The Atrioventricular Conduction Axis Revisited for the 21st Century.

Although first described in the final decade of the 19th century, the axis responsible for atrioventricular conduction has long been the source of multiple controversies. Some of these continue to reverberate. When first described by His, for example, many doubted the existence of the bundle we now name in his honour, while Kent suggested that multiple pathways crossed the atrioventricular junctions in the normal heart. It was Tawara who clarified the situation, although many of his key definitions have not universally been accepted. In key studies in the third decade of the 20th century, Mahaim then suggested the presence of ubiquitous connections that provided "paraspecific" pathways for atrioventricular conduction. In this review, we show the validity of these original investigations, based on our own experience with a large number of datasets from human hearts prepared by serial histological sectioning. Using our own reconstructions, we show how the atrioventricular conduction axis can be placed back within the heart. We emphasise that newly emerging techniques will be key in providing the resolution to map cellular detail to the gross evidence provided by the serial sections.

Clinical Implications of Buccinator Fiber Attachment on Interventions Aiming at Enhancing the Peri-Implant Keratinized Mucosa: An Ex-Vivo Study.

A clinical observation usually encountered after vestibuloplasty or interventions aiming at deepening the vestibule with or without simultaneous free epithelialized grafts in the posterior ridges is that they are subjected to major dimensional changes attributed to the buccinator fibers attachment. Hence, this study aimed at assessing the attachment of the buccinator muscles in relation to other anatomical landmarks. An ex-vivo study was performed in cadaver heads to explore the association of fibers attachment in relation to the distance from the crestal aspect of edentulous alveolar process (CAP) and the vestibular depth (VD), crestal band of keratinized mucosa (KM), and ridge height (RH). Interestingly, VD and KM were found to be strongly correlated. Likewise, VD/KM and CAP-BUC were further noted being correlated. CAP-BUC was negatively correlated with RH. Accordingly, the more atrophic the alveolar ridge (being more noticeable in the mandible) is, the shallower the vestibule, the lesser the crestal band of KM and the more crestal attachment of the buccinator muscular fibers. That might be the reason why whenever performing free epithelized graft in the posterior ridges to enhance the peri-implant soft tissue phenotype and deepening the vestibule, the graft is subjected to major dimensional changes.

Caracterización de la autonomía como indicador clave en las habilidades de aprender a aprender en estudiantes de medicina

Fundamento: la autonomía permite a los estudiantes pensar por sí mismos, con sentido crítico e independencia, tener en cuenta diferentes puntos de vista y actuar en correspondencia con ellos. Constituye un indicador necesario en el estudio de las habilidades de aprender a aprender. Objetivo: caracterizar la autonomía como indicador de las habilidades de aprender a aprender en estudiantes de medicina. Métodos: se empleó un diseño mixto de investigación del tipo explicativo secuencial. La investigación se realizó de octubre de 2021 a marzo de 2022 en la Universidad de Ciencias Médicas de Cienfuegos. La muestra no probabilística, intencionada, quedó constituida por 255 estudiantes del primer año de la carrera de Medicina. Para la recolección de información se utilizó el cuestionario que evalúa el nivel de formación de las habilidades de aprender a aprender, observaciones a actividades docentes y grupos focales. Resultados: la autonomía está presente en el 45,4 % de los estudiantes, según cuestionario. En los grupos focales algunos estudiantes reconocen presentar insuficiencias en algunos indicadores de la autonomía, lo que se corresponde con los datos obtenidos en las observaciones a las actividades docentes. Conclusiones: la autonomía como indicador clave de las habilidades de aprender a aprender en los estudiantes del primer año de la Universidad de Ciencias Médicas de Cienfuegos se caracterizó por una baja expresión en los procesos de aprendizaje de los estudiantes de medicina.

Background: autonomy allows students to think for themselves, critically and independently, take into account different points of view and act accordingly. It constitutes a necessary indicator in the study of learning-to-learn skills. Objective: to characterize autonomy as an indicator of learning-to-learn skills in medical students. Methods: a mixed research design of the sequential explanatory type was used. The research was carried out from October 2021 to March 2022 at the Cienfuegos University of Medical Sciences. The intentional, non-probabilistic sample was made up of 255 Medicine first-year students. The questionnaire that evaluates the learning to learn skills training level, observations of teaching activities and focus groups were used to collect information. Results: autonomy is present in 45.4% of the students, according to the questionnaire. In the focus groups, some students acknowledge presenting deficiencies in some autonomy indicators, which corresponds to the data obtained in the observations of teaching activities. Conclusions: autonomy as a learning to learn skills key indicator in the Cienfuegos Medical Sciences University first-year students, was characterized by a low expression in the medical students' learning processes.

Aproximación a las mediciones a nivel nano, con énfasis en la biomedicina

Este artículo pretende alertar acerca de la relevancia de las nanociencias y la nanotecnología acompañada por la nanometrología para el desarrollo de las naciones en el siglo XXI. Se utilizó SciElo como base de datos, con las palabras clave: nanotecnología, nanomedicina, unidades de salud cubanas. El artículo realiza una aproximación a la nanotecnología con enfoque internacional y regional. Describe algunas aplicaciones de las nanotecnologías, con énfasis en la nanomedicina, así como los dilemas y consideraciones éticas asociadas a estas. Advierte acerca de la nocividad para la salud del hombre de algunos de estos desarrollos. Defiende la idea de que la nanometrología, resulta imprescindible para el logro de desarrollos tecnológicos, con mayor relevancia en el campo de la nanomedicina, así como que la nanotecnología debe ser tratada como la ciencia del siglo XXI por el impacto social, cultural y económico que tendrá, y con esto puede cambiar al mundo.

This article aims to alert about the relevance of nanosciences and nanotechnology accompanied by nanometrology for the nations development in the 21st century. Scielo was used as a database, with the keywords: nanotechnology, nanomedicine, Cuban health units. The article makes an approach to nanotechnology with an international and regional approach. It describes some applications of nanotechnologies, with an emphasis on nanomedicine, as well as the dilemmas and ethical considerations associated with them. It advises about these developments' harmfulness to human health, also defends the idea that nanometrology is essential for the technological developments achievement, with greater relevance in the nanomedicine field, as well as that nanotechnology should be treated as the 21st century science due to the social, cultural and economic impact that will have, and this can change the world.

Relationship between the aortic root and the atrioventricular conduction axis.

Damage to the atrioventricular conduction axis continues to be a problem subsequent to transcatheter implantation of aortic valvar prostheses. Accurate knowledge of the precise relationships of the conduction axis relative to the aortic root could greatly reduce the risk of such problems. Current diagrams highlighting these relationships rightly focus on the membranous septum. The current depictions, however, overlook a potentially important relationship between the superior fascicle of the left bundle branch and the nadir of the semilunar hinge of the right coronary leaflet of the aortic valve. Recent histological investigations demonstrate, in many instances, a very close relationship between the left bundle branch and the right coronary aortic leaflet. The findings also highlight two additional variable features, which can be revealed by clinical imaging. The first of these is the extent of an inferoseptal recess of the left ventricular outflow tract. The second is the extent of rotation of the aortic root within the base of the left ventricle. Much more of the conduction axis is within the confines of the circumference of the outflow tract when the root is rotated in counterclockwise fashion as assessed from the perspective of the imager, with this finding itself associated with a much narrower inferoseptal recess. A clear understanding of the marked variability within the aortic root is key to avoiding future problems with atrioventricular conduction.

Vulnerability of the ventricular conduction axis during transcatheter aortic valvar implantation: A translational pathologic study.

The ventricular components of the conduction axis remain vulnerable following transcatheter aortic valvar replacement. We aimed to describe features which may be used accurately by interventionalists to predict the precise location of the conduction axis, hoping better to avoid conduction disturbances. We scanned eight normal adult heart specimens by 3T magnetic resonance, using the images to simulate histological sections in order accurately to place the conduction axis back within the heart. We then used histology, tested in two pediatric hearts, to prepare sections, validated by the magnetic resonance images, to reveal the key relationships between the conduction axis and the aortic root. The axis was shown to have a close relationship to the nadir of the right coronary leaflet, in particular when the aortic root was rotated in counterclockwise fashion. The axis was more vulnerable in the setting of a narrow inferoseptal recess, when the inferior margin of the membranous septum was above the plane of the virtual basal ring, and when minimal myocardium was supporting the right coronary sinus. The features identified in our study are in keeping with the original description provided by Tawara, but at variance with more recent accounts. They suggest that the vulnerability of the axis during transcatheter valvar replacement can potentially be inferred on the basis of knowledge of the position of the aortic root within the ventricular base. If validated by clinical studies, our findings may better permit avoidance of new-onset left bundle branch block following transcatheter aortic valvar replacement.

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.

Molecular monitoring of patient response to painkiller drugs.

INTRODUCTION: Non-steroidal anti-inflammatory drugs and opioids are widely prescribed for the treatment of mild to severe pain. Wide interindividual variability regarding the analgesic efficacy and adverse reactions to these drugs (ADRs) exist although the mechanisms responsible for these ADRs are not well understood. AREAS COVERED: We provide an overview of the clinical impact of variants in genes related to the pharmacokinetics and pharmacodynamics of painkillers, as well as those associated with the susceptibility to ADRs. In addition, we discuss the current pharmacogenetic-guided treatment recommendations for the therapeutic use of non-steroidal anti-inflammatory drugs and opioids. EXPERT OPINION: In the light of the data analyzed, common variants in genes involved in pharmacokinetic and pharmacodynamic processes may partially explain the lack of response to painkiller treatment and the occurrence of adverse drug reactions. The implementation of high-throughput sequencing technologies may help to unveil the role of rare variants as considerable contributors to explaining the interindividual variability in drug response. Furthermore, a consensus between the diverse pharmacogenetic guidelines is necessary to extend the implementation of pharmacogenetic-guided prescription in daily clinical practice. Additionally, the physiologically based pharmacokinetic and pharmacodynamic modeling techniques may contribute to the improvement of these guidelines and facilitate clinician drug dose adjustment.

Anatomy of the left atrial appendage for the interventional cardiologist.

Exact knowledge of the anatomy of the left atrial appendage (LAA) is crucial for LAA isolation by catheter ablation and for interventional LAA occlusion in patients with atrial fibrillation. This review outlines the current anatomical understanding of LAA morphology from ostium to distal lobes, myocardial fiber orientation and wall structure, and adjacent structures such as the left upper pulmonary vein with the Coumadin ridge, the circumflex artery with its side branches, the aortic root, pulmonary artery, and the pericardial space. Insight into these details will facilitate these interventions and reduce the risk of complications.

Anatomical knowledge for the ablation of left and right atrial flutter.

The different forms of atrial flutter (AFL) and atrial macroreentrant tachycardias are strongly related to the atrial anatomy in structurally normal atria, and even more so in patients with dilated chambers or with previous interventions. Atrial anatomy, macro- and microscopic tissue disposition including myocardial fibers, conduction system and connective tissue is complex. This review summarizes knowledge of atrial anatomy for the interventional electrophysiologist to better understand the pathophysiology of and ablation options for these complex arrhythmias, as well as to perform catheter ablation procedures safely and effectively.

Biomédicos y desarrollos tecnológicos: binomio indispensable para las unidades de salud en tiempos de COVID-19

RESUMEN La preocupación que tiene la sociedad en todos los países acerca de la salud sigue siendo mayor que sobre cualquier otro aspecto. Una calidad de vida óptima solo es posible con una salud favorable. Ante los recientes eventos de la COVID-19, la importancia de la tecnología médica en la atención del paciente ha resultado evidente. El trabajo pretende mostrar el relevante papel que juega la rama biomédica, su influencia e impacto en los procesos de las unidades de salud. Resume algunos de los desarrollos tecnológicos logrados desde el contexto internacional hasta el local en el complejo escenario epidemiológico en el que se encuentra el planeta. Describe la necesaria cronología del sistema electromédico en Cuba con énfasis en Cienfuegos. Defiende la idea de que es necesario un cambio conceptual acerca del importante papel que juega la rama biomédica, su influencia e impacto en los procesos de las unidades y que los ingenieros biomédicos y electromédicos, así como los licenciados y técnicos en electromedicina, merecen un adecuado reconocimiento ante la comunidad científica por sus tangibles logros en tiempos de Covid-19. Ellos también salvan vidas.

ABSTRACT The concern that society has in all countries about health continues to be greater than about any other aspect. An optimal quality of life is only possible with favorable health. Given the recent COVID-19 events, the importance of medical technology in patient care has become apparent. The aim of this work is to show the relevant role played by the biomedical branch, its influence and impact on the processes of health units. It summarizes some of the technological developments achieved from the international to the local context in the complex epidemiological scene in which the planet finds itself. It describes the necessary chronology of the electromedical system in Cuba with an emphasis on Cienfuegos. It defends the idea that a conceptual change is necessary about the important role played by the biomedical branch, its influence and impact on the processes of the units and that biomedical and electromedical engineers, as well as electromedical graduates and technicians, deserve an adequate recognition before the scientific community for their tangible achievements in Covid-19 times. They also save lives.

Miniseries 1-Part IV: How frequent are fasciculo-ventricular connections in the normal heart?

AIMS: Seeking to account for accessory atrioventricular conduction potentially leading to ventricular pre-excitation, Mahaim in the mid-20th century had described pathways between the atrioventricular conduction axis and the muscular ventricular septum. We aimed to look for such 'paraspecific' connections in adult human hearts. METHODS AND RESULTS: We serially sectioned 21 hearts, covering the triangle of Koch and the aortic root, and assessing the atrioventricular node, the penetration of the conduction axis, and the bundle branches in our search for fasciculo-ventricular connections. We also calculated the length of the non-branching bundle, and if present the origin of the fasciculo-ventricular connections. The non-branching bundle was 3.6 ± 1.7 mmin length, varying from 1.7 mm to 7.2 mm. Fasciculo-ventricular connections were found in more than half of the hearts, making direct contact with the muscular septum at an average of 3.5 ± 1.7 mm from the origin of the left bundle branch, with the site of origin varying from 1.1 mm to 5.5 mm from the first fascicle of the left bundle branch. In three hearts, additional fasciculo-fascicular connections were observed in the left bundle branch. Two loops were small, but one loop extended over 9.5 mm. CONCLUSION: We endorse the finding of Mahaim that fasciculo-ventricular pathways exist in most human hearts. We presume the identified connections had the capability of producing ventricular pre-excitation. More studies are needed to determine the potential clinical manifestations.

Miniseries 1-Part II: the comparative anatomy of the atrioventricular conduction axis.

AIMS: The arrangement of the conduction axis is markedly different in various mammalian species. Knowledge of such variation may serve to question the validity of using animals as prospective models for design of systems for clinical use. METHODS AND RESULTS: We compared the arrangement of the atrioventricular conduction axis in human, murine, canine, porcine, and bovine hearts, examining serially sectioned datasets from 20 human, 16 murine, 3 porcine, 5 canine, and 1 bovine hearts. We also analysed computed tomographic datasets obtained from bovines and one human heart. Unlike the situation in the human heart, there is no formation of an atrioventricular fibrous membranous septum in the murine, canine, porcine, nor bovine hearts. Canine, porcine, and bovine hearts also lack an infero-septal recess, when defined as a fibrous plate supporting the buttress of the atrial septum. In these species, half of the non-coronary leaflet is directly opposed to the ventricular septal surface. CONCLUSION: There is a long right-sided non-branching component of the axis, which skirts the attachment of the non-coronary sinus of the aortic root. In the bovine heart, moreover, the left bundle branch usually extends intramyocardially as a solitary tape before surfacing and ramifying on the left ventricular septal surface. The difference in the atrioventricular conduction axis between species may influence the anatomical substrates for atrioventricular re-entry tachycardia, as well as providing inferences for assessing the risks of transcatheter implantation of the aortic valve. Further studies are now needed to assess these possibilities.

Miniseries 1-Part I: the Development of the atrioventricular conduction axis.

Despite years of research, many details of the formation of the atrioventricular conduction axis remain uncertain. In this study, we aimed to clarify the situation. We studied three-dimensional reconstructions of serial histological sections and episcopic datasets of human embryos, supplementing these findings with assessment of material housed at the Human Developmental Biological Resource. We also examined serially sectioned human foetal hearts between 10 and 30 weeks of gestation. The conduction axis originates from the primary interventricular ring, which is initially at right angles to the plane of the atrioventricular canal, with which it co-localizes in the lesser curvature of the heart loop. With rightward expansion of the atrioventricular canal, the primary ring bends rightward, encircling the newly forming right atrioventricular junction. Subsequent to remodelling of the outflow tract, part of the primary ring remains localized on the crest of the muscular ventricular septum. By 7 weeks, its atrioventricular part has extended perpendicular to the septal parts. The atrioventricular node is formed at the inferior transition between the ventricular and atrial parts, with the transition itself marking the site of the penetrating atrioventricular bundle. Only subsequent to muscularization of the true second atrial septum does it become possible to recognize the definitive node. The conversion of the developmental arrangement into the definitive situation as seen postnatally requires additional remodelling in the first month of foetal development, concomitant with formation of the inferior pyramidal space and the infero-septal recess of the subaortic outflow tract.

The atrioventricular conduction axis and the aortic root-Inferences for transcatheter replacement of the aortic valve.

Conduction problems still occur following transcatheter aortic valvar replacement. With this in mind, we have assessed the relationship of the conduction axis to the aortic root. We used serial histological sections, made perpendicular to the base of the triangle of Koch in nine hearts, and perpendicular to the aortic root in 11 hearts. We first defined the extent of the fibrous tissues forming the boundaries of an infero-septal recess of the subaortic outflow tract, found in all datasets but one. When the recess was present, the axis penetrated through its rightward wall, giving rise to the left bundle branch prior to entering the outflow tract. The axis itself was usually on the crest of the ventricular septum, but could be deviated leftward or rightward. Its proximity to the virtual basal plane reflected the angulation of the muscular septum. On average, the superior edge of the left bundle was within 3.3 mm of the hinge of the right coronary leaflet, with a range from 0.4 to 10.2 mm. The arrangement was markedly different in the case lacking an infero-septal recess. Our findings necessitated a redefinition of the right fibrous trigone and the central fibrous body. The atrioventricular conduction axis, having entered the aortic root, is usually closest at the hinge of the right coronary leaflet. Knowledge of the depth of the infero-septal recess, and the angulation of the muscular ventricular septal, may help to avoid conduction problems following transcatheter implantation of the aortic valve.

Electrophysiological and histological characterization of atrial scarring in a model of isolated atrial myocardial infarction.

Background: Characterization of atrial myocardial infarction is hampered by the frequent concurrence of ventricular infarction. Theoretically, atrial infarct scarring could be recognized by multifrequency tissue impedance, like in ventricular infarction, but this remains to be proven. Objective: This study aimed at developing a model of atrial infarction to assess the potential of multifrequency impedance to recognize areas of atrial infarct scar. Methods: Seven anesthetized pigs were submitted to transcatheter occlusion of atrial coronary branches arising from the left coronary circumflex artery. Six weeks later the animals were anesthetized and underwent atrial voltage mapping and multifrequency impedance recordings. The hearts were thereafter extracted for anatomopathological study. Two additional pigs not submitted to atrial branch occlusion were used as controls. Results: Selective occlusion of the atrial branches induced areas of healed infarction in the left atrium in 6 of the 7 cases. Endocardial mapping of the left atrium showed reduced multi-frequency impedance (Phase angle at 307 kHz: from -17.1° ± 5.0° to -8.9° ± 2.6°, p < .01) and low-voltage of bipolar electrograms (.2 ± 0.1 mV vs. 1.9 ± 1.5 mV vs., p < .01) in areas affected by the infarction. Data variability of the impedance phase angle was lower than that of bipolar voltage (coefficient of variability of phase angle at307 kHz vs. bipolar voltage: .30 vs. .77). Histological analysis excluded the presence of ventricular infarction. Conclusion: Selective occlusion of atrial coronary branches permits to set up a model of selective atrial infarction. Atrial multifrequency impedance mapping allowed recognition of atrial infarct scarring with lesser data variability than local bipolar voltage mapping. Our model may have potential applicability on the study of atrial arrhythmia mechanisms.

La atención psicológica en un centro de aislamiento en tiempos de COVID-19

RESUMEN La situación actual generada por la pandemia de la COVID-19 afecta a todos los seres humanos, fundamentalmente a aquellos vinculados a personas enfermas o infectadas por el virus. Los profesionales de la Psicología en el contexto nacional e internacional aportan sus saberes y brindan ayuda a los pacientes y al personal de la salud. En el trabajo se pretende exponer las experiencias de la atención psicológica en un centro de aislamiento de personas contactos de pacientes con COVID-19.

ABSTRACT The current situation generated by the COVID-19 pandemic affects all human beings, mainly those linked to people who are sick or infected by the virus. Psychology professionals in the national and international context contribute their knowledge and provide help to patients and health personnel. The article aims to expose the experiences of psychological care in an isolation center for contact persons of patients with COVID-19.