Vessel Replacement Research Articles

Abstract 360: Development of a Human Tissue-Engineered Blood Vessel from Adipose-Derived Stem Cells

There exists a clear need for alternative sources of small-diameter vascular grafts for treating the millions of patients who suffer from cardiovascular disease each year. Bypass surgery or replacement of defective vessels is often required to treat coronary heart disease, but there is a limited supply of suitable autologous grafts, and synthetic grafts are ineffective for replacement of small-diameter vessels. Inherent thrombogenicity, compliance mismatch, and limited patency rates are all complications with current options. Tissue engineering has the potential to overcome these limitations by producing a readily-available vascular graft completely from biological material. It is the objective of this study to fabricate such a small-diameter tissue engineered blood vessel (TEBV) by using the human amniotic membrane as a mechanically-sound biological substrate. Our technology begins by differentiating adipose-derived stem cells into smooth muscle cells (SMCs) and seeding them onto a flat sheet of the amniotic membrane. We assessed our hypothesis that several types of SMCs can successfully attach and proliferate on this membrane by fluorescently staining cell nuclei with DAPI and characteristic SMC actin filaments with phallotoxins. After 7 days in static culture, the cell-seeded sheet was wrapped around a 3mm O.D. removable mandrel with 6-7 revolutions to develop a tubular construct with architecture akin to that of a muscular artery’s tunica media layer. After a 2 week static culture period, the TEBV was characterized for its biochemical and mechanical properties. We examined the contraction of the vessel in response to carbachol, a specific agonist for SMCs, and compared our results with the contraction of porcine coronary arteries. Burst pressure and elastic modulus tests were also performed. The mechanical integrity of this construct can be further improved upon its exposure to appropriate physiological conditions in a perfusion bioreactor. We show that adipose-derived endothelial cells (ECs) can be also be seeded into the lumen of this construct to prevent platelet adhesion. In conclusion, we have developed a small-diameter TEBV with off-the-shelf availability using a completely biological material seeded with patient-own stem cells.

A Fibrillar Biodegradable Scaffold for Blood Vessels Tissue Engineering

In recent years there has been a growing interest for the development of tubular scaffolds employed to assist the replacement of small blood vessels. Materials designed for this purpose need to be biodegradable, have good mechanical properties and improve cell adhesion, proliferation and differentiation. To obtain biomaterials with these properties, electrospinning seems to be one of the most useful technique. Several biodegradable synthetic polymers or constituents of the extracellular matrix (ECM) have been electrospun showing optimal mechanical properties and biodegradability. However, such polymers are lacking in versatile chemical structure affordable to immobilize growth factors or chemokines. The glycosaminoglycan heparin is able to bind several growth factors like vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) and, when grafted onto the scaffold surface it is able to attract cells thus improving their proliferation and differentiation.Aim of this research was the production and the preliminary in vitro biological characterization of a new biodegradable material, obtained by electrospun a polyaminoacid-graft-polyester copolymer. The electrospun biomaterial has been successfully grafted with heparin exploiting the better chemical reactivity of the polyaminoacid portions of the graft copolymer. Then its morphology has been investigated by scanning electron microscopy (SEM) and the potential biodegradability of the material has been studied until 60 days. Preliminary biological data in vitro, on human endothelial cells, show a good compatibility of the scaffold obtained by electrospinning, with regard to cell adhesion and proliferation. Experiments are in progress to evaluate the effects of heparin on cell differentiation.

Mussel-Inspired Immobilization of Vascular Endothelial Growth Factor (VEGF) for Enhanced Endothelialization of Vascular Grafts

Most polymeric vascular prosthetic materials have low patency rate for replacement of small diameter vessels (<5 mm), mainly due to failure to generate healthy endothelium. In this study, we present polydopamine-mediated immobilization of growth factors on the surface of polymeric materials as a versatile tool to modify surface characteristics of vascular grafts potentially for accelerated endothelialization. Polydopamine was deposited on the surface of biocompatible poly(L-lactide-co-ε-caprolactone) (PLCL) elastomer, on which vascular endothelial growth factor (VEGF) was subsequently immobilized by simple dipping. Surface characteristics and composition were investigated by using scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Immobilization of VEGF on the polydopamine-deposited PLCL films was effective (19.8 ± 0.4 and 197.4 ± 19.7 ng/cm(2) for DPv20 and DPv200 films, respectively), and biotin-mediated labeling of immobilized VEGF revealed that the fluorescence intensity increased as a function of the concentration of VEGF solution. The effect of VEGF on adhesion of HUVECs was marginal, which may have been masked by polydopamine layer that also enhanced cell adhesion. However, VEGF-immobilized substrate significantly enhanced proliferation of HUVECs for over 7 days of in vitro culture and also improved their migration. In addition, immobilized VEGF supported robust cell to cell interactions with strong expression of CD 31 marker. The same process was effective for immobilization of basic fibroblast growth factor, demonstrating the robustness of polydopamine layer for secondary ligation of growth factors as a simple and novel surface modification strategy for vascular graft materials.

Tri-layered vascular grafts composed of polycaprolactone, elastin, collagen, and silk: Optimization of graft properties

The purpose of this study was to create seamless, acellular, small diameter bioresorbable arterial grafts that attempt to mimic the extracellular matrix and mechanical properties of native artery using synthetic and natural polymers. Silk fibroin, collagen, elastin, and polycaprolactone (PCL) were electrospun to create a tri-layered structure for evaluation. Dynamic compliance testing of the electrospun grafts ranged from 0.4–2.5%/100 mmHg, where saphenous vein (1.5%/100 mmHg) falls within this range. Increasing PCL content caused a gradual decrease in medial layer compliance, while changes in PCL, elastin, and silk content in the adventitial layer had varying affects. Mathematical modeling was used to further characterize these results. Burst strength results ranged from 1614–3500 mmHg, where some exceeded the capacity of the pressure regulator. Four week degradation studies demonstrated no significant changes in compliance or burst strength, indicating that these grafts could withstand the initial physiological conditions without risk of degradation. Overall, we were able to manufacture a multi-layered graft that architecturally mimics the native vascular wall and mechanically matches the gold standard of vessel replacement, saphenous vein.

Heparin-Modified Small-Diameter Nanofibrous Vascular Grafts

Due to high incidence of vascular bypass procedures, an unmet need for suitable vessel replacements exists, especially for small-diameter vascular grafts. Here we produced 1-mm diameter vascular grafts with nanofibrous structure via electrospinning, and successfully modified the nanofibers by the conjugation of heparin using di-amino-poly(ethylene glycol) (PEG) as a linker. Antithrombogenic activity of these heparin-modified scaffolds was confirmed in vitro. After 1 month implantation using a rat common carotid artery bypass model, heparin-modified grafts exhibited 85.7% patency, versus 57.1% patency of PEGylated grafts and 42.9% patency of untreated grafts. Post-explant analysis of patent grafts showed complete endothelialization of the lumen and neovascularization around the graft. Smooth muscle cells were found in the surrounding neo-tissue. In addition, greater cell infiltration was observed in heparin-modified grafts. These findings suggest heparin modification may play multiple roles in the function and remodeling of nanofibrous vascular grafts, by preventing thrombosis and maintaining patency, and by promoting cell infiltration into the three-dimensional nanofibrous structure for remodeling.

Effects of a Pseudophysiological Environment on the Elastic and Viscoelastic Properties of Collagen Gels

Vascular tissue engineering focuses on the replacement of diseased small-diameter blood vessels with a diameter less than 6 mm for which adequate substitutes still do not exist. One approach to vascular tissue engineering is to culture vascular cells on a scaffold in a bioreactor. The bioreactor establishes pseudophysiological conditions for culture (medium culture, 37°C, mechanical stimulation). Collagen gels are widely used as scaffolds for tissue regeneration due to their biological properties; however, they exhibit low mechanical properties. Mechanical characterization of these scaffolds requires establishing the conditions of testing in regard to the conditions set in the bioreactor. The effects of different parameters used during mechanical testing on the collagen gels were evaluated in terms of mechanical and viscoelastic properties. Thus, a factorial experiment was adopted, and three relevant factors were considered: temperature (23°C or 37°C), hydration (aqueous saline solution or air), and mechanical preconditioning (with or without). Statistical analyses showed significant effects of these factors on the mechanical properties which were assessed by tensile tests as well as stress relaxation tests. The last tests provide a more consistent understanding of the gels' viscoelastic properties. Therefore, performing mechanical analyses on hydrogels requires setting an adequate environment in terms of temperature and aqueous saline solution as well as choosing the adequate test.

Elastomeric degradable biomaterials by photopolymerization-based CAD-CAM for vascular tissue engineering

A predominant portion of mortalities in industrial countries can be attributed to diseases of the cardiovascular system. In the last decades great efforts have been undertaken to develop materials for artificial vascular constructs. However, bio-inert materials like ePTFE or PET fail as material for narrow blood vessel replacements (coronary bypasses). Therefore, we aim to design new biocompatible materials to overcome this. In this paper we investigate the use of photoelastomers for artificial vascular constructs since they may be precisely structured by means of additive manufacturing technologies. Hence, 3D computer aided design and manufacturing technologies (CAD-CAM) offer the possibility of creating cellular structures within the grafts that might favour ingrowth of tissue. Different monomer formulations were screened concerning their suitability for this application but all had drawbacks, especially concerning the suture tear resistance. Therefore, we chose to modify the original network architecture by including dithiol chain transfer agents which effectively co-react with the acrylates and reduce crosslink density. A commercial urethane diacrylate was chosen as base monomer. In combination with reactive diluents and dithiols, the properties of the photopolymers could be tailored and degradability could be introduced. The optimized photoelastomers were in good mechanical accordance with native blood vessels, showed good biocompatibility in in vitro tests, degraded similar to poly(lactic acid) and were successfully manufactured with the 3D CAD-CAM technology.

In vivo visualization of the origination of skin graft vasculature in a wild-type/GFP crossover model

IntroductionSkin substitutes are increasingly produced in tissue engineering, but still the understanding of the physiological skin revascularization process is lacking. To study in vivo conditions we recently introduced a mouse model, in which we already characterized the angiogenic changes within the wound bed and the skin graft. The aim of this study was to identify the origination of the vasculature during skin graft revascularization in vivo and to track vessel development over time. MethodsWe created a crossover wild-type/GFP skin transplantation model, in which each animal carried the graft from the other strain. The preparation of the modified dorsal skin fold chamber including cross-over skin grafting was performed in male C57BL/6J wild-type mice (n=5) and C57BL/6-Tg(ACTB-EGFP)1Osb/J mice (n=5). Intravital microscopy in 12 areas of wild-type and GFP skin grafts was performed daily over a time period of 10days. ResultsGraft reperfusion started after 48–72h. After reperfusion GFP-positive structures from the wound bed were visible in the graft capillaries with the highest density in the center of the graft. Overall, we observed a replacement of existing graft capillaries with vessels from the wound bed in 68% of the vessels. Of note, vessel replacement occurred in almost 100% of graft vessels in the periphery. Additionally, vessels within the graft showed a temporary angiogenic response between days 3–8, which originated predominantly from the autochthonous graft vasculature, but also contained already grown-in vessels from the wound bed. ConclusionsThese in vivo data indicate an early in-growth of angiogenic bed vessels into the existing vascular channels of the graft and subsequent centripetal replacement. Additionally we observed a temporary angiogenic response of the autochthonous capillaries of the skin graft with contribution from bed vessels. These findings further support the theory that sprouting angiogenesis from the wound bed in combination with the replacement of existing graft vessels are the key factors in skin graft taking. Thus, manufacturing of skin substitutes should be aimed at providing pre-formed vascular channels within the construct to improve vascularization.

Tissue Engineering of Blood Vessels: Functional Requirements, Progress, and Future Challenges

Vascular disease results in the decreased utility and decreased availability of autologus vascular tissue for small diameter (< 6 mm) vessel replacements. While synthetic polymer alternatives to date have failed to meet the performance of autogenous conduits, tissue-engineered replacement vessels represent an ideal solution to this clinical problem. Ongoing progress requires combined approaches from biomaterials science, cell biology, and translational medicine to develop feasible solutions with the requisite mechanical support, a non-fouling surface for blood flow, and tissue regeneration. Over the past two decades interest in blood vessel tissue engineering has soared on a global scale, resulting in the first clinical implants of multiple technologies, steady progress with several other systems, and critical lessons-learned. This review will highlight the current inadequacies of autologus and synthetic grafts, the engineering requirements for implantation of tissue-engineered grafts, and the current status of tissue-engineered blood vessel research.

Transcription Factor Nkx2-3 Controls the Vascular Identity and Lymphocyte Homing in the Spleen

The vasculature in the spleen and peripheral lymph nodes (pLNs) is considerably different, which affects both homing of lymphocytes and antigenic access to these peripheral lymphoid organs. In this paper, we demonstrate that in mice lacking the homeodomain transcription factor Nkx2-3, the spleen develops a pLN-like mRNA expression signature, coupled with the appearance of high endothelial venules (HEVs) that mediate L-selectin-dependent homing of lymphocytes into the mutant spleen. These ectopic HEV-like vessels undergo postnatal maturation and progressively replace MAdCAM-1 by pLN addressin together with the display of CCL21 arrest chemokine in a process that is reminiscent of HEV formation in pLNs. Similarly to pLNs, development of HEV-like vessels in the Nkx2-3-deficient spleen depends on lymphotoxin-β receptor-mediated signaling. The replacement of splenic vessels with a pLN-patterned vasculature impairs the recirculation of adoptively transferred lymphocytes and reduces the uptake of blood-borne pathogens. The Nkx2-3 mutation in BALB/c background causes a particularly disturbed splenic architecture, characterized by the near complete lack of the red pulp, without affecting lymph nodes. Thus, our observations reveal that the organ-specific patterning of splenic vasculature is critically regulated by Nkx2-3, thereby profoundly affecting the lymphocyte homing mechanism and blood filtering capacity of the spleen in a tissue-specific manner.

Identification of a coronary stem cell in the human heart

Human ischemic cardiomyopathy is characterized by de novo cardiomyogenesis, which is limited to the surviving portion of the ventricle, and by organ hypertrophy that develops as a chronic response to ischemic injury. Although myocyte hypertrophy and myocyte regeneration restore the original myocardial mass, the coronary vasculature remains defective and the extent and regulation of myocardial perfusion are severely impaired. Recently, vascular stem cells (VSCs) have been identified in the coronary circulation. VSCs express c-kit and the vascular endothelial growth factor receptor-2, KDR. These cells are self-renewing, clonogenic, and multipotent in vitro and in vivo. In animal models of critical coronary artery stenosis, VSCs form large conductive coronary arteries and their distal branches. This degree of vasculogenesis replaces partly the function of the occluded coronary artery improving myocardial perfusion and positively interfering with the development of the post-infarction myopathy. Cell therapy directed to the restoration of the integrity of the coronary circulation, the replacement of atherosclerotic coronary vessels, or both, would change dramatically the goal of cell therapy for the ischemic heart: the prevention of myocardial injury would become the end-point of cell therapy rather than the partial recovery of established damage.

The false aneurysm after iatrogenic arterial puncture: Incidence, risk factors, and surgical treatment

Due to the increased number of arterial punctures performed during angiography and angioplasty, the incidence of false aneurysms after arterial puncture has increased in significance. It was reported as 0.05–2%; with careful sonographic follow-up it may be twice as high. The goal of the retrospective investigation (28 patients with false aneurysms) was to elucidate risk factors leading to failure of spontaneous closure of the arterial site, and to examine symptoms and clinical courses. False aneurysms became manifest on average 16.4 days after puncture. Highest risk was seen in obese patients (64.3%), where the number of tangential and multiple vessel punctures was also highest. Further risk factors were local sclerosis, hypertension, diabetes, poor general condition, and coagulopathies. Twelve false aneurysms (42.8%) were found incidentally; diagnosis was made in all patients sonographically. In 89.3%, primary suture or patchplasty was possible and in 10.7%, more extensive vessel replacement was necessary. Postoperative complications included local infection (7.14%), recurrent false aneurysm (3.5%), and arterial bleeding (3.5%). At an average follow-up of 4.25 years, no local occlusions nor recurrent false aneurysms were seen. Preventative measures in high-risk patients (more precise puncture, prolonged compression) could reduce the morbidity of false aneurysms after puncture. Longer follow-up period would be necessary to show up the true incidence of false aneurysms and provide information on the asymptomatic courses. Surgery must be performed by experienced vascular surgeons as only at time of operation can the full extent of the arterial lesion be identified and the necessary corrective vascular procedures be performed.

The role of shear stress on mechanically stimulated engineered vascular substitutes: influence on mechanical and biological properties

Vascular tissue engineering represents a promising field in the replacement of diseased vessels. The biological properties of three-dimensional (3D) collagen scaffolds indicate this material as a valid choice for vascular tissue engineering. Unfortunately, mechanical properties still remain unsatisfactory, due to a low burst pressure resistance and a plastic deformation. The use of a bioreactor to apply appropriate mechanical stresses have already shown a remodelling effect on the extracellular matrix and the behaviour of cells. In this study, we have shown the effect of the mechanical stress on elastin synthesis, which has a direct effect on the mechanical properties of the tissue-engineered vessel. We measured and compared the stress-strain curves, the elastic modulus and tenacity of a collagen tubular scaffold in the presence of C2C12 murine myoblasts cells, before and after the maturation in the bioreactor, applying a shear stress of 5 dynes/cm(2) for 3 days. Interesting evidence concerning the extracellular matrix structure, which significantly modify the biomechanical characteristics of the cellular scaffold, were observed, underlying the importance of focusing more effort in the research field of physiologically-guided 3D tissue-engineered substitutes.

The Mechanical Properties of Electrospun Collagen/PCL Single Fibers and Fibrous Scaffolds

Collagen/Poly-ε-caprolactone (PCL) blended fibers were electrospun from a solution of 2.5% wt./vol. bovine collagen, 2.5% wt./vol. PCL and 95% 1,1,1,3,3,3-hexaflouro-2-propanol (HFP). A combined atomic force microscopic (AFM)/optical microscopic technique was used to study the properties of individual fibers in buffer. Mechanical testing of fibers was done using the AFM to laterally stretch individual fibers suspended over 13.5μm wide groves in a transparent substrate. The optical microscope, located below the sample, was used to monitor the stretching process. Fibrous scaffolds of these blends were also electrospun to test the bulk mechanical properties. A total of 5ml of 5% wt./vol. solution of blended collagen/PCL was used to electrospin scaffolds with a 4.75mm inner diameter to be used to for blood vessel tissue replacements. Dots are applied to the surface of the scaffold which is then subjected to cyclic loading under wet conditions while video is being recorded of the test. When a replicable elastic mechanical behavior is achieved, the strain found in the loading part of the cycle is analyzed using non-contact video strain measurements. By testing the single fiber mechanical properties of these blends as well as the bulk mechanical properties of a fibrous scaffold we are able to determine the mechanical differences of the fibers on both a micro and macro scaffold. These results can be used to better develop tissue engineered scaffolds for blood vessel replacements.

Preservation of human artery function following prolonged cold storage with a new solution

Blood vessels are an important tissue for allogenic vessel replacement surgery, which is needed for example following infection of artificial grafts. For tissue banking, European legislation requires evidence of tissue sterility with assays performed over 1 week. Currently, used cold storage solutions do not protect vascular function longer than 2 days. This does not allow completion of microbiological testing. This discrepancy has almost completely stopped vessel banking in Europe. We compared the recently developed storage solution TiProtec (Dr F Köhler Chemie, Bensheim, Germany) with traditionally used histidine-tryptophan-ketoglutarate (HTK) solution, 0.9% NaCl, and phosphate-buffered saline (physiological saline solution [PSS]) solution for extended cold (4°C) storage up to 25 days. Isolated rings of human internal mammary artery were studied with respect to several parameters of vessel function, including vessel tone development, endothelium-dependent and endothelium-independent relaxation, and tissue reductive capacity. Vessels stored in NaCl or PSS for ≥10 hours failed to develop tone after rewarming. Mammary arteries stored in HTK for 4 hours at 4°C initially showed a well-preserved vessel function with respect to vessel tone development, as well as endothelial and smooth muscle dilatative function. However, following 4 days of cold storage, vessel tone development and dilatative responses were significantly impaired. In contrast, arteries stored in TiProtec showed full preservation of vessel tone as well as endothelial and smooth muscle function after 4 days of cold storage. Even after 10 days of cold storage, endothelium-dependent relaxation was approximately 50% of control, and smooth muscle function was fully preserved. Over 2 weeks, tissue reductive capacity was significantly better maintained after cold storage in TiProtec compared with vessels stored in NaCl. In contrast to traditional HTK, NaCl, or PSS storage, TiProtec solution offers an excellent potential for prolonged cold storage of human arteries, which may close the existing gap between legal requirements for tissue banking and current cold preservation methods.

Strong in Biomaterials and Polymer Science

What was most interesting and important to our reader in 2010? Among the 270 articles published in the last two years the topics drug and gene delivery and tissue engineering could assemble the most citations in 2010, followed by more classical polymer topics such as biodegradable polymers, glycol- and biopolymers (Table 1). It's thus fair to say: Macromolecular Bioscience is strong in biomaterials and polymer science. What was most interesting to me? I have to admit that I was deeply impressed by the outstanding topical issues we published within the last year. In November, a special issue on “Instructive Materials for Functional Tissue Engineering” guest-edited by Anita Driessen-Mol, Carlijn V. C. Bouten, and Frank P. T. Baaijens (Eindhoven University of Technology, The Netherlands) highlighted topics such as cardiac repair, heart valves and blood vessel replacements, and in situ bone formation, just to name a few. Issue 9 was dedicated to “Polymers in Biomedicine” (guest-edited by Andreas Lendlein, GKSS Research Center Teltow, Germany). With the help of board member Jan C.M. van Hest (Radboud University Nijmegen, The Netherlands) we published an impressive issues on “Micro- and Nanocapsules for Biological and Biomedical Applications”. The renaissance of “Analytical Ultracentrifugation”, a topical issue organized by one of our newer board members, Helmut Cölfen (University of Konstanz, Germany) on the occasion of the 125th birthday of Theodor Svedberg, concentrated on a less classical, though not less interesting topic for Macromolecular Bioscience. All in all, the anniversary year of Macromolecular Bioscience was a year of great topical diversity, which has made it so exciting for me. A year of celebrations? Not only. It was also a year of hard work. Dealing with roughly 10% more submissions as compared to 2009, we were still able to reduce the average time to initial decision of all published articles to 35 days. But there is even more to be happy about. The number of article accesses (full-text downloads) and the number of total citations both increased by more than 20%. After one decade, Macromolecular Bioscience confirms its position among the top 5 biomaterials and the top 10 polymer journals with an ISI impact factor of 3.108. Finally, we welcome two new members to our international advisory board: We are looking forward to an intensified cooperation with Helmut Schlaad (MPI of Colloids and Interfaces, Golm, Germany) and Brent Sumerlin (Southern Methodist University, Dallas, USA). Not only our board members, but also our critical reviewers, our authors, and last but not least our readers contribute to the success of Macromolecular Bioscience. It's time to thank all of you for your commitment and your ongoing interest in our journal. Together, we are looking forward to the exciting second decade of Macromolecular Bioscience.

Bacterial cellulose modified with xyloglucan bearing the adhesion peptide RGD promotes endothelial cell adhesion and metabolism-a promising modification for vascular grafts

Today, biomaterials such as polytetrafluorethylene (ePTFE) are used clinically as prosthetic grafts for vascular surgery of large vessels (>5 mm). In small diameter vessels, however, their performance is poor due to early thrombosis. Bacterial-derived cellulose (BC) is a new promising material as a replacement for blood vessels. This material is highly biocompatible in vivo but shows poor cell adhesion. In the native blood vessel, the endothelium creates a smooth non-thrombogenic surface. In order to sustain cell adhesion, BC has to be modified. With a novel xyloglucan (XG) glycoconjugate method, it is possible to introduce the cell adhesion peptide RGD (Arg-Gly-Asp) onto bacterial cellulose. The advantage of the XG-technique is that it is an easy one-step procedure carried out in water and it does not weaken or alter the fiber structure of the hydrogel. In this study, BC was modified with XG and XGRGD to asses primary human vascular endothelial cell adhesion, proliferation, and metabolism as compared with unmodified BC. This XG-RGD-modification significantly increased cell adhesion and the metabolism of seeded primary endothelial cells as compared with unmodified BC whereas the proliferation rate was affected only to some extent. The introduction of an RGD-peptide to the BC surface further resulted in enhanced cell spreading with more pronounced stress fiber formation and mature phenotype. This makes BC together with the XG-method a promising material for synthetic grafts in vascular surgery and cardiovascular research.

Large-Sized Bilateral Axillary Artery Aneurysms in a Patient with Marfan Syndrome: A Case Report

A 46-year-old man presented with large bilateral aneurysm of the axillary arteries combined with Marfan syndrome. Treatment consisted of axillary aneurysm resection and vessel replacement. Postoperative computed tomographic angiography confirmed good flow in the bilateral axillary artery, and the patient recovered without complication.

Efficacy of amiodarone on refractory ventricular fibrillation resistant to lidocaine and cardioversion during weaning from cardiopulmonary bypass in aortic valve replacement for severe aortic stenosis with left ventricular hypertrophy

Intravenous injection of amiodarone, a class III anti-arrhythmic is widely used for persistent refractory arrhythmias. We present a case report suggesting the efficacy of amiodarone in refractory ventricular fibrillation (Vf) during weaning from cardiopulmonary bypass (CPB). A 66-year-old woman with hypertension had a medical examination as a result of an episode of palpitations and syncope. Echocardiography and an invasive hemodynamic study revealed severe aortic stenosis (AS) with left ventricular (LV) hypertrophy because of calcified degeneration in a congenital bicuspid aortic valve (AV). Aortic valve replacement (AVR) was scheduled under general anesthesia and CPB. Intraoperative diagnosis was AS with calcified AV, LV hypertrophy, and aneurysm of ascending aorta (Ao). AVR with a biological valve, artificial vessel replacement of ascending Ao, and excision of the outflow myocardial septum were performed under CPB with intermittent antegrade blood cardioplegia at a body temperature (BT) of 24°C. The patient suffered from Vf at a BT of 35.3°C. Vf was not responsive to lidocaine 100mg and 10 direct current (DC) shocks. After continuous intravenous infusion of amiodarone 225mg/h for 10min and a single intravenous injection of amiodarone 150mg followed by a single DC shock, she returned to normal sinus rhythm. Sinus rhythm was maintained by continuous intravenous infusion of amiodarone 60mg/h. Total CPB time was 5h 43min. Aortic cross-clamping time was 3h 50min. Administration of amiodarone is effective for refractory Vf resistant to lidocaine and cardioversion during weaning from CPB in cardiac surgery for heart diseases with LV hypertrophy.

Social Change and the Evolution of Ceramic Production and Distribution in a Maya Community (review)

Reviewed by: Social Change and the Evolution of Ceramic Production and Distribution in a Maya Community Chandra D. Bhimull (bio) Social Change and the Evolution of Ceramic Production and Distribution in a Maya Community. By Dean E. Arnold. Boulder: University Press of Colorado, 2008. Pp. xxxii+351. $65. The concept of change is central to Dean Arnold's book. On the one hand, this is not new. For decades, historically minded anthropologists have wrestled with how to identify and evaluate dynamic processes. On the other hand, Arnold's book differs because it uses a narrow scope and a microscale to analyze transformation. Written by a specialist of ceramic ethnoarchaeology, its focus is on nearly forty years of pottery production and circulation among members of a Maya community in Ticul, Yucatán. Arnold argues that social, political, and economic changes materialize in pottery. Adopting anthropology's unique holistic perspective, he identifies and combines at least five paradigms that scholars have used to interpret change. As a result, readers weave through analytical frames such as specialization and evolving complexity, evolutionary processes, technological choice, cognitive anthropology, and engagement theory. In thirty-two years, Arnold took ten trips to Yucatán. From the vantage point that extended fieldwork afforded, he observed and participated in the [End Page 770] daily lives of potters. He watched as the demand for pots changed, altering patterns of consumption accordingly. He observed how weather, water, and other natural things shaped desire, and he saw how the advent of tourism and mechanized technology altered it. "The development of municipal piped water in the 1960s" shattered "consumer demand for water-carrying and storage vessels" (p. 124). How industrialization impacts indigenous ways interests Arnold. References to ritual provide insight into the important but shifting roles that potters and their products play in demarcated space and time. For instance, various kinds of clay containers are used for ceremonies transacted on the Day of the Dead. Traditionally, members of the community purchased items such as bowls for food and burners for candles and incense. However, as Arnold notes, increased access to metal pots has "led to the replacement of clay cooking vessels with metal ones" (p. 124). Alongside industrialization, Arnold glimpses globalization. A sharp opponent of synchronic studies, he defines globalization as a historical process. In doing so, he dismantles distinctions such as the globalized present and the non-globalized past, stating pointedly that "cultural evolution in the present is accelerating at a rapid pace, collapsing centuries of cultural evolution into the span of a scholar's lifetime" (p. 20). Arnold's analysis of globalization is peripheral, but it is difficult to read and not realize that international forces are influencing contemporary village life in Ticul. To what extent are these external influences new? What counts as change? These questions haunt this book. Arnold is meticulous in his efforts. He is attentive to details such as fabrication and firing technologies, forming techniques and turntables, and clay and temper procurement. Serious consideration of such factors risks diverting awareness away from the impact of long-term, large-scale transformation: conquest, colonization, independence, and revolution. Investigating historical events in tandem with current forms of social change could further disintegrate the artificial divides we carve into time; it could push us to wonder how people identify change for themselves. Pottery is an important part of everyday life in Ticul. There are pots for plants, food, flowers, incense, music, coins, ashes, and souvenirs. They surface in stories. They are sold in markets. This book motivates us to be mindful of the mutable material processes that make pots possible. [End Page 771] Chandra D. Bhimull Dr. Bhimull is assistant professor of anthropology and African-American studies at Colby College in Maine. Copyright © 2010 The Society for the History of Technology