Functional substrate mapping of atrium in patients with atrial scar: A novel method to predict critical isthmus of atrial tachycardia.

Atrial tachycardia (AT) is a common rhythm disorder, especially in patients with atrial structural abnormalities. Although voltage mapping can provide a general picture of structural alterations which are mainly secondary to prior ablations, surgery or pressure/volume overload, data is scarce regarding the functional characteristics of low voltage regions in the atrium to predict critical isthmus of ATs. Recently, functional substrate mapping (FSM) emerged as a potential tool to evaluate the functionality of structurally altered regions in the atrium to predict critical sites of reentry. Current evidence suggested a clear association between deceleration zones of isochronal late activation mapping (ILAM) during sinus/paced rhythm and critical isthmus of reentry in patients with left AT. Therefore, these areas seem to be potential ablation targets even not detected during AT. Furthermore, abnormal conduction detected by ILAM may also have a role to identify the potential substrate and predict atrial fibrillation outcome after pulmonary vein isolation. Despite these promising findings, the utility of such an approach needs to be evaluated in large-scale comparative studies. In this review, we aimed to share our experience and review the current literature regarding the use of FSM during sinus/paced rhythm in the prediction of re-entrant ATs and discuss future implications and potential use in patients with atrial low-voltage areas.

Hyperbaric oxygen therapy and mechanical resistence of the colonics anastomosis in rats with peritonitis / Oxigenoterapia hiperbárica e resistência mecânica das anastomoses cólicas em ratos com peritonite

PURPOSE: To analyze the effects of hyperbaric oxygen therapy (HBO) on the mechanical resistance of anastomosis performed in rats' distal colon presenting peritonitis induced by ligature and cecal punction using the Total Energy Rupture biomechanical test (ETR). METHODS: It was used 45 rats divided into three groups of 15 animals each. In Control Group (CG), it was performed anastomosis in distal colon without peritonitis. In Peritonitis Group (PG), it was performed anastomosis six hours after the induction of peritonitis by ligature and cecal punction. In Hyperbaric Chamber Group (HCG), it was performed six hours after the induction of peritonitis by ligature and cecal punction. The animals on CG and PG were kept at place air while the animals on HCG were placed on an experimental hyperbaric chamber in order to inhale oxygen at 100 percent, two absolute atmospheres, for 120 minutes, for four consecutive days. Euthanasia took place on the fifth day of the experiment. All the animals underwent to Total Energy Rupture Biomechanical Resistance test (ETR). Total Energy Rupture was defined as the necessary internal energy stored up to promote the colon rupture after an external traction force imposition. RESULTS: The Peritonitis Group presents smaller average ETR than Control Group. There was no statistical difference between Peritonitis Group and Hyberbaric Chamber Group. CONCLUSION: Hyperbaric oxygen therapy did not alter the mechanical resistance of anastomosis performed in distal colon of rats under the presence of peritonitis induced by ligature and cecal puncture.

OBJETIVO: Analisar o efeito da oxigenoterapia hiperbárica (HBO) sobre a resistência mecânica de anastomoses realizadas em cólon distal de ratos na presença de peritonite induzida por ligadura e punção cecal utilizando o teste biomecânico de Energia Total de Ruptura (ETR). MÉTODOS: Foram utilizados 45 ratos distribuídos em três grupos de 15 animais. No Grupo Controle (GC), realizou-se anastomose no cólon distal sem peritonite. No Grupo Peritonite (GP), realizou-se anastomose seis horas após a indução da peritonite por ligadura e punção cecal. No Grupo Câmara Hiperbárica (GCH), realizou-se anastomose seis horas após a indução da peritonite por ligadura e punção cecal. Os animais dos GC e GP foram mantidos em ar ambiente. Os animais do GCH foram colocados em uma câmara hiperbárica experimental para inalarem oxigênio a 100 por cento, a duas atmosferas absolutas, durante 120 minutos, por quatro dias consecutivos. A eutanásia ocorreu no quinto dia do experimento. Todos os animais foram submetidos ao Teste de Resistência Biomecânico Energia Total de Ruptura (ETR). A Energia Total de Ruptura foi definida como a energia interna acumulada necessária para promover o rompimento do cólon após a imposição de uma força externa de tração. RESULTADOS: O Grupo Peritonite apresentou menor média de ETR que o Grupo Controle. Não houve diferença estatística entre o Grupo Peritonite e o Grupo Câmara Hiperbárica. CONCLUSÃO: A oxigenoterapia hiperbárica não alterou a resistência mecânica de anastomoses realizadas no cólon distal de ratos na presença de peritonite induzida por ligadura e punção cecal.