Experimental Determination of Corneal Elastic Constants and Their Use in Biomechanical Modeling

Corneal biomechanics aims to establish the physico-mathematical bases that allow for predicting the corneal response to physiological and pathological situations by creating models of tissue behavior. Determining the characteristic parameters of these models is a formidable challenge in the biomechanical modeling process. To contribute to corneal tissue characterization, an experimental set-up was designed, built and tested to study corneal behavior by applying changes in pressure. The elastic constants of porcine corneas were determined, and a Young’s modulus of 0.188 MPa and 26.22% hysteresis were obtained. A computational cornea model was developed to analyze the influence of different factors. Minor variations in the applied conditions were found for apical displacement and pachymetry, and the corneal behavior was reproduced. However, the optical power behavior was affected by variations in the applied conditions, and the experimentally obtained data could not be reproduced. Despite its importance, this parameter has not been analyzed in-depth by other studies, which shows that the quality of a biomechanical cornea model should not be evaluated only by apical displacement.

Ebstein’s Anomaly, Left Ventricular Noncompaction and Gerbode-Like Defect Triad (Fetal Diagnosis and Neonatal Course)

Ebstein’s anomaly is characterized by the apical displacement of the septal and posterior leaflets of the tricuspid valve with atrialization of the right ventricle (RV). It is commonly associated with other heart defects including left ventricular noncompaction. We describe a case of prenatally diagnosed Ebstein’s anomaly in association with left ventricular noncompaction and a septal defect between the left ventricle and the atrialized portion of the RV (Gerbode-like defect). The patient underwent a modified Blalock−Taussig shunt followed by Glenn procedure because of severe RV hypoplasia and RV outflow tract obstruction. The patient tolerated both procedures and is doing clinically well in anticipation of Fontan procedure for single ventricle palliation.

Taurodontism in dental genetics

Taurodontism is a dental anomaly defined by enlargement of the pulp chamber of multirooted teeth with apical displacement of the pulp floor and bifurcation of the roots. Taurodontism can be an isolated trait or part of a syndrome. A study was conducted to document the dental and craniofacial aspects of genetic thin bone disorders in South Africa. Sixty-four individuals with Osteogenesis imperfecta (OI), one individual with Pyle disease and one with Torg-Winchester syndrome respectively, were assessed clinically, radiographically and at a molecular level. Ten patients with OI XI and those with Pyle disease and Torg-Winchester syndrome had taurodontism. Taurodontism has been identified in several genetic disorders necessitating cognizance of the possible existence and implications of this characteristic when managing patients in the dental environment. Further studies should be directed toward identifying the incidence, etiology, and molecular pathways leading to taurodontism and its relationship to genetic syndromes.

Effects of intracorneal ring segments on the biomechanical response of the ectatic cornea to air-puff: A patient-specific numerical analysis

The assessment of the underlying factors that influence the biomechanics and dynamics of the cornea is essential for preserving the safety and efficacy of refractive surgeries. In the present work, the operated cornea with intracorneal ring segments (ICRSs) in a patient-specific finite-element model (FEM) was subjected to the air-puff. Then, the dynamic deformation parameters predicted by the FEM were obtained and compared with the corresponding values in clinical measurements. In this study, the effects of ICRS design, position, and implementation procedure in six different surgical scenarios were examined on the induced corneal stresses, deformation behavior, and shape regularization. While surgical scenarios with arc lengths of 160° (single and double segment), 355° implemented with the tunnel incision method provided similar maximum apical displacement (MAD) and highest concavity radius of curvature HCR), they induced significantly different flattening effects. The surgical scenarios with the segment of 160° arc-length implemented in nasal–temporal direction showed an approximately 15% higher reduction in mean corneal power ([Formula: see text]) value than the superior–inferior direction. From a solid-mechanics perspective, the study of ICRS mechanics in the cornea also confirmed the importance of the implementation position to achieve satisfactory flattening outcomes. Comparison of the two types of ICRS implementation procedures showed that, although the pocket method demonstrated a 10.23% higher MAD, it induced a higher reduction in the HCR of 21.65% compared with tunnel incision. The developed numerical model demonstrated the direct correlation of the ICRS insertion site with induced contact stresses and ICRS position stability. The study hypothesizes the significant influence of ICRS implementation position and procedure on the corneal biomechanical and dynamical behaviors. The proposed approach can be assessed as a robust and novel framework for planning optimized corneal refractive surgeries.

Papillary Muscles Abnormalities in Athletes With Otherwise Unexplained T‐Wave Inversion in the ECG Lateral Leads

Background Papillary muscles (PMs) abnormalities may be associated with ECG repolarization abnormalities. We aimed to evaluate the relation between lateral T‐wave inversion (TWI) and PMs characteristics in a cohort of athletes with no clinically demonstrable cardiac disease. Methods and Results We included 53 athletes (median age, 20 years; 87% men) with lateral TWI and no evidence of heart disease on clinical and cardiac magnetic resonance evaluation. A group of healthy athletes with normal ECG served as controls. We evaluated the PMs dimensions, such as diameters, area, volume, mass, and ratio between PMs and left ventricular mass, and the prevalence of PMs apical displacement. Compared with controls, athletes with TWI showed PMs hypertrophy with significantly increased PMs diameters, area, volume, and mass. The ratio between PMs and left ventricular mass was 4.4% in athletes with TWI and 3.0% in controls ( P <0.001). A PMs/left ventricular mass ratio >3.5% showed 85% sensitivity and 76% specificity for differentiating between athletes with TWI and controls. Apical displacement of PMs was found in 25 (47%) athletes with TWI versus 9 (17%) controls ( P =0.001). At multivariable analysis, PMs/left ventricular mass ratio and apical displacement remained independent predictors of TWI. Clinical outcome of the athletes with TWI and PMs abnormalities was uneventful despite continuation of their sports activity. Conclusions PMs hypertrophy and apical displacement may underlie otherwise unexplained lateral TWI in the athlete. Lateral TWI associated with PMs abnormalities appears as a distinct anatomo‐clinical condition characterized by a favorable outcome.

Taurodontismo – Série de casos em pacientes jovens não sindrômicos e sindrômicos associado à hipodontia

Several human dentition developmental anomalies are reported in the literature. The etiology of these occurrences is related to genetic, environmental or sometimes idiopathic factors. Taurodontism is defined as apical displacement of the pulp floor and consequent enlargement of the pulp chamber in multiradicular teeth. It is a result of the failure to invaginate Hertwigs epithelial sheath horizontally and commonly expresses bilaterally. This morphological pattern of molars is observed in ruminant animals and was also found in ancient Neanderthals. Association of this condition to syndromes is not exclusive, it may be associated with genetic disorders such as Down Syndrome, Klinefelter Syndrome, among others. The diagnosis is exclusively radiographic, with no alterations in the dental element crown. Among the consequences is the complexity of endodontic treatment, greater fragility of taurodontic teeth submitted to endodontics and lower orthodontic anchorage of these elements. In this paper, three case reports of patients with taurodontism are described, two of them associated with hypodontia and one in a Down Syndrome patient. This paper also includes a literature review and discussion with the main clinical implications of this occurrence.

Relationship between papillary muscles abnormalities and apparently unexplained infero-lateral T-wave inversion in athletes

Aims To evaluate by cardiac magnetic resonance (CMR) if left ventricle papillary muscle abnormalities, such as hypertrophy and abnormal location, may be the anatomo-functional substrates responsible for TWI inversion in lateral or infero-lateral leads in otherwise healthy athletes. Methods We included competitive athletes with TWI in lateral or infero-lateral leads in the absence of cardiac diseases detected by CMR. The control population included healthy athletes with normal ECG, matched for age and gender. We compared thickness, volume (both absolute and relative to the cardiac mass) and position of the papillary muscles between cases and controls. Results We included 53 athletes with apparently unexplained TWI in the lateral or infero-lateral leads (median age 20 years (17–42), 86.8% males) and 53 athletes with no TWI matched for age and gender. 4 patients (7.6%) had family history for cardiomyopathy or sudden cardiac death. Athletes with TWI showed more hypertrophic papillary muscles compared to controls, with statistically significant difference in diameter, area and volume (p&lt;0.01). The median ratio between the papillary muscles and the left ventricular mass was 4.4% among athletes with TWI versus 3% among those without TWI (p&lt;0.001). Papillary muscles showed apical displacement in 47% of cases, compared to 17% in the control group (p=0.001). Conclusions Idiopathic TWI in lateral or infero-lateral leads is associated with left ventricle papillary muscle hypertrophy and their apical displacement detected by CMR. The comprehension of clinical and prognostic significance of papillary muscle abnormalities responsible for these ventricular repolarization alterations requires further studies. Example Funding Acknowledgement Type of funding source: None

Treatment of Complex Mandibular Body Fractures and Functional Reimplantation of the Maxillary Alveolar Fragment

Introduction. This report aims at demonstrating the treatment of complex mandibular fracture functional reimplantation of the maxillary alveolar fragment (FRAF), denoting the possibility and feasibility of this reduction with an excellent prognosis. Case Report. Patient E.M.S, 25 years old, male, leucoderma, referred to the Emergency Room of our institute. He reported being a victim of physical aggression, occlusal alteration, limitation of mouth opening, sensibility loss in the mentalis region, right infraorbital, and denied visual alteration. On physical examination, during the inspection and palpation, the crackling was observed in the right mandibular region and apical displacement of the maxillary alveolar process, corresponding to elements 13, 14, and 15. Conclusion. The rigid fixation of the complex jaw fracture and alveolar maxilla process, through functional reduction, indicated satisfactory applicability, and favorable prognosis.

Ebstein’s anomaly

Ebstein’s anomaly (EA) is a rare malformation of the tricuspid valve (TV), characterized by apical displacement of the annular attachments of the septal and inferior (mural) leaflets into the right ventricular (RV) cavity, with varying degrees of adherence to the underlying myocardium. The natural history is quite variable and depends on the severity and presence of associated arrhythmias, which plays a significant role with regard to the prognosis. Prenatal diagnosis is associated with higher perinatal mortality, as these usually represent the severe end of the disease spectrum. Different surgical strategies have been employed, although the cone operation, introduced in the past decade, has significantly changed the surgical approach and improved the outcomes of these patients. This chapter presents the case of a newborn with an antenatal diagnosis of EA who presented with severe cyanosis and major arrhythmias at birth requiring intensive care management for the first month of life. After some years of being relatively asymptomatic, he re-presented with recurrent arrhythmias and decreased exercise tolerance, requiring multiple interventions. His clinical course and management are presented, together with a detailed review of this disease from the anatomical aspects to its diagnosis and medico-surgical management.