Dissertations / Theses on the topic 'Arterial grafts'

Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Elliot Chaikof; Committee Member: Marc Levenston; Committee Member: Robert Nerem; Committee Member: Vincent Conticello; Committee Member: Yadong Wang. Part of the SMARTech Electronic Thesis and Dissertation Collection.

There is a significant need for small diameter vascular grafts to be used in peripheral vascular surgery; however autologous grafts are not always available, synthetic grafts perform poorly and allografts and xenografts degenerate, dilate and calcify after implantation. We hypothesized that chemical stabilization of acellular xenogenic arteries would generate off-the-shelf grafts resistant to thrombosis, dilatation and calcification. To test this hypothesis, we decellularized porcine renal arteries, stabilized elastin with pentagalloyl glucose and collagen with carbodiimide/activated heparin and implanted them as trans- position grafts in the abdominal aorta of rats as direct implants and separately as indirect, isolation-loop implants. All implants resulted in high patency and animal survival rates, ubiquitous encapsulation within a vascularized collagenous capsule, and exhibited lack of lumen thrombogenicity and no graft wall calcification. Peri-anastomotic neo-intimal tissue overgrowth was a normal occurrence in direct implants; however this reaction was circumvented in indirect implants. Notably, implantation of non- treated control scaffolds exhibited marked graft dilatation and elastin degeneration; however PGG significantly reduced elastin degradation and prevented aneurismal dilatation of vascular grafts. Overall these results point to the outstanding potential of crosslinked arterial scaffolds as small diameter vascular grafts.

Peripheral vascular grafts are used for the treatment of peripheral arterial disease and arteriovenous grafts for vascular access in end stage renal disease. The development of neo-intimal hyperplasia and thrombosis in the distal anastomosis remains the main reason for occlusion in that region. The local haemodynamics produced by a graft in the host vessel is believed to significantly affect endothelial function. Single spiral flow is a normal feature in medium and large sized vessels and it is induced by the anatomical structure and physiological function of the cardiovascular system. Grafts designed to generate a single spiral flow in the distal anastomosis have been introduced in clinical practice and are known as spiral grafts. In this work, spiral peripheral vascular and arteriovenous grafts were compared with conventional grafts using ultrasound and computational methods to identify their haemodynamic differences. Vascular-graft flow phantoms were developed to house the grafts in different surgical configurations. Mimicking components, with appropriate acoustic properties, were chosen to minimise ultrasound beam refraction and distortion. A dual-beam two-dimensional vector Doppler technique was developed to visualise and quantify vortical structures downstream of each graft outflow in the cross-flow direction. Vorticity mapping and measurements of circulation were acquired based on the vector Doppler data. The flow within the vascular-graft models was simulated with computed tomography based image-guided modelling for further understanding of secondary flow motions and comparison with the experimental results. The computational assessments provided a three-dimensional velocity field in the lumen of the models allowing a range of fluid dynamic parameters to be predicted. Single- or double-spiral flow patterns consisting of a dominant and a smaller vortex were detected in the outflow of the spiral grafts. A double- triple- or tetra-spiral flow pattern was found in the outflow of the conventional graft, depending on model configuration and Reynolds number. These multiple-spiral patterns were associated with increased flow stagnation, separation and instability, which are known to be detrimental for endothelial behaviour. Increased in-plane mixing and wall shear stress, which are considered atheroprotective in normal vessels, were found in the outflow of the spiral devices. The results from the experimental approach were in agreement with those from the computational approach. This study applied ultrasound and computational methods to vascular-graft phantoms in order to characterise the flow field induced by spiral and conventional peripheral vascular and arteriovenous grafts. The results suggest that spiral grafts are associated with advanced local haemodynamics that may protect endothelial function and thereby may prevent their outflow anastomosis from neo-intimal hyperplasia and thrombosis. Consequently this work supports the hypothesis that spiral grafts may decrease outflow stenosis and hence improve patency rates in patients.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2005.
David N. Ku, Committee Chair ; Alexander Rachev, Committee Co-Chair ; Elliot L. Chaikof, Committee Member. Includes bibliographical references.

In this dissertation, a methodology for comparing large arteries and tissue engineered vascular grafts is presented. This methodology is based on general porohyperelastic transport swelling theory (PHETS). Suites of experiments are introduced to determine material and transport properties of each vessel. These properties include elasticity, permeability, diffusivity, and convection coefficient. Finite element models (FEMs) were then used to model investigate arterial wall fluid flow and mobile species transport under quasi-static and pulsatile conditions. Rabbit carotid arteries were compared to rabbit aortas. The carotid was more elastic and permeable then the aorta. The pulsatile fluid wall flux was very different from the quasi-static and pulsatile in vivo conditions in these vessels. Tissue engineered vascular grafts (TEVGs) were fabricated in a bioreactor using high and low wall shear stress conditions. The elevated stiffness of ePTFE TEVGs significantly affects the fluid and species transport under both quasi-static and pulsatile conditions. A repeating influx/efflux condition developed in the large arteries and TEVGs during pulsatile pressurization. These conditions provide fluid/species transport pathways in arteries and TEVGs in pulsatile environments. The theoretical basis for ABAQUS FEMs coupled convection/diffusion of neutral species and water was developed. This will allow the analysis of mobile species concentration and flux in complex FEMs of soft biological structures. The theory and FEMs should also be useful in the study of vascular diseases, TEVG development, and drug transport in soft tissues.

Bibliografische Beschreibung Knepper, Robert Darstellung des Verlaufs der Arteria palatina major unter dem Aspekt der Entnahme autologer Bindegewebstransplantate aus dem Gaumen Universität Leipzig, Dissertation 68 Seiten, 43 Literaturangaben, 42 Abbildungen, 12 Tabellen, 4 Anlagen Referat: Die sich stets weiterentwickelnden Verfahren zahnärztlicher Chirurgie bringen auch neue Anforderungen an den Operateur mit sich. Vor allem im Bereich der ästhetischen Korrektur von weichgewebigen Defekten im Bereich des Zahnhalteapparates gilt es, auf dem neuesten Stand zu sein, um moderne Zahnheilkunde anbieten zu können. Profunde Kenntnisse zur Topographie anatomischer Strukturen sind dabei für den Zahnarzt, den Spezialisten für Parodontologie und den Oralchirurgen unabdingbar. Um die dafür notwendige praktische Anleitung zu erhalten, können Mediziner am Institut für Anatomie der Universität Leipzig Kurse absolvieren, so z.B. auch angehende zahnärztliche Implantologen. Hierbei interessiert die Teilnehmer neben dem praktischen Vorgehen auch der Verlauf von Gefäßen und Nerven im Operationsgebiet. Anatomische Atlanten stellen die betreffenden Areale idealisiert und ohne Berücksichtigung der individuellen Variationsbreite dar. Zugänge, wie sie in der Klinik benötigt werden, finden sich selten. Aus diesem Grund wurde in der vorliegenden Arbeit an sechs vollständigen und 21 geteilten humanen Kopfpräparaten (alle Ethanol-Glycerin fixiert) die A. palatina major präpariert und der klinischen Situation gegenübergestellt. Diese Arterie wurde gewählt, da ihr Versorgungsgebiet – der Gaumen – die bevorzugte Spenderregion autologer Bindegewebstransplantate ist. Dadurch wird die Lücke der oft unzureichenden Verknüpfung der klinischen Situation mit dem anatomischen Korrelat geschlossen. Des Weiteren wurde an diesen Präparaten eine in der Literatur als sicher beschriebene Entnahmestelle vermessen und die Werte den bekannten gegenübergestellt. Um diese Messwerte beurteilen zu können, wurde außerdem die Frage gestellt, inwieweit die Fixierung der Präparate deren Beschaffenheit verändert. Dies wurde in einem Versuch mit dentalen Volumentomogrammen von frisch angefertigten und anschließend fixierten Präparaten untersucht. Auf Grund der Tatsache, dass Humanpräparate nur für einen begrenzten Zeitraum zur Verfügung stehen, ist ein wesentlicher Aspekt dieser makroskopisch-anatomischen Arbeit die fotografische Dokumentation der präparierten Gefäßstrecken, bei der ästhetische u.a. Gesichtspunkte beachtet werden müssen. Da dies auch für andere makroskopische Arbeiten am Institut für Anatomie von Interesse ist, wurde dieser Teil so ausführlich beschrieben, dass er als Anleitung dienen kann.

The purpose of this study was to investigate the presence of arterial insufficiency in patients undergoing CABG surgery and whether arterial insufficiency is a risk factor for postoperative wound infections in the harvesting leg. Patients who had CABG surgery were enrolled consecutively. A total of 144 patients participated in the study. During their hospital stay demographic data was recorded, as well as pre-, intra-, and postoperative tests and risk factors. The patients answered a questionnaire regarding postoperative wound infections 30 days after surgery patients answered a questionnaire regarding infections. The known and potential risk factors that were recorded were BMI, HB, tobacco usage, diagnosed diabetes, hyperglycemia, duration of surgery, the lowest temperature during surgery and clinical or subclinical arterial insufficiency. The result showed that 34% had postoperative wound infections in the harvesting leg and 26 patients had an ABI (Ankel Brachial Index) indicating arterial insufficiency. There was no significant relationship between ABI and postoperative wound infections in the lower extremity in the total study group (p = 0.36) nor among men (p = 0.92). There was a significant correlation between ABI and postoperative wound infections in the lower extremity (p = 0.02) among women. The conclusion is that arterial insufficiency is more prevalent in women. The relationship between postoperative infections of the lower limbs and arterial insufficiency was significant for the participating women, but not in the total group nor among the men.

A novel technique for saphenous vein (SV) graft harvesting, the No-touch technique (NT), has been developed at the Dept. of Cardiovascular surgery, Örebro University hospital. With NT the SV is harvested with a pedicle of surrounding tissue. This avoids graft spasm and eliminates the need for distension. The surrounding tissue acts as a structural support and is a rich source of vaso-dilating agents. A randomized controlled trial (RCT) has shown a significantly higher patency rate for NT SV grafts compared to SV grafts harvested with conventional technique (CT). This thesis evaluates some of the properties of the surrounding tissue and compares patency rates between NT SV and radial artery (RA) grafts and patency rates for internal thoracic artery (ITA) grafts harvested with and without surrounding tissue. Paper I investigated vasa vasorum (VV) in SV grafts and showed that the NT preserves an intact VV whereas CT does not. This could be one of the mechanisms underlying the improved patency for NT SV grafts. Paper II evaluated VV and associated nitric oxide (NO) in SV and arterial grafts. SV grafts showed a higher number and larger VV, which correlated with NO production, compared to arterial grafts. NT SV grafts showed higher activity for e-NOS compared to CT SV grafts. Paper III is a RCT comparing patency rates between NT SV and RA grafts, three years after surgery, showing a significantly higher patency rate for NT SV grafts. Paper IV is a RCT comparing patency rates for ITA graft harvested with and without surrounding tissue and did not show any difference between graft preparations. In conclusion, the NT for SV graft harvesting preserves an intact vasa vasorum and associated NO production. NT SV grafts show a higher patency rate than RA grafts. Harvesting of ITA with or without surrounding tissue does not affect patency rate.

Introduction Bypass surgery for infrainguinal disease is indicated when a patient presents with chronic (disabling claudication or chronic limb-threatening ischaemia) or acute ischemia. Duplex ultrasound surveillance can be used in the follow-up period to detect grafts in risk of failure. If detected before occlusion occurs an intervention can prolong patency. Aim The purpose of this study was to evaluate the outcome of the procedure, whether there are factors associated with no improvement, and to elucidate the value of routine ultrasound surveillance. Methods Patients who underwent lower extremity bypass surgery at Falu hospital between 2010 and 2020 were identified from the national registry Swedvasc. Clinical outcome was based on change in the Rutherford classification. Duplex ultrasound measured peak systolic velocities. A significant stenosis was defined as a 2-3.5-fold increase in ratio of adjacent velocities in the bypass. For a non-significant stenosis, the ratio had to be increased but by less than 2 times. Results 114 patients underwent bypass surgery. Mean age was 70 years. Postoperative surveillance was carried out for 78 patients. Of these, 40 (51.3%) presented with an abnormality and further 30 of them (75%) received further intervention. There was a correlation between cardiac risk and outcome at the 30-day follow-up. For the majority of the not-surveilled, a major adverse event occurred within 1 year. Conclusions Bypass surgery was beneficial for the majority. Cardiac risk was a negative predictor for outcome. Most patients attending the surveillance benefited from early detection of risk of graft failure. To improve its value and efficacy, guidelines are needed within the clinic.

Introdução: Apesar de bons resultados descritos na literatura, o substituto ideal para a utilização como remendo no fechamento arterial ainda não existe. Por este motivo, ainda há espaço para a busca por remendo que seja biocompatível, e que apresente facilidade de manuseio e resultados satisfatórios. Avaliamos remendos arteriais de silicone (polidimetilsiloxano com reforço em poliéster - PDMSr) em comparação com remendos arteriais de PTFEe. Objetivo: O objetivo deste trabalho é comparar, em modelo experimental, em coelhos, os resultados de remendos arteriais feitos em PDMSr com remendos de PTFEe. Materiais e Método: A amostra foi definida em 10 animais que completassem todas as etapas da pesquisa em cada grupo. Os animais foram submetidos à laparotomia mediana e abertura longitudinal da aorta de aproximadamente 8mm, realizando-se o seu fechamento com remendo do grupo selecionado, seguido do fechamento por planos. Os animais foram mantidos em biotério até o 60º PO, quando, então, realizou-se arteriografia de controle, e análise macro e microscópica de peça. Resultados: Para se atingir a amostra desejada, foram necessários 12 procedimentos no grupo PDMSr e 16 no grupo PTFEe. Ocorreram 2 óbitos no grupo PDMSr e 6 no grupo PTFEe. Apesar do número maior de óbitos no grupo PTFEe não houve diferença estatística na sobrevida entre os grupos. Um animal do grupo PDMSr apresentou monoparesia em pata posterior direita e um animal do grupo PTFEe apresentou hérnia incisional. Não houve diferença estatística nas complicações entre os grupos. O tempo operatório foi estatisticamente maior no grupo PTFEe quando comparamos todos os animais, fato que não se repetiu quando excluímos os animais que faleceram. O peso e o tempo operatório foram estatisticamente maiores nos animais que morreram. Todos os animais que chegaram ao final do tempo de estudo apresentavam aorta patente. Na análise macroscópica da peça, houve, estatisticamente, maior reação tecidual periprótese no grupo PTFEe. A microscopia eletrônica de varredura evidenciou cobertura de todo o remendo de PDMSr por tecido similar ao endotélio, enquanto, nos remendos de PTFEe, o crescimento limitou-se às bordas da linha de sutura e ilhas isoladas no seu centro. Conclusão: O material estudado apresentou resultados comparáveis ao do PTFEe, porém com menor reação tecidual local e maior proliferação celular para a luz do vaso. Apesar de novos estudos serem necessários, inclusive para avaliação de uso em humanos, o presente estudo apresenta resultados promissores que encorajam a continuidade de sua pesquisa
Introduction: Although good results are reported for various materials for use as patches for arterial closure, as yet none of these is ideal. Therefore, research is continuing into development of a patch that is biocompatible and provides ease of handling, while having satisfactory outcomes. A new silicone arterial patch (polydimethylsiloxane reinforced with polyester fabric, PDMSr) was compared with patches made of expanded polytetrafluoroethylene (ePTFE). Objective: To compare the outcomes between arterial patches made of PDMSr with those made of ePTFE, in an experimental rabbit model. Materials and Method: Rabbits were placed in two groups, and received either PDMSr or ePTFE arterial patches (PDMSr group and ePTFE group, respectively). The animals underwent laparotomy and longitudinal opening of the aorta, which was then closed with the selected patch, followed by suture of all layers. The animals were kept in their cages until the 60th postoperative day, when arteriography, removal of the aorta, and macroscopic and optic and scanning electron microscopic analyzes of the aorta were performed. Ten rabbits from each group that had completed all stages of the research were included in analyses. Results: Twelve procedures were performed in the PDMSr group and 16 in the ePTFE group. There were 2 deaths in the PDMSr group and 6 in the ePTFE group. Despite the higher number of deaths in the ePTFE group, there was no statistical difference in survival rate between the groups. One animal in the PDMSr group developed monoparesis in its right hind paw and 1 animal in the ePTFE group had an incisional hernia. There was no statistical difference in complications between the groups. The operative time was significantly longer in the ePTFE group when all animals were included in analysis, but not when animals that died were excluded. Body weight was significantly greater and operative time was significantly longer in animals that died. Postsurgical aortic patency in the survival animals was 100% in both groups by arteriography. Macroscopically, tissue reaction around the prosthesis was greater in the ePTFE group (statistically significant). Microscopically, the PDMSr patches were entirely covered with a cellular endothelium-like tissue, while tissue growth on the ePTFE patches was limited to the edges of the suture line and to isolated central islands. Conclusion: The two materials showed comparable outcomes; however, PDMSr showed cellular proliferation to the entire graft, and less local inflammatory reaction compared with ePTFE. Although further studies are required, including assessment in humans, the results of the present study indicate that PDMSr shows promise as an arterial patch material

Objetivos: O objetivo deste estudo é analisar a perviedade da artéria torácica interna direita (ATID) pediculada, anteroaórtica em anastomose para a região anterior do coração na cirurgia de revascularização do miocárdio (RM), em relação à artéria torácica interna esquerda (ATIE). Métodos: No período de dezembro de 2008 a dezembro de 2011, 100 pacientes foram selecionados para serem submetidos a cirurgia de RM sem circulação extracorpórea (CEC), de forma prospectiva. Eles foram agrupados em Grupo 1 (G-1) e Grupo 2 (G-2), cada um com 50 pacientes, com randomização por computador e conhecimento da técnica no início da cirurgia. No G-1, os pacientes receberam ATIE para a região anterior do coração e complementação da RM com a ATID livre para ramos da circunflexa (CX) e outros enxertos arteriais ou venosos para a coronária direita (CD) e/ou ramos. Os pacientes do G-2 receberam ATID pediculada para a região anterior do coração e complementação da RM com ATIE, pediculada, para ramos da CX e outros enxertos arteriais ou venosos para a CD e/ou ramos. A perviedade das artérias torácicas internas direita e esquerda foi avaliada através de angiotomografia coronária multislice, 64 canais, no 6º mês de pós-operatório. Resultados: Os dois grupos eram semelhantes quanto aos dados clínicos de pré-operatório, como exemplo: diabetes mellitus, hipertensão arterial sistêmica, obesidade. Os dois grupos apresentaram predominância do sexo masculino com 75,6% e 88% nos grupos 1 e 2, respectivamente. Cinco pacientes migraram do G-1 para o G-2 em virtude de doença ateromatosa na aorta ascendente e um deles foi excluído por ter que utilizar enxerto composto. A média de anastomoses distais no G-1 foi de 3,48 (DP=0,72), e no G-2 foi de 3,20 (DP=0,76). Não ocorreu mediastinite em nenhum paciente. Uma paciente do G-1 apresentou osteomielite, e necessitou de intervenção cirúrgica. Dois pacientes do G-1 foram submetidos a reoperação por sangramento. Os resultados das angiotomografias coronarianas com 96 pacientes re-estudados mostram que todas as ATIs, fosse a direita ou a esquerda, utilizadas pediculadas para a região anterior do coração encontravam-se sem oclusões ou estenoses, configurando 100% de perviedade. No G-1, um enxerto livre da ATID para ramos da CX apresentava oclusão total, em dois pacientes havia estenose leve, em um deles havia estenose moderada na anastomose proximal na aorta ascendente e outro apresentava diminuição de calibre na sua porção distal. Em três pacientes o enxerto de segmento de veia safena para ramos da CD se encontravam ocluídos. No G-2, dois pacientes apresentavam oclusão total na ATIE pediculada para ramos da CX, e outro apresentava estenose moderada na porção distal da ATIE utilizada sequencial para dois ramos marginais. Em dois pacientes o enxerto de segmento de veia safena para ramos da CD se encontravam ocluídos. Não houve óbitos em nenhum dos grupos. Conclusão: A cirurgia de RM com utilização da ATID pediculada, anterógrada para o RIA, apresenta resultado semelhante ao da ATIE utilizada para essa mesma coronária.
Objective: To analyze the patency of the pedicled, anteroaortic, right internal mammary artery (RIMA) anastomosed to the left anterior descending (LAD) and branches in coronary artery bypass graft surgery (CABG), in comparison with the left internal mammary artery (LIMA). Methods: From December 2008 to December 2011, 100 patients were selected to undergo a prospective off-pump coronary artery bypass graft surgery and were randomly divided by computer into Group 1 (G-1) and Group 2 (G-2), so that the technique was known at the beginning of the surgery. In each group, with 50 patients, the patency of both right and left internal mammary arteries, which were used pedicled to the LAD, was comparatively studied through coronary computed tomography angiography. G-1 had 50 patients who received the LIMA to the LAD or LAD/diagonal (sequential) and had the CABG complemented with the free RIMA to circumflex branches and other arterial or venous grafts to the right coronary artery (RCA) and/or branches. G-2 had 50 patients who received the pedicled RIMA to the LAD or LAD/diagonal (sequential) and had the CABG complemented with the pedicled LIMA to circumflex branches and other arterial or venous grafts to the RCA and/or branches. Results: Both groups were similar in pre-operative clinical data, such as: diabetes mellitus, systemic arterial hypertension, obesity. Also, there was predominance of males in both groups, with 75,6% and 88% in Groups 1 and 2 respectively. Five patients were switched from G-1 to G-2 owing to atheromatous disease in the ascending aorta, and one of them was dropped for having to use composite graft. The average of distal anastomosis in G-1 was 3,48 (standard deviation (SD=0,72) and in G-2 was 3,20 (SD=0,76). Mediastinitis didn\'t occur in any patient. A patient from G-1 had osteomyelitis that required surgical intervention. Two patients from G-1 underwent reoperation because of bleeding. The 64-slice coronary computed tomography angiography was performed in the 6th postoperative month; 96 patients have been re-studied so far and all pedicled IMAs to the LAD were patent. In G-1 a free RIMA graft to the circumflex branches presented total occlusion, another two had a discreet stenosis and in one moderate at the proximal anastomosis and one more had a string signal at the distal portion. In G-2 two patients had total occlusion of the pedicled LIMA to circumflex artery branches, and another one presented moderate stenosis at its distal portion. In two patients the saphenous vein graft to the RCA branches were occluded. There were no deaths in any of the groups. Conclusion: The CABG surgery using the pedicled, anteroaortic RIMA to the LAD has a similar outcome to that of the LIMA used for this same coronary.

Submitted in partial fulfilment of the requirements for the Degree of Doctor of Technology: Clinical technology, Durban University of Technology, 2011.
Surgical revascularization of the coronary arteries is a cornerstone of cardiothoracic surgery. The enduring nature of coronary artery bypass grafting (CABG) bespeaks of its history and proven efficacy. However, cerebral deoxygenation during on-pump coronary artery bypass graft surgery may be associated with adverse neurological sequelae. Advanced age and the incidence of preoperative co-morbidity in patients presenting for coronary artery bypass graft surgery increases the potential for stroke and other adverse perioperative outcomes (Murkin, Adams, Quantz, Bainbridge and Novick, 2007). It is hypothesized, that by using the brain as an index organ, interventions to improve cerebral oxygenation would have systemic benefits for cardiac surgical patients. In an attempt to predict those patients that are predisposed to cerebral complications, investigators have used neurological monitoring ie, Near infrared spectroscopy (NIRS) to enhance detection of hypoxic conditions associated with neurological injury (Hoffman, 2006). Serum S100B protein has been used as a biochemical marker of brain injury during cardiac surgery. Elevated levels serve as a potential marker of brain cell damage and adverse neurological outcomes (Einav, Itshayek, Kark, Ovadia, Weiniger and Shoshan, 2008). Aims and Objectives of the study This prospective, quantitative, interventional study was carried out to maintain cerebral tissue oxygen saturation during cardiopulmonary bypass above 75% of the baseline level by implementation of a proposed interventional protocol. The analysis of S100B which is a marker of neurological injury and optimization of regional cerebral oxygen saturation would allow for the formulation of an algorithm which could be implemented during on-pump coronary artery bypass graft surgery as a preventive clinical measure further reducing the risk of neurological injury. Central venous lines (CVP) are inserted routinely during cardiac surgery. Central venous oxygen saturation is a global marker of tissue oxygenation. A secondary aim of the study was to determine if a correlation existed between central venous and cerebral tissue oxygen saturations. If a positive correlation existed then central venous oxygen saturation could be used as a surrogate measure of cerebral tissue oxygen saturation during on-pump coronary artery bypass graft surgery. This study is one of the first done in the South African population group. Methods Forty (40) patients undergoing on-pump coronary artery bypass graft surgery were recruited at Inkosi Albert Luthuli Central Hospital. Patients were randomized into a control group (n=20) and interventional group (n=20) using a sealed envelope system. The envelope contained designation to either group. Envelopes were randomly chosen. Intraoperative regional cerebral oxygen saturation (rSO2 ) monitoring with active display and treatment intervention protocol was administered for the interventional group. In the control group regional cerebral oxygen saturation monitoring was not visible to the perfusionist operating the heart lung machine during cardiopulmonary bypass (blinded). Recording of regional cerebral saturation was conducted by an independent person (another perfusionist) who was not involved in the management of the case so as to ensure that no interventions were carried out on the control group. Arterial blood samples for the measurement of serum S100B were taken pre and postoperatively. An enzyme immunoassay (ELISA) was used for the quantitative and comparative measurement of human S100B concentrations for both groups. Central venous oxygen saturation was monitored from the CVP using the Edwards Vigileo monitor. Cerebral monitoring constituted the use of Near infrared spectroscopy monitoring using the Invos 5100c, Somonetics Corp, Troy MI monitor. Adhesive optode pads were be placed over each fronto- temporal area for cerebral oxygen measurement. During cardiopulmonary bypass, eight time period measurements of mean arterial pressure (MAP), heart rate, temperature, activated clotting time (ACT), patient oxygen saturation (SpO2), partial pressure of carbon dioxide (pCO2), haematocrit, lactate, pH, haemoglobin (Hb), base excess (BE), potassium (K+), sodium (Na+), glucose, calcium (Ca2+), central venous oxygen saturation (ScvO2), cerebral tissue oxygen saturation (rSO2), fraction inspired oxygen (FiO2 ), sweep rate, pump flow rate (cardiac index), and percentage isoflurane per patient were taken. The time periods when data was recorded included: 5 minutes after onset of cardiopulmonary bypass, aortic cross clamping, after cardioplegic arrest, during distal anastomosis, during proximal anastomosis, during rewarming, after aortic cross clamp release and before termination of cardiopulmonary bypass. Baseline measurements were also taken. Clinical data recorded for both groups included: the number of grafts performed, cardiopulmonary bypass time, cross clamp time, red blood cells administered (packed cells), amount of adrenalin infused and total cerebral desaturation time. A prioritized intraoperative management protocol to maintain rSO2 values above 75% of the baseline threshold during cardiopulmonary bypass was followed. Cerebral desaturation was defined as a decrease in saturation values below 70% of baseline for more than one minute. Interventions commenced within 15 seconds of decrease below 75% of baseline value. Results The results of the study show that there was a highly significant difference in the change in S100B concentrations pre and post surgery between the interventional and control groups. The intervention vii group showed a smaller increase in S100B concentration of 37.3 picograms per millilitre (pg/ml) while the control group showed a larger increase of 139.3 pg/ml. Therefore, the control group showed a significantly higher increase in S100B concentration over time than the intervention group (p < 0.001). Maximizing pump flow rates was the most common intervention used (45 times) followed by maintaining partial pressure of carbon dioxide to approximately 40 mmHg (28 times), increasing mean arterial pressure by administration of adrenalin (11 times) and administration of red blood cells to increase haematocrit (11 times). There was a highly statistically significant treatment effect within the intervention group for each of the above interventions compared with no intervention. The above mentioned interventions significantly affected right and left cerebral oxygen saturations. However, administration of red blood cells was not found to significantly increase right (p = 0.165) and left (p = 0.169) cerebral oxygen saturation within the intervention group. The study highlighted a significant difference between the intervention and control groups in terms of cerebral desaturation time (p <0.001). The mean desaturation time for the control group was 63.85 minutes as compared to 24.7 minutes in the interventional group. Cerebral desaturation occurred predominantly during aortic cross clamping, distal anastomosis of coronary arteries and aortic cross clamp release. Predictors of cerebral oxygen desaturation included, partial pressure of carbon dioxide (pCO2), temperature, pump flow rate (LMP), mean arterial pressure (MAP), haematocrit, heart rate (HR) and patient oxygen saturation (SpO2). Central venous oxygen saturation was not significantly related to right (p = 0.244) or left (p = 0.613) cerebral oxygen saturations. Therefore central venous oxygen saturation cannot be used as a surrogate measure of cerebral tissue oxygen saturation during on-pump coronary artery bypass graft surgery. viii Conclusion These findings demonstrate the positive effect of optimizing cerebral oxygen saturation using an interventional protocol on markers of neurological injury (S100B). Optimization of pump flow rate, partial pressure of carbon dioxide and mean arterial pressure would result in increased cerebral oxygen saturation levels and a reduction in neurological injury. Therefore, an algorithm incorporating these interventions can be formulated. Monitoring specifically for brain oxygen saturation together with an effective treatment protocol to deal with cerebral desaturation during on-pump CABG must be advocated.

Introduction: Cardiovascular surgery is a relatively young but progressively evolving field in medicine. More specifically, in the past decades, cardiac surgery achieved significant advances in understanding the causes, progression and treatments of ischemic heart disease (IHD). The IHD is the most common coronary disease, and it ranks first in morbidity and mortality in the developed world. It justifies the need for significant fundamental research as well as its study in clinical practice. It now includes specialized cardiovascular centres with the complex specialized treatments. A group of interventional cardiologists capable of performing routine examinations of the coronary veins using selective angiography has been established. They can eventually also perform percutaneous coronary interventions with direct stent implants. Thus the advances have been made in comprehensive indication of the patients towards their optimal treatments under the regime of a cardio-team. Such team comprises of a cardio-surgeon, interventional cardiologist, echocardiography specialist and the attending physician who is usually the cardiologist. The IHD treatments involve preventive cardiology with the regime measures and checks, pharmacotherapy, interventional cardiology and cardiac surgery to spa treatment and...

Kang, Ning.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2009.
Includes bibliographical references.
Abstract also in Chinese.
Abstracts --- p.i
Abbreviations --- p.v
List of Figures and Tables --- p.vii
Contents --- p.viii
Chapter Chapter 1: --- Introduction --- p.1
Chapter 1. --- Saphenous vein graft patency after coronary artery bypass grafting --- p.1
Chapter 2. --- Mechanism of vein graft failure and therapeutic strategies --- p.8
Chapter 2.1 --- Mechanism --- p.15
Chapter 2.2 --- Therapeutic strategies --- p.18
Chapter 3. --- Summary --- p.22
Chapter 4. --- References --- p.23
Chapter Chapter 2: --- Animal model and laboratory investigations --- p.34
Chapter 1. --- Surgical procedure --- p.35
Chapter 2. --- Postoperative management --- p.37
Chapter 3. --- Adenoviral-mediated gene transfer ex vivo for gene therapy study --- p.38
Chapter 4. --- Laboratory investigations --- p.39
Chapter 5. --- Statistical analysis --- p.40
Chapter 6. --- Summary --- p.41
Chapter 7. --- References --- p.41
Chapter Chapter 3: --- "Impact of osteopontin expression in vein grafts on VSMC migration, proliferation, and neointimal formation" --- p.42
Chapter 1. --- Introduction --- p.42
Chapter 2. --- Methods and materials --- p.43
Chapter 3. --- Results --- p.43
Chapter 4. --- Discussion --- p.49
Chapter 5. --- Summary --- p.52
Chapter 6. --- References --- p.53
Chapter Chapter 4: --- Potential Role of gene therapy in prevention of vein graft failure --- p.56
Chapter 1. --- Vectors --- p.56
Chapter 2. --- "Reporter gene, timing and titer" --- p.57
Chapter 3. --- Candidate genes --- p.58
Chapter 4. --- Summary --- p.64
Chapter 5. --- References --- p.66
Chapter Chapter 5: --- Conclusions --- p.70
Acknowledgements --- p.72

Bibliografische Beschreibung Knepper, Robert Darstellung des Verlaufs der Arteria palatina major unter dem Aspekt der Entnahme autologer Bindegewebstransplantate aus dem Gaumen Universität Leipzig, Dissertation 68 Seiten, 43 Literaturangaben, 42 Abbildungen, 12 Tabellen, 4 Anlagen Referat: Die sich stets weiterentwickelnden Verfahren zahnärztlicher Chirurgie bringen auch neue Anforderungen an den Operateur mit sich. Vor allem im Bereich der ästhetischen Korrektur von weichgewebigen Defekten im Bereich des Zahnhalteapparates gilt es, auf dem neuesten Stand zu sein, um moderne Zahnheilkunde anbieten zu können. Profunde Kenntnisse zur Topographie anatomischer Strukturen sind dabei für den Zahnarzt, den Spezialisten für Parodontologie und den Oralchirurgen unabdingbar. Um die dafür notwendige praktische Anleitung zu erhalten, können Mediziner am Institut für Anatomie der Universität Leipzig Kurse absolvieren, so z.B. auch angehende zahnärztliche Implantologen. Hierbei interessiert die Teilnehmer neben dem praktischen Vorgehen auch der Verlauf von Gefäßen und Nerven im Operationsgebiet. Anatomische Atlanten stellen die betreffenden Areale idealisiert und ohne Berücksichtigung der individuellen Variationsbreite dar. Zugänge, wie sie in der Klinik benötigt werden, finden sich selten. Aus diesem Grund wurde in der vorliegenden Arbeit an sechs vollständigen und 21 geteilten humanen Kopfpräparaten (alle Ethanol-Glycerin fixiert) die A. palatina major präpariert und der klinischen Situation gegenübergestellt. Diese Arterie wurde gewählt, da ihr Versorgungsgebiet – der Gaumen – die bevorzugte Spenderregion autologer Bindegewebstransplantate ist. Dadurch wird die Lücke der oft unzureichenden Verknüpfung der klinischen Situation mit dem anatomischen Korrelat geschlossen. Des Weiteren wurde an diesen Präparaten eine in der Literatur als sicher beschriebene Entnahmestelle vermessen und die Werte den bekannten gegenübergestellt. Um diese Messwerte beurteilen zu können, wurde außerdem die Frage gestellt, inwieweit die Fixierung der Präparate deren Beschaffenheit verändert. Dies wurde in einem Versuch mit dentalen Volumentomogrammen von frisch angefertigten und anschließend fixierten Präparaten untersucht. Auf Grund der Tatsache, dass Humanpräparate nur für einen begrenzten Zeitraum zur Verfügung stehen, ist ein wesentlicher Aspekt dieser makroskopisch-anatomischen Arbeit die fotografische Dokumentation der präparierten Gefäßstrecken, bei der ästhetische u.a. Gesichtspunkte beachtet werden müssen. Da dies auch für andere makroskopische Arbeiten am Institut für Anatomie von Interesse ist, wurde dieser Teil so ausführlich beschrieben, dass er als Anleitung dienen kann.:Inhaltsverzeichnis Abkürzungen VI 1. Einleitung 1 1.1. Problemstellung 1 1.2. Anatomische Grundlagen 3 1.2.1. Embryologische Entwicklung 3 1.2.2. Topographie 4 1.2.3. Mikroskopische Anatomie 7 1.3. Entnahme autologer Gewebstransplantate in der zahnärztlichen Chirurgie 7 1.3.1. Physiologie der freien Gewebstransplantation 7 1.3.2. Spenderregionen 9 1.3.3. Fallbeispiel 10 1.3.4. Verletzung der A. palatina major und Blutungskontrolle 11 2. Material und Methode 12 2.1. Untersuchungsmaterial 12 2.1.1. Wesentliche Angaben zum vorliegenden Material 12 2.1.2. Ethanol-Glycerin Fixierung 15 2.2. Präparationstechniken 16 2.3. Messmethoden 20 2.4. Statistische Auswertung 22 2.5. Einfluss der Fixierungsmethode auf das Präparationsmaterials 22 2.5.1. Materialveränderung durch die Fixierung 22 2.5.2. Versuchsaufbau 23 2.5.3. Dentale Volumentomografie 28 2.5.4. Verwendeter Dentaler Volumentomograph 29 2.5.5. DVT-Auswertungssoftware und Messmethode 30 2.6. Fotografische Dokumentation und Nachbearbeitung 32 2.6.1. Verwendete Hardware 32 2.6.2. Verwendete Software 33 2.6.3. Theoretische Grundlagen 35 2.6.4. Durchführung 38 2.6.5. Nachbearbeitung der Bilder 39 3. Ergebnisse 41 3.1. Vergleich zwischen klinischer Situation und anatomischem Präparat 42 3.2. Vermessung der Lage der A. palatina major 50 3.3. Verhalten von Weichgewebe unter dem Einfluss verschiedener Fixantien 52 3.4. Ergebnisse der Fotodokumentationen anatomischer Präparate 56 3.5. Fotografische Darstellung präformierter Körperhöhlen 58 4. Diskussion 60 4.1. Vergleich der Messergebnisse zur Lage der A. palatina major 60 4.2. Schlussfolgerungen aus dem DVT-Versuch 61 4.2.1. Vergleich der Messdaten für Kochen 61 4.2.2. Einfluss von Fixantien auf Weichgewebe 62 4.2.3. Aussagekraft der im DVT-Versuch ermittelten Werte 62 4.3. Kritische Einschätzung des Materials und der Methoden 63 4.3.1. Veränderungen der Anatomie unter Berücksichtigung der Präparation 63 4.3.2. Aussagekraft bezüglich Alter und Geschlecht der Spender 63 4.3.3. Kritische Einschätzung der angewandten Methoden 64 4.4. Weiterverwendung des Materials und der Erkenntnisse 65 4.4.1. Weiterverwendung Bildtafeln 65 4.4.2. Weiterverwendung DVT Versuchsaufbau 66 4.4.3. Weiterverwendung fotografische Anleitung 66 5. Zusammenfassung 67 6. Verzeichnis der Abbildungen 69 7. Verzeichnis der Tabellen 71 8. Literaturverzeichnis 72 9. Danksagung 76 10. Erklärung eigenständige Abfassung 77 11. Lebenslauf 78 Anlagen 79