Abdominal Aorta Of Dogs Research Articles

Rapid endothelialization and thin luminal layers in vascular grafts using silk fibroin.

The histological effects of silk fibroin (SF) in vascular grafts have not been clarified comprehensively in a large-animal model. This study aimed to observe the histological changes in vascular grafts by using Bombyx mori SF in a dog model. A splice graft consisting of SF and control grafts were implanted in the abdominal aorta of dogs, and the histological characteristics of the 2 types of grafts in each splice graft were compared. Five splice grafts consisted of one graft made of polyester (PE) fibers coated with SF and another coated with gelatin, 4 splice grafts consisted of one graft made of SF fibers coated with gelatin and another made of PE fibers coated with gelatin, and 2 splice grafts consisted of one graft made of SF fibers coated with SF and another made of PE fibers coated with SF. The graft made of PE fibers coated with SF showed more endothelial cells than the graft made of PE fibers coated with gelatin. The grafts using SF as a coating material or graft fibers showed a thinner luminal layer than the grafts made of PE fibers coated with gelatin. This study suggests that SF use for vascular grafts has advantages of rapid endothelialization and tendency to form thin luminal layers.

In Vivo Recellularization of Plain Decellularized Xenografts With Specific Cell Characterization in the Systemic Circulation: Histological and Immunohistochemical Study

Decellularized biological scaffolds have been used for the tissue engineering of heart valves with good results in the pulmonary circulation. However, little information is available on the recellularization of plain decellularized biological scaffolds in the systemic circulation. The aim of this study was to determine whether plain decellularized xenografts (PDXs) can recellularize with specific cell characterization in the systemic circulation. The xenogenic aortic valved conduit grafts of rabbits were implanted in the abdominal aorta of dogs after decellularization. The grafts were explanted at 4, 12, or 24 weeks after implantation for histological, immunohistochemical examination, scanning electron microscope, and Western blot analysis. Although the valvular structures were completely lost after implantation, supravalvular conduits showed normal shapes and endothelialization. The PDXs were repopulated with basic vascular cell components in approximate natural proportions without immunological responses. The PDXs had been recellularized with specific cell characterization in the systemic circulation.

Activity and distribution of superoxide dismutase in the layers of polyester grafts.

The aim of the present study was to evaluate superoxide dismutase (Cu, Zn-SOD) activity in the principal layers of polyester grafts implanted into the abdominal aorta of dogs. The grafts were examined 7 days and 1, 4 and 12 months after the operation. It was found that SOD activity occurred in all polyester graft layers during the whole experiment. The neointima activity ws 1.5-fold lower during the 1st month; with the passage of time, it became 2-fold lower than in the normal aorta (p < 0.01). SOD activity in the medial and outer graft layers behaved similarly: it was lowest after 7 days, increased after 1 month and significantly decreased after 4 and 12 months (p < 0.01). Our study shows that the activity of SOD is low in polyester grafts and it can thus be inferred that protection against the superoxide anion is inadequate.

In vivo protein adsorption onto polymers: a transmission electron microscopic study.

This paper reports in vivo protein adsorption onto polymers, including Biomer, PEO grafted Biomer (B-PEO-4K), heparin immobilized Biomer with PEO spacers (B-PEO-4K-HEP), and HEMA-Styrene block copolymer (H-S). Vascular grafts (6 mm ID, 7 cm in length) were fabricated with Biomer, coated on their luminal surfaces with test polymers, and implanted into the abdominal aorta of dogs. After 3 weeks-1 month, the grafts were retrieved and processed for TEM and SEM. TEM measured the thickness of adsorbed protein layers stained with a OsO4 solution, and the distribution pattern of adsorbed proteins (albumin, IgG and fibrinogen) using the immunoperoxidase technique. Retrieved grafts of Biomer and B-PEO-4K showed mural thrombi along the graft length, while thrombus formation on B-PEO-4K-HEP and H-S grafts was limited to the anastomotic sites. SEM pictures of B-PEO-4-HEP and H-S surfaces demonstrated clear morphology, with minimal platelet adhesion and activation, and microthrombi. Biomer and B-PEO-4K demonstrated a thick proteinaceous layer (1000-2000 A), whereas B-PEO-4K-HEP and H-S showed what can be described as a monolayer protein thickness (200-300 A). B-PEO-4K-HEP and H-S showed a monolayer-like adsorbed protein pattern, with high concentrations of albumin and IgG, and less fibrinogen, while Biomer and B-PEO-4K showed multilayered patterns with relatively high concentrations of fibrinogen, and less albumin. These results suggest that the surface properties of polymer may control protein adsorption pattern, and the composition of adsorbed protein is essential to in vivo long-term blood compatibility.

Effects of nifedipine on the hemodynamic response to clamping and declamping of the abdominal aorta in dogs

Clamping and declamping of the infrarenal abdominal aorta may adversely affect cardiovascular function, particularly in the presence of heart disease. This effect may be further altered by drugs used in the treatment of symptomatic coronary artery disease. The effect of nifedipine on the hemodynamic response to aortic clamping and declamping was determined in 12 dogs anesthetized with 50% nitrous oxide and 0.6% end-tidal isoflurane and monitored with aortic, left ventricular (LV), and thermodilution pulmonary artery catheters. Six dogs received a nifedipine bolus of 100 μg/kg followed by an infusion of 4 /gmg/kg/min. Six dogs did not receive any nifedipine and served as controls. Before clamping, nifedipine produced immediate decreases in arterial pressure, systemic vascular resistance (SVR), and LV dP/dt, and a modest increase in cardiac output (CO). During aortic clamping, nifedipine-treated dogs demonstrated marked increases in heart rate (HR), dP/dt, and CO while maintaining a low SVR. There were no significant changes upon declamping. The nifedipine-treated animals maintained a high CO and low SVR. Thus, nifedipine greatly altered the hemodynamic responses to aortic clamping and declamping. Awareness of these alterations is important when caring for patients being treated with nifedipine who are undergoing aortic surgery.

Blood flow through new microvessels: factors that affect regrowth of vasa vasorum

A segment of abdominal aorta in dogs was transplanted to its original position (high PO2) or to the femoral vein (low PO2), and a segment of thoracic aorta was transplanted to its original position. Two days after grafting to each location, there was no blood flow (measured with microspheres) through vasa vasorum. After 2 and 4 wk, blood flow through vasa was restored to normal, or above normal, levels in all grafts. Vasa in grafts did not have smooth muscle, and they were not responsive to adenosine. Medial necrosis occurred in grafts of thoracic aorta but not in grafts of abdominal aorta. There was cellular degeneration and medial atrophy in grafts of abdominal aorta to the femoral vein. We conclude that 1) revascularization of the aorta by vasa vasorum is rapid; 2) new vasa do not have smooth muscle, and they are not responsive to vasoactive stimuli; and 3) medial necrosis occurs in grafts in which delivery of oxygen to media is compromised, either by low luminal PO2 or by interruption of medial vasa (in thoracic aorta), but not when the abdominal aorta is excised and reanastomosed. Absence of medial necrosis in grafts of abdominal aorta indicates that diffusion from the lumen of the vessel is adequate to nourish the vessel. This finding provides evidence that adventitial vasa, in contrast to medial vasa, are not essential for nourishment of the vessel wall.

金網型‐高有孔性‐リング付無縫合人工血管の末梢動脈血行再建への応用に関する実験的研究

金網型‐高有孔性‐リング付無縫合人工血管の末梢動脈血行再建への応用に関する実験的研究

Microporous hydrophilic polyurethane vascular grafts as substitutes in the abdominal aorta of dogs

Polyurethanes are emerging as promising biomaterials. A microporous vascular graft fabricated from Mitrathane®, a new polyetherurethane urea, appeared to be particularly interesting according to in vitro evaluation and was tested in vivo as an infrarenal aortic substitute (i.d. 5 mm) in 24 dogs. After implantation for scheduled periods ranging from 4 h to 6 mnth, morphology evaluation and healing analysis of the grafts were performed. At harvesting, 18 grafts were patent and 6 were thrombosed. The thrombosed grafts had been implanted for 4 h (1 graft), 1 mnth (2 grafts) and 6 mnth (3 grafts). No macroscopic deposits other than red mural thrombi were observed. At 1 mnth complete external encapsulation was observed in 2 grafts. The capsule then contracted and became thinner; over the long term it shrank, became translucent and incomplete at 6 mnth. Yellow and brown stains appeared on many of the grafts. Characterization of the brown stains showed them to be iron (Fe 3+) and the yellow stains were associated with the deposition of a bile pigment (bilirubin).

Content and distribution of collagen in venous and polyester aortal grafts

The studies were carried out on autogenous venous and polyester grafts implanted in the abdominal aorta of dogs. These grafts were excised 1, 4, and 36 months after implantation and together with the normal arteries and veins, after dissection into intimal, medial, and adventitial layers, tested for their hydroxyproline and nitrogen content. It was found that the collagen content and the hydroxyproline/nitrogen ratio in the various layers of the venous and polyester grafts increased as time elapsed after the operation. The increase in collagen content was, however, much higher in the polyester grafts than in the venous. The relative index of the collagen content expressed by the above ratio was found to be almost equal in the intimal and medial layers of the venous and polyester grafts 3 years after the operation and to be slightly higher than the content in the corresponding layers of the normal arteries and veins.

Cathepsin D activity of venous and polyester vascular grafts implanted in the abdominal aorta of the dog

Autogenous veins and polyester prostheses were implanted in the abdominal aorta of dogs. The venous or polyester grafts were removed together with sections of the normal arteries and veins 1 month, 4 months, and 3 years after the operation. This material was then dissected into the intimal, medial, and adventitial layers, and homogenized after which their cathepsin D activity was determined. It was found that the cathepsin D activity was far higher in all the layers of the venous grafts, particularly in the polyester grafts, than in the corresponding layers of the normal arteries and veins.

Partial standing wave formation above an abdominal aortic stenosis.

Reflection from an arterial discontinuity, such as a stenosis, would be expected to produce partial standing waves of pressure and flow proximal to the stenosis. This phenomenon is demonstrated by determining the amplitude changes of the harmonic components of pressure and flow waves recorded at three sites at different distances from an experimental stenosis of the abdominal aorta in dogs. To minimise the effect of reflections from other arterial sites, such as the peripheral beds, the animals were vasodilated. Impedance and propagation velocity measurements were made to estimate the contribution of peripheral reflections in the harmonic components of the aortic pressure and flow pulses. In general, the peripheral contribution appeared to be small for harmonics greater than the first. The results indicate that, for the 'closed' type of reflection at the stenosis, a pressure antinode and a flow node occur immediately proximal to the stenosis. As the distance from the stenosis to the measurement site is increased, nodes and antinodes of pressure and flow occur at frequencies which correspond to integer multiples of lambda/4. Similar fluctuations take place in the impedance modulus proximal to the stenosis, such that close to the stenosis the modulus is a maximum, at the lambda/4 distance the modulus is a minimum and at the lambda/2 distance it is again a maximum. The extent of these impedance changes with distance indicates that the attenuation of the reflected, backwardgoing waves is greater than found for forwardgoing waves and that the diagnostic assessment of a vascular obstruction by means of a proximal measurement of pressure or flow may be subject to error if the measurement is not made close to the obstruction.

Determinants of systemic hydraulic power in unanesthetized dogs.

ARTICLESDeterminants of systemic hydraulic power in unanesthetized dogsRH CoxRH CoxPublished Online:01 Mar 1974https://doi.org/10.1152/ajplegacy.1974.226.3.579MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByDynamic Arterial Elastance During Experimental Endotoxic Septic Shock: A Potential Marker of Cardiovascular Efficiency2 October 2020 | Frontiers in Physiology, Vol. 11Novel wave power analysis linking pressure-flow waves, wave potential, and the forward and backward components of hydraulic powerJonathan P. Mynard and Joseph J. Smolich15 April 2016 | American Journal of Physiology-Heart and Circulatory Physiology, Vol. 310, No. 8Wave intensity analysis of right ventricular and pulmonary vascular contributions to higher pulmonary than aortic blood pressure in fetal lambsJoseph J. Smolich, Jonathan P. Mynard, and Daniel J. Penny1 September 2010 | American Journal of Physiology-Heart and Circulatory Physiology, Vol. 299, No. 3The Influence of Intraarterial Prostaglandin E1on Vascular Hydraulic Impedance and Infrainguinal Graft PatencyEuropean Journal of Vascular and Endovascular Surgery, Vol. 22, No. 3Cardiovascular Effects of Intravenous Diltiazem in Dogs with Iatrogenic Atrial FibrillationJournal of Veterinary Internal Medicine, Vol. 14, No. 4Assessment of aortic pressure power components and their link to overall elastic and resistive arterial propertiesMedical & Biological Engineering & Computing, Vol. 37, No. 3Left Ventricular Afterload and Ventriculo-Arterial CouplingArterial wave propagation phenomena, ventricular work, and power dissipationAnnals of Biomedical Engineering, Vol. 23, No. 6Cardiovascular response in patients with and without myocardial ischaemia during dobutamine echocardiography stress test for coronary artery diseaseClinical Physiology, Vol. 15, No. 3Hemodynamic analysis could resolve the pulsatile blood flow controversyThe Annals of Thoracic Surgery, Vol. 58, No. 4Hemodynamics and wall shear rate in the abdominal aorta of dogs. Effects of vasoactive agents.Circulation Research, Vol. 75, No. 4The use of automatic blood pressure monitors in the burned patientBritish Journal of Plastic Surgery, Vol. 43, No. 3Modified asymmetric T-tube model to infer arterial wave reflection at the aortic rootIEEE Transactions on Biomedical Engineering, Vol. 36, No. 8Wave reflection and hydraulic impedance in the healthy arterial system: a controversial subjectMedical & Biological Engineering & Computing, Vol. 26, No. 3Baroreceptor control of central and regional hemodynamics with isoflurane in the dogActa Anaesthesiologica Scandinavica, Vol. 32, No. 2Aging and aortic impedance in beagle dogsMechanisms of Ageing and Development, Vol. 42, No. 1Effective length of the arterial circulation determined in the dog by aid of a model of the systemic input impedanceIEEE Transactions on Biomedical Engineering, Vol. 35, No. 1Total systemic arterial compliance and aortic characteristic impedance in the dog as a function of pressure: A model based studyComputers and Biomedical Research, Vol. 20, No. 2Aging and Vascular ImpedanceCharacteristics of vascular hydraulic load in patients with heart failure.Circulation, Vol. 72, No. 1The effects of peripheral impedance and inotropic state on the power output of the left ventricle in dogs.Circulation Research, Vol. 50, No. 1Circulatory Correlates: Vascular Impedance, Resistance, and Capacity1 January 2011Control of Vasomotor Function and the Hemodynamic Consequences of the Contractile Behavior of ArteriesLeft ventricular afterload and systemic hydraulic power during in-series cardiac assistance: Studies using intraaortic balloon pumping in dogsAnnals of Biomedical Engineering, Vol. 5, No. 2Assessment of Cerebrovascular Hydraulic Input ImpedanceIEEE Transactions on Biomedical Engineering, Vol. BME-23, No. 5Baroreceptor reflex control of arterial hemodynamics in the dog.Circulation Research, Vol. 37, No. 6 More from this issue > Volume 226Issue 3March 1974Pages 579-587 Copyright & PermissionsCopyright © 1974 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1974.226.3.579PubMed4361539History Published online 1 March 1974 Published in print 1 March 1974 Metrics

Conduction of cardiovascular sound along arteries.

The velocity of the transmission of the second heart sound in the thoracic aorta of dogs was measured. The average velocity was found to be 5.7 meters per second. The figure agrees well with the published figures for the pulse wave velocity in the thoracic aorta of dogs. It was shown in humans that the velocity with which the second heart sound is conducted along the carotid artery does not change appreciably with frequency between 25 and 100 cycles per second. The average increase in velocity of 2.7% per half octave increase in frequency is, with 30% probability, due to random errors. The fraction of the energy of a murmur transmitted in the form of a transverse vibration along the abdominal aorta of dogs was estimated from recordings made before and after the transverse motion of the arterial wall was impeded with a clamp. Most of the energy of the murmur was found to be transmitted in the form of a transverse vibration in the aortic wall. It was concluded that most of the energy of cardiovascular sound in arteries is transmitted in a mode which is exactly analogous to the transmission of the pulse wave. Some puzzling features of intravascular sound conduction, such as the apparent transmission of murmurs mainly in the direction of flow, could be explained on this basis.

Use of enzyme-digested heterografts as segmental arterial substitutes. III. Follow-up observations on two-year-old aortic implants.

In a previous report, 1 the early results of implantation of enzymatically digested bovine heterografts into the abdominal aorta of dogs were described. Bovine arteries were stripped of most of their parenchymatous proteins by controlled enzyme action, leaving tubular prostheses composed mostly of collagen. These tubes were implanted into dogs as aortic substitutes in the hope that, with most of their immunologically reactive proteins removed, the implants would be better tolerated by the host while yet maintaining their effectiveness as arterial substitutes. Short-term observations seem to corroborate this hypothesis, and histological comparisons of treated and control heterografts after implantation indicate a markedly diminished host reaction to the enzyme-digested vessel. In a second report, 2 the physical characteristics of the elastica and collagen components of the arterial wall were investigated. It was shown that collagen derived from arteries by digestion with the enzyme ficin is highly resistant to mechanical stress, whereas

EXPERIMENTS OUTLINING THE LIMITATIONS OF OPERATIONS ON THE ABDOMINAL AORTA

1. Injuries of the abdominal aorta in dogs may be corrected with subsequent perfect restoration of the continuity of the vessel. 2. The complete occlusion of the aorta for a period of 30 minutes is not necessarily followed by serious consequences. 3. In cases in which a portion of the aorta must be resected, an arterial segment taken from another animal can be safely utilized as a transplant. 4. While the reestablishment of the continuity of the severed aorta by the circular suture is possible, the approximation of the severed ends during the suture entails such injury that thrombosis frequently occurs. Therefore, when the aorta is completely severed, the introduction of a transplanted segment is indicated. 5. An arterial tube of increased caliber made of smaller vessels such as the carotid lends itself readily as a transplant to the severed aorta, with a reasonable assurance of reestablishing the continuity of this vessel. 6. Defects in the aorta can be readily corrected by the use of fascial transplants with a minimum danger of thrombosis.