Background: Despite the successful development in cardiac surgery, cerebrovascular accidents (CVA) remain a devastating complication. Aortic atherosclerosis has been identified as a major risk factor for CVA. The present thesis addresses this question in relation to aortic manipulation during cardiac surgery, being divided into a clinical (I-II) and an experimental part (III-V). Material and methods: Consecutive cardiac surgery cases (n=2641) were analyzed. Patients with CVA were extracted from a database designed to monitor clinical symptoms. Patient records were used to confirm clinical data and diagnosis. Subdivision was made into three groups: control subjects, immediate, and delayed CVA, being analyzed for neurological symptoms (I). Patients with CVA who also had been investigated with computer tomography (CT) (n=77) were further evaluated in terms of hemispheric and vascular distribution of lesions. The CT-findings were compared with CVA symptoms (II). An aortic perfusion model was developed using cadaver aorta onto which multiple cross-clamp manipulations were applied (III). Washout samples of perfusate were analyzed by computerized image processing and with subdivision into different particle spectra. The model was further developed with the introduction of intraluminal manipulation from cannula and intra-aortic filter (IV). A technique for macro-anatomic mapping of plaque distribution of cadaver thoracic aorta was developed (V). Variation in plaque density was analyzed in different anatomical segments, monitored by digital image analysis. Hazards associated with surgical manipulation were studied by superimposing cannulation and cross-clamp sites onto the aortic maps in a blinded fashion. Results: The incidence of immediate and delayed CVA was 3.0% and 0.9%, respectively. Aortic quality was a strongly associated with immediate but not delayed CVA. Left-sided symptoms of immediate CVA were significantly more frequent than of the contra-lateral side. Positive signs on CT were seen in 66% of the CVA patients. Right-hemispheric lesions were more frequent compared with the contra-lateral side and the middle-cerebral artery territory dominated. Aortic cross-clamping produced a substantial output of particulate matter. Manipulation by intra-aortic filter produced a significant washout of embolic particles that escaped the filter, although some particles were captured. Cannulation was an additional source of embolic material. In terms of plaque distribution was the anterior wall of the ascending part and arch of the aorta more affected than its posterior side. However, observing a plaque in the anterior wall of this aortic segment predicted to 83% a concomitant plaque in the posterior wall. Increased age correlated positively with plaque density. The theoretical chance of interfering with a plaque during cannulation and/or clamp positioning was 45.8%. Conclusions: Both CT scans and clinical symptoms confirmed that CVA after cardiac surgery had a right-hemispheric predominance. The perfusion model resulted in a profound output of material during cross-clamp maneuvers. The intra-aortic filter successfully collected particles but also generated embolic debris on its own. Aortic cannulation was an additional source of embolic debris. Plaques were frequently found in the cadaveric aorta, and there was a high risk of plaque interference during surgical manipulation. As expected, plaque density was age-dependent.

published_or_final_version / Physiology / Master / Master of Medical Sciences

TEVAR has been used extensively to treat TBAD. The principle of treatment involve placement of a stent graft in the true lumen to cover the primary tear, thereby excluding the false lumen. Success depends on a combination of factors: reduction of false lumen pressure and perfusion, thrombosis of the false lumen, and remodeling of the aorta leading to eventual healing. The long-term goals are to prevent continuous growth of the false lumen, reinterventions, and aneurysm rupture. The success of TEVAR depends on a combination of factors, including the blood flow and pressure in the two aortic lumens, and remodeling is a dynamic process. Much controversy exists regarding the ideal timing of TEVAR, its efficacy in effecting complete false lumen exclusion, the long-term durability of the repair, and the fate of the aortic size. The objective of this thesis is to examine the morphological and hemodynamic changes within the aortic lumens after TEVAR, using a combination of ex-vivo animal models and computational tomography analysis. The residual pressure of the true and false lumens in TBAD models was studied. Volumetric analyses of CT scan of patients were compared. The ultimate goals are to determine if it is beneficial to treat type B dissections early, and to determine long-term morphological results. In ex-vivo hemodynamic study, 28 fresh porcine aortas models were created to simulate three different pathological scenarios of TBAD: model A represented pre-treated TBAD; model B represented post-treated TBAD with patent false lumen; and model C represented chronic stage of post-treated TBAD with false lumen thrombosis. True lumen and false lumen pressure differences were compared between the three models. Pressure effect was successfully reduced by 30% in model C in comparison with the other two models. No hemodynamic parameters were significantly different between model A and model B. Aortic remodeling parameters were volumetrically analyzed and compared between two groups of patients who underwent endo-grafting for uncomplicated TBAD (group A) and dissecting aneurysms (group B). Modern DIOCM processing workstations and software were used to reconstruct thoracic aorta with serial CT scans. The true lumen, false lumen, thrombus and aortic size were measured volumetrically. Stent graft migration and area of inlet and outlet were also quantified. There were progressive migration and continuous expansion of the stent graft on patients in both groups. Favorable aortic remodeling was observed in most. One fourth of all patients demonstrated aortic volume increase at 36 months. However, there was no difference between group A and group B in terms of stent graft re-shaping and aortic remodeling. In conclusion, Aortic remodeling after TEVAR in treating TBAD is a continuous process. There were no significant differences between chronic dissections and dissecting aneurysms in all morphological parameters. Treating chronic dissections before aneurysm formation does not seem to have a morphologic advantage. Sealing of primary entry tear with introducing thrombosis could significantly reduce false lumen pressure. However, the remaining pressure accumulations should be considered to reduce by further excluding distal reentry tears in those patients who undergo progressive false lumen expansion after TEVER. / published_or_final_version / Surgery / Doctoral / Doctor of Philosophy

No description available.

No description available.

No description available.

Abdominal Aortic Aneurysms (AAA) are amongst the top ten most common cause of death in those over 55 years of age. The disease is usually asymptomatic, often being diagnosed incidentally. Once diagnosed, elective repair of an AAA results in excellent long-term survival with a 3-5% operative mortality. However, up to one half of patients present with ruptured aneurysms, a complication that carries an 80% mortality in the community, and of those reaching hospital, a 50% mortality. Clearly early diagnosis and treatment results in improved survival. Screening for AAA, with ultrasound, would detect aneurysms early, prior to rupture. However, debate continues over the cost effectiveness of population based screening programmes. The identification of a sub-population at a higher risk of developing AAA would increase the yield of a screening prograrmne. A number of populations have been examined, none of which have received international acceptance. About 20% of patients with an AAA have a family history of an aneurysm. The disease is also considered to be a disease of Caucasians, both facts suggesting a strong genetic component to the disease. Perhaps a genetically identified sub-population at a high risk of developing an AAA would prove to be an ideal population for screening. This thesis examines the incidence of aneurysms and the family histories of patients with AAA in the Otago region of New Zealand. Almost twenty percent of the population has a family history of AAA. DNA was collected from each of these patients for genetic analysis. The population was divided into familial AAA and non-familial AAA for the purpose of genetic analysis and compared to a control population. AAA is believed to be a disease of Caucasians; a non-Caucasian population with a low incidence of AAA may prove to be a good control population for genetic studies. A literature review demonstrated a higher incidence of AAA in Caucasians than other ethnic groups and within Caucasians a higher incidence in patients of Northern European origin. The incidence was low in Asian communities, even in studies involving of migrant Asian populations. The New Zealand Maori are believed to have originated from South East Asia, therefore could be expected to have a low incidence of AAA and would make an ideal control population for genetic studies. A pilot study was undertaken to examine the incidence of AAA in the New Zealand Maori. The age standardised incidence of AAA proved to be at least equal in Maori to non-Maori, with a more aggressive form of the disease in Maori, manifesting with a younger age at presentation and a higher incidence of ruptured aneurysms at diagnosis. It is well known that at the time of surgery, an AAA

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted.

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted.

Acompanha 1 CD-ROM / Orientador: Roberto Jorge da Silva Franco / Banca: Fernando Almeida / Banca: Eduardo Aguilar Arca / Resumo: Pacientes com doença renal crônica usualmente apresentam intolerância ao exercício e aumento de rigidez arterial. O objetivo desse estudo foi avaliar a associação entre o condicionamento físico e a pressão arterial central, espessura da camada íntima-média de carótida e rigidez arterial em pacientes com doença renal crônica, além de analisar a interação desses fatores com as variáveis clínicas e laboratoriais. Foi avaliada a pressão arterial central, velocidade de onda de pulso e índice de amplificação de 22 pacientes utilizando o aparelho Sphygmocor. Também foi determinada a espessura da camada íntima-média de carótida por meio da ultrasonografia. O condicionamento físico foi avaliado pela medida do VO2 máximo, estimado por ergometria utilizando o protocolo de Bruce. De acordo com o VO2 máximo, 2 grupos de pacientes foram obtidos. Grupo I (GI) com valores abaixo da mediana e Grupo II (GII) com valores acima. O GI apresentou diferenças estatísticas com relação à velocidade da onde de pulso e do índice de amplificação, configurando maior rigidez arterial. Os valores de massa gorda, proteína C-reativa, hemoglobina e albumina foram estatisticamente diferentes entre os grupos. A massa gorda e proteína C-reativa foram maiores no GI do que no GII. A hemoglobina e albumina, ao contrário, foram maiores no GII do que no GI. A espessura da camada íntima-média de carótida e a pressão arterial central foram similares entre os grupos. Melhor condicionamento físico foi associado com menor rigidez arterial em pacientes com doença renal crônica / Abstract: Chronic kidney disease patients usually presents exercise intolerance and increased arterial stiffness. The aim of this study was to evaluate the association between physical fitness and the degree of arterial stiffness in chronic kidney disease patients, as well to analyze its relation with clinical variables. Twenty-two patients were evaluated by central blood pressure, pulse wave velocity and augmentation index using Sphygmocor device. Carotid intima-media wall thickness was assessed by ultrasonography and fitness performance estimated by VO2 max using Bruce protocol treadmill test. Patients were distributed in two groups according to the median value obtained for VO2 max: Group 1 (GI) with VO2 max below the median and Group 2 (GII) with values above the median. The GI presented significant increase of pulse wave velocity and augmentation index configuring higher arterial stiffness for this group. Other clinical variables as fat mass, C-reactive protein, were higher in GI and hemoglobin and albumin, on the contrary, were higher in GII Carotid intima-media wall thickness and central blood pressure were similar in both groups. Better fitness was associated with lower arterial stiffness in CKD patients / Mestre