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 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.

Cardiac Assist With a Twist: Apical Torsion as a Means to Improve Failing Heart Function

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Dennnis R. Trumble ◽  
Walter E. McGregor ◽  
Roy C. P. Kerckhoffs ◽  
Lewis K. Waldman
Keyword(s):  
Stroke Volume ◽  
Computer Model ◽  
Computational Models ◽  
Heart Function ◽  
Imaging Techniques ◽  
Wall Stress ◽  
Similar Proportion ◽  
Stroke Work ◽  
Drug Induced

Changes in muscle fiber orientation across the wall of the left ventricle (LV) cause the apex of the heart to turn 10–15 deg in opposition to its base during systole and are believed to increase stroke volume and lower wall stress in healthy hearts. Studies show that cardiac torsion is sensitive to various disease states, which suggests that it may be an important aspect of cardiac function. Modern imaging techniques have sparked renewed interest in cardiac torsion dynamics, but no work has been done to determine whether mechanically augmented apical torsion can be used to restore function to failing hearts. In this report, we discuss the potential advantages of this approach and present evidence that turning the cardiac apex by mechanical means can displace a clinically significant volume of blood from failing hearts. Computational models of normal and reduced-function LVs were created to predict the effects of applied apical torsion on ventricular stroke work and wall stress. These same conditions were reproduced in anesthetized pigs with drug-induced heart failure using a custom apical torsion device programmed to rotate over various angles during cardiac systole. Simulations of applied 90 deg torsion in a prolate spheroidal computational model of a reduced-function pig heart produced significant increases in stroke work (25%) and stroke volume with reduced fiber stress in the epicardial region. These calculations were in substantial agreement with corresponding in vivo measurements. Specifically, the computer model predicted torsion-induced stroke volume increases from 13.1 to 14.4 mL (9.9%) while actual stroke volume in a pig heart of similar size and degree of dysfunction increased from 11.1 to 13.0 mL (17.1%). Likewise, peak LV pressures in the computer model rose from 85 to 95 mm Hg (11.7%) with torsion while maximum ventricular pressures in vivo increased in similar proportion, from 55 to 61 mm Hg (10.9%). These data suggest that: (a) the computer model of apical torsion developed for this work is a fair and accurate predictor of experimental outcomes, and (b) supra-physiologic apical torsion may be a viable means to boost cardiac output while avoiding blood contact that occurs with other assist methods.

scholarly journals Aerobic capacities in the skeletal muscles of Weddell seals: key to longer dive durations?

2002 ◽  
Vol 205 (23) ◽  
pp. 3601-3608 ◽  
Author(s):  
S. B. Kanatous ◽  
R. W. Davis ◽  
R. Watson ◽  
L. Polasek ◽  
T. M. Williams ◽  
...  
Keyword(s):  
Aerobic Capacity ◽  
Skeletal Muscles ◽  
Marine Mammals ◽  
Fiber Type ◽  
Weddell Seal ◽  
Weddell Seals ◽  
Terrestrial Mammals ◽  
Hypoxic Conditions ◽  
Long Duration ◽  
Energy Conserving

SUMMARYIn contrast to terrestrial animals that function under hypoxic conditions but display the typical exercise response of increasing ventilation and cardiac output, marine mammals exercise under a different form of hypoxic stress. They function for the duration of a dive under progressive asphyxia,which is the combination of increasing hypoxia, hypercapnia and acidosis. Our previous studies on short-duration, shallow divers found marked adaptations in their skeletal muscles, which culminated in enhanced aerobic capacities that are similar to those of atheltic terrestrial mammals. The purpose of the present study was to assess the aerobic capacity of skeletal muscles from long-duration divers. Swimming and non-swimming muscles were collected from adult Weddell seals, Leptonychotes weddelli, and processed for morphometric analysis, enzymology, myoglobin concentrations and fiber-type distribution. The results showed that the skeletal muscles of Weddell seals do not have enhanced aerobic capacities compared with those of terrestrial mammals but are adapted to maintain low levels of an aerobic lipid-based metabolism, especially under the hypoxic conditions associated with diving. The lower aerobic capacity of Weddell seal muscle as compared with that of shorter-duration divers appears to reflect their energy-conserving modes of locomotion, which enable longer and deeper dives.

Increased Wall Stress of Saccular Versus Fusiform Aneurysms of the Descending Thoracic Aorta

2011 ◽  
Vol 25 (8) ◽  
pp. 1129-1137 ◽  
Author(s):  
Derek P. Nathan ◽  
Chun Xu ◽  
Alison M. Pouch ◽  
Krishnan B. Chandran ◽  
Benoit Desjardins ◽  
...  
Keyword(s):  
Thoracic Aorta ◽  
Wall Stress ◽  
Descending Thoracic Aorta

Pattern of function of left ventricle of mammals

1965 ◽  
Vol 209 (1) ◽  
pp. 22-32 ◽  
Author(s):  
J. P. Holt ◽  
Helga Kines ◽  
E. A. Rhode
Keyword(s):  
Left Ventricle ◽  
Stroke Volume ◽  
Systolic Pressure ◽  
Wall Stress ◽  
Limited Range ◽  
Left Ventricular ◽  
Elasticity Constant ◽  
Systolic Volume ◽  
Total Potential ◽  
Internal Volume

Since, over a limited range, rubber has elastic properties similar to contracted cardiac muscle, a method for determining the elasticity constant of rubber left ventricle models has been developed and used to determine the elasticity constant of the contracted mammalian left ventricle. Serial determinations of left ventricular end-systolic pressure, enddiastolic volume, end-systolic volume, and stroke volume were carried out following increased blood volume and stepwise hemorrhages in rabbits, dogs, swine, horses, and cattle. The end-systolic pressure-volume relationship of the ventricle of these animals was found to be similar to that of rubber ventricle models, hemiprolate spheroids, and thick-walled spheres; evidence is presented that the contracted left ventricle, and rubber models of it, function as an equivalent thick-walled sphere having the same wall mass and internal volume. From the linear relationship between "average" wall stress and "average" circumference, equations are derived relating chamber internal volume and: systolic pressure, total potential energy, and energy dissipated in ejection of the stroke volume.

Spatial Variations in the Mechanical Properties of the Porcine Thoracic Aorta

2011 ◽  
Author(s):  
Jungsil Kim ◽  
Seungik Baek
Keyword(s):  
Mechanical Properties ◽  
Vascular Disease ◽  
Thoracic Aorta ◽  
Aortic Wall ◽  
Vascular Tissue ◽  
Experimental Studies ◽  
Wall Stress ◽  
Clinical Decision ◽  
Arterial Tree

Characterization of the mechanical properties of a blood vessel is essential in understanding the progression of a vascular disease and for computational studies of vascular adaptation. For example, stiffness of vascular tissue is one of the major indicators to diagnose the vascular disease and make a clinical decision. Although previous studies reported the heterogeneity of the mechanical properties of arterial wall along the arterial tree [2], little was taken account for its circumferential variations. With the lack of experimental studies for investigating the circumferential variation, the aortic wall is typically assumed to have uniform deformation. Our previous study, however, has observed that there are circumferential variations in aortic wall stress and stiffness [1]. In addition to our previous study, we investigate further regional variations of the porcine thoracic aorta in both circumferential and longitudinal directions during the inflation test. Hence, we additionally test the distal thoracic aorta at each anterior and posterior side, respectively, and compare with the proximal thoracic aorta.

Management of thoracic aortic lesions - the future is endovascular

VASA ◽  
2012 ◽  
Vol 41 (3) ◽  
pp. 163-176 ◽  
Author(s):  
Weidenhagen ◽  
Bombien ◽  
Meimarakis ◽  
Geisler ◽  
A. Koeppel
Keyword(s):  
Thoracic Aorta ◽  
Clinical Decision Making ◽  
Treatment Options ◽  
Clinical Decision ◽  
Clinical Results ◽  
Treatment Modalities ◽  
Traumatic Rupture ◽  
Descending Thoracic Aorta ◽  
New Treatment ◽  
Aneurysm Dissection

Open surgical repair of lesions of the descending thoracic aorta, such as aneurysm, dissection and traumatic rupture, has been the “state-of-the-art” treatment for many decades. However, in specialized cardiovascular centers, thoracic endovascular aortic repair and hybrid aortic procedures have been implemented as novel treatment options. The current clinical results show that these procedures can be performed with low morbidity and mortality rates. However, due to a lack of randomized trials, the level of reliability of these new treatment modalities remains a matter of discussion. Clinical decision-making is generally based on the experience of the vascular center as well as on individual factors, such as life expectancy, comorbidity, aneurysm aetiology, aortic diameter and morphology. This article will review and discuss recent publications of open surgical, hybrid thoracic aortic (in case of aortic arch involvement) and endovascular repair in complex pathologies of the descending thoracic aorta.

Penetrating atherosclerotic ulcer aneurysm of the innominate artery

VASA ◽  
2009 ◽  
Vol 38 (3) ◽  
pp. 263-266 ◽  
Author(s):  
Yuan ◽  
Tager
Keyword(s):  
Conservative Treatment ◽  
Thoracic Aorta ◽  
Open Surgery ◽  
Innominate Artery ◽  
Ruptured Aneurysm ◽  
Descending Thoracic Aorta ◽  
Penetrating Atherosclerotic Ulcer ◽  
Descending Aorta

Penetrating atherosclerotic ulcer of the aorta is uncommon, and usually develops in the descending thoracic aorta. Rarely this condition involves the branch vessels of the aorta. We report a case of ruptured aneurysm of the innominate artery resulting from penetrating atherosclerotic ulcer. Open surgery was the treatment of choice for the ruptured aneurysm, while conservative treatment was recommended for the associated penetrating atherosclerotic ulcers of the descending aorta.

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