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Objective: The objectives were to estimate the performance of the IOTA-ADNEX model test after its incorporation into the ultrasound tests of our third-grade hospital gynecology service, as well as to assess whether its capacity of accuracy is modified when taking into account the patient's menopausal status. Methods: A cross-sectional study was conducted to clinically evaluate the diagnostic performance of the IOTA-ADNEX model test, which was performed between January 2016 and December 2021. The study included 573 women with an adnexal injury who underwent surgical excision within 180 days after ultrasound diagnosis and histological confirmation (gold standard). After the ultrasound exam, the injuries were classified using the ADNEX model. The study estimated the area under the receiver-operating-characteristics curve (AUC) of the ADNEX model for classifying between benign and malignant adnexal masses and compared the performance by menopausal state. Sensitivity and specificity were determined for different cut-off points. Results: Out of the 573 women, 183 (31.9%) had a malignant tumor. The AUC of the ADNEX model for differentiating between benign and malignant adnexal masses at the time of ultrasound examination was 0.92 and the best malignancy threshold, detected by Youden index, was 22.5%. At this cut-off, the sensitivity of the ADNEX model was 91.8% and the specificity was 76.4%. However, it varies according to menopausal status: in the group of pre-menopausal patient, sensitivity was 86.1% (95% CI, 85.4%–86.8%) and specificity was 81.3% (95% CI, 85.4%–86.8%). In the postmenopausal group, sensitivity was 96.1% (95% CI, 95.6%–96.7%) and specificity was 68.5% (95% CI, 68.1%–68.8%)...(AU)

Objetivo: Los objetivos eran estimar el rendimiento del test IOTA ADNEX model después de su incorporación en el estudio ecográfico en nuestro servicio de ginecología, en un hospital de tercer nivel, así como evaluar si su capacidad de precisión se modifica al tener en cuenta el estado menopáusico de la paciente. Método: Se llevó a cabo un estudio transversal para evaluar clínicamente el rendimiento diagnóstico del test IOTA ADNEX model, el cual se realizó entre enero de 2016 y diciembre de 2021. El estudio incluyó a 573 mujeres con una lesión anexial que se sometieron a tratamiento quirúrgico en un plazo de 180 días después del diagnóstico por ecografía y confirmación histológica (gold standard). Después de realizar la ecografía, las lesiones fueron clasificadas utilizando el modelo ADNEX. El estudio estimó el área bajo la curva (AUC) del modelo ADNEX para diferenciar entre masas anexiales benignas y malignas, y se comparó el rendimiento según el estado menopáusico. Se determinó la sensibilidad y la especificidad para diferentes puntos de corte. Resultados: De las 573 mujeres, 183 (31,9%) tenían un tumor maligno. El AUC del modelo ADNEX para diferenciar entre masas anexiales benignas y malignas en el momento del examen ecográfico fue de 0,92 y el umbral de malignidad óptimo, detectado por el índice de Youden, fue del 22,5%. Con este punto de corte, la sensibilidad (SE) del modelo ADNEX fue del 91,8% y la especificidad (SP) fue del 76,4%. Sin embargo, esto varía según el estado menopáusico: en el grupo de pacientes premenopáusicas, la sensibilidad fue del 86,1% (IC del 95%: 85,4-86,8%) y la especificidad fue del 813% (IC del 95%: 85,4-86,8%). En el grupo de pacientes posmenopáusicas, la sensibilidad fue del 96,1% (IC del 95%: 95,6-96,7%) y la especificidad fue del 68,5% (IC del 95%: 68,1-68,8%)...(AU)

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Longitudinal dissociation of the aggregated specialized cardiomyocytes within the non-branching portion of atrioventricular conduction axis has proved a controversial topic for both morphologists and electrophysiologists. We have now used morphological methods, including three-dimensional assessment, to revisit, in human, canine, and bovine hearts, the presence or absence of interconnections between the aggregated cardiomyocytes making up the non-branching bundle. We analyzed three datasets from human and canine hearts, and two from bovine hearts, using longitudinal and orthogonal serial histological sections. In addition, we assessed three hearts using translucent India ink injected specimens, permitting assessment of the three-dimensional arrangement of the cardiomyocytes. Using the longitudinal sections, we found numerous oblique interconnections between the groups of specialized cardiomyocytes. When assessing orthogonal sections, we noted marked variation in the grouping of the cardiomyocytes. We interpreted this finding as evidence of bifurcation and convergence of the groups seen in the longitudinal sections. The three-dimensional assessment of the bovine material confirmed the presence of the numerous interconnections. The presence of multiple connections between the cardiomyocytes in the non-branching bundle rules out the potential for longitudinal dissociation.

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The cerebrovascular system provides crucial functions that maintain metabolic and homeostatic states of the brain. Despite its integral role of supporting cerebral viability, the topological organization of these networks remains largely uncharacterized. This void in our knowledge surmises entirely from current technological limitations that prevent the capturing of data through the entire depth of the brain. We report high-resolution reconstruction and analysis of the complete vascular network of the entire brain at the capillary level in adult female and male mice using a vascular corrosion cast procedure. Vascular network analysis of the whole brain revealed sex-related differences of vessel hierarchy. In addition, region-specific network analysis demonstrated different patterns of angioarchitecture between brain subregions and sex. Furthermore, our group is the first to provide a three-dimensional analysis of the angioarchitecture and network organization in a single reconstructed tomographic data set that encompasses all hierarchy of vessels in the brain of the adult mouse.

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Autosomal dominant Alzheimer disease (AD) is caused by rare mutations in one of three specific genes. This is in contrast to idiopathic, late-onset AD (LOAD), which has a more polygenetic risk profile and represents more than 95% of cases. Previously, we have demonstrated that increased expression of microRNA (miRNA)-34a (miR-34a) in AD brain targets genes linked to synaptic plasticity, energy metabolism, and resting state network activity. Here we report the generation of a heterozygous, conditional miR-34a overexpression mouse (miR-34a+/-(TetR-TetO-miR-34a) Transgenic Mice). Doxycycline-treated mice of either sex exhibited profound behavioral impairment compared to untreated groups with only 1-2 months of over-expression of miR-34a. Cognitive impairment of individual mice in T- and Y-maze tasks correlated with elevated miR-34a expression in many parts of the brain including the hippocampus and prefrontal cortex, regions which are known to be involved in this task and implicated in LOAD dysfunction. Immunocytochemistry of brain sections from mice show high amyloid ß and phosphorylated tau-specific staining in the hippocampus and cortex. Analysis of protein samples from these mice revealed that miR-34a targets specific genes involved in memory formation, amyloid precursor protein (APP) metabolism and phosphorylation-dephosphorylation of tau. Thus, our results suggest that the polygenetic dysfunction caused by miR-34a may occur in LOAD and disclose miR-34a as a potential therapeutic target. SIGNIFICANCE STATEMENT: Late-onset Alzheimer disease (LOAD) is associated with multiple gene alleles, a polygenetic profile of risk factors that is difficult to model in animals. Our approach to modeling LOAD was to produce a conditional over-expressing, miR-34a mouse using doxycycline-induction to activate expression. We observed that miR-34a over-expression results in a rapid cognitive impairment, associated with accumulation of intracellular Aß and tau hyperphosphorylation in multiple brain regions. Targets for miR-34a, including ADAM10, NMDAR 2B, and SIRT1 RNAs, were profoundly reduced by miR-34a over-expression. Collectively, these results indicate that a rapid, profound cognitive decline and Alzheimer's disease neuropathology can be induced with miR-34a over-expression, suggesting that this animal model may represent a polygenetic risk factor model for LOAD.

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Heart rate variability (HRV) is a widely used measure that reflects autonomic (parasympathetic) control of the heart. HRV has been linked with attentional performance, but it is unclear to what extent resting HRV is associated with both attention and attentional maintenance. In order to address this, we calculated HRV in seventy-four young and healthy volunteers (43 men, age: 21.6 ±â€¯2.4), who completed the D2 Test of Attention (D2), which was used to calculate an index of Concentration Performance (CP) and a measure of attention maintenance, the coefficient of variation (CV). After accounting for the effects of sex and age on HRV, there was no significant association between HRV and CP (p = .2), but a significant relationship between HRV and CV (p = .03). Overall, our study demonstrates that attention maintenance, but not attentional performance, is associated with higher resting state HRV which suggests that attentional performance from D2 subtest-to-subtest may reflect HRV's facilitation of behaviour flexibility.

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OBJECTIVE: While CVD risk has decreased in the general population during the last decade, the situation in patients with schizophrenia (SCZ) and bipolar disorder (BD) is unknown. METHODS: We compared CVD risk factors in patients with SCZ and BD recruited from 2002-2005 (2005 sample, N = 270) with patients recruited from 2006-2017 (2017 sample, N = 1011) from the same catchment area in Norway. The 2017 sample was also compared with healthy controls (N = 922) and the general population (N range = 1285-4587, Statistics Norway) from the same area and period. RESULTS: Patients with SCZ and BD in the 2017 sample had significantly higher level of most CVD risk factors compared to healthy controls and the general population. There was no significant difference in the prevalence of CVD risk factors in SCZ between the 2005 and 2017 samples except a small increase in glucose in the 2017 sample. There were small-to-moderate reductions in hypertension, obesity, total cholesterol, low-density lipoprotein, systolic and diastolic blood pressure in the BD 2017 sample compared to the 2005 sample. CONCLUSION: Despite major advances in health promotion during the past decade, there has been no reduction in the level of CVD risk factors in patients with SCZ and modest improvement in BD.

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Evidence of executive dysfunction in autism spectrum disorders (ASD) across development remains mixed and establishing its role is critical for guiding diagnosis and intervention. The primary objectives of this meta-analysis is to analyse executive function (EF) performance in ASD, the fractionation across EF subdomains, the clinical utility of EF measures and the influence of multiple moderators (for example, age, gender, diagnosis, measure characteristics). The Embase, Medline and PsychINFO databases were searched to identify peer-reviewed studies published since the inclusion of Autism in DSM-III (1980) up to end of June 2016 that compared EF in ASD with neurotypical controls. A random-effects model was used and moderators were tested using subgroup analysis. The primary outcome measure was Hedges' g effect size for EF and moderator factors. Clinical sensitivity was determined by the overlap percentage statistic (OL%). Results were reported according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A total of 235 studies comprising 14 081 participants were included (N, ASD=6816, Control=7265). A moderate overall effect size for reduced EF (Hedges' g=0.48, 95% confidence interval (CI) 0.43-0.53) was found with similar effect sizes across each domain. The majority of moderator comparisons were not significant although the overall effect of executive dysfunction has gradually reduced since the introduction of ASD. Only a small number of EF measures achieved clinical sensitivity. This study confirms a broad executive dysfunction in ASD that is relatively stable across development. The fractionation of executive dysfunction into individual subdomains was not supported, nor was diagnostic sensitivity. Development of feasible EF measures focussing on clinical sensitivity for diagnosis and treatment studies should be a priority.

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The neuropeptide oxytocin has shown promise as a treatment for symptoms of autism spectrum disorders (ASD). However, clinical research progress has been hampered by a poor understanding of oxytocin's dose-response and sub-optimal intranasal delivery methods. We examined two doses of oxytocin delivered using a novel Breath Powered intranasal delivery device designed to improve direct nose-to-brain activity in a double-blind, crossover, randomized, placebo-controlled trial. In a randomized sequence of single-dose sessions, 17 male adults with ASD received 8 international units (IU) oxytocin, 24IU oxytocin or placebo followed by four social-cognitive tasks. We observed an omnibus main effect of treatment on the primary outcome measure of overt emotion salience as measured by emotional ratings of faces (η2=0.18). Compared to placebo, 8IU treatment increased overt emotion salience (P=0.02, d=0.63). There was no statistically significant increase after 24IU treatment (P=0.12, d=0.4). The effects after 8IU oxytocin were observed despite no significant increase in peripheral blood plasma oxytocin concentrations. We found no significant effects for reading the mind in the eyes task performance or secondary outcome social-cognitive tasks (emotional dot probe and face-morphing). To our knowledge, this is the first trial to assess the dose-dependent effects of a single oxytocin administration in autism, with results indicating that a low dose of oxytocin can significantly modulate overt emotion salience despite minimal systemic exposure.

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Approximately 5-10% of chronic myeloid leukemia (CML) patients are found to have structural or numerical additional chromosomal abnormality (ACAs) in addition to the characteristic t(9;22)(q34;q11.2) BCR/ABL1 at the time of diagnosis. The prognostic significance of such additional chromosomal abnormalities has been controversial. Translocation t(11;14)(q13;q32) CCND1-IGH is typically associated with mantle cell lymphoma or a subset of plasma cell myeloma and is exceedingly rare in myeloid neoplasm. Here we report a unique case describing a patient found at diagnosis of chronic phase CML to have both the Philadelphia chromosome as well as t(11;14)-a rare cytogenetic combination. The patient was treated with imatinib with appropriate hematologic response but persistent disease by FISH and RT-PCR. She was switched to dasatinib and eventually achieved cytogenetic remission in both translocations, but still with persistent RT-PCR evidence of BCR-ABL1 fusion. As cyclin D1 is a regulatory subunit of cyclin-dependent kinases CDK4 and CDK6 and is required for the cells to progress through the G1 phase of the cell cycle, overexpression of cyclin D1 will likely promote cells into cell cycle. This may further augment proliferation in addition to upregulated ABL1 kinase activity in the index case. It may also contribute to the resistance to imatinib, as imatinib only targets on BCR-ABL fusion. Therefore, the addition of t(11;14)(q13;q32) may have significant implication in patient management.

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Polygenetic risk factors and reduced expression of many genes in late-onset Alzheimer's disease (AD) impedes identification of a target(s) for disease-modifying therapies. We identified a single microRNA, miR-34a that is over expressed in specific brain regions of AD patients as well as in the 3xTg-AD mouse model. Specifically, increased miR-34a expression in the temporal cortex region compared to age matched healthy control correlates with severity of AD pathology. miR-34a over expression in patient's tissue and forced expression in primary neuronal culture correlates with concurrent repression of its target genes involved in synaptic plasticity, oxidative phosphorylation and glycolysis. The repression of oxidative phosphorylation and glycolysis related proteins correlates with reduced ATP production and glycolytic capacity, respectively. We also found that miR-34a overexpressed neurons secrete miR-34a containing exosomes that are taken up by neighboring neurons. Furthermore, miR-34a targets dozens of genes whose expressions are known to be correlated with synchronous activity in resting state functional networks. Our analysis of human genomic sequences from the tentative promoter of miR-34a gene shows the presence of NFκB, STAT1, c-Fos, CREB and p53 response elements. Together, our results raise the possibilities that pathophysiology-induced activation of specific transcription factor may lead to increased expression of miR-34a gene and miR-34a mediated concurrent repression of its target genes in neural networks may result in dysfunction of synaptic plasticity, energy metabolism, and resting state network activity. Thus, our results provide insights into polygenetic AD mechanisms and disclose miR-34a as a potential therapeutic target for AD.

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The number of publications investigating heart rate variability (HRV) in psychiatry and the behavioral sciences has increased markedly in the last decade. In addition to the significant debates surrounding ideal methods to collect and interpret measures of HRV, standardized reporting of methodology in this field is lacking. Commonly cited recommendations were designed well before recent calls to improve research communication and reproducibility across disciplines. In an effort to standardize reporting, we propose the Guidelines for Reporting Articles on Psychiatry and Heart rate variability (GRAPH), a checklist with four domains: participant selection, interbeat interval collection, data preparation and HRV calculation. This paper provides an overview of these four domains and why their standardized reporting is necessary to suitably evaluate HRV research in psychiatry and related disciplines. Adherence to these communication guidelines will help expedite the translation of HRV research into a potential psychiatric biomarker by improving interpretation, reproducibility and future meta-analyses.

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Accumulating research demonstrates the potential of intranasal delivery of psychopharmacological agents to treat a range of psychiatric disorders and symptoms. It is believed that intranasal administration offers both direct and indirect pathways to deliver psychopharmacological agents to the central nervous system. This administration route provides a unique opportunity to repurpose both old drugs for new uses and improve currently approved drugs that are indicated for other administration routes. Despite this promise, however, the physiology of intranasal delivery and related assumptions behind the bypassing of the blood brain barrier is seldom considered in detail in clinical trials and translational research. In this review, we describe the current state of the art in intranasal psychopharmacological agent delivery research and current challenges using this administration route, and discuss important aspects of nose-to-brain delivery that may improve the efficacy of these new therapies in future research. We also highlight current gaps in the literature and suggest how research can directly examine the assumptions of nose-to-brain delivery of psychopharmacological agents in humans.

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OBJECTIVE: Despite current diagnostic systems distinguishing schizophrenia (SZ) and bipolar disorder (BD) as separate diseases, emerging evidence suggests they share a number of clinical and epidemiological features, such as increased cardiovascular disease (CVD) risk. It is not well understood if poor cardiac autonomic nervous system regulation, which can be indexed non-invasively by the calculation of heart rate variability (HRV), contributes to these common CVD risk factors in both diseases. METHOD: We calculated HRV in 47 patients with SZ, 33 patients with BD and 212 healthy controls. Measures of symptom severity were also collected from the patient groups. RESULTS: Heart rate variability was significantly reduced in both these disorders in comparison with the healthy participants; however, there were no HRV differences between disorders. Importantly, these reductions were independent of the medication, age or body mass index effects. There was also preliminary evidence that patients with reduced HRV had increased overall and negative psychosis symptom severity regardless of SZ or BD diagnosis. CONCLUSION: We suggest that HRV may provide a possible biomarker of CVD risk and symptom severity in severe mental illness. Thus, our results highlight the importance of cardiometabolic screening across SZ and bipolar spectrum disorders.

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Despite the promise of intranasal oxytocin (OT) for modulating social behavior, recent work has provided mixed results. This may relate to suboptimal drug deposition achieved with conventional nasal sprays, inter-individual differences in nasal physiology and a poor understanding of how intranasal OT is delivered to the brain in humans. Delivering OT using a novel 'Breath Powered' nasal device previously shown to enhance deposition in intranasal sites targeted for nose-to-brain transport, we evaluated dose-dependent effects on social cognition, compared response with intravenous (IV) administration of OT, and assessed nasal cavity dimensions using acoustic rhinometry. We adopted a randomized, double-blind, double-dummy, crossover design, with 16 healthy male adults completing four single-dose treatments (intranasal 8 IU (international units) or 24 IU OT, 1 IU OT IV and placebo). The primary outcome was social cognition measured by emotional ratings of facial images. Secondary outcomes included the pharmacokinetics of OT, vasopressin and cortisol in blood and the association between nasal cavity dimensions and emotional ratings. Despite the fact that all the treatments produced similar plasma OT increases compared with placebo, there was a main effect of treatment on anger ratings of emotionally ambiguous faces. Pairwise comparisons revealed decreased ratings after 8 IU OT in comparison to both placebo and 24 IU OT. In addition, there was an inverse relationship between nasal valve dimensions and anger ratings of ambiguous faces after 8-IU OT treatment. These findings provide support for a direct nose-to-brain effect, independent of blood absorption, of low-dose OT delivered from a Breath Powered device.

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The role of non-diagnostic features in the pathophysiology of autism spectrum disorders (ASDs) is unclear. Increasing evidence suggests immune system alterations in ASD may be implicated in the severity of behavioral impairment and other developmental outcomes. The primary objective of this meta-analysis was to investigate if there is a characteristic abnormal cytokine profile in ASD compared with healthy controls (HCs). We identified relevant studies following a search of MEDLINE, EMBASE, PsycINFO, Web of Knowledge and Scopus. A meta-analysis was performed on studies comparing plasma and serum concentrations of cytokines in unmedicated participants with ASD and HCs. Results were reported according to PRISMA statement. Seventeen studies with a total sample size of 743 participants with ASD and 592 HC were included in the analysis. Nineteen cytokines were assessed. Concentrations of interleukin (IL)-1beta (P<0.001), IL-6 (P=0.03), IL-8 (P=0.04), interferon-gamma (P=0.02), eotaxin (P=0.01) and monocyte chemotactic protein-1 (P<0.05) were significantly higher in the participants with ASD compared with the HC group, while concentrations of transforming growth factor-ß1 were significantly lower (P<0.001). There were no significant differences between ASD participants and controls for the other 12 cytokines analyzed. The findings of our meta-analysis identified significantly altered concentrations of cytokines in ASD compared to HCs, strengthening evidence of an abnormal cytokine profile in ASD where inflammatory signals dominate.

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The food health regulations from Chile control their manufacturing, distribution and storage. Due to the lack of published data on the implementation of the regulations, we evaluated the continuity of the cold chain in five factories of sausages, using pate and cheese head as control products. The results showed deficiencies in the maintenance of cold chain, mainly in the distribution and retailing of products. In addition, statistically significant differences (Student t test) were detected between the bacterial count of initial sample (at the factory) and final (after 5 days, p<0.05), indicating the breakdown of the cold food chain and the increase in microbial load. Since food preservation has a direct impact on public health of the population, further studies are needed to evaluate the cold chain operation in Chile.

El Reglamento Sanitario de los Alimentos Chileno regula la fabricación, distribución y almacenamiento de éstos. Debido a la falta de datos publicados sobre la aplicación del reglamento, se evaluó la continuidad de la cadena de frío en 5 fábricas de cecinas, utilizando paté y queso de cabeza como productos controles. Los resultados mostraron deficiencias en la mantención de la cadena de frío, principalmente en la distribución y venta minorista de productos. Además, se detectaron diferencias estadísticamente significativas (prueba t de Student) entre el recuento bacteriano de muestra inicial (en la fábrica) y una final (después de 5 días), P< 0,05) indicando la ruptura de la cadena de frío en alimentos con el aumento de su carga microbiológica. Debido a que la conservación de alimentos repercute directamente en la salud pública de la población, se necesita de otros estudios para evaluar el funcionamiento de la cadena de frío en Chile.

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La hiperplasia lipomatosa del septum interauricular (HLSI) es una entidad benigna de naturaleza desconocida que se caracteriza por la acumulación de grasa no encapsulada en el interior del surco interauricular sin participación de la fosa oval. A pesar de su carácter benigno, clínicamente se ha asociado con arritmias cardiacas, generalmente de origen supraventricular, insuficiencia cardiaca y muerte súbita. Presentamos el caso de una mujer de edad media (47 años), con obesidad mórbida e insuficiencia cardiaca congestiva, que falleció súbitamente y la autopsia puso de manifiesto una HLSI. El estudio macroscópico de la pieza de resección mostró un tamaño de 5 x 2,5 cm y la histología típica de esta entidad, es decir, adipocitos maduros y pocos lipoblastos entremezclados con miocitos auriculares. Hemos analizado microscópicamente los nodos sinoauricular y auriculoventricular, lo que puso de manifiesto que la infiltración grasa los rodeada pero no los aislaba del miocardio auricular de trabajo circundante. El miocardio del ventrículo izquierdo y del tabique interventricular presentaba áreas con una intensa fibrosis intersticial por isquémica crónica y que esta fibrosis pudo ser la causa de una arritmia ventricular y muerte súbita. Aunque esta entidad es cada vez más frecuentemente reconocida gracias al desarrollo creciente de las técnicas de imagen no invasivas, rara vez necesita ser corregida quirúrgicamente (AU)

The lipomatous hyperplasia of the interatrial septum (LHIS) is a benign entity of unknown nature, characterized by the accumulation of fat tissue not encapsulated into the interatrial groove without participation of the fossa ovalis. Despite its benign nature, it has been clinically associated with cardiac arrhythmias, usually of supraventricular origin, heart failure and sudden death. We present the case of a woman of middle age (47 years), with morbid obesity and heart failure congestive who died suddenly and the autopsy revealed a LHIS. The macroscopic study of resection piece showed a size of 5 x 2.5 cm and the typical histology of this entity, i.e. mature adipocytes and few lipoblastos interspersed with atrial myocytes. We have analysed microscopically both sinoatrial and atrioventricular nodes, which they revealed fat tissue infiltration that surrounded them but not isolated from atrial working myocardium. The interventricular septum and left ventricle myocardium presented areas with severe interstitial fibrosis by chronic ischemic and this fibrosis may be the cause of ventricular arrhythmia and sudden death. Although this entity is most frequently recognized due to the development of noninvasive imaging techniques, rarely needs to be corrected surgically (AU)

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The inferior right atrial isthmus consisting of the terminal crest, the network of pectinate muscles, and the vestibule shows very complex anatomical structure. It is seen as potential substrate for atrial flutter. In this work we present results from an electro-anatomical characterization of this region based on Cardiac Near Field recordings taken from five preparations of rabbit atrium. Pectinate muscles in the region of interest were divided into three segments: central as well as proximal and distal with respect to the terminal crest. Electrograms measured in these segments showed differences in the degree of fractionation, i.e. the numbers of distinct local activation events, indicating heterogeneities in microstructure. From 249 recording sites 63.9% showed no fractionation, 26.9% showed two activation events, and 9.2% were highly fractionated. The proximal starting sequence of activation in a series of adjacent pectinate muscles is not sorted but rather seems to be arbitrary. The same applies to the arrival sequence of activation close to the vestibule. In the network of pectinate muscles on average one proximal segment branches into two central strands and two central strands merge into one distal stem.

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Atrial structures are important in the current era of cardiac interventions using percutaneous transcatheter procedures. Understanding their locations and component parts helps to reduce risks of procedural-related damage. The general arrangement of the myofibers that make up the atrial walls is reviewed to provide a morphologic basis for atrial conduction and potential substrates of arrhythmias. The right atrium, dominated by its appendage, is characterized by having an extensive array of pectinate muscles. These extend almost perpendicularly from the terminal crest. The left atrium has relatively smooth walls and a small tubular-shaped appendage. The myofibers show changes in orientations when traced through the thickness of the walls. Extensions of atrial myocardium onto the pulmonary veins and the superior caval vein are common. Apart from Bachmann's bundle, there are other muscular bridges of variable numbers and sizes that provide interatrial connections, connections between the left atrium and the coronary sinus, and connections between the muscular sleeves of the right pulmonary veins and the right atrium. The purpose of this review is to summarize the three-dimensional arrangement of gross atrial structures, the myoarchitecture and variations in muscular interatrial connections. These are important features in intra- and interatrial conduction.

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