Zero-stress states of human pulmonary arteries and veins

1998 ◽  
Vol 85 (3) ◽  
pp. 867-873 ◽  
Author(s):  
W. Huang ◽  
R. T. Yen
Keyword(s):  
Pulmonary Arteries ◽  
Outer Wall ◽  
External Pressure ◽  
Opening Angle ◽  
Arterial Tree ◽  
Human Lungs ◽  
Normal Human ◽  
Residual Strains ◽  
Stress States ◽  
Arteries And Veins

The zero-stress states of the pulmonary arteries and veins from order 3 to order 9 were determined in six normal human lungs within 15 h postmortem. The zero-stress state of each vessel was obtained by cutting the vessel transversely into a series of short rings, then cutting each ring radially, which caused the ring to spring open into a sector. Each sector was characterized by its opening angle. The mean opening angle varied between 92 and 163° in the arterial tree and between 89 and 128° in the venous tree. There was a tendency for opening angles to increase as the sizes of the arteries and veins increased. We computed the residual strains based on the experimental measurements and estimated the residual stresses according to Hooke’s law. We found that the inner wall of a vessel at the state in which the internal pressure, external pressure, and longitudinal stress are all zero was under compression and the outer wall was in tension, and that the magnitude of compressive stress was greater than the magnitude of tensile stress.

Direct measurement of transverse residual strains in aorta

1996 ◽  
Vol 270 (2) ◽  
pp. H750-H759 ◽  
Author(s):  
H. C. Han ◽  
Y. C. Fung
Keyword(s):  
Stress State ◽  
Outer Layer ◽  
Residual Strain ◽  
Longitudinal Axis ◽  
Outer Wall ◽  
Residual Strains ◽  
Stress States ◽  
Sectional Surface ◽  
Thoracic And Abdominal ◽  
Load State

Residual strains were measured in the porcine aorta. Segments were cut from the aorta perpendicular to its longitudinal axis. Microdots of water-insoluble black ink were sprinkled onto the transverse sectional surface of the segments in the no-load state. The segments were then cut radially, and sectional zero-stress states were approached. The coordinates of selected microdots (2-20 microns) were digitized from photographs taken in the no-load state and the zero-stress state. Residual strains in the transverse section were calculated from the displacement of the microdots. The circumferential residual strains on the inner wall and outer wall were calculated from the circumferential lengths in the no-load state and the zero-stress state. Results show that the circumferential residual strain is negative (compressive) in the inner layer of the aortic wall and positive (tensile) in the outer layer, whereas the radial residual strain is tensile in the inner layer and compressive in the outer layer. This residual strain distribution reduces the stress concentration in the aorta under physiological load. The experimental results compared well with theoretical estimations of a cylindrical model. Regional difference of the residual strain exists and is significant (P < 0.01), e.g., the circumferential residual strains on the inner wall of the ascending, descending thoracic, and abdominal regions of the aorta are -0.133 +/- 0.019, -0.074 +/- 0.020, and -0.046 +/- 0.017 (mean +/- SD), respectively. More radial cuts of a segment produced no significant additional strains. This means that an aortic segment after one radial cut can be considered as the zero-stress state.

Strain distribution in small blood vessels with zero-stress state taken into consideration

1992 ◽  
Vol 262 (2) ◽  
pp. H544-H552 ◽  
Author(s):  
Y. C. Fung ◽  
S. Q. Liu
Keyword(s):  
Stress State ◽  
Blood Vessels ◽  
Pulmonary Arteries ◽  
Vena Cava ◽  
Large Error ◽  
Opening Angle ◽  
Stress And Strain ◽  
Passive Deformation ◽  
Angle Alpha ◽  
Residual Strains

The active and passive deformation of a blood vessel is related to the stress in it. Any analysis of stress and strain must begin with the zero-stress state. Recent reports on large blood vessels such as the aorta, pulmonary arteries, and vena cava have shown that, at zero-stress state, blood vessels are not tubes, but opens sectors. This report presents data on the zero-stress state of small blood vessels with lumen diameters down to approximately 50 microns. Zero-stress state of a vessel was obtained by cutting the vessel into rings and then the rings into sectors; each sector is characterized by an opening angle, alpha. In rat ileal and plantar arterioles, the opening angles are in the order of 100-250 degrees; those in the venules are in the order of 50-100 degrees. The effect of norepinephrine on the opening angle alpha is minor; it decreases alpha of the superior mesenteric artery, and increases alpha of the ileocecocolic and ileal arteries. EDTA has little effect on alpha of arteries greater than 100 microns in diameter, but decreases alpha of arteries less than 100 microns. The physiological meaning of the opening angle is demonstrated in terms of the residual strains in a vessel at the no-load state and homeostatic strains at normal blood pressure. The strains in real vessels are compared with those in hypothetical vessels having an opening angle of zero. It is shown that ignoring the opening angle will cause a large error in strain evaluation.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Linked opening angle and histological and mechanical aspects of the proximal pulmonary arteries of healthy and pulmonary hypertensive rats and calves

2011 ◽  
Vol 301 (5) ◽  
pp. H1810-H1818 ◽  
Author(s):  
Lian Tian ◽  
Steven R. Lammers ◽  
Philip H. Kao ◽  
Mark Reusser ◽  
Kurt R. Stenmark ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Wall Thickness ◽  
Arterial Wall ◽  
Chronic Hypoxia ◽  
Pulmonary Arteries ◽  
Opening Angle ◽  
Histological Structure ◽  
Arterial Remodeling ◽  
Stiffness Ratio ◽  
Arterial Wall Thickness

Understanding how arterial remodeling changes the mechanical behavior of pulmonary arteries (PAs) is important to the evaluation of pulmonary vascular function. Early and current efforts have focused on the arteries' histological changes, their mechanical properties under in vitro mechanical testing, and their zero-stress and no-load states. However, the linkage between the histology and mechanical behavior is still not well understood. To explore this linkage, we investigated the geometry, residual stretch, and histology of proximal PAs in both adult rat and neonatal calf hypoxic models of pulmonary hypertension (PH), compared their changes due to chronic hypoxia across species, and proposed a two-layer mechanical model of artery to relate the opening angle to the stiffness ratio of the PA outer to inner layer. We found that the proximal PA remodeling in calves was quite different from that in rats. In rats, the arterial wall thickness, inner diameter, and outer layer thickness fraction all increased dramatically in PH and the opening angle decreased significantly, whereas in calves, only the arterial wall thickness increased in PH. The proposed model predicted that the stiffness ratio of the calf proximal PAs changed very little from control to hypertensive group, while the decrease of opening angle in rat proximal PAs in response to chronic hypoxia was approximately linear to the increase of the stiffness ratio. We conclude that the arterial remodeling in rat and calf proximal PAs is different and the change of opening angle can be linked to the change of the arterial histological structure and mechanics.

scholarly journals Effect of fulvine on pulmonary arteries and veins of the rat

Thorax ◽  
1974 ◽  
Vol 29 (5) ◽  
pp. 522-529 ◽  
Author(s):  
C. A. Wagenvoort ◽  
N. Wagenvoort ◽  
H. J. Dijk
Keyword(s):  
Pulmonary Arteries ◽  
Arteries And Veins

Heterogeneity in role of endothelium-derived NO in pulmonary arteries and veins of full-term fetal lambs

1995 ◽  
Vol 268 (4) ◽  
pp. H1586-H1592 ◽  
Author(s):  
Y. Gao ◽  
H. Zhou ◽  
J. U. Raj
Keyword(s):  
Nitric Oxide ◽  
Isometric Force ◽  
Pulmonary Veins ◽  
Pulmonary Arteries ◽  
Full Term ◽  
Fourth Generation ◽  
Cyclic Monophosphate ◽  
Arteries And Veins ◽  
Endothelium Dependent Relaxation

Endothelium-derived nitric oxide (EDNO) modulates fetal pulmonary vasoactivity. The role of EDNO in regulation of vasomotor tone in fetal pulmonary arteries vs. that in veins is not known. We have investigated the role of EDNO in the responses of pulmonary arteries and veins of full-term fetal lambs. Fourth-generation pulmonary arterial and venous rings were suspended in organ chambers filled with modified Krebs-Ringer bicarbonate solution (95% O2-5% CO2 at 37 degrees C), and their isometric force was measured. N omega-nitro-L-arginine had no effect on the resting tension of pulmonary arteries with endothelium but caused contraction of pulmonary veins with endothelium. The basal level of intracellular guanosine 3',5'-cyclic monophosphate (cGMP) of pulmonary veins with endothelium was higher than that of arteries with endothelium. In pulmonary arteries, bradykinin, but not acetylcholine, induced endothelium-dependent relaxation and an increase in cGMP content. In pulmonary veins, acetylcholine, but not bradykinin, induced endothelium-dependent relaxation and an increase in cGMP content. Agonist-induced maximal relaxation and increases in cGMP content were smaller in pulmonary arteries than in veins. All these endothelium-dependent responses were abolished by N omega-nitro-L-arginine. In tissues without endothelium, nitric oxide induced significantly less relaxation and less increase in cGMP content in pulmonary arteries than in pulmonary veins. All vessels relaxed similarly to 8-bromoguanosine 3',5'-cyclic monophosphate. Our data suggest that the role of EDNO in modulating tone differs between pulmonary arteries and veins in full-term fetal lambs.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic lung lymph fistula that only drains the left lung

1995 ◽  
Vol 269 (4) ◽  
pp. R943-R947
Author(s):  
Y. Kikuchi ◽  
H. Nakazawa ◽  
D. L. Traber
Keyword(s):  
Arterial Pressure ◽  
Pulmonary Arterial Pressure ◽  
Mediastinal Lymph Node ◽  
Pulmonary Veins ◽  
Pulmonary Arteries ◽  
Left Lung ◽  
Lymph Flow ◽  
Pulmonary Arterial ◽  
The Right ◽  
Arteries And Veins

We developed a chronic lung fistula that drains only the left lung, allowing for evaluation of injury in a single lung. To remove lymph drainage from the right lung into the caudal mediastinal lymph node, the right lower pulmonary ligament was severed. Pneumatic occluders were placed on the left pulmonary arteries and veins. To ensure that lymph drained from only the left lung, we increased the right pulmonary arterial pressure (RPAP) from 21.2 +/- 0.5 to 36.5 +/- 0.6 mmHg. The left pulmonary arterial pressure (LPAP) was kept at wedge pressure level for 1 h by inflating pneumatic occluders. Lymph flow from the left lung fistula was stable during this occlusion. Six hours after recovery was increased the LPAP from a baseline level of 19.1 +/- 1.0 to 36.4 +/- 0.9 mmHg and the RPAP from 21.2 +/- 0.5 to 38.0 +/- 0.8 mmHg for 2 h by inflating the pneumatic occluders on the left and right pulmonary veins. Lymph flow increased from 5.3 +/- 1.0 to 28.0 +/- 2.9 ml/h. Reflection coefficient was calculated at 0.80 +/- 0.02.

scholarly journals A case of Multiple Unilateral Pulmonary arteriovenous Malformation Relapse: Efficacy of embolization treatment

Open Medicine ◽  
2015 ◽  
Vol 10 (1) ◽  
Author(s):  
Rossella Masiello ◽  
Carlo Iadevaia ◽  
Edoardo Grella ◽  
Carmelindo Tranfa ◽  
Francesco Cerqua ◽  
...  
Keyword(s):  
Bronchial Artery ◽  
Pulmonary Arteries ◽  
Clinical Manifestations ◽  
Transcatheter Embolization ◽  
Functional Improvement ◽  
Embolization Treatment ◽  
Angio Ct ◽  
Vascular Alteration ◽  
Arteries And Veins ◽  
Ischemic Events

Abstract Pulmonary arteriovenous Malformations (PAVMs) are a rare vascular alteration characterized by abnormal communications between the pulmonary arteries and veins resulting in an extracardiac right-to-left (R-L) shunt. The majority of PAVMs are associated with an autosomal dominant vascular disorder also known as Osler-Weber- Rendu Syndrome. PAVMs appearance can be both single and multiple. Clinical manifestations include hypoxemia, dyspnea cyanosis, hemoptysis and cerebrovascular ischemic events or abscesses. We report a case of an 18 year old female with severe respiratory failure caused by a relapse of multiple unilateral pulmonary arterovenous fistula. Symptoms at admission include dyspnea, cyanosis and clubbing. The patient underwent pulmonary angio-TC scan, brain CT and echocardiography. The thoracic angio-CT scan showed the presence of PAVMs of RUL and RLL; a marked increase of right bronchial artery caliber and its branches with an aneurismatic dilatation was also observed. The patient underwent percutaneous transcatheter embolization using Amplatzer Vascular Plug IV; a relevant clinical and functional improvement was subsequently recorded. Embolization is effective in the treatment of relapsing PAVMS.

Nonlinear Spline Method for Buckling Analysis of Steel Strip

2010 ◽  
Vol 145 ◽  
pp. 14-19
Author(s):  
Jian Qin ◽  
Qing Dong Zhang ◽  
Jie Tao Dai
Keyword(s):  
Function Method ◽  
Spline Function ◽  
Steel Strip ◽  
Rolling Process ◽  
Buckling Analysis ◽  
Spline Method ◽  
Residual Strains ◽  
Stress States ◽  
Rigid Plane ◽  
The Waves

The paper deals with numerical considerations of buckling phenomena in steel strip during rolling and leveling of sheet metal. The self-equilibrating stress states due to residual strains caused by the rolling process are calculated by the spline function method. The developed numerical model provides an estimation of buckling critical loads and wave configuration. It is shown how the waves observed on the strip sliding over or lying on a rigid plane, so one can provide information about the distribution of the differences in the plastic strains over the width of the strip which leads to the buckled configuration. The spline function method proposed in this paper is simpler and more convenient than traditional finite element method in the buckling analysis.

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