. The mid-descending thoracic aorta was excised. An interposition Dacron graft was robotically sewn in an end-to-end fashion to the descending thoracic aorta using interrupted nitinol clips. Results All animals survived the procedure. Mean aortic clamp time was 55 ± 14 minutes. All anastomoses were completed without difficulty with a mean total anastomotic time of 42 ± 11 minutes. The anastomoses were challenged for bleeding by administrating α1-adrenergic receptor agonists to a systolic blood pressure of 200 mm Hg with no evidence of leak. Discussion Robotic replacement of the thoracic aorta is feasible and reproducible. This procedure provides the standard Dacron graft repair with its known long-term results. The added value of robotic technology to the therapeutic armamentarium in the treatment of thoracic aortic aneurysms may be worth the effort required for procedural development. Furthermore, it may serve as a valid alternative to endovascular treatment of thoracic aortic aneurysms.

scholarly journals “ELEPHANT TRUNK” AND ENDOVASCULAR STENTGRAFTING – A HYBRID APPROACH TO THE TREATMENT OF EXTENSIVE THORACIC AORTIC ANEURYSM

2013 ◽  
Vol 56 (2) ◽  
pp. 80-82 ◽  
Author(s):  
Tomáš Holubec ◽  
Jan Raupach ◽  
Jan Dominik ◽  
Jan Vojáček
Keyword(s):  
Thoracic Aorta ◽  
Thoracic Aortic Aneurysm ◽  
Hybrid Approach ◽  
Giant Aneurysm ◽  
Aortic Aneurysms ◽  
Elephant Trunk ◽  
Mortality And Morbidity ◽  
Thoracic Aortic Aneurysms ◽  
Ventricular Septum Defect ◽  
Elephant Trunk Technique

A hybrid approach to elephant trunk technique for treatment of thoracic aortic aneurysms combines a conventional surgical and endovascular therapy. Compared to surgery alone, there is a presumption that mortality and morbidity is reduced. We present a case report of a 42-year-old man with a giant aneurysm of the entire thoracic aorta, significant aortic and tricuspid regurgitation and ventricular septum defect. The patient underwent multiple consecutive operations and interventions having, among others, finally replaced the entire thoracic aorta with the use of the hybrid elephant trunk technique.

scholarly journals Thoracic aorta aneurysm- a rare cause of chronic backache with mediastinal shadow: case report

2018 ◽  
Vol 4 (12) ◽  
pp. 296
Author(s):  
Akash Mathur ◽  
Devleena Gangopadhyay ◽  
Ashutosh Daga ◽  
Puneet Saxena ◽  
Hemant Malhotra
Keyword(s):  
Case Report ◽  
Thoracic Aorta ◽  
Beta Blockers ◽  
Left Lung ◽  
Lower Lobe ◽  
Symptomatic Treatment ◽  
Aortic Aneurysms ◽  
Aorta Aneurysm ◽  
Thoracic Aortic Aneurysms ◽  
Thoracic Aorta Aneurysm

<p class="abstract">Thoracic aortic aneurysms (TAA) are rarely symptomatic. A 55 year old male presents with longstanding chronic backache. CXR showed left hilar shadow with collapse of left lung. Considering the CXR findings and with the patient being chronic smoker a strong possibility of carcinoma lung with bony metastasis was kept and further CECT chest was done. The CECT chest was suggestive of a thoracic aorta aneurysm with thrombosis compressing left principal bronchus and its lower lobar branch resulting in distal area of collapse and consolidation of left lower lobe. These findings were further confirmed on CT angiography. The patient was thus diagnosed as a case of descending thoracic aorta aneurysm probably of atherosclerotic etiology with thrombosis. Patient was started on beta blockers and ACE inhibitors along with supportive and symptomatic treatment and was further transferred to the department of CTVS for surgical intervention. Thus, this case report here signifies that possibility of thoracic aorta aneurysm should always be considered in a patient with chronic backache specially in presence of mediastinal shadow on CXR.</p>

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