Atrial fibrillation (AF) is the disordered activation of the atrial myocardium, which is a major cause of stroke. Currently, the most effective, minimally traumatic treatment for AF is percutaneous catheter ablation to isolate arrhythmogenic areas from the rest of the atrium. The standard in vitro evaluation of ablation catheters through lesion studies is a resource intensive effort due to tissue variability and visual measurement methods, necessitating large sample sizes and multiple prototype builds. A computational test bed for ablation catheter evaluation was built in SolidWorks® using the morphology and dimensions of the left atrium adjacent structures. From this geometry, the physical model was built in COMSOL Multiphysics®, where a combination of the laminar fluid flow, electrical currents, and bioheat transfer was used to simulate radiofrequency (RF) tissue ablation. Simulations in simplified 3D geometries led to lesions sizes within the reported ranges from an in-vivo ablation study. However, though the ellipsoid lesion morphologies in the full atrial model were consistent with past lesion studies, perpendicularly oriented catheter tips were associated with decreases of -91.3% and -70.0% in lesion depth and maximum diameter. On the other hand, tangentially oriented catheter tips produced lesions that were only off by -28.4% and +7.9% for max depth and max diameter. Preliminary investigation into the causes of the discrepancy were performed for fluid velocities, contact area, and other factors. Finally, suggestions for further investigation are provided to aid in determining the root cause of the discrepancy, such that the test bed may be used for other ablation catheter evaluations.

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Objective: The primary aim of this study was to assess patients’ preferences between radiofrequency ablation (RFA) versus hepatic resection (HR) for the treatment of small hepatocellular carcinomas (HCC). Methods: Decision analysis was performed by using probability trade-off (PTO) technique to elicit patients’ preferences and the strength of their decisions. Results: The vast majority of the study population preferred RFA over HR (70% vs. 30%, p=0.001). Their initial choice changed if 5-year survival benefit after surgery was at least 14% superior to RFA and if the 3-year disease-free survival advantage was at least 13% better than ablation. Conclusions: The results of this study suggest that fully informed cirrhotic patients would prefer RFA if diagnosed with early stage HCC even if able to undergo surgery.

Small intestinal neuroendocrine tumor (SI-NET) is the most common small bowel tumor in Europe and USA, with an annual incidence of around 0.3-1.3/100000 persons. SI-NETs are the most common type of gastroenteropancreatic NETs (GEP-NETs), and they are known for their ability to produce hormones such as tachykinins and serotonin, as well as for their favorable long-term prognosis in comparison to gastrointestinal adenocarcinoma. The overall aim of the thesis was to investigate unknown or unclear aspects of SI-NET disease, in connection with prognosis, treatment and follow-up. Paper I confirmed several known negative prognostic factors and also showed, for the first time, that para-aortal lymph node metastases and peritoneal carcinomatosis were associated with worse survival by multivariable analyses. Locoregional surgery was associated with a low post-operative mortality, and a prolonged long-term survival by multivariable analysis. In Paper II we continued to investigate peritoneal carcinomatosis and found it be a risk factor not only for death, but also for emergency re-surgery. Furthermore, genetic analyses of samples from primary tumors in patients with and without peritoneal carcinomatosis showed a difference in the DNA between these two groups. In Paper III the outcome after liver surgery and/or radiofrequency ablation of liver metastases was investigated. To summarize, no difference in survival was seen in patients treated with surgery/radiofrequency ablation in comparison with matched controls. However, a superior radiological response of liver metasases and lower U-5-HIAA values were seen in patients subjected to liver surgery and/or radiofrequency ablation compared to matched controls. Paper IV compared ultrasonography, computed tomography and 11C-5HTP-PET in the follow-up after radiofrequency ablation of NET liver metastases. The study concluded that 11C-5HTP-PET depicted all residual tumors after RFA and that it, if used, should be combined with computed tomography for easier interpretation, as RFA areas are not clearly distinguishable with 11C-5HTP-PET alone. Paper V studied gallstone complications after somatostatin analog treatment in SI-NET patients, and concluded that there was a rather high risk to be subjected to a cholecystectomy due to biliary colic, cholecystitis, cholangitis or pancreatitis after primary surgery in somatostatin analog treated patients.

Nors vietinis naviko progresavimas yra esminė problema, atliekant piktybinių navikų kepenyse radijo dažnio abliaciją, dažniausiai tai yra vienintelis rodiklis, apibrėžiantis šio gydymo metodo veiksmingumą. Mūsų tyrimo tikslas buvo nustatyti kompiuterinės tomografijos ir ultragarso tyrimų bei histologinio stulpelinės biopsijos medžiagos, paimtos iš abliuoto naviko, histologinio tyrimo rezultato reikšmę anksti vertinant radijo dažnio abliacijos veiksmingumą. Tyrimo medžiaga ir metodai: Į tyrimą buvo įtraukti 68 pirminiai ir metastaziniai kepenyse esantys navikai. Radijo dažnio abliacija buvo atliekama naudojant perfuzijos elektrodus. Navikai prieš abliaciją ir po jos atliekant kontrolinius tyrimus buvo vertinami kompiuterinės tomografijos ir ultragarsinio tyrimo metodais. Po abliacijos praėjus vienam mėnesiui buvo atliekama abliacijos zonos punkcinė stulpelinė biopsija, audiniai tiriami histologiškai. Rezultatai ir išvados: Galutinei analizei buvo tinkami 58 sėkmingai gydyti navikai. Radiologinio stebėjimo metu buvo nustatyti devyni (15,5 %) vietinio naviko progresavimo atvejai. Vidutinis analizuotų navikų stebėjimo laikas buvo 16,3 mėnesiai (nuo 1,7 iki 38,7 mėnesių). Nustatyta, kad: 1. Biopsijos medžiagos, paimtos iš abliacijos zonos praėjus vienam mėnesiui po naviko, esančio kepenyse, radijo dažnio abliacijos, histologinio tyrimo rezultatas neleidžia prognozuoti vietinio naviko progresavimo 2. Naviko dydis 30 mm ir naviko lokalizacija arčiau kaip per 5 mm nuo didesnio nei 3... [toliau žr. visą tekstą] / Local tumour progression remains the main problem after radiofrequency ablation of liver tumours and it is usually the only measure of treatment efficacy. The aim of our study was to investigate and evaluate the prognostic value of computed tomography and ultrasonography as well as the histological result of core biopsy material from ablated tumour on assessment of radiofrequency ablation effectiveness. Materials and methods: We have studied 68 malignant primary and metastatic hepatic tumours treated by radiofrequency ablation. Ablation was performed using perfusion electrodes. Evaluation of tumours before ablation and follow up was performed by means of contrast enhanced computed tomography and ultrasonography. Ablation zone was biopsied for histological examination. Results and conclusions: 58 successfully treated hepatic tumours were suitable for the final analysis. The local progression of nine (15.5 %) tumours was detected on follow up. Mean follow up time for analysed tumours was 16.3 months with a range from 1.7 to 38.7 months. It was showed, that: 1. The result of histological examination of ablation zone biopsy material taken one month after radiofrequency ablation of malignant liver tumour does not predict local tumour progression. 2. Tumour size 30 mm and larger and tumour proximity closer than 5 mm to hepatic vessels larger than 3 mm are significant risk factors for local tumour progression after radiofrequency ablation of malignant liver tumours 3. Tumour type... [to full text]

Local tumour progression remains the main problem after radiofrequency ablation of liver tumours and it is usually the only measure of treatment efficacy. The aim of our study was to investigate and evaluate the prognostic value of computed tomography and ultrasonography as well as the histological result of core biopsy material from ablated tumour on assessment of radiofrequency ablation effectiveness. Materials and methods: We have studied 68 malignant primary and metastatic hepatic tumours treated by radiofrequency ablation. Ablation was performed using perfusion electrodes. Evaluation of tumours before ablation and follow up was performed by means of contrast enhanced computed tomography and ultrasonography. Ablation zone was biopsied for histological examination. Results and conclusions: 58 successfully treated hepatic tumours were suitable for the final analysis. The local progression of nine (15.5 %) tumours was detected on follow up. Mean follow up time for analysed tumours was 16.3 months with a range from 1.7 to 38.7 months. It was showed, that: 1. The result of histological examination of ablation zone biopsy material taken one month after radiofrequency ablation of malignant liver tumour does not predict local tumour progression. 2. Tumour size 30 mm and larger and tumour proximity closer than 5 mm to hepatic vessels larger than 3 mm are significant risk factors for local tumour progression after radiofrequency ablation of malignant liver tumours 3. Tumour type... [to full text] / Nors vietinis naviko progresavimas yra esminė problema, atliekant piktybinių navikų kepenyse radijo dažnio abliaciją, dažniausiai tai yra vienintelis rodiklis, apibrėžiantis šio gydymo metodo veiksmingumą. Mūsų tyrimo tikslas buvo nustatyti kompiuterinės tomografijos ir ultragarso tyrimų bei histologinio stulpelinės biopsijos medžiagos, paimtos iš abliuoto naviko, histologinio tyrimo rezultato reikšmę anksti vertinant radijo dažnio abliacijos veiksmingumą. Tyrimo medžiaga ir metodai: Į tyrimą buvo įtraukti 68 pirminiai ir metastaziniai kepenyse esantys navikai. Radijo dažnio abliacija buvo atliekama naudojant perfuzijos elektrodus. Navikai prieš abliaciją ir po jos atliekant kontrolinius tyrimus buvo vertinami kompiuterinės tomografijos ir ultragarsinio tyrimo metodais. Po abliacijos praėjus vienam mėnesiui buvo atliekama abliacijos zonos punkcinė stulpelinė biopsija, audiniai tiriami histologiškai. Rezultatai ir išvados: Galutinei analizei buvo tinkami 58 sėkmingai gydyti navikai. Radiologinio stebėjimo metu buvo nustatyti devyni (15,5 %) vietinio naviko progresavimo atvejai. Vidutinis analizuotų navikų stebėjimo laikas buvo 16,3 mėnesiai (nuo 1,7 iki 38,7 mėnesių). Nustatyta, kad: 1. Biopsijos medžiagos, paimtos iš abliacijos zonos praėjus vienam mėnesiui po naviko, esančio kepenyse, radijo dažnio abliacijos, histologinio tyrimo rezultatas neleidžia prognozuoti vietinio naviko progresavimo 2. Naviko dydis 30 mm ir naviko lokalizacija arčiau kaip per 5 mm nuo didesnio nei 3... [toliau žr. visą tekstą]

Vienas iš būdų padėti pacientams, sergantiems kepenų navikais, yra lokalus naviko sunaikinimas radiodažnine abliacija. Pagrindine šio metodo problema išlieka aukštas naviko atkryčio dažnis. Disertacijos tikslas yra ištirti procesus, vykstančius radiodažnine abliacija paveiktame kepenų audinyje, išsiaiškinti šių procesų mechanizmus bei hipertermijos sąlygojamus pakitimus audinio, ląstelės ir subląsteliniame lygmenyje. Retrospektyviu tyrimu įvertintas pacientų, kuriems KMUK Chirurgijos klinikoje buvo atlikta kepenų navikų radiodažninė abliacija, navikų atkryčio dažnis, jo atsiradimo laikas ir veiksniai, galintys sąlygoti atkrytį. Eksperimentiškai įvertinti fizikiniai veiksniai, sąlygojantys šilumos plitimą kepenų audinyje, jų įtaka kepenų audinio pažeidimo mąstui ir tolygumui. Nustatyti morfologiniai ir biocheminiai pakitimai, vykstantys pereinamojoje kepenų audinio pažeidimo zonoje, bei šių pakitimų atsiradimo laikas. Ištirti pereinamosios kepenų audinio pažeidimo zonos hepatocitų mitochondrijų funkcijų pokyčiai ir apoptozės proceso vyksmui reikalingų energetinių resursų susidarymas, eksperimentiškai modeliuojant šios zonos temperatūrinius kitimus. Tyrimo naujumą lemia tai, kad darbe nustatyta jog apoptozės procesas pereinamoje radiodažninio pažeidimo zonoje gali būti nustatomas praėjus valandai po terminio pažeidimo. Eksperimentuose su hepatocitų mitochondrijomis nustatėme iki šiol neaprašytą neigiamą hipertermijos poveikį kepenų ląstelių mitochondrijų funkciniams rodikliams. / Radiofrequency ablation is one of the most widely accepted method for the local ablation of liver tumors. One of the negative aspects of this method is a high local recurrence rate, which is associated with the worse survival. The aim of the dissertation was to explore the processes in radiofrequency ablation affected liver tissue, ascertain the mechanisms of these processes and hyperthermia induced changes in the liver tissue, cells and subcellular level. The liver tumor recurrence rate, time and factors that could determine the recurrence were estimated using retrospective analysis of data. The physical parameters determining the spreading of the heat in liver tissue in experimental model and the influence of these parameters on extent and homogeneity of the damage were determined. The morphological and biochemical changes in the remote from the heat source zone were determined and the time of these changes was detected. The changes of liver cells mitochondria functions and the intracellular formation of energy resources necessary for these processes in subcellular level (apoptosis) were investigated simulating temperature changes in experimental model. The scientific novelty was governed by the data those support the activation of apoptotic pathway in the early period after exposure to hyperthermia. Our experimental study revealed yet unpublished data of the adverse effects of hyperthermia on the key functional parameters of the mitochondria.

Objective: The primary aim of this study was to assess patients’ preferences between radiofrequency ablation (RFA) versus hepatic resection (HR) for the treatment of small hepatocellular carcinomas (HCC). Methods: Decision analysis was performed by using probability trade-off (PTO) technique to elicit patients’ preferences and the strength of their decisions. Results: The vast majority of the study population preferred RFA over HR (70% vs. 30%, p=0.001). Their initial choice changed if 5-year survival benefit after surgery was at least 14% superior to RFA and if the 3-year disease-free survival advantage was at least 13% better than ablation. Conclusions: The results of this study suggest that fully informed cirrhotic patients would prefer RFA if diagnosed with early stage HCC even if able to undergo surgery.

Orientador: Marcone Lima Sobreira / Resumo: Introdução: A doença venosa em sua apresentação mais grave, úlcera venosa em atividade ou cicatrizada, afeta de 2 – 6 milhões de pessoas, se considerarmos a população acima de 70 anos. A terapia de compressão (EC) é considerada o tratamento clínico mais eficaz para úlcera venosa(UV), mas a recorrência deve ser prevenida com o tratamento da hipertensão venosa. Evidências sugerem que a recorrência da úlcera é diminuída com a cirurgia venosa superficial, com superioridade de intervenções endovenosas minimamente invasivas, como laser (EVLA) ou ablação por radiofrequência (RF), sobre o tratamento cirúrgico clássico. A escleroterapia com espuma (EE) tem demonstrado também eficácia na correção da hipertensão venosa, sendo seu uso cada vez mais difundido. Entretanto, ainda faltam evidências comparando as técnicas entre si com a terapia compressiva clássica. Objetivo: Comparar as técnicas endovenosas, como radiofrequência (RF) e endolaser (ELVA), com escleroterapia por espuma (EE) e o tratamento clínico por meio de elastocompressão em pacientes com insuficiência venosa crônica (IVC) avançada (CEAP 6). Casuística e Métodos: Estudo prospectivo, controlado e randomizado. Foram incluídos 126 (cento e vinte e seis) pacientes, num total de 139 (cento e trinta e nove) pernas com úlceras venosas ativas, randomizados de maneira independente em 4 grupos: Radiofrequência ou Laser ou Espuma ou Elastocompressão. A área da ferida foi determinada em cm2, com controle fotográfico das úlceras venosas ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: ABSTRACT: Introduction: Venous disease in its more serious presentation, healed or open venous ulcers, affects 2 – 6 million people worldwide. Compression therapy (EC) is considered the most effective clinical treatment for venous ulcers (VU) ; however, recurrence is prevented by treating underlying venous hypertension. Current evidence suggests that ulcer recurrence is reduced by superficial venous surgery. Minimally invasive endovenous treatment modalities, such as laser (EVLA) or radiofrequency ablation (RF) have shown superiority over the classic open surgical treatment. Foam sclerotherapy (EE) has also been shown to be effective in treating venous hypertension, Nonetheless, there isn’t enough evidence comparing all these techniques against classic compression therapy. Objective: To compare catheter-based endovenous techniques, such as radiofrequency (RF) and endolaser (ELVA) with foam sclerotherapy (EE) and clinical treatment using elastic compression in patients with advanced chronic venous disease (IVC) (CEAP 6). Methods: Randomized, open label, controlled trialy. One hundred twenty-six (N=126) patients in a total of 139 (one hundred thirty-nine) legs with active venous ulcers, were randomized and enrolled in an independent manner into 4 groups: RF, EVLA, EE or EC.. The wound area was measured in cm2. Photographic assessment of venous ulcer healing along with ultrasonography control. Major adverse events, such as deep vein thrombosis, pulmonary embolism, and death were... (Complete abstract click electronic access below) / Doutor