Gamma Knife radiosurgery for the management of glomus jugulare tumors: A systematic review and report of the experience of a radioneurosurgery unit in Latin America.

Background: Glomus jugulare tumors (GJTs) are rare and mainly affect women between the 5th and 6th decades of life. Its localization and anatomic relationships make conventional surgical treatment difficult and with a considerable risk of complications. This manuscript aims to describe the results of Gamma Knife radiosurgery (GKR) in patients with GJT treated in a single center in Latin America, as well as to systematically review the literature to determine the clinical and radiological effectiveness of this technique. Methods: A search of information from January 1995 to June 2023 was performed. Twenty-two articles reporting 721 GJT patients treated with GKR were included in the study. Variables such as symptomatic control, control of tumor size, and complications were evaluated. These variables were described using measures of central tendency and proportions. For the institutional experience, 77 patients with GJT tumors were included in the study. Pre-treatment clinical variables and follow-up data were collected from medical charts and phone interviews. The Short Form-36 scale was applied to assess the quality of life. The data were analyzed using the statistical program STATA17.0. Results: A total of 721 patients were considered. The median of patients included in these studies was 18.5. The mean age was 58.4 years. The median of symptom control was 89%, and the median of imaging control was 95.7%. In our institution, 77 patients were included in the study. The mean age was 53.2 years. The median hospital stay was 4.92 hours. For the clinical follow-up, information on 47 patients was obtained. An improvement in pre-treatment symptoms was described in 58%, with general symptomatic control of 97%. The tumor-control rate was 95%, and there were statistically significant differences in six of the nine Short Form-36 scale domains. Conclusion: GKR is an effective, safe, and cost-effective technique that offers a high degree of symptomatic and tumor size control in patients with GJT.

Patient-specific analysis of bicuspid aortic valve hemodynamics using a fully coupled fluid-structure interaction model.

Bicuspid aortic valve (BAV), the most common congenital heart disease, is prone to develop significant valvular dysfunction and aortic wall abnormalities such as ascending aortic aneurysm. Growing evidence has suggested that abnormal BAV hemodynamics could contribute to disease progression. In order to investigate BAV hemodynamics, we performed 3D patient-specific fluid-structure interaction (FSI) simulations with fully coupled blood flow dynamics and valve motion throughout the cardiac cycle. Results showed that the hemodynamics during systole can be characterized by a systolic jet and two counter-rotating recirculation vortices. At peak systole, the jet was usually eccentric, with asymmetric recirculation vortices and helical flow motion in the ascending aorta. The flow structure at peak systole was quantified using the vorticity, flow rate reversal ratio and local normalized helicity (LNH) at four locations from the aortic root to the ascending aorta. The systolic jet was evaluated with the peak velocity, normalized flow displacement, and jet angle. It was found that peak velocity and normalized flow displacement (rather than jet angle) gave a strong correlation with the vorticity and LNH in the ascending aorta, which suggests that these two metrics could be used for clinical noninvasive evaluation of abnormal blood flow patterns in BAV patients.

Patient-Specific Heart Geometry Modeling for Solid Biomechanics Using Deep Learning.

Automated volumetric meshing of patient-specific heart geometry can help expedite various biomechanics studies, such as post-intervention stress estimation. Prior meshing techniques often neglect important modeling characteristics for successful downstream analyses, especially for thin structures like the valve leaflets. In this work, we present DeepCarve (Deep Cardiac Volumetric Mesh): a novel deformation-based deep learning method that automatically generates patient-specific volumetric meshes with high spatial accuracy and element quality. The main novelty in our method is the use of minimally sufficient surface mesh labels for precise spatial accuracy and the simultaneous optimization of isotropic and anisotropic deformation energies for volumetric mesh quality. Mesh generation takes only 0.13 seconds/scan during inference, and each mesh can be directly used for finite element analyses without any manual post-processing. Calcification meshes can also be subsequently incorporated for increased simulation accuracy. Numerous stent deployment simulations validate the viability of our approach for large-batch analyses. Our code is available at https://github.com/danpak94/Deep-Cardiac-Volumetric-Mesh.

Assessing sustainable operational conditions of a bottoming organic Rankine cycle using zeotropic mixtures: An energy-emergy approach.

In this work, an Organic Rankine Cycle system is used to produce electricity from the waste heat of an internal combustion engine (ICE). The toluene, and cyclohexane, are the selected pure fluids to be compared with the zeotropic mixtures. The zeotropic mixtures used as working fluids are cyclohexane/R11 (0.2/0.8), cyclohexane/R11 (0.25/0.75), and cyclohexane/R11 (0.3/0.7). An energy, exergy and emergy analysis was conducted to assess the sustainability of the whole system and the viability of the zeotropic mixture from the environmental point of view. Finally, a multi-objective optimization was carried out. The results showed that the zeotropic mixtures have better performance compared with the selected pure fluids when the net power and the exergy efficiency are considered. The pure fluids had a better Emergy Sustainability Index (ESI) index by 10% on average, there is not a big difference on this parameter so the advantages of using zeotropic mixtures as working fluids for this type of system cannot t be ignored. However, using the mixture the system obtained a lower Environmental load Ratio (ELR) value compared to cyclohexane and toluene. Finally, the multi-objective optimization was able to maximize the exergy efficiency for the working fluids by about 9.7% and reduce the ESI by 50.94%. This study intends to show the advantage and disadvantage of using zeotropic mixtures as working fluid on waste heat recovery systems that uses Organic Rankine cycle from the environmental point of view and using emergy as a way to asses the sustainability of the whole system.

Quantification of mitral regurgitation after transcatheter edge-to-edge repair: Comparison of echocardiography and patient-specific in silico models.

BACKGROUND: Doppler echocardiographic (echo) assessment of residual mitral regurgitation (MR) after transcatheter edge-to-edge repair (TEER) is challenging and often subjective. This study aimed to evaluate the accuracy and feasibility of standardized quantitative echo methods for assessment of MR severity after MitraClip repair by comparing measurements against a reference MR severity obtained from patient-specific in silico models. METHODS: Post-procedure hemodynamics were simulated under five different MitraClip configurations in previously validated patient-specific in silico models for the treatment of functional MR. The residual regurgitant volume was calculated as in clinical practice using four quantitative virtual echo methods: pulsed Doppler, volumetric, proximal isovelocity surface area (PISA) and vena contracta area (VCA). Multiple permutations were performed for each method. Virtual echo MR results were evaluated against reference MR values directly extracted from the 5 patient-specific in silico models. RESULTS: The echo methods with the greatest accuracy were the three-dimensional (3D) volumetric method (r = 0.957, bias -0.8 ± 1.2 ml, p = 0.01), the 3D VCA method wherein velocity time integrals were evaluated for each jet assessed (r = 0.919, bias -1.5 ± 1.7 ml, p = 0.03), and the 3D PISA method integrating surface areas throughout systole (r = 0.98, bias -2.0 ± 0.9 ml, p = 0.003). The pulsed Doppler and 2D volumetric methods had technical limitations that may result in a high underestimation or overestimation of the MR severity after TEER. In the case of multiple regurgitant jets, a more accurate MR assessment was obtained when all significant jets were evaluated. CONCLUSIONS: Clinically, the 3D volumetric, 3D VCA and 3D PISA methods gave the most accurate MR quantification after TEER. Three-dimensional echo technologies harbor the potential of becoming the non-invasive imaging tool of choice for MR quantification after complex transcatheter mitral interventions.

Gamma Knife radiosurgery - 12 years of experience in a high-complexity center of a middle-income country.

Background: Gamma Knife radiosurgery (GKR) is a technique that consists of the release of a high dose of ionizing radiation onto a therapeutic target, which has been previously delimited. This technique was described by Lars Leksell and Borje Larsson in 1951. In Colombia, there is only one GKR unit functioning machine nowadays. The objective of this study is to describe the institutional experience of a single institution with Gamma Knife Perfexion over 12 years. Methods: We conducted a retrospective observational study. A total of 1906 medical records, taken from the period between May 4, 2010, and May 4, 2022, were included in the study. Descriptive analysis was performed through STATA 17 as statistic tool. Measures of central tendency were calculated depending on the distribution of the continuous data and proportions were taken into account in the case of qualitative variables. Results: A total of 1906 procedures were performed. Patients from 1 year to 99 years old were treated, with a median age of 51 years. The most frequent diagnoses were meningioma (20.8%), arteriovenous malformation (AVM) (17%), vestibular schwannoma (15.6%), metastases (9.81%), and trigeminal neuralgia (9.12%). At 3-year posttreatment, in meningiomas, tumor size stability was observed in 57.3%, size decrease in 36%, and disappearance in 1.3%. In AVM, complete obliteration of the lesion was described in 36.8% and a decrease in size in 52.6%. Intracranial hemorrhage occurred in 5.2% during the follow-up period and 3.5% of all treated patients required a new procedure due to residual malformation. In vestibular schwannomas, tumor size remained stable in 62.2% and decreased in 28.8%. No new cases of facial paralysis after the procedure were described. At 1-year posttreatment, in metastasis, the size of the lesions remained stable in 40% of the patients, decreased in 47.5%, and disappeared in 2.5%. In trigeminal neuralgia, 88.4% of patients had pain relief and recurrences occurred in 16.6%. Acute complications were generally uncommon, the main ones being headache, pain at frame fixation points, and nausea. Conclusion: Our experience suggests that GKR is a noninvasive procedure with a broad spectrum of clinical applications, low frequency of complications, feasible, with good enough control size of tumor and vascular lesions in images, and good clinical results in the medium and long term.

Comparative computational analysis of PASCAL and MitraClip implantation in a patient-specific functional mitral regurgitation model.

Transcatheter mitral leaflet approximation with MitraClip has proven to be a viable treatment option for heart failure patients with functional mitral regurgitation (MR). PASCAL is a similar clip device, but it has design features that differentiate it from MitraClip. The effects of the different clip designs are largely unknown. In this study, using a patient-specific, mitral valve-left ventricle heart model, we performed finite-element (FE) simulations to provide a head-to-head comparison of the post-operative effects that PASCAL and MitraClip have on mitral valve (MV) geometry and biomechanics in a functional MR patient. The two devices were modeled as approximations of the real devices, and three implantation configurations were simulated for each device. The results showed that for this patient case, PASCAL caused less MV deformation than MitraClip. Additionally, PASCAL implantation reduced the stresses and strains in the MV leaflets compared to pre-repair conditions, while MitraClip implantation caused them to increase. Although complete coaptation was not achieved, both devices improved leaflet coaptation and were viable MR treatment options. The FE simulations in this study can be used to quantify biomechanics involved in clip treatments and improve our understanding of complex interactions between human hosts and percutaneous clip devices.

Computational Analysis of Virtual Echocardiographic Assessment of Functional Mitral Regurgitation for Validation of Proximal Isovelocity Surface Area Methods.

BACKGROUND: Mitral regurgitation (MR) quantification by the proximal isovelocity surface area (PISA) method remains challenging. Using computer models, the authors evaluated the accuracy of different PISA methods and quantified their errors. METHODS: Five functional MR computer models of different geometric and tethering abnormalities were created, validated, and treated as phantom models, from which the reference values were directly obtained. Virtual two-dimensional (2D) PISA and three-dimensional (3D) PISA (both peak and integrated values) were performed on these phantom models. By comparing virtual PISA results with reference values, the accuracy of different PISA methods was evaluated, and their sources of errors were quantified. RESULTS: Compared with reference values of regurgitant flow rate, excellent correlations were found for true PISA (r = 0.99, bias = 32.3 ± 35.3 mL/sec), 3D PISA (r = 0.97, bias = -24.4 ± 55.5 mL/sec), followed by multiplane 2D hemicylindrical PISA (r = 0.88, bias = -24.1 ± 85.4 mL/sec) and hemiellipsoidal PISA (r = 0.91, bias = -55.7 ± 96.6 mL/sec). Weaker correlations were found for single-plane 2D hemispherical PISA (parasternal long-axis: r = 0.71, bias = -77.6 ± 124.5 mL/sec; apical two-chamber: r = 0.69, bias = -52.0 ± 122.0 mL/sec; apical four-chamber: r = 0.82, bias = -65.5 ± 107.3 mL/sec). For regurgitant volume quantification, integrated PISA was more accurate than peak PISA. The bias of 3D PISA improved from -12.7 ± 7.8 mL (peak PISA) to -2.1 ± 5.3 mL (integrated PISA). CONCLUSIONS: For functional MR quantification, 2D hemispherical PISA had significant underestimation, multiplane 2D hemiellipsoidal and hemicylindrical PISA showed improved accuracy, and 3D PISA was the most accurate. The PISA method is subject to both systematic underestimation due to the Doppler angle effect and systematic overestimation when regurgitant flow is not perpendicular to PISA contour. Integrated PISA is able to capture dynamic MR and is therefore more accurate than peak PISA. The sum of regurgitant flow rates is the most feasible way to perform integrated PISA.

The role of stress concentration in calcified bicuspid aortic valve.

Calcific aortic valve disease (CAVD) is the most common valvular heart disease in the aging population, and is now believed to be a slow, progressive, yet actively regulated process. The disease progression can be divided into two phases: initiation phase associated with lipid deposition and inflammation response, and the later propagation phase with active calcification growth. It has been hypothesized that elevated mechanical stress plays a major role in both phases of disease progression. In order to identify a direct link between leaflet stress and calcification development, we performed patient-specific finite-element (FE) analyses of six bicuspid aortic valves (BAV), where the leaflets, raphe and calcifications were all considered. The results showed that during the initiation phase, calcium buildup is likely to occur along the leaflet-root attachment curve (ATC), and the commissures, which are subject to the most drastic changes in stress during the cardiac cycle. During the propagation phase, the presence of calcification would lead to local stress concentration along its boundary, hence further calcification growth. Three patterns of calcification formation were identified on BAV leaflets: 'radial', which extended radially from ATC into the leaflet belly region; 'commissure to commissure', which extended circumferentially along the coaptation; and 'raphe', which located in the vicinity of the raphe. Furthermore, we found a strong correlation between regions with a high risk of calcium buildup and regions with elevated mechanical stress. The high-risk regions predicted at diastole on the non-calcified leaflet from FE models agreed reasonably well with the in vivo calcification locations, which indicates that patient-specific FE modelling could help us to evaluate the potential risk of calcification formation in the early stage of CAVD.

A Comprehensive Engineering Analysis of Left Heart Dynamics After MitraClip in a Functional Mitral Regurgitation Patient.

Percutaneous edge-to-edge mitral valve (MV) repair using MitraClip has been recently established as a treatment option for patients with heart failure and functional mitral regurgitation (MR), which significantly expands the number of patients that can be treated with this device. This study aimed to quantify the morphologic, hemodynamic and structural changes, and evaluate the biomechanical interaction between the MitraClip and the left heart (LH) complex of a heart failure patient with functional MR using a fluid-structure interaction (FSI) modeling framework. MitraClip implantation using lateral, central and double clip positions, as well as combined annuloplasty procedures were simulated in a patient-specific LH model that integrates detailed anatomic structures, incorporates age- and gender-matched non-linear elastic material properties, and accounts for mitral chordae tethering. Our results showed that antero-posterior distance, mitral annulus spherecity index, anatomic regurgitant orifice area, and anatomic opening orifice area decreased by up to 28, 39, 52, and 71%, respectively, when compared to the pre-clip model. MitraClip implantation immediately decreased the MR severity and improved the hemodynamic profile, but imposed a non-physiologic configuration and loading on the mitral apparatus, with anterior and posterior leaflet stress significantly increasing up to 210 and 145% during diastole, respectively. For this patient case, while implanting a combined central clip and ring resulted in the highest reduction in the regurgitant volume (46%), this configuration also led to mitral stenosis. Patient-specific computer simulations as used here can be a powerful tool to examine the complex device-host biomechanical interaction, and may be useful to guide device positioning for potential favorable clinical outcomes.

Finite element analysis of MitraClip procedure on a patient-specific model with functional mitral regurgitation.

Mitral valve (MV) repair with the MitraClip device has been shown to reduce mitral regurgitation severity and improve clinical outcomes in symptomatic patients at high surgical risk. MitraClip was recently approved in the US for the treatment of functional mitral regurgitation (FMR), which significantly expands the number of patients that can be treated with this device. This study aims to quantify the morphologic changes and evaluate the biomechanical interaction between the MitraClip device and the mitral apparatus of a real patient case with FMR using computational modeling. MitraClip procedures using a central and a lateral clip were simulated in a validated MV-left ventricle finite element (FE) model with severe MR. The patient-specific model integrated detailed geometries of the left ventricle, mitral leaflets and chordae, incorporated age- and gender-matched nonlinear hyperelastic human material properties, and accounted for chordae tethering forces. Central and lateral positioning gave similar biomechanical outcomes resulting in an improved but incomplete MV coaptation. Antero-posterior distance, annulus area, valve opening orifice area, and regurgitant orifice area decreased by up to 26%, 19%, 48% and 63% when compared to the pre-clip model, respectively. Anterior and posterior leaflet peak stresses increased by up to 64% and 62% after clip placement, respectively, and were located at the region of clip grasp. Similarly, anterior and posterior leaflet peak strains increased by up to 20% and 10%, respectively. FE modeling, as used here, can be a powerful tool to examine the complex MitraClip-host biomechanical interaction.

Comparative quantification of primary mitral regurgitation by computer modeling and simulated echocardiography.

Clinical investigations have demonstrated that mitral regurgitation (MR) quantification using echocardiography (echo) may significantly underestimate or overestimate the regurgitant volume, especially for two-dimensional (2D) echo. Computer modeling and simulated echo were conducted to evaluate the fundamental assumptions in the echo quantification of primary MR that is due to posterior mitral leaflet prolapse. The theoretical flaw of the proximal isovelocity surface area (PISA) method originates from the assumption that the MR flow rate is the product of the isovelocity surface area and aliasing velocity, which is only valid when the velocity vectors are perpendicular to the isovelocity surface. Other factors such as the Doppler angle effect, the view planes of 2D echo, and the single time instant of PISA were also analyzed. We find that the hemielliptic PISA method gives the smallest error for moderate and severe MR cases compared with other PISA methods. Compared with the PISA method, the volumetric technique (VT) is theoretically more robust. By considering correction factors that are caused by nonflat velocity profiles and the closing volume of the aortic valve, the accuracy of the VT method can be significantly improved. The corrected volumetric technique provides more accurate results compared with the PISA methods, especially for mild MR.NEW & NOTEWORTHY We evaluate the accuracy of common echocardiography techniques for the quantification of primary mitral regurgitations using computer modeling. The hemielliptic proximal isovelocity surface area (PISA) method gives the smallest error (within 15%) for moderate and severe mitral regurgitation cases compared with other PISA methods. The volumetric method is theoretically more robust than the PISA method. The accuracy of the volumetric method can be improved by a correction factor around 0.7 because of the nonflat velocity profiles and the closing volume of the aortic valve.

The Impact of Self-Expandable Transcatheter Aortic Valve Replacement on Concomitant Functional Mitral Regurgitation: A Comprehensive Engineering Analysis.

BACKGROUND: Mitral regurgitation (MR) is present in a large proportion of patients who undergo transcatheter aortic valve replacement (TAVR). However, existing clinical data on the impact of TAVR on early post-procedural MR severity are contradictory. Using a comprehensive computational engineering methodology, this study aimed to evaluate quantitatively the structural and hemodynamic impact of TAVR on aortic-mitral continuity and MR severity in a rigorously developed and validated patient-specific left heart (LH) computer model with aortic stenosis and concomitant functional MR. METHODS: TAVR procedure was virtually simulated using a self-expandable valve (SEV) at three implantation heights. Pre- and post-TAVR LH dynamics as well as intra-operative biomechanics were analyzed. RESULTS: No significant differences in early MR improvement (<10%) were noted at the three implantation depths when compared to the pre-TAVR state. The high deployment model resulted in the highest stress in the native aortic leaflets, lowest stent-tissue contact force, highest aortic-mitral angle, and highest MR reduction for this patient case. When comparing SEV vs. balloon-expandable valve (BEV) performance at an optimal implantation height, the SEV gave a higher regurgitant volume ⋅ than the pre-TAVR model (40.49 vs 37.59 ml), while the BEV model gave the lowest regurgitant volume (33.84 vs 37.59 ml). CONCLUSIONS: Contact force, aortic-mitral angle, and valve annuli compression were identified as possible mechanistic parameters that may suggest avenues for acute MR improvement. Albeit a single patient parametric study, it is our hope that such detailed engineering analysis could shed some light into the underlying biomechanical mechanisms of TAVR impact on MR.

Computer simulations of transapical mitral valve repair with neochordae implantation: Clinical implications.

Objectives: Transapical beating heart neochordae implantation is an innovative mitral valve repair technique that has demonstrated promising clinical results in patients with primary mitral regurgitation. However, as clinical experience continues to increase, neochordae implantation criteria have not been fully standardized. The aim of this study was to investigate the biomechanical effects of selecting an antero-lateral apical access site compared with a postero-lateral site, and suboptimal neochordae length compared with optimal suture length, on restoring physiologic left heart dynamics. Methods: Transapical neochordae implantation using 3 and 4 sutures was computer simulated under 3 posterior mitral leaflet prolapse conditions: isolated P2, multiscallop P2/P3 and multiscallop P2/P1. Physiologic, pre- and postrepair left heart dynamics were evaluated using a fluid-structure interaction modeling framework. Results: Despite the absence of residual mitral regurgitation in all postrepair models with optimal neochordae length, selecting an antero-lateral apical entry site for the treatment of P2/P3 prolapse generated a significant increase (>80%) in neochordae tension and P2 peak stress, with respect to a postero-lateral entry site. During isolated P2 prolapse repair, although neochordae overtension by 5% led to minimal hemodynamic changes in the regurgitant volume compared with using an optimal suture length, a significant increase in systolic and diastolic neochordae tension (>300%) and posterior leaflet average stress (70%-460%) was quantified. On the other hand, neochordae undertension by 5% led to worsening of regurgitation severity. Conclusions: This parametric computer study represents a further step toward an improved understanding of the biomechanical outcomes of transapical neochordae technologies.

Transapical mitral valve repair with neochordae implantation: FSI analysis of neochordae number and complexity of leaflet prolapse.

Transapical mitral valve repair with neochordae implantation is a relatively new minimally invasive technique to treat primary mitral regurgitation. Quantifying the complex biomechanical interaction and interdependence between the left heart structures and the neochordae during this procedure is technically challenging. The aim of this parametric computational study is to investigate the immediate effects of neochordae number and complexity of leaflet prolapse on restoring physiologic left heart dynamics after optimal transapical neochordae repair procedures. Neochordae implantation using three and four sutures was modeled under three clinically relevant prolapse conditions: isolated P2, multi-scallop P2/P3, and multi-scallop P2/P1. A fluid-structure interaction (FSI) modeling framework was used to evaluate the left heart dynamics under baseline, prerepair, and postrepair states. Despite immediate restoration of leaflet coaptation and no residual mitral regurgitation in all postrepair models, the average and peak stresses in the repaired scallop(s) increased >40% and >100%, respectively, compared with the baseline state. Additionally, anterior mitral leaflet marginal chordae tension increased >30%, while posterior mitral leaflet chordae tension decreased at least 30%. No marked differences in hemodynamic performance, in native and neochordae forces, and in leaflet stress were found when implanting three or four sutures. We report, to our knowledge, the first set of time-dependent in silico FSI human neochordae tension measurements during transapical neochordae repair. This work represents a further step towards an improved understanding of the biomechanical outcomes of minimally invasive mitral valve repair procedures.

The impact of balloon-expandable transcatheter aortic valve replacement on concomitant mitral regurgitation: a comprehensive computational analysis.

The aortic and mitral valves function in a reciprocal interdependent fashion. However, the impact of transcatheter aortic valve replacement (TAVR) on the aortic-mitral continuity and severity of mitral regurgitation (MR) are poorly understood. In this study, a comprehensive engineering analysis was performed to investigate the impact of TAVR on MR severity and left heart dynamics in a retrospective patient case who harbours bicuspid aortic valve stenosis and concomitant functional MR. The TAVR procedure was computer simulated using a balloon-expandable valve, and the impact of three implantation heights on aortic-mitral coupling, MR severity and device performance were analysed. The accuracy and predictability of the computer modelling framework were validated with pre- and post-operative echo data. The highest deployment model resulted in higher stresses in the native leaflets, contact radial force and stent recoil, while the midway implantation model gave better haemodynamic performance and MR reduction in this patient case. Although the regurgitant volume decreased (less than 10%) for the three deployment configurations, no significant differences in MR severity improvement and mitral leaflet tethering were found. Acute improvement in MR was (i) due to the mechanical compression of the stent against the aortic-mitral curtain, (ii) due to an immediate drop in the ventricular pressure and transmitral pressure gradient. Albeit a single real clinical case, it is our hope that such detailed engineering computational analysis could shed light on the underlying biomechanical mechanisms of TAVR impact on MR.

Author Correction: New insights into mitral heart valve prolapse after chordae rupture through fluid-structure interaction computational modeling.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Evaluation of transcatheter heart valve biomaterials: Computational modeling using bovine and porcine pericardium.

OBJECTIVE: The durability of bioprosthetic heart valve (BHV) devices, commonly made of bovine (BP) and porcine (PP) pericardium tissue, is partly limited by device calcification and tissue degeneration, which has been associated with pathological levels of mechanical stress. This study investigated the impacts of BP and PP tissues with different thicknesses and tissue mechanical properties in BHV applications. METHODS: Second Harmonic Generation (SHG) imaging was employed to visualize the collagen fibers on each side of the pericardium. Structural constitutive modeling that incorporates collagen fiber distribution obtained from multiphoton microscopy for each tissue type were derived to characterize the corresponding biaxial mechanical testing data collected in a previous study. The models were verified through finite element (FE) simulations of the biaxial test and implemented in valve closing simulations. RESULTS: Smooth side collagen fibers were found to correlate with the mechanical response. BHVs with adult (ABP) and calf (CBP) BP tissues had lower maximum principal stresses than those with PP and fetal (FBP) BP tissues. Collagen fiber orientation along the circumferential axis resulted in lower maximum principal stresses and more uniform and symmetric stress distributions throughout the valve. CONCLUSIONS: The use of PP and FBP tissue resulted in higher peak stresses than ABP and CBP tissues in the given valve design. Additionally, ensuring collagen fiber orientation along the circumferential axis led to lower maximum stresses felt by the valve leaflets, which could also improve BHV durability.

Chronic bronchitis: High prevalence in never smokers and underdiagnosis- A population-based study in Colombia.

The objective of the article was to establish the prevalence, underdiagnosis, and risk factors of chronic bronchitis (CB) in a general population in five Colombian cities. Cross-sectional study using a probabilistic sampling technique in five Colombian cities was adopted. The CB definition was "cough and expectoration for three or more months per year for at least two consecutive years." Underdiagnosis was considered in subjects with clinical definition without previous medical diagnosis. Univariate χ2 or Student's t-test and logistic regression analysis were used. The study included 5539 subjects. The prevalence was 5.5%, the underdiagnosis 50.3%, and 33.7% of the cases were in nonsmokers (53.6% in women vs. 16.9% in men, p < 0.001). The adjusted risk factors were living in Bogota, current smoking, male, age ≥ 64 years, low education, indoor wood smoke exposure, and occupational exposure to vapors, gases, dust, and fumes. CB is a common disease among adults in Colombia. The underdiagnosis was high and there were a large proportion of cases in nonsmokers, particularly in women. Our findings support the association of CB with indoor wood smoke and occupational exposures.

Ultrasonido para accesos vasculares centrales. Un concepto de seguridad que se renueva día a día: revisión / Ultrasound for central vascular access. A safety concept that is renewed day by day: review

Abstract Background: Ultrasound (US)-guided central venous catheterization is intended to reduce complications, enhance success rates on the first attempt, and increase accuracy, thus becoming a standard in clinical practice. Objectives: To review the relevant literature on the importance of US as a guide to central venous access and to describe the benefits of this tool and the impact of its use on the safety of the procedure. Methods: A narrative review of various medical literature databases and recognized guidelines (National Guideline Clearinghouse, New Zealand Guidelines, National Institute for Clinical Excellence, Cochrane, and JAMA). Results: High-quality evidence recommends US-guided inter nal jugular vein access as the preferred approach in routine practice. However, different other anatomical sites may be necessary for vascular access depending on the clinical setting. Related complications associated with landmark-guided techni ques range between 0.3% and 18.8% and depend on multiple conditions such as patient characteristics and access site. US has been associated with a reduction in the relative risk of complica tions, failed attempts, and failed first attempt of 57%, 86%, and 41%, respectively. Conclusion: US should be used routinely in central vascular access. Current evidence supports this recommendation for the internal jugular vein approach, but no so for the other approaches, in cases of difficult or failed access using conventional approaches.

Resumen Introducción: El catéter guiado por ultrasonido busca impactar en la incidencia de complicaciones, aumentar las tasas de éxito en el primer intento, e incrementar la precisión; convirtiéndose en estándar en la práctica clínica. Objetivo: Elaborar una revisión de la literatura más relevante sobre la importancia del ultrasonido (US) como guía para la canulación de accesos vasculares centrales y hacer una descripción sobre los beneficios de esta herramienta y cómo impacta en la seguridad del procedimiento Métodos: Revisión narrativa; se consultaron diferentes bases de datos, como National Guideline Clearinghouse, New Zeland Guidelines, Medline, NICE, Cochrane, JAMA. Resultados: El abordaje para un catéter venoso central que tiene suficiente evidencia para recomendar su uso rutinario guiado por US, es en vena yugular interna, pero no quiere decir que ésta deba prevalecer sobre situaciones en las cuales esté indicado un catéter venoso central por otra vía. Las complicaciones de las técnicas guiadas por referencias anatómicas oscilan entre 0,3% a 18,8%, por múltiples variables como la población de pacientes, sitio de inserción; se han impactado con el uso del US en reducción del riesgo relativo de complicaciones, intentos fallidos y fracaso primer intento en 57%, 86% y 41%, respectiva mente. Conclusión: El ultrasonido debe ser rutinario para obtener un acceso vascular central, la evidencia actual soporta esta reco mendación en vena yugular interna, no tanto así para los demás abordajes; en aquellos casos de canalización difícil o fallida por métodos convencionales, en cualquiera de las vías descritas hay que utilizar el ecógrafo como herramienta para garantizar el éxito.