Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Background Although abdominal aortic aneurysm (AAA) growth is non-linear, serial measurements of aneurysm diameter are the mainstay of aneurysm surveillance and contribute to decisions on timing of intervention. Aneurysm biology plays a key part in disease evolution but is not currently routinely assessed in clinical practice. Magnetic Resonance Imaging (MRI) and Positron Emission Tomography-Computed Tomography (PET-CT) provide insight into disease processes on a cellular or molecular level, and represent exciting new imaging biomarkers of disease activity. Macrophage-mediated inflammation may be assessed using ultrasmall superparamagnetic particles of iron oxide (USPIO) MRI and the PET radiotracer 18FSodium Fluoride (18F-NaF) identifies microcalcification which is a response to underlying necrotic inflammation. The central aim of this thesis was to investigate these imaging modalities in patients with AAA. Methods and Results USPIO MRI: MULTI-CENTRE STUDY In a prospective multi-centre observational cohort study, 342 patients (85.4% male, mean age 73.1±7.2 years, mean AAA diameter 49.6±7.7mm) with asymptomatic AAA ≥4 cm anteroposterior diameter underwent MRI before and 24-36 hours after intravenous administration of USPIO. Colour maps (depicting the change in T2* caused by USPIO) were used to classify aneurysms on the basis of the presence of USPIO uptake in the aneurysm wall, representing mural inflammation. Intra- and inter-observer agreement were found to be very good, with proportional agreement of 0.91 (kappa 0.82) and 0.83 (kappa 0.66), respectively. At 1 year, there was 29.3% discordant classification of aneurysms on repeated USPIO MRI and at 2 years, discordance was 65%, suggesting that inflammation evolves over time. In the observational study, after a mean of 1005±280 days of follow up, there were 126 (36.8%) aneurysm repairs and 17 (5.0%) ruptures. Participants with USPIO enhancement (42.7%) had increased aneurysm expansion rates (3·1±2·5 versus 2·5±2·4 mm/year; difference 0·6 [95% confidence intervals (CI), 0·02 to 1·2] mm/year, p=0·0424) and had higher rates of aneurysm rupture or repair (69/146=47·3% versus 68/191=35·6%; difference 11·7%, 95% CI 1·1 to 22·2%, p=0·0308). USPIO MRI was therefore shown to predict AAA expansion and the composite of rupture or repair, however this was not independent of aneurysm diameter (c-statistic, 0·7924 to 0·7926; unconditional net reclassification -13·5%, 95% confidence intervals -36·4% to 9·3%). 18F-NaF PET-CT: SINGLE-CENTRE STUDY A sub-group of 76 patients also underwent 18F-NaF PET-CT, which was evaluated using the maximum tissue-to-background ratio (TBRmax) in the most diseased segment (MDS), a technique that showed very good intra- (ICC 0.70-0.89) and inter-observer (ICC 0.637-0.856) agreement. Aneurysm tracer uptake was compared firstly in a case-control study, with 20 patients matched to 20 control patients for age, sex and smoking status. 18F-NaF uptake was higher in aneurysm when compared to control aorta (log2TBRmax 1.712±0.560 vs. 1.314±0.489; difference 0.398 (95% CI 0.057, 0.739), p=0.023), or to non-aneurysmal aorta in patients with AAA (log2TBRmax 1.647±0.537 vs. 1.332±0.497; difference 0.314 (95% CI 0.0685, 0.560), p=0.004). An ex vivo study was performed on aneurysm and control tissue, which demonstrated that 18F-NaF uptake on microPET-CT was higher in the aneurysm hotspots and higher in aneurysm tissue compared to control tissue. Histological analysis suggested that 18F-NaF was highest in areas of focal calcification and necrosis. In an observational cohort study, aneurysms were stratified by tertiles of TBRmax in the MDS and followed up for 510±196 days, with 6 monthly serial ultrasound measurements of diameter. Those in the highest tertile of tracer uptake expanded more than 2.5 times more rapidly than those in the lowest tertile (3.10 [3.58] mm/year vs. 1.24 [2.41] mm/year, p=0.008) and were also more likely to experience repair or rupture (15.3% vs. 5.6%, log-rank p=0.043). In multivariable analyses, 18F-NaF uptake on PET-CT emerged as an independent predictor of AAA expansion (p=0.042) and rupture or repair (HR 2.49, 95% CI1.07, 5.78; p=0.034), even when adjusted for age, sex, body mass index, systolic blood pressure, current smoking and, crucially, aneurysm diameter. Conclusion These are the largest USPIO MRI and PET-CT studies in AAA disease to date and the first to investigate 18F-NaF. Both USPIO MRI and 18F-NaF PET-CT are able to predict AAA expansion and the composite of rupture and repair, with 18F-NaF PETCT emerging as the first imaging biomarker that independently predicts expansion and AAA events, even after adjustment for aneurysm diameter. This represents an exciting new predictor of disease progression that adds incremental value to standard clinical assessments. Feasibility and randomised clinical trials are now required to assess the potential of this technique to change the management and outcome of patients with AAA.

Introdução: O aneurisma de aorta abdominal (AAA) é uma importante causa de morbimortalidade na população idosa. O tratamento endovascular está associado a menor morbimortalidade que o tratamento convencional, no entanto, necessita de um seguimento rigoroso com exames de imagem contrastados para confirmação da exclusão do saco aneurismático. Considerando que a formação de um aneurisma é um processo multifatorial complexo, envolvendo a remodelação destrutiva do tecido conjuntivo em todo o segmento afetado da parede da aorta e que este processo envolve uma inflamação crônica local, uma diminuição no número de células do músculo liso da túnica média, e fragmentação da matriz extracelular da aorta e ainda que um perfil de expressão aberrante de miRNAs tem sido associada a doenças humanas, incluindo disfunção cardiovascular propôs-se então a realização deste estudo envolvendo todo este processo. O objetivo principal foi quantificar e avaliar a resposta da expressão dos miRNAs à correção endovascular de aneurisma de aorta abdominal com base em dosagens séricas no seguimento de seis meses. População e Método: Foram recrutados 30 pacientes consecutivos com AAA sem outras doenças inflamatórias associadas, do Ambulatório de Cirurgia Vascular e Endovascular do HCFMRPUSP com indicação de tratamento endovascular. Foram escolhidos para estudo e dosagens séricas os miRNA-191 e miRNA-455-3p. A expressão diferencial dos miRNAs foi realizada pelo método de PCR em tempo real, após extração do RNA das amostras de sangue total em dois momentos, pré- operatório e após 6 meses de pós-operatório. Além disso, ferramentas de bioinformática foram utilizadas para determinar vias fisiopatológicas relacionadas ao AAA. Foram Colhidos dados de perfil demográfico, de seguimento clinico e exames de imagem com angiotomografia no pré-operatórios e após 6 meses. Resultados: Foi observado uma hiperexpressão dos miR-191 e miR-455-3p no sangue total dos pacientes com AAA. O tratamento endovascular dos pacientes com AAA resultou em diminuição significativa das expressões dos miRNAs estudados, indicando que a exclusão do saco aneurismático altera as expressões dos mesmos. Adicionalmente, as expressões dos miR-191 e miR-455-3p não apresentaram correlação com o diâmetro do aneurisma e a análise da influência dos diversos tipos de dispositivos utilizados para o tratamento endovascular dos AAA, não mostrou diferenças significativas nas expressões dos miR-191 e miR-455-3p. Conclusões: A hiperexpressão dos miR-191 e miR-455-3p com sua significativa redução apos o tratamento endovascular, pode sugerir a utilização dessas moléculas como potenciais biomarcadores no seguimento desses pacientes. Novos estudos com maior número de casos devem ser realizados com o objetivo de validar os dados obtidos incluindo pacientes com eventuais vazamentos. / Background: Abdominal aortic aneurysm (AAA) is an important cause of morbidity and mortality in the elderly population. Endovascular treatment is associated with lower morbidity and mortality than conventional treatment, however, it requires a rigorous follow-up with contrast imaging tests to confirm the aneurysmal sac exclusion. Considering that the formation of an aneurysm is a complex multifactorial process, involving the destructive remodeling of the connective tissue throughout the affected segment of the aortic wall and that this process involves a chronic local inflammation, a decrease in the number of smooth muscle cells of the media tunic, and fragmentation of the extracellular matrix of the aorta and although an aberrant expression profile of miRNAs has been associated with human diseases, including cardiovascular dysfunction, it was proposed to carry out this study involving this whole process. The main objective was to quantify and evaluate miRNA expression response to endovascular correction of abdominal aortic aneurysm based on serum dosages at the six-month follow-up. Population and Method: We recruited 30 consecutive patients with AAA without other associated inflammatory diseases from the Ambulatory of Vascular and Endovascular Surgery of the HCFMRPUSP with indication of endovascular treatment. The miRNA-191 and miRNA-455-3p were selected for study and serum dosages. The differential expression of the miRNAs was performed by the real-time PCR method, after extraction of RNA from the whole blood samples at two moments, preoperatively and after 6 months of follow-up. In addition, bioinformatics tools were used to determine pathophysiological pathways related to AAA. Demographic profile, clinical follow-up and imaging examinations with angiotomography performed in the preoperative period and after 6 months were collected. Results: Hyperexpression of miR-191 and miR-455-3p in whole blood of AAA patients was observed. The endovascular treatment of patients with AAA resulted in a significant decrease in the expression of the miRNAS studied, indicating that the exclusion of the aneurysmal sac altered their expression. In addition, the expression of miR-191 and miR-455-3p showed no correlation with the diameter of the aneurysm and analysis of the influence of the various types of devices used for the endovascular treatment of AAA did not show significant differences in the expression of miR-191 And miR-455-3p. Conclusions: The hyperexpression of miR- 191 and miR-455-3p with its significant reduction after endovascular treatment may suggest the use of these molecules as potential biomarkers in the follow-up of these patients. New studies with a greater number of cases should be performed with the objective of validating the data obtained including patients with possible endoleaks.

Computational Fluid Dynamic Simulation of Intracranial Aneurysms Analysis of time-dependent changes of hemodynamic parameters - the road the clinical use Hemodynamics are involved in the genesis of intracranial aneurysms and time- dependent changes of their parameters lead to aneurysm growth, stabilization or rupture. Definition of these changes using computational fluid hemodynamics could significantly contribute to the understanding of aneurysmal development and rupture and could enable the routine use of mathematical simulations. In this study, computational fluid dynamics were performed for nine incidental aneurysms. Five aneurysms were monitored throughout time and factors leading to aneurysm rupture were analyzed. In four aneurysms the influence of the hemodynamics on the growth was defined. Major growth occurred in areas of low wall shear stress and oscillatory index. These areas increased in size during growth time. Contrary to this, neck shape remodeling occurred in areas with large wall shear stress and pressure. Throughout the follow-up of ruptured aneurysms, the minimal wall shear stress decreased, and the area of low wall shear stress increased significantly. The results indicate that decreasing values of minimal wall shear stress and increasing values of low wall shear stress area...

Tato práce se zabývá problematikou aneurysmat břišní aorty a možností využít konečnoprvkovou deformačně-napěťovou analýzu těchto aneurysmat ke stanovení rizika ruptury. První část práce je věnována úvodu do problematiky, popisu kardiovaskulární soustavy člověka s důrazem na abdominální aortu, anatomii, fyziologii a patologii stěny tepny s důrazem na procesy vedoucí ke vzniku aneurysmatu. Dále se práce věnuje rizikovým faktorům přispívajících ke vzniku aneurysmat spolu s analýzou současných klinických postupů ke stanovení rizika ruptury spolu se srovnáním navrhovaného kritéria maximálního napětí. Dominantní část této disertace je věnována identifikaci faktorů ovlivňujících napjatost a deformaci stěny aneurysmatu spolu s návrhem nových postupů, prezentací vlastních poznatků vedoucích ke zpřesnění určení rizika ruptury pomocí deformačně- napěťové analýzy a metody konečných prvků. Nejprve je analyzován vliv geometrie, vedoucí k závěru, že je nezbytné používání individuálních geometrií pacienta. Dále je pozornost zaměřena na odbočující tepny, které ve stěně působí jako koncentrátor napětí a mohou tedy ovlivňovat napjatost v ní. Jako další podstatný faktor byl identifikován vliv nezatížené geometrie a bylo napsáno makro pro její nalezení, které bylo opět zahrnuto jako standardní součást do výpočtového modelu. Mechanické vlastnosti jak stěny aneurysmatu, tak intraluminálního trombu jsou experimentálně testovány pomocí dvouosých zkoušek. Také je zde analyzován vliv modelu materiálu, kde je ukázáno, že srovnávání maximálních napětí u jednotlivých modelů materiálu není vhodné díky zcela rozdílným gradientům napětí ve stěně aneurysmatu. Dále je zdůrazněna potřeba znalosti distribuce kolagenních vláken ve stěně a navržen program k jejímu získání. Intraluminální trombus je analyzován ve dvou souvislostech. Jednak je ukázán vliv jeho ruptury na napětí ve stěně a jednak je analyzován vliv jeho poroelastické struktury na totéž. Posledním identifikovaným podstatným faktorem je zbytková napjatost ve stěně. Její významnost je demonstrována na několika aneurysmatech a i tato je zahrnuta jako integrální součást do našeho výpočtového modelu.Na závěr jsou pak navrženy další možné směry výzkumu.

Introdução: O aneurisma de aorta abdominal (AAA) é uma doença prevalente e silenciosa também relacionada com a atividade inflamatória. Atualmente, a abordagem endovascular tem sido utilizada como principal técnica devido à inúmeras vantagens. Porém tem uma maior taxa de reintervenções e necessita de seguimento periódico com angiotomografias, o que aumenta custos e tem implicações como alteração da função renal além do acúmulo progressivo de radiação. Tais condições justificam a busca por possíveis biomarcadores que possam contribuir para um melhor seguimento. Objetivos: Neste estudo, buscou-se correlacionar o microRNA-1281, proteína C reativa (PCR) e a avaliação da função renal de indivíduos com AAA com a evolução dos mesmos após o tratamento endovascular. Pacientes e métodos: Foram selecionados 30 pacientes consecutivos do Ambulatório de Cirurgia Vascular e Endovascular do HCFMRP-USP, no período de janeiro de 2104 a novembro de 2015, com aneurisma de aorta abdominal e com indicação para tratamento endovascular. As dosagens séricas e avaliações angiotomográficas foram feitas no pré-operatório e 6 meses após a intervenção. Resultados: Houve uma hiperexpressão do microRNA-1281 nos pacientes com aneurisma e uma significativa redução dos seus níveis séricos após a correção endovascular. A expressão do miRNA-1281 apresentou correlação positiva com o clearence de creatinina. Houve também correlação positiva da PCR com a presença do aneurisma, e com seu diâmetro e não houve alteração significativa da função renal mensurada através das dosagens séricas de uréia, creatinina e cálculo indireto de clearence. Conclusão: O estudo mostrou que o miRNA 1281 tem boa correlação com a evolução favorável pós-tratamento endovascular do AAA, não se observando o mesmo com a proteína C reativa. Novos estudos são necessários para validar e complementar tais achados. / Introduction: Abdominal aortic aneurysm (AAA) is a prevalent and silent disease. Currently, the endovascular approach has been widely used and is the main technique due to the innumerable advantages. However, it has a higher rate of reintervention and requires periodic follow-up with tomography over the years, which increases its costs and has implications such as altered renal function besides the accumulation of radiation. Such conditions justify the search for possible biomarkers that may perhaps replace CT. Objectives: In this study, we sought to correlate the microRNA-1281, Creactive protein (CRP) and the renal function evaluation of individuals with AAA with their evolution after endovascular treatment. Patients and methods: We selected 30 consecutive patients from the Ambulatory of Vascular and Endovascular Surgery of the HCFMRP-USP, in the period from January of 2104 until November of 2015, with abdominal aortic aneurysm and with indication for endovascular treatment. Serum dosages were made preoperatively and 6 months after the intervention Results: There was a hyperexpression of the micro-RNA -1281 in patients with aneurysm and a significant reduction of their serum levels after endovascular correction. Expression of miRNA-1281 showed a positive correlation with creatinine clearence. There was also a positive correlation of CRP with the presence of the aneurysm, and with its diameter, and there was no significant alteration of renal function measured through serum urea, creatinine and indirect clearance calculations. Conclusion: The study showed that 1281 miRNAs may prove to be a potential biomarker for eventual follow-up of patients undergoing AAA endovascular repair. New studies are needed to validate and complement these findings.

Introdução: O aneurisma de aorta abdominal (AAA) é uma doença prevalente e silenciosa também relacionada com a atividade inflamatória. Atualmente, a abordagem endovascular tem sido utilizada como principal técnica devido à inúmeras vantagens. Porém tem uma maior taxa de reintervenções e necessita de seguimento periódico com angiotomografias, o que aumenta custos e tem implicações como alteração da função renal além do acúmulo progressivo de radiação. Tais condições justificam a busca por possíveis biomarcadores que possam contribuir para um melhor seguimento. Objetivos: Neste estudo, buscou-se correlacionar o microRNA-1281, proteína C reativa (PCR) e a avaliação da função renal de indivíduos com AAA com a evolução dos mesmos após o tratamento endovascular. Pacientes e métodos: Foram selecionados 30 pacientes consecutivos do Ambulatório de Cirurgia Vascular e Endovascular do HCFMRP-USP, no período de janeiro de 2104 a novembro de 2015, com aneurisma de aorta abdominal e com indicação para tratamento endovascular. As dosagens séricas e avaliações angiotomográficas foram feitas no pré-operatório e 6 meses após a intervenção. Resultados: Houve uma hiperexpressão do microRNA-1281 nos pacientes com aneurisma e uma significativa redução dos seus níveis séricos após a correção endovascular. A expressão do miRNA-1281 apresentou correlação positiva com o clearence de creatinina. Houve também correlação positiva da PCR com a presença do aneurisma, e com seu diâmetro e não houve alteração significativa da função renal mensurada através das dosagens séricas de uréia, creatinina e cálculo indireto de clearence. Conclusão: O estudo mostrou que o miRNA 1281 tem boa correlação com a evolução favorável pós-tratamento endovascular do AAA, não se observando o mesmo com a proteína C reativa. Novos estudos são necessários para validar e complementar tais achados. / Introduction: Abdominal aortic aneurysm (AAA) is a prevalent and silent disease. Currently, the endovascular approach has been widely used and is the main technique due to the innumerable advantages. However, it has a higher rate of reintervention and requires periodic follow-up with tomography over the years, which increases its costs and has implications such as altered renal function besides the accumulation of radiation. Such conditions justify the search for possible biomarkers that may perhaps replace CT. Objectives: In this study, we sought to correlate the microRNA-1281, Creactive protein (CRP) and the renal function evaluation of individuals with AAA with their evolution after endovascular treatment. Patients and methods: We selected 30 consecutive patients from the Ambulatory of Vascular and Endovascular Surgery of the HCFMRP-USP, in the period from January of 2104 until November of 2015, with abdominal aortic aneurysm and with indication for endovascular treatment. Serum dosages were made preoperatively and 6 months after the intervention Results: There was a hyperexpression of the micro-RNA -1281 in patients with aneurysm and a significant reduction of their serum levels after endovascular correction. Expression of miRNA-1281 showed a positive correlation with creatinine clearence. There was also a positive correlation of CRP with the presence of the aneurysm, and with its diameter, and there was no significant alteration of renal function measured through serum urea, creatinine and indirect clearance calculations. Conclusion: The study showed that 1281 miRNAs may prove to be a potential biomarker for eventual follow-up of patients undergoing AAA endovascular repair. New studies are needed to validate and complement these findings.

Aim of the study was to analyze the influence of comorbidities, demographic and surgical risk factors on early and late results of non-ruptured and ruptured abdominal aortic aneurysm. In the introduction the aim of the study and objectives are listed. In the review of the literature main problems of pending topic are analyzed. The methodology is described in a special chapter. The results of 373 patients’ surgical treatment of abdominal aortic aneurysm were analyzed. Eighty-four of them were operated due to the abdominal aortic aneurysm rupture. Follow-up results of 153 patients were analyzed in a special chapter. The influence of comorbidities, demographic and surgical risk factors on mortality and complication rate after operations for ruptured abdominal aortic aneurysm were assessed. Analysis of follow-up results clarified risk factors influencing survival after operation of abdominal aortic aneurysm. Assessment of the results showed that mean age of patients is lower and comorbidities is more severe as compared with the data presented for Western countries. The patients’ age, condition of cardiac and pulmonary systems, volume of operation were the most influencing risk factors on the outcome of surgical treatment of the abdominal aortic aneurysm. / Tyrimo tikslas – išanalizuoti gretutinių ligų ir demografinių bei chirurginių rizikos veiksnių įtaką neplyšusios bei plyšusios pilvinės aortos aneurizmos artimiems bei atokiesiems chirurginio gydymo rezultatams. Įvade išdėstomi tyrimo tikslai bei uždaviniai, pateikiama literatūros apžvalga, kurioje apibendrinamos pagrindinės su nagrinėjama tema susijusios problemos. Atskirame skyriuje aprašyta tyrimo metodika. Disertacijoje išnagrinėti 373 pacientų, operuotų dėl pilvinės aortos aneurizmos, gydymo rezultatai. Aštuoniasdešimt keturi jų gydyti dėl plyšusios pilvinės aortos aneurizmos. Atskirai išnagrinėta 153 pacientų vėlyvieji gydymo rezultatai. Nustatyta mirtingumo ir komplikacijų po plyšusių pilvinės aortos aneurizmų operacijų priklausomybė nuo įvairių rizikos veiksnių artimuoju pooperaciniu laikotarpiu. Skyriuje, kur analizuojami vėlyvieji operacijų rezultatai, nustatyti svarbiausieji veiksniai, nulemiantys išgyvenamumą. Išsamūs šių tyrimų rezultatai pateikti dviejuose disertacijos skyriuose. Nustatyta, kad tiriamųjų pacientų amžiaus vidurkis buvo mažesnis, o gretutinės patologijos buvo daugiau palyginus su duomenimis, pateiktais Vakarų šalių literatūroje. Taip pat nustatyta, kad didžiausią įtaką gydymo rezultatams darė paciento amžius, širdies bei plaučių patologija, operacijos apimtis.

Tyrimo tikslas – išanalizuoti gretutinių ligų ir demografinių bei chirurginių rizikos veiksnių įtaką neplyšusios bei plyšusios pilvinės aortos aneurizmos artimiems bei atokiesiems chirurginio gydymo rezultatams. Įvade išdėstomi tyrimo tikslai bei uždaviniai, pateikiama literatūros apžvalga, kurioje apibendrinamos pagrindinės su nagrinėjama tema susijusios problemos. Atskirame skyriuje aprašyta tyrimo metodika. Disertacijoje išnagrinėti 373 pacientų, operuotų dėl pilvinės aortos aneurizmos, gydymo rezultatai. Aštuoniasdešimt keturi jų gydyti dėl plyšusios pilvinės aortos aneurizmos. Atskirai išnagrinėta 153 pacientų vėlyvieji gydymo rezultatai. Nustatyta mirtingumo ir komplikacijų po plyšusių pilvinės aortos aneurizmų operacijų priklausomybė nuo įvairių rizikos veiksnių artimuoju pooperaciniu laikotarpiu. Skyriuje, kur analizuojami vėlyvieji operacijų rezultatai, nustatyti svarbiausieji veiksniai, nulemiantys išgyvenamumą. Išsamūs šių tyrimų rezultatai pateikti dviejuose disertacijos skyriuose. Nustatyta, kad tiriamųjų pacientų amžiaus vidurkis buvo mažesnis, o gretutinės patologijos buvo daugiau palyginus su duomenimis, pateiktais Vakarų šalių literatūroje. Taip pat nustatyta, kad didžiausią įtaką gydymo rezultatams darė paciento amžius, širdies bei plaučių patologija, operacijos apimtis. / Aim of the study was to analyze the influence of comorbidities, demographic and surgical risk factors on early and late results of non-ruptured and ruptured abdominal aortic aneurysm. In the introduction the aim of the study and objectives are listed. In the review of the literature main problems of pending topic are analyzed. The methodology is described in a special chapter. The results of 373 patients’ surgical treatment of abdominal aortic aneurysm were analyzed. Eighty-four of them were operated due to the abdominal aortic aneurysm rupture. Follow-up results of 153 patients were analyzed in a special chapter. The influence of comorbidities, demographic and surgical risk factors on mortality and complication rate after operations for ruptured abdominal aortic aneurysm were assessed. Analysis of follow-up results clarified risk factors influencing survival after operation of abdominal aortic aneurysm. Assessment of the results showed that mean age of patients is lower and comorbidities is more severe as compared with the data presented for Western countries. The patients’ age, condition of cardiac and pulmonary systems, volume of operation were the most influencing risk factors on the outcome of surgical treatment of the abdominal aortic aneurysm.

Colonic ischaemia (CI), Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are devastating complications after abdominal aortic aneurysm (AAA) surgery. The aims of this thesis were to study the incidence and clinical consequences of IAH/ACS and the association between CI and intra-abdominal pressure (IAP) among patients undergoing OR for ruptured AAA (rAAA), to compare extraluminal pHi monitoring, with standard intra-luminal monitoring among patients operated on for AAA, and to study the frequency and clinical consequences of IAH/ACS after endovascular repair (EVAR) for rAAA. The incidence of ACS was 26% in a retrospective study of 27 patients undergoing OR for rAAA. Consensus definitions on IAH/ACS were appropriate for patients after OR for rAAA: 78% (7/9) of patients with IAH grade III or IV developed organ failure and all patients who developed CI had some degree of IAH. Active fluid resuscitation treating hypovolaemia to avoid CI may partly cause IAH. The association between CI and IAP was investigated in a prospective study on 29 patients operated on for rAAA, 86% (25/29) were treated for hypovolaemia and ten (34%) had both IAH and CI. Since monitoring colonic perfusion is very important and there is no ideal method, a new technique, extraluminal colonic tonometry to detect colonic perfusion was compared with standard intraluminal tonometry. Although, this new method was not able to determine the severity of ischaemia it may serve as a screening test. EVAR of rAAA is feasible and patients may benefit from this less invasive procedure. Of 29 patients treated with this technique, 10% developed ACS, and all patients except one with preoperative shock developed some degree of IAH. In conclusion, IAP/ACS is common after both OR and EVAR for rAAA, and is associated with adverse outcome. Monitoring IAP and colonic perfusion with timely intervention may improve outcome.