Evidence for concealed fasciculo-ventricular connections as revealed by His bundle pacing.

BACKGROUND: It is almost 100 years ago since Mahaim described the so-called paraspecific connections between the ventricular conduction axis and the crest of the muscular ventricular septum, believing such pathways to be ubiquitous. These pathways, however, have yet to be considered as potential pathways for septal activation during His bundle pacing. MATERIALS: So as to explore the hypothesis that specialised septal pathways might provide the substrate for septal activation during His bundle pacing, we compared the findings from 22 serially sectioned histological datasets and 34 different individuals undergoing His bundle pacing. RESULTS: We found histologically specialised pathways connecting the branching component of the atrioventricular conduction axis with the crest of the muscular ventricular septum in almost four-fifths of the histological datasets. In 32 of 34 patients undergoing His bundle pacing, the QRS complex closely resembled published images of known conduction through fasciculo-ventricular pathways. In only two patients was a delta wave not seen at any pacing voltages. Capture of these connections varied according to pacing voltage, a finding which correlated with the distance of the pathways from the site of penetration of the ventricular conduction axis. Ventricular activation times remained normal in the presence of the delta wave at higher pacing voltage but were prolonged at lower voltages. CONCLUSIONS: Our histologic findings confirm fasciculo-ventricular connections, initially described by Mahaim as being paraspecific, are likely ubiquitous. Analysis of 12-lead electrocardiograms leads us to conclude that fasciculo-ventricular pathways, concealed during sinus rhythm, become manifest with His bundle pacing.

Re-evaluating the electro-vectorcardiographic criteria for left bundle branch block.

The criteria for left bundle branch block have gained growing interest in the last few years. In this overview, we discuss diagnostic and prognostic aspects of different criteria. It was already shown that stricter criteria, including longer QRS duration and slurring/notching of the QRS, better identify responders to cardiac resynchronization therapy. We also include aspects of ST/T concordance and discordance and vectorcardiography, which could further improve in the fine-tuning of the left bundle branch criteria.

Oil rich in carotenoids instead of vitamins C and E as a better option to reduce doxorubicin-induced damage to normal cells of Ehrlich tumor-bearing mice: hematological, toxicological and histopathological evaluations.

The development of therapeutic strategies to attenuate chemotherapy toxicity represents an area of great interest in cancer research, and among them is nutritional therapy based on antioxidants. As research on this topic is still controversial and scarce, we aim to investigate the effects of antioxidant supplementation with vitamin C, vitamin E or pequi oil, a carotenoid-rich oil extracted from pequi (Caryocar brasiliense), on doxorubicin (DX)-induced oxidative damage to normal cells in Ehrlich solid tumor-bearing mice. Tumor weight and volume, histopathology, morphometry and immunohistochemistry were used to assess the treatments' efficacy in containing tumor aggressiveness and regression, while possible toxicity of treatments was assessed by animals' weight, morphological analysis of the heart, liver and kidneys, hemogram, and serum levels of total bilirubin, direct bilirubin, indirect bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyl transferase (GGT), alkaline phosphatase, creatinine and urea. Although all the chemotherapeutic treatments increased internal necrosis area and reduced the positive Ki-67 cells compared to non-treated tumors, the treatments with pequi oil provided before tumor inoculation (PTDX) or in continuous and concurrent administration with doxorubicin (PTPDX) were more effective in containing tumor growth, besides increasing lymphocyte-dependent immunity and reducing the adverse side effects associated with DX-induced oxidative damage to normal cells, mainly the PTDX treatment. Vitamins C and E given before tumor inoculation and chemotherapy were not successful against doxorubicin-induced cardiotoxicity, besides increasing doxorubicin-induced nephrotoxicity, indicating that, at least for doxorubicin, pequi oil instead of vitamins C and E would be the best option to reduce its adverse effects.

Dextran-functionalized magnetic fluid mediating magnetohyperthermia for treatment of Ehrlich-solid-tumor-bearing mice: toxicological and histopathological evaluations.

Dextran-functionalized maghemite fluid (DexMF) has been tested to treat Ehrlich-solid-tumor-bearing mice, evidencing its potential use in mediating magnetohyperthermia in breast cancer treatment. However, although magnetic nanoparticles tend to accumulate in tumor tissues, part of the nanomaterial can reach the blood stream, and then the organism. The aim of this study was to investigate the acute systemic effects of the intratumoral injection of DexMF mediating magnetohyperthermia in the treatment of an advanced clinical Ehrlich-solid-tumor, assessed through histopathological analyses of liver, kidneys, heart and spleen, comet assay, micronucleus test, hemogram, and serum levels of bilirubin, aspartate aminotransferase, alanine aminotransferase, gamma glutamyl transferase, alkaline phosphatase, creatinine, and urea. The tumor's histopathology and morphometry were used to assess its aggressiveness and regression. DexMF mediating hyperthermia was effective in containing tumor aggressiveness and in inducing tumor regression, besides showing no toxic effects. Its physical characteristics also suggest that it is safe to use in other biomedical applications.