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A procedure for solving, suboptimally, the traveling salesman problem is presented. The set of points on the traveling salesman tour is distributed over a region having the shape of a circular or ring sector. The procedure is based on an optimal partition of the sector and reduces the tour construction to a sorting problem. Namely, the tour is constructed by visiting the points in radial or angular order depending on the part of the sector on which they are located. The optimal partition is derived by a continuous approximation of the set of points. It is defined by a single parameter and simple analytical expressions for it are obtained. A great number of numerical tests were carried out to evaluate the performance of the procedure. These tests allowed a measure of the difference from the optimum solution that could be obtained for problems up to a few hundred points. The results show that the euclidean length of the tours produced by the partition procedure grows, on average, like AN , where A is the region area and N the number of points. The initial tours are improved by means of the Or’s algorithm and the final tours obtained are nearly as good as those given by more intrincate improvement heuristics. The whole procedure, that is, the tour construction and improvement heuristics, is rather simple to implement on a computer, which makes it very appealing to use in routing software.

Percutaneous balloon mitral valvotomy (BMV) is an alternative therapeutic method for patients with mitral stenosis. We studied 62 patients (56 females, mean age 36.4 years) who underwent balloon mitral valvotomy. Five patients were pregnant and in New York Heart Association Functional Class IV. Doppler echocardiographic studies were performed prior to the procedure, and at 7 days, 6 months, 12 months, and 24 months after the procedure. We studied the following parameters: echo-score by the sum of valvular mobility, thickening, and calcification, and subvalvular disease, graded from 1 to 4; and mitral valve area (MVA) and mitral pressure gradient (MPG) by Doppler echocardiography. The patients were separated into two groups: group I with an echo-score less than or equal to 8 (40 patients), and group II with an echo-score greater than or equal to 9 (22 patients). Mitral valve area and MPG were compared with hemodynamics through the correlation coefficient and linear regression. Comparison between groups I and II was performed using the unpaired Student's t-test. Follow-up of MVA and MPG was analyzed by analysis of variance. The Student's t-test did not show any significant difference between MVA and MPG before balloon mitral valvotomy. There was significant decrease of MVA in group II (P less than 0.01) in the last three studies. There was significant increase in MPG in group II (P less than 0.01) in every postvalvotomy study. The analysis of variance of group I showed statistical increase of the MVA, and significant decrease of the MPG after BMV. The analysis of variance of group II showed significant increase in MVA and significant decrease in MPG between the pre- and the first postvalvotomy study. There was significant decrease (P less than 0.01) in MVA, and increase in MPG in the three postvalvotomy studies. Complications included mitral regurgitation, residual interatrial communication, pericardial effusion due to an atrial wall perforation, and peripheral embolization. Atrial fibrillation did not significantly alter the results of BMV. Results were considered positive when MVA was greater than 1.5 cm 2 and area increase was greater than 25%. Patients with an echo-score less than or equal to 8 (group I) benefit from BMV, with a positive predictive value greater than 78%. In pregnant patients the symptomatology was alleviated by BMV, without any signs of fetal compromise.

Apesar dos avanços no entendimento da fisiopatologia e dos recursos terapêuticos atualmente disponíveis, a cardiomiopatia dilatada (CMD) permanece como uma condição com alta mortalidade, sendo que a disfunção microvascular é um dos mecanismos relacionados à piora da função cardíaca. Nos últimos anos, novas técnicas de ecocardiografia vêm sendo utilizadas para avaliação da disfunção microvascular, incluindo a medida de velocidade de fluxo coronário pelo Doppler da artéria coronária descendente anterior (ADA), e a análise quantitativa do fluxo miocárdico pela ecocardiografia com perfusão miocárdica em tempo-real (EPMTR). No presente estudo, avaliamos o valor prognóstico da reserva de velocidade de fluxo coronário (RVFC), obtida pelo Doppler da ADA, e da reserva de fluxo miocárdico (RFM), obtida pela EPMTR, para predizer morte e transplante cardíaco em pacientes com CMD de origem não isquêmica. Adicionalmente, avaliamos se as medidas de reserva de fluxo acrescentam valor prognóstico sobre variáveis clínicas e ecocardiográficas que já são conhecidas como preditores de eventos nesta população. Estudamos 195 pacientes com CMD (130 homens, média etária 54 ± 12 anos) que apresentavam fração de ejeção do ventrículo esquerdo inferior a 35% pelo ecocardiograma e ausência de sinais de doença arterial coronária obstrutiva por angiografia coronária invasiva ou por método não invasivo (cintilografia de perfusão miocárdica ou angiotomografia de coronárias). Foram analisados parâmetros ecocardiográficos convencionais de função sistólica e diastólica do ventrículo esquerdo em repouso. A velocidade de fluxo coronário foi determinada pelo Doppler pulsado na ADA e a dinâmica das microbolhas no miocárdio foi quantificada pela EPMTR utilizando programas computacionais específicos, tanto em repouso como durante o estresse pelo dipiridamol (0,84 mg/Kg). As RVFC, RFM e reserva de velocidade de repreenchimento de microbolhas no miocárdio (reserva ) foram obtidas pela relação entre os parâmetros de fluxo durante a hiperemia e em repouso, sendo consideradas diminuídas quando os valores estavam abaixo de 2,0. O tempo médio de acompanhamento foi de 29 meses (variando de 6 a 69 meses). Neste período, 45 pacientes (24%) apresentaram eventos, sendo 43 mortes de causa cardíaca e 2 transplantes cardíacos. Na análise univariada foram preditores de eventos: etiologia chagásica, classe funcional de insuficiência cardíaca, uso de inibidores da enzima conversora de angiotensina e/ou bloqueadores dos receptores de angiotensina II (fator protetor), diâmetros ventriculares e do átrio esquerdo, volumes ventriculares, fração de ejeção, disfunção diastólica, grau de insuficiência mitral, RVFC, RFM e reserva . Na análise multivariada, foram preditores independentes de eventos o diâmetro do átrio esquerdo (razão de chances = 1,16 por unidade de aumento; intervalo de confiança 95% = 1,078 1,264; p