scholarly journals The mechanical properties of fin whale arteries are explained by novel connective tissue designs.

1996 ◽  
Vol 199 (4) ◽  
pp. 985-997 ◽  
Author(s):  
J M Gosline ◽  
R E Shadwick
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Aortic Arch ◽  
Thoracic Aorta ◽  
Collagen Fibre ◽  
External Diameter ◽  
Collagen Fibres ◽  
Descending Aorta ◽  
Fin Whale ◽  
Terrestrial Mammals

The aortic arch and the descending aorta in the fin whale (Balaenoptera physalus) are structurally and mechanically very different from comparable vessels in other mammals. Although the external diameter of the whale's descending thoracic aorta (approximately 12 cm) is similar to that predicted by scaling relationships for terrestrial mammals, the wall thickness:diameter ratio in the whale (0.015) is much smaller than the characteristic value for other mammals (0.05). In addition, the elastic modulus of the thoracic aorta (12 MPa at 13 kPa blood pressure) is about 30 times higher than in other mammals. In contrast, the whale's aortic arch has a wall thickness/diameter ratio (0.055) and an elastic modulus (0.4 MPa) that are essentially identical to those for other mammals. However, the aortic arch is unusual in that it can be deformed biaxially to very large strains without entering a region of high stiffness caused by the recruitment of fully extended collagen fibres. Chemical composition studies indicate that the elastin:collagen ratio is high in the aortic arch (approximately 2:1) and that this ratio falls in the thoracic (approximately 1:2) and abdominal (approximately 1:3) aortas, but the magnitude of the change in composition does not account for the dramatic difference in mechanical properties. This suggests that there are differences in the elastin and collagen fibre architecture of these vessels. The descending aorta contains dense bands of tendon-like, wavy collagen fibres that run in the plane of the arterial wall, forming a fibre-lattice that runs in parallel to the elastin lamellae and reinforces the wall, making it very stiff. The aortic arch contains a very different collagen fibre-lattice in which fibres appear to have a component of orientation that runs through the thickness of the artery wall. This suggests that the collagen fibres may be arranged in series with elastin-containing elements, a difference in tissue architecture that could account for both the lower stiffness and the extreme extensibility of the whale's aortic arch. Thus, both the structure and the mechanical behaviour of the lamellar units in the aortic arch and aorta of the whale have presumably been modified to produce the unusual mechanical and haemodynamic properties of the whale circulation.

Dilatation of the entire thoracic aorta in patients with bicuspid aortic valve: a magnetic resonance angiography study

VASA ◽  
2005 ◽  
Vol 34 (3) ◽  
pp. 181-185 ◽  
Author(s):  
Westhoff-Bleck ◽  
Meyer ◽  
Lotz ◽  
Tutarel ◽  
Weiss ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Angiography ◽  
Aortic Valve ◽  
Pulmonary Artery ◽  
Aortic Arch ◽  
Thoracic Aorta ◽  
Aortic Root ◽  
Ascending Aorta ◽  
Descending Aorta ◽  
Severe Aortic Regurgitation

Background: The presence of a bicuspid aortic valve (BAV) might be associated with a progressive dilatation of the aortic root and ascending aorta. However, involvement of the aortic arch and descending aorta has not yet been elucidated. Patients and methods: Magnetic resonance angiography (MRA) was used to assess the diameter of the ascending aorta, aortic arch, and descending aorta in 28 patients with bicuspid aortic valves (mean age 30 ± 9 years). Results: Patients with BAV, but without significant aortic stenosis or regurgitation (n = 10, mean age 27 ± 8 years, n.s. versus control) were compared with controls (n = 13, mean age 33 ± 10 years). In the BAV-patients, aortic root diameter was 35.1 ± 4.9 mm versus 28.9 ± 4.8 mm in the control group (p < 0.01). The diameter of the ascending aorta was also significantly increased at the level of the pulmonary artery (35.5 ± 5.6 mm versus 27.0 ± 4.8 mm, p < 0.001). BAV-patients with moderate or severe aortic regurgitation (n = 18, mean age 32 ± 9 years, n.s. versus control) had a significant dilatation of the aortic root, ascending aorta at the level of the pulmonary artery (41.7 ± 4.8 mm versus 27.0 ± 4.8 mm in control patients, p < 0.001) and, furthermore, significantly increased diameters of the aortic arch (27.1 ± 5.6 mm versus 21.5 ± 1.8 mm, p < 0.01) and descending aorta (21.8 ± 5.6 mm versus 17.0 ± 5.6 mm, p < 0.01). Conclusions: The whole thoracic aorta is abnormally dilated in patients with BAV, particularly in patients with moderate/severe aortic regurgitation. The maximum dilatation occurs in the ascending aorta at the level of the pulmonary artery. Thus, we suggest evaluation of the entire thoracic aorta in patients with BAV.

scholarly journals Determinants of mechanical properties in the developing ovine thoracic aorta

1999 ◽  
Vol 277 (4) ◽  
pp. H1385-H1391 ◽  
Author(s):  
Sarah M. Wells ◽  
B. Lowell Langille ◽  
J. Michael Lee ◽  
S. Lee Adamson
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Tensile Stress ◽  
Thoracic Aorta ◽  
Adult Life ◽  
Perinatal Period ◽  
Developmental Changes ◽  
Cross Linking ◽  
Postnatal Life ◽  
Collagen Cross Linking

We previously reported changes in mechanical properties and collagen cross-linking of the ovine thoracic aorta during perinatal development and postnatal maturation, and we now report changes in biochemical composition (elastin, collagen, and DNA contents per mg wet wt) over the same developmental intervals. A comparison of results from the present and previous studies has yielded novel and important observations concerning the relationship between aortic mechanics and composition during maturation. Developmental changes in aortic incremental elastic modulus at low tensile stress ( E low) closely followed changes in relative elastin content (i.e., per mg wet wt). An 89% increase in E low during the perinatal period was associated with a 69% increase in relative elastin content, whereas neither variable changed during postnatal life. Incremental elastic modulus at high tensile stress ( E high) did not change during the perinatal period but increased 88% during postnatal life. This pattern closely paralleled changes in collagen cross-linking index, which did not change perinatally but almost doubled postnatally. In contrast, relative collagen content (per mg wet wt) increased only slightly from fetal to adult life, a trend that was unrelated to aortic mechanics. Substantial, progressive decreases in measures of wall viscosity (pressure wave attenuation coefficient and viscoelastic phase angle) from fetal to adult life followed the pattern observed for relative DNA (smooth muscle cell) content (per mg wet wt). Our findings suggest that accumulation of elastin per milligram wet weight contributes most to developmental changes in E low, change in collagen cross-linking is the primary determinant of developmental changes in E high, and cell accumulation contributes most to developmental changes in wall viscosity.

Arterial mechanics in the fin whale suggest a unique hemodynamic design

1994 ◽  
Vol 267 (3) ◽  
pp. R805-R818 ◽  
Author(s):  
R. E. Shadwick ◽  
J. M. Gosline
Keyword(s):  
Thoracic Aorta ◽  
Arterial Wall ◽  
Carotid Arteries ◽  
Fold Increase ◽  
Arterial Tree ◽  
Balaenoptera Physalus ◽  
Descending Aorta ◽  
Fin Whale ◽  
Internal Radius ◽  
Characteristic Pressure

An analysis of the dimensions of the aortic tree and the mechanical properties of arterial wall tissues in the fin whale (Balaenoptera physalus) is presented. The aortic arch is greatly expanded, having an internal radius at an estimated mean blood pressure (13 kPa) that is 2.5 times greater than that of the descending thoracic aorta. At this pressure, the elastic modulus of the arch wall (0.4 MPa) is 30 times less than that of the descending aorta (12 MPa). Consequently, even though some capacitance is provided anteriorly by the relatively compliant innominate and carotid arteries, > 90% of the arterial capacitance resides in the arch. The characteristic pressure wave velocity (C0) and impedance (Z0) were calculated from vessel dimensions and elasticity. A predicted 20-fold increase in Z0 between the arch and thoracic aorta should provide a major reflecting site, effectively uncoupling the arch from the remainder of the arterial tree. The dimensions of the arch relative to the likely pressure wavelengths within it suggest that it acts like a compliant windkessel that greatly reduces the pulsatility of the inflow to the descending aorta, which itself likely acts as a rigid, tapered manifold. It is suggested that the presence of both a highly compliant arch and a relatively rigid descending aorta is an adaptation for diving.

scholarly journals Bioelastic properties of the aorta in children, adolescents and young adults after cardiac transplantation: a cardiovascular magnetic resonance study

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
F Mueller ◽  
K Gummel ◽  
B Reich ◽  
H Latus ◽  
C Jux ◽  
...  
Keyword(s):  
Aortic Arch ◽  
Thoracic Aorta ◽  
Cardiac Transplantation ◽  
Ascending Aorta ◽  
Control Group ◽  
Cross Sectional ◽  
Descending Aorta ◽  
Aortic Isthmus ◽  
Myocardial T1 ◽  
Study Population

Abstract Background Long-term complications after cardiac transplantation are common and typically include arterial hypertension and coronary allograft vasculopathy. Few studies also suggested that heart transplant recipients have an increased arterial stiffness. Purpose This prospective study aimed to assess the bioelastic properties of the aorta as well as LV function, morphology and structure in children and young adults after cardiac transplantation. Methods CMR studies from 34 patients (median age: 17.1 years, range: 8–24 years) who underwent cardiac transplantation in childhood were analysed. Aortic anatomy and distensibility were assessed at five locations of the thoracic aorta using steady-state free precession cine sequences. Pulse wave velocity (PWV) of the aortic arch and the descending thoracic aorta was measured from 2-dimensional phase contrast images. Size and function of the left atrium and the ventricles were assessed from a stack of short axis slices. Myocardial T1 times were determined using a standard MOLLI sequence. Results Cross-sectional areas of the ascending aorta and the aortic arch tended to be lower in patients compared to controls (ascending aorta 464.5±172.5 mm2 vs. 515.3±186.3 mm2, aortic arch 342.4±113.3 mm2 vs. 376.9±148.5 mm2) whereas cross-sectional areas of the descending aorta tended to be higher (aortic isthmus 283.7±102.1 mm2 vs. 257.9±89.5 mm2, aorta descendens diaphragmal 218.4±75.8 mm2 vs. 214.2±75.0 mm2) and showed a correlation with systolic blood pressure (r=0.33). PWV was higher in the aortic arch (4.8±2.4 m/s vs. 3.6±0.7 m/s). Aortic distensibility was slightly higher at all measuring points in the study population compared to the control group and showed an increase with rising distance from the heart (ascending aorta 10.5±5.8 10–3 mm Hg-1, aortic isthmus 13.1±7.5 10–3 mm Hg-1, descending aorta 16.6±6.8 10–3 mm Hg-1). Biventricular volumes were slightly reduced in the patient group compared to the control group but this was not statistically significant. Only left ventricular mass messured during the systolic phase was higher in the study population compared to the control group (males 55.1 g/m2 vs. 53.0 g/m2, females 46.2 g/m2 vs. 45.2 g/m2). T1 mapping demonstrated increased T1 times in the heart-transplanted group compared to published data in healthy adults. In particular, T1 times of the lateral and inferior myocardial segments were higher. Conclusion Patients who underwent cardiac transplantation in childhood seem to have a reduced bioelasticity of the thoracic aorta. Increased myocardial T1 times suggesting alterations in myocardial structure. FUNDunding Acknowledgement Type of funding sources: None.

scholarly journals Aortic Blunt Trauma Analysis during a Frontal Impact

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Mario Alberto Grave-Capistrán ◽  
Arturo Yishai Prieto-Vázquez ◽  
Christopher René Torres-SanMiguel
Keyword(s):  
Aortic Arch ◽  
Thoracic Aorta ◽  
Severity Index ◽  
Biological Properties ◽  
Original Position ◽  
Medical Attention ◽  
Artery Wall ◽  
Three Dimensional Model ◽  
Descending Aorta ◽  
Compression Load

The aorta is the largest artery of the human body, and it is considered in the continuous medium mechanics as a hyperelastic material for its biological properties. The thoracic aorta is directly affected in vehicular collision events by compression generated between the ribcage and the three-point seatbelt tension producing injuries in the artery wall. A three-dimensional model of the thoracic aorta was constructed from digital tomographic images considering the ascending aorta, the aortic arch, and the descending aorta. The model obtained presents acceptable characteristics such as a length of 222.8 mm and an ascending aortic diameter of 22.7 mm, 22.7 mm in the aortic arch, and 16.09 mm in the descending aorta. A 150 ms time numerical simulation was developed through the finite element method (MEF), and the model was analyzed simulating a compression load on the artery at its front location. Boundary conditions were considered by selecting specific nodes in the model, such as the points where the artery is held in the thorax with other elements. In addition, displacement nodes were considered to establish a natural behavior of the artery. The outcomes show significant displacements in the artery wall. The most affected areas are the aortic arch and descending aorta, whose displacements reach 14 mm from their original position. Based on the abbreviated injury scale (AIS), the degree of injury to the aorta in this collision event is estimated, an AIS 2 with a moderate severity index and required medical attention.

Comparison of pulse-wave velocity in different aortic regions in relation to the extent and severity of atherosclerosis between young and older Kurosawa and Kusanagi-Hypercholesterolemic (KHC) rabbits

2000 ◽  
Vol 99 (5) ◽  
pp. 393-404 ◽  
Author(s):  
Shin-ichiro KATSUDA ◽  
Masamitsu HASEGAWA ◽  
Masahiko KUSANAGI ◽  
Tsuyoshi SHIMIZU
Keyword(s):  
Elastic Modulus ◽  
Pulse Wave Velocity ◽  
Aortic Arch ◽  
Thoracic Aorta ◽  
Wave Velocity ◽  
Abdominal Aorta ◽  
Aortic Wall ◽  
Pulse Wave ◽  
Age Groups ◽  
Ascending Aorta

The present study was performed to investigate the effects of the development of atherosclerosis on foot-to-foot pulse-wave velocity (PWV) from the ascending aorta to different positions along the aorta in Kurosawa and Kusanagi-Hypercholesterolemic (KHC) rabbits aged 10–12 and 22–24 months old, in relation to the percentage fractional lesioned area (PFLA) in different aortic regions through which the pulse wave travels, as well as the rheological and pathohistological properties of the aortic wall. PWV, when measured in the KHC rabbit from the ascending aorta to each aortic position, showed the highest value on passage through the aortic arch, decreased with conduction to the distal thoracic aorta, reached the minimal value on passage to the distal thoracic aorta or to the middle abdominal aorta in the 10–12- and 22–24-month-old animals respectively, and increased gradually on conduction to the iliac artery. PWV at all aortic regions examined was significantly greater in the 22–24-month-old than in the 10–12-month-old KHC rabbits. PFLA, when measured in the aortic region from the ascending aorta to each aortic position, was maximal in the aortic arch and decreased gradually towards the peripheral aorta in both age groups. PFLA in the 22–24-month-old group was significantly greater than that in the 10–12-month-old group in all aortic regions examined. The atherosclerotic aortic wall showed a significantly lower elastic modulus in the young KHC rabbits compared with age-matched normal rabbits. A significantly higher elastic modulus was observed in the older KHC rabbits compared with that in the younger animals of both strains, associated with the progression of sclerosis. These findings indicate that the increase in PWV is due mainly to an increase with aging in the extent and severity of atherosclerosis in vessels in which the pulse wave travels.

Thoracic endograft placement using a transfemoral snare in a patient with angled aortic arch

Vascular ◽  
2021 ◽  
pp. 170853812110244
Author(s):  
Sencer Çamci ◽  
Selma Ari ◽  
Hasan Ari ◽  
Mehmet T Göncü
Keyword(s):  
Aortic Arch ◽  
Thoracic Aorta ◽  
Male Patient ◽  
Subclavian Artery ◽  
Femoral Artery ◽  
Left Subclavian Artery ◽  
Endovascular Aneurysm Repair ◽  
Descending Aorta ◽  
Thoracic Endovascular Aneurysm Repair ◽  
Aneurysm Repair

Objective In complex anatomical challenges, endovascular endograft implantation to the thoracic aorta may not be performed. Various techniques have been put forward for endograft therapy. In this report, we present the effect of femoral snare support for a patient with an aortic arch angle. Method Thoracic endovascular aneurysm repair (TEVAR) was used for treating a 60-year-old male patient who suffered from severe angulation in the arcus aorta and aneurysmal enlargement of the left subclavian artery and descending aorta. The endovascular graft could not be advanced into the aortic arch with the guidewire because of the aortic arch angle. Therefore, the TEVAR graft distal end was caught with the snare advanced from the femoral artery, and the TEVAR graft was advanced into the aortic arch. Conclusion and result The femoral snare technique is a simple and successful method for endograft implantation of the aortic arch disease without the risk of heart trauma, especially in cases with aortic arch tortuosity.

scholarly journals Blood flow in the rabbit aortic arch and descending thoracic aorta

2011 ◽  
Vol 8 (65) ◽  
pp. 1708-1719 ◽  
Author(s):  
P. E. Vincent ◽  
A. M. Plata ◽  
A. A. E. Hunt ◽  
P. D. Weinberg ◽  
S. J. Sherwin
Keyword(s):  
Blood Flow ◽  
Aortic Arch ◽  
Thoracic Aorta ◽  
Ductus Arteriosus ◽  
Local Variation ◽  
Descending Thoracic Aorta ◽  
Local Flow ◽  
Descending Aorta ◽  
Flow Features ◽  
Realistic Representation

The distribution of atherosclerotic lesions within the rabbit vasculature, particularly within the descending thoracic aorta, has been mapped in numerous studies. The patchy nature of such lesions has been attributed to local variation in the pattern of blood flow. However, there have been few attempts to model and characterize the flow. In this study, a high-order continuous Galerkin finite-element method was used to simulate blood flow within a realistic representation of the rabbit aortic arch and descending thoracic aorta. The geometry, which was obtained from computed tomography of a resin corrosion cast, included all vessels originating from the aortic arch (followed to at least their second generation) and five pairs of intercostal arteries originating from the proximal descending thoracic aorta. The simulations showed that small geometrical undulations associated with the ductus arteriosus scar cause significant deviations in wall shear stress (WSS). This finding highlights the importance of geometrical accuracy when analysing WSS or related metrics. It was also observed that two Dean-type vortices form in the aortic arch and propagate down the descending thoracic aorta (along with an associated skewed axial velocity profile). This leads to the occurrence of axial streaks in WSS, similar in nature to the axial streaks of lipid deposition found in the descending aorta of cholesterol-fed rabbits. Finally, it was observed that WSS patterns within the vicinity of intercostal branch ostia depend not only on local flow features caused by the branches themselves, but also on larger-scale flow features within the descending aorta, which vary between branches at different locations. This result implies that disease and WSS patterns in the vicinity of intercostal ostia are best compared on a branch-by-branch basis.

Pressure-volume characteristics of aortas of harbor and Weddell seals

1986 ◽  
Vol 251 (1) ◽  
pp. R174-R180 ◽  
Author(s):  
E. A. Rhode ◽  
R. Elsner ◽  
T. M. Peterson ◽  
K. B. Campbell ◽  
W. Spangler
Keyword(s):  
Mechanical Properties ◽  
Stroke Volume ◽  
Thoracic Aorta ◽  
Marine Mammals ◽  
Wall Stress ◽  
Stroke Work ◽  
Descending Thoracic Aorta ◽  
Weddell Seals ◽  
Terrestrial Mammals ◽  
Total Potential

The mechanical properties of the radially enlarged proximal segment of the aorta of diving marine mammals was studied on 15 excised aortas of harbor seals and five aortas of Weddell seals. This was done by recording static pressure-volume relationships for the whole thoracic aorta, the aortic bulb, and the descending thoracic aorta and passive length-tension measurements of aortic strips. Aortic bulb volume distensibility was found to be much greater than that of the descending thoracic aorta or of an equivalent aortic segment of terrestrial mammals. The consequences were that the total potential energy and volume that may be stored within the aortic bulb is very large, with a capacity for storage of the stroke work of more than two normal heart beats and a volume of more than three times normal stroke volume. The aortic bulb has an average radius and wall thickness twice that of the descending aorta, but at any level of distension the wall stress (g/cm2) is the same throughout. The static mechanical properties of aortic strips from the bulb and descending thoracic aortas were not markedly different, so that the differences in the pressure-volume relationships are explained by differences in geometry of the two sections. The expanded aortic bulb functions through energy and volume storage actions and through uncoupling actions to maintain arterial pressures and stroke volume at near predive levels during a dive.

scholarly journals Effects of Organophosphate Insecticides on Mechanical Properties of Rat Aorta

2011 ◽  
pp. 39-46 ◽  
Author(s):  
B. GUVENC TUNA ◽  
N. OZTURK ◽  
U. COMELEKOGLU ◽  
B. C. YILMAZ
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Thoracic Aorta ◽  
High Stress ◽  
Chronic Administration ◽  
Female Rats ◽  
Control Group ◽  
Stress Strain ◽  
High Stress Region ◽  
Stress Region

The present study was carried out to search whether organophosphate pesticides affect the mechanical properties of the thoracic aorta. Wistar female rats (aged 6-8 weeks) were assigned randomly to a control group and groups treated with either dichlorvos or chlorpyriphos for 90 days at a dose of 5 mg/kg/day. After that period, animals were killed and thoracic aorta strips in longitudinal direction were isolated. The stress, strain and elastic modulus were obtained from the strips. Our results showed that chronic administration of chlorpyriphos and dichlorvos caused downward shift of the stress-strain relations compared to the control curve. The elastic modulus-stress curve revealed distinct characteristics in the low and high stress regions. A power function was used to simulate the low stress region while a line was fit to the high stress region. Curve fitting procedure illustrated that both pesticides influenced mainly the high stress region, but they had diverse effects at the low stress region. The results also imply that chlorpyriphos and dichlorvos decrease the strength of the aorta and therefore might influence the response of the aorta to mechanical loading induced by blood pressure.

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