The athlete's heart: allometric considerations on published papers and relation to cardiovascular variables

To evaluate the morphology of the "athlete's heart", left ventricular (LV) wall thickness (WT) and end-diastolic internal diameter (LVIDd) at rest were addressed in publications on skiers, rowers, swimmers, cyclists, runners, weightlifters (n = 927), and untrained controls (n = 173) and related to the acute and maximal cardiovascular response to their respective disciplines. Dimensions of the heart at rest and functional variables established during the various sport disciplines were scaled to body weight for comparison among athletes independent of body mass. The two measures of LV were related (r = 0.8; P = 0.04) across athletic disciplines. With allometric scaling to body weight, LVIDd was similar between weightlifters and controls but 7%-15% larger in the other athletic groups, while WT was 9%-24% enlarged in all athletes. The LVIDd was related to stroke volume, oxygen pulse, maximal oxygen uptake, cardiac output, and blood volume (r =  ~ 0.9, P < 0.05), while there was no relationship between WT and these variables (P > 0.05). In conclusion, while cardiac enlargement is, in part, essential for the generation of the cardiac output and thus stroke volume needed for competitive endurance exercise, an enlarged WT seems important for the development of the wall tension required for establishing normal arterial pressure in the enlarged LVIDd.

Trabeculations of the porcine and human cardiac ventricles are different in number but similar in total volume

An intricate meshwork of trabeculations lines the luminal side of cardiac ventricles. Compaction, a developmental process, is thought to reduce trabeculations by adding them to the neighboring compact wall which is then enlarged. When pig, a plausible cardiac donor for xenotransplantation, is compared to human, the ventricular walls appear to have fewer trabeculations. We hypothesized the trabecular volume is proportionally smaller in pig than in human. Macroscopically, we observed in 16 pig hearts that the ventricular walls harbor few but large trabeculations. Close inspection revealed a high number of tiny trabeculations, a few hundred, within the recesses of the large trabeculations. While tiny, these were still larger than embryonic trabeculations and even when considering their number, the total tally of trabeculations in pig was much fewer than in human. Volumetrics based on high-resolution MRI of additional six pig hearts compared to six human hearts, revealed the left ventricles were not significantly differently trabeculated (21.5 versus 22.8%, respectively), and the porcine right ventricles were only slightly less trabeculated (42.1 vs 49.3%, respectively). We then analyzed volumetrically 10 pig embryonic hearts from gestational day 14-35. The trabecular and compact layer always grew, as did the intertrabecular recesses, in contrast to what compaction predicts. The proportions of the trabecular and compact layers changed substantially, nonetheless, due to differences in their growth rate rather than compaction. In conclusion, processes that affect the trabecular morphology do not necessarily affect the proportion of trabecular-to-compact myocardium and they are then distinct from compaction.

Spatially organized cellular communities form the developing human heart

The heart, which is the first organ to develop, is highly dependent on its form to function1,2. However, how diverse cardiac cell types spatially coordinate to create the complex morphological structures that are crucial for heart function remains unclear. Here we integrated single-cell RNA-sequencing with high-resolution multiplexed error-robust fluorescence in situ hybridization to resolve the identity of the cardiac cell types that develop the human heart. This approach also provided a spatial mapping of individual cells that enables illumination of their organization into cellular communities that form distinct cardiac structures. We discovered that many of these cardiac cell types further specified into subpopulations exclusive to specific communities, which support their specialization according to the cellular ecosystem and anatomical region. In particular, ventricular cardiomyocyte subpopulations displayed an unexpected complex laminar organization across the ventricular wall and formed, with other cell subpopulations, several cellular communities. Interrogating cell-cell interactions within these communities using in vivo conditional genetic mouse models and in vitro human pluripotent stem cell systems revealed multicellular signalling pathways that orchestrate the spatial organization of cardiac cell subpopulations during ventricular wall morphogenesis. These detailed findings into the cellular social interactions and specialization of cardiac cell types constructing and remodelling the human heart offer new insights into structural heart diseases and the engineering of complex multicellular tissues for human heart repair.

Radiation therapy in the thoracic region: Radio-induced cardiovascular disease, cardiac delineation and sparing, cardiac dose constraints, and cardiac implantable electronic devices

Radiation therapy in the thoracic region may deliver incidental ionizing radiation to the surrounding healthy structures, including the heart. Radio-induced heart toxicity has long been a concern in breast cancer and Hodgkin's lymphoma and was deemed a long-term event. However, recent data highlight the need to limit the dose to the heart in less favorable thoracic cancers too, such as lung and esophageal cancers in which incidental irradiation led to increased mortality. This article will summarize available cardiac dose constraints in various clinical settings and the types of radio-induced cardiovascular diseases encountered as well as delineation of cardiac subheadings and management of cardiac devices. Although still not completely deciphered, heart dose constraints remain intensively investigated and the mean dose to the heart is no longer the only dosimetric parameter to consider since the left anterior descending artery as well as the left ventricle should also be part of dosimetry constraints.

Spatially resolved multiomics of human cardiac niches

The function of a cell is defined by its intrinsic characteristics and its niche: the tissue microenvironment in which it dwells. Here we combine single-cell and spatial transcriptomics data to discover cellular niches within eight regions of the human heart. We map cells to microanatomical locations and integrate knowledge-based and unsupervised structural annotations. We also profile the cells of the human cardiac conduction system1. The results revealed their distinctive repertoire of ion channels, G-protein-coupled receptors (GPCRs) and regulatory networks, and implicated FOXP2 in the pacemaker phenotype. We show that the sinoatrial node is compartmentalized, with a core of pacemaker cells, fibroblasts and glial cells supporting glutamatergic signalling. Using a custom CellPhoneDB.org module, we identify trans-synaptic pacemaker cell interactions with glia. We introduce a druggable target prediction tool, drug2cell, which leverages single-cell profiles and drug-target interactions to provide mechanistic insights into the chronotropic effects of drugs, including GLP-1 analogues. In the epicardium, we show enrichment of both IgG+ and IgA+ plasma cells forming immune niches that may contribute to infection defence. Overall, we provide new clarity to cardiac electro-anatomy and immunology, and our suite of computational approaches can be applied to other tissues and organs.

Anatomical and biometric study of the mitral valve apparatus: application in valve repair surgery

OBJECTIVE

Most mitral valve repair techniques provide excellent surgical results by removing regurgitation, but all of these techniques simultaneously reduce posterior valve mobility. A comprehensive biometric study of the mitral valve apparatus will provide landmarks that would help improve this posterior valve mobility.

MATERIALS AND METHODS

Thirty one (31) human hearts have been studied, from 14 women and 17 men. The characteristics of the studied sample were analyzed descriptively. The difference in means of the variables between women and men were tested using a Student t test. Correlations between the different measures were determined by simple regression analysis. Mean values are shown with ± 1 standard deviation and the limit of significance was set at 0.05.

RESULTS

The mean weight of the hearts was 275.3 ± 2.4 g. The anteroposterior diameter of the mitral annulus was 29.3 ± 1.22 mm, the intertrigonal distance was 25.2 ± 3.50 mm and the anterior leaflet to posterior leaflet ratio was 1.9 ± 0.10, the length of the chordae A2 = 19.4 ± 1.15 mm and P2 = 14.5 ± 0.85 mm. The length of the anterior papillary muscle averaged 30.9 ± 7.20 mm and that of the posterior one 30.0 ± 8.75 mm. The comparison of the different values measured between women and men showed no statistically significant difference (p > 0.05). There was no correlation between these different measured values (p > 0.05).

CONCLUSION

A perfect knowledge of anatomy and biometry is therefore essential to offer alternative techniques that reproduce the real anatomy and physiology with a complete reconstruction of the mitral valve.

Normal Ventricular and Regional Blood Flow Volumes and Native T1 Values in Healthy Japanese Children Obtained from Comprehensive Cardiovascular Magnetic Resonance Imaging

Age-related mean and reference ranges for ventricular volumes and mass, regional blood flow measurements, and T1 values using cardiovascular magnetic resonance (CMR) imaging are yet to be established for the pediatric population. Especially in infants and toddlers, no consistent flow volume sets or T1 values have been reported. The purpose of this study was to determine the relevant normal values.Twenty-three children (aged 0.1-15.3 years) without cardiovascular diseases were included. Comprehensive CMR imaging including cine, 2-dimensional phase-contrast, and native T1 mapping, were performed. Ventricular volumes and masses, 11 sets of regional blood flow volumes, and myocardial and liver T1 values were measured. All intraclass correlation coefficient values were > 0.94, except for the right ventricular mass (0.744), myocardial (0.868) and liver T1 values (0.895), reflecting good to excellent agreement between rates.Regression analysis showed an exponential relationship between body surface area (BSA) and ventricular volumes, mass, and regional blood flow volumes (normal value = a*BSAb). Left ventricular myocardial T1 values were regressed on linear regression with age (normal value = -7.39*age + 1091), and hepatic T1 values were regressed on a quadratic function of age (normal value = 0.923*age2 -18.012*age + 613).Comparison of the 2 different methods for the same physical quantities by Bland-Altman plot showed no difference except that the right ventricular stroke volume was 1.5 mL larger than the main pulmonary trunk flow volume.This study provides the normal values for comprehensive CMR imaging in Japanese children.

Multiscale model of heart growth during pregnancy: integrating mechanical and hormonal signaling

Pregnancy stands at the interface of mechanics and biology. The growing fetus continuously loads the maternal organs as circulating hormone levels surge, leading to significant changes in mechanical and hormonal cues during pregnancy. In response, maternal soft tissues undergo remarkable growth and remodeling to support the mother and baby for a healthy pregnancy. We focus on the maternal left ventricle, which increases its cardiac output and mass during pregnancy. This study develops a multiscale cardiac growth model for pregnancy to understand how mechanical and hormonal cues interact to drive this growth process. We coupled a cell signaling network model that predicts cell-level hypertrophy in response to hormones and stretch to a compartmental model of the rat heart and circulation that predicts organ-level growth in response to hemodynamic changes. We calibrated this multiscale model to data from experimental volume overload and hormonal infusions of angiotensin 2 (AngII), estrogen (E2), and progesterone (P4). We then validated the model's ability to capture interactions between inputs by comparing model predictions against published observations for the combinations of VO + E2 and AngII + E2. Finally, we simulated pregnancy-induced changes in hormones and hemodynamics to predict heart growth during pregnancy. Our model produced growth consistent with experimental data. Overall, our analysis suggests that the rise in P4 during the first half of gestation is an important contributor to heart growth during pregnancy. We conclude with suggestions for future experimental studies that will provide a better understanding of how hormonal and mechanical cues interact to drive pregnancy-induced heart growth.

Gestational hypercholesterolemia programs hepatic steatosis in a sex-specific manner in ApoE-deficient mice

Maternal hypercholesterolemia (MHC), a pathological condition characterized by an exaggerated rise in maternal serum cholesterol during pregnancy, may influence offspring hepatic lipid metabolism and increase the risk of nonalcoholic fatty liver disease (NAFLD). As NAFLD is characterized by a sexual dimorphic response, we assessed whether early-life exposure to excessive cholesterol influences the development of NAFLD in offspring and whether this occurs in a sex-specific manner. Female apoE-/- mice were randomly assigned to a control (CON) or a high cholesterol (CH; 0.15%) diet prior to breeding. At parturition, a cross-fostering approach was used to establish three groups: (1) normal cholesterol exposure throughout gestation and lactation (CON-CON); (2) excessive cholesterol exposure throughout gestation and lactation (CH-CH); and (3) excessive cholesterol exposure in the gestation period only (CH-CON). Adult male offspring (PND 84) exposed to excessive cholesterol during gestation only (CH-CON) demonstrated hepatic triglyceride (TG) accumulation and reduced lipogenic gene expression. However, male mice with a prolonged cholesterol exposure throughout gestation and lactation (CH-CH) had a similar, but not exacerbated hepatic response. Further, with the exception of higher serum TG in adult CH-CH females, evidence for a programming effect in female offspring was largely absent in comparison with males. These results indicate a sexual dimorphic response with respect to the effect of MHC on later life hepatic steatosis and highlight the gestation period as the most influential malprogramming window for hepatic lipid dysfunction in males.

Depressive Symptoms, Cardiac Structure and Function, and Risk of Incident Heart Failure With Preserved Ejection Fraction and Heart Failure With Reduced Ejection Fraction in Late Life

Background Depressive symptoms are associated with heightened risk of heart failure (HF), but their association with cardiac function and with HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF) in late life is unclear. We aimed to determine the prevalence of depression in HFpEF and in HFrEF in late life, and the association of depressive symptoms with cardiac function and incident HFpEF and HFrEF. Methods and Results We studied 6025 participants (age, 75.3±5.1 years; 59% women; 20% Black race) in the ARIC (Atherosclerosis Risk in Communities) study at visit 5 who underwent echocardiography and completed the Center for Epidemiologic Studies Depression Scale questionnaire. Among HF-free participants (n=5086), associations of Center for Epidemiologic Studies Depression Scale score with echocardiography and incident adjudicated HFpEF and HFrEF were assessed using multivariable linear and Cox proportional hazards regression. Prevalent HFpEF, but not HFrEF, was associated with a higher prevalence of depression compared with HF-free participants (P<0.001 and P=0.59, respectively). Among HF-free participants, Center for Epidemiologic Studies Depression Scale score was not associated with cardiac structure and function after adjusting for demographics and comorbidities (all P>0.05). Over 5.5-year follow-up, higher Center for Epidemiologic Studies Depression Scale score was associated with heightened risk of incident HFpEF (hazard ratio [HR] [95% CI], 1.06 [1.04-1.12]; P=0.02), but not HFrEF (HR [95% CI], 1.02 [0.96-1.08]; P=0.54), independent of echocardiographic measures, NT-proBNP (N-terminal pro-B-type natriuretic peptide), troponin, and hs-CRP (high-sensitivity C-reactive protein) (HR [95% CI], 1.06 [1.00-1.12]; P=0.04). Conclusions Worse depressive symptoms predict incident HFpEF in late life, independent of common comorbidities, cardiac structure and function, and prognostic biomarkers. Further studies are necessary to understand the mechanisms linking depression to risk of HFpEF.

Cardiac structure and function in elite female athletes: A systematic review and meta-analysis

We conducted a meta-analysis to synthesize the best available evidence comparing cardiac biventricular structure and function using cardiac magnetic resonance imaging (CMR) and transthoracic echocardiography (TTE) in elite female athletes and healthy controls (HC). Chronic exposure to exercise may induce cardiac chamber enlargement as a means to augment stroke volume, a condition known as the "athlete's heart." These changes have not been clearly characterized in female athletes. Multiple databases were searched from inception to June 18, 2019. Outcomes of interest included left ventricular (LV) and right ventricular (RV) dimensional, volumetric, mass, and functional assessments in female athletes. Most values were indexed to body surface area. The final search yielded 22 studies, including 1000 female athletes from endurance, strength, and mixed athletic disciplines. CMR-derived LV end-diastolic volume (LVEDV) and RV end-diastolic volume (RVEDV) were greater in endurance athletes (EA) versus HC (17.0% and 18.5%, respectively; both p < 0.001). Similarly, TTE-derived LVEDV and RVEDV were greater in EA versus HC (16.8% and 28.0%, respectively; both p < 0.001). Both LVEF and RVEF were lower in EA versus HC, with the most pronounced difference observed in RVEF via TTE (9%) (p < 0.001). LV stroke volume was greater in EA versus HC via both CMR (18.5%) and TTE (13.2%) (both p < 0.05). Few studies reported data for the mixed athlete (MA) population and even fewer studies reported data for strength athletes (SA), therefore a limited analysis was performed on MA and no analysis was performed on SA. This evidence-synthesis review demonstrates the RV may be more susceptible to ventricular enlargement. General changes in LV and RV structure and function in female EA mirrored changes observed in male counterparts. Further studies are needed to determine if potential adverse outcomes occur secondary to these changes.

Associations of the Dietary Approaches to Stop Hypertension dietary pattern with cardiac structure and function

BACKGROUND AND AIMS

Various food groups have been associated with measures of left ventricular geometry and function. Whether the Dietary Approaches to Stop Hypertension (DASH) dietary pattern in mid-life is associated with a favorable cardiac structure and function later in life is unknown.

METHODS AND RESULTS

The study population consisted of the Atherosclerosis Risk in Communities study participants free of cardiovascular disease at study visit 3 in 1993-1995. Dietary intake was assessed by food frequency questionnaire at study visits 1 (1987-1989) and 3 (1993-1995). Participants who underwent transthoracic echocardiograms at the Jackson field center at visit 3 (n = 1974) and at all field centers at study visit 5 (2011-2013; n = 4651) were included in this study. General linear regression was used to evaluate associations between dietary intake and markers of cardiac structure and function adjusting for potential confounders. Higher DASH score was associated with lower left ventricle mean wall thickness and higher absolute value of longitudinal strain at visit 5 (ptrend = 0.004 and < 0.001, respectively).

CONCLUSION

The DASH dietary pattern in midlife was favorably associated with left ventricle structure and systolic function later in life. These results emphasize the importance of adhering to a healthy eating plan as one lifestyle measure to preserve cardiac structure and function.

Sex- and age- specific normal values of left ventricular functional and myocardial mass parameters using threshold-based trabeculae quantification

Background

The threshold-based (TB) trabeculated and papillary muscle mass (TPM) quantification method for cardiac MRI (CMR) calculates different values than conventional contouring techniques. We aimed to identify the sex- and age-related normal reference ranges for left ventricular (LV) myocardial mass values, volumetric and functional parameters and the correspondence of these parameters using the TB method.

Methods

Healthy European adults (n = 200, age: 39.4 ± 12 years, males: 100) were examined with CMR and evaluated with a TB postprocessing method. They were stratified by sex and age (Group A: 18–29, Group B: 30–39, Group C: 40–49, Group D: >50 years). The calculated parameters were indexed to body surface area (i).

Results

The normal reference ranges for the studied parameters were assessed in each age group. Significant biometric differences in LV parameters and mass-to-volume ratios were found between males and females, and the left ventricular compacted myocardial mass (LVCMi) and TPMi differences remained significant after stratification by age. Unlike other LV volumetric and functional parameters and mass-to-volume ratios, the TPMi, the LVCMi and the TPMi-to-LVCMi ratio did not differ among age groups in males or females. This finding was strengthened by the lack of correlation between TPMi and age.

Conclusions

Age- and sex-related normal reference ranges for LV volumetric and functional parameters and LVCMi and TPMi values were established using a TB postprocessing method. TPMi, LVCMi and their ratio did not change over time. The TPMi-to-LVCMi and the mass-to-volume ratios might have clinical utility in the differential diagnosis of conditions with LV hypertrabeculation.

Accelerating whole-heart 3D T2 mapping: Impact of undersampling strategies and reconstruction techniques

PURPOSE

We aim to determine an advantageous approach for the acceleration of high spatial resolution 3D cardiac T2 relaxometry data by comparing the performance of different undersampling patterns and reconstruction methods over a range of acceleration rates.

METHODS

Multi-volume 3D high-resolution cardiac images were acquired fully and undersampled retrospectively using 1) optimal CAIPIRINHA and 2) a variable density random (VDR) sampling. Data were reconstructed using 1) multi-volume sensitivity encoding (SENSE), 2) joint-sparsity SENSE and 3) model-based SENSE. Four metrics were calculated on 3 naïve swine and 8 normal human subjects over a whole left-ventricular region of interest: root-mean-square error (RMSE) of image signal intensity, RMSE of T2, the bias of mean T2, and standard deviation (SD) of T2. Fully sampled data and volume-by-volume SENSE with standard equally spaced undersampling were used as references. The Jaccard index calculated from one swine with acute myocardial infarction (MI) was used to demonstrate preservation of segmentation of edematous tissues with elevated T2.

RESULTS

In naïve swine and normal human subjects, all methods had similar performance when the net reduction factor (Rnet) <2.5. VDR sampling with model-based SENSE showed the lowest RMSEs (10.5%-14.2%) and SDs (+1.7-2.4 ms) of T2 when Rnet>2.5, while VDR sampling with the joint-sparsity SENSE had the lowest bias of mean T2 (0.0-1.1ms) when Rnet>3. The RMSEs of parametric T2 values (9.2%-24.6%) were larger than for image signal intensities (5.2%-18.4%). In the swine with MI, VDR sampling with either joint-sparsity or model-based SENSE showed consistently higher Jaccard index for all Rnet (0.71-0.50) than volume-by-volume SENSE (0.68-0.30).

CONCLUSIONS

Retrospective exploration of undersampling and reconstruction in 3D whole-heart T2 parametric mapping revealed that maps were more sensitive to undersampling than images, presenting a more stringent limiting factor on Rnet. The combination of VDR sampling patterns with model-based or joint-sparsity SENSE reconstructions were more robust for Rnet>3.

Novel G-CSF conjugated anionic globular dendrimer: Preparation and biological activity assessment

The most crucial role of granulocyte colony-stimulating factor (G-CSF) in the body is to increase the strength of immune system. In recent years, research on the use of nanoparticles in pharmaceuticals has been considered, most of which have been for drug-loading purposes. In this study, a novel G-CSF conjugated dendrimer was synthesized and characterized using different techniques. In vitro cytotoxicity was assessed on A549 and L929 cells, while abnormal toxicity was studied in mice. In vitro and in vivo biological activities were assessed in NFS60 cells and rats, respectively. In addition, in vivo distribution, plasma half-life, and histopathological effect were studied in rat. The characterization tests confirmed the successful conjugation. There was no difference between G-CSF cytotoxicity before and after conjugation, and no difference with the control group. No mice showed abnormal toxicity. Although in vitro biological activity revealed both conjugated and free G-CSF promote proliferation cells, biological activity decreased significantly after conjugation about one-third of the unconjugated form. Nonetheless, in vivo biological activity of conjugated G-CSF increased by more than 2.5-fold relative to the unconjugated form, totally. Fortunately, no histopathologic adverse effect was observed in vital rat tissues. Also, in vivo distribution of the conjugate was similar to the native protein with an enhanced terminal half-life. Our data revealed that G-CSF conjugated dendrimer could be considered as a candidate to improve the in vivo biological activity of G-CSF. Moreover, multivalent capability of the dendrimer may be used for other new potentials of G-CSF in future perspectives.

Blood pressure variability and night-time dipping assessed by 24-hour ambulatory monitoring: Cross-sectional association with cardiac structure in adolescents

Greater blood pressure (BP) is associated with greater left ventricular mass indexed to height2.7 (LVMi2.7) in adolescents. This study examined whether greater BP variability and reduced night-time dipping are associated with cardiac remodeling in a general population of adolescents. A cross-sectional analysis was undertaken in 587 UK adolescents (mean age 17.7 years; 43.1% male). BP was measured in a research clinic and using 24-hour ambulatory monitoring. We examined associations (for both systolic and diastolic BP) of: 1) clinic and 24-hour mean BP; 2) measures of 24-hour BP variability: standard deviation weighted for day/night (SDdn), variability independent of the mean (VIM) and average real variability (ARV); and 3) night-time dipping with cardiac structures. Cardiac structures were assessed by echocardiography: 1) LVMi2.7; 2) relative wall thickness (RWT); 3) left atrial diameter indexed to height (LADi) and 4) left ventricular internal diameter in diastole (LVIDD). Higher systolic BP was associated with greater LVMi2.7. Systolic and diastolic BP were associated with greater RWT. Associations were inconsistent for LADi and LVIDD. There was evidence for associations between both greater SDdn and ARV and higher RWT (per 1 SD higher diastolic ARV, mean difference in RWT was 0.13 SDs, 95% CI 0.045 to 0.21); these associations with RWT remained after adjustment for mean BP. There was no consistent evidence of associations between night-time dipping and cardiac structure. Measurement of BP variability, even in adolescents with blood pressure in the physiologic range, might benefit risk of cardiovascular remodeling assessment.

Application of 3D printing technology combined with PBL teaching model in teaching clinical nursing in congenital heart surgery: A case-control study

We aimed to explore the application of three-dimensional (3D) printing technology with problem-based learning (PBL) teaching model in clinical nursing education of congenital heart surgery, and to further improve the teaching quality of clinical nursing in congenital heart surgery. In this study, a total of 132 trainees of clinical nursing in congenital heart surgery from a grade-A tertiary hospital in 2019 were selected and randomly divided into 3D printing group or traditional group. The 3D printing group was taught with 3D printed heart models combined with PBL teaching technique, while the traditional group used conventional teaching aids combined with PBL technique for teaching. After the teaching process, the 2 groups of nursing students were assessed and surveyed separately to evaluate the results. Compared to the traditional group, the theoretical scores, clinical nursing thinking ability, self-evaluation for comprehensive ability, and teaching satisfaction from the questionnaires filled by the 3D printing group were all higher than the traditional group. The difference was found to be statistically significant (P < .05). Our study has shown the 3D printing technology combined with the PBL teaching technique in the clinical nursing teaching of congenital heart surgery achieved good results.

Linking statistical shape models and simulated function in the healthy adult human heart

Cardiac anatomy plays a crucial role in determining cardiac function. However, there is a poor understanding of how specific and localised anatomical changes affect different cardiac functional outputs. In this work, we test the hypothesis that in a statistical shape model (SSM), the modes that are most relevant for describing anatomy are also most important for determining the output of cardiac electromechanics simulations. We made patient-specific four-chamber heart meshes (n = 20) from cardiac CT images in asymptomatic subjects and created a SSM from 19 cases. Nine modes captured 90% of the anatomical variation in the SSM. Functional simulation outputs correlated best with modes 2, 3 and 9 on average (R = 0.49 ± 0.17, 0.37 ± 0.23 and 0.34 ± 0.17 respectively). We performed a global sensitivity analysis to identify the different modes responsible for different simulated electrical and mechanical measures of cardiac function. Modes 2 and 9 were the most important for determining simulated left ventricular mechanics and pressure-derived phenotypes. Mode 2 explained 28.56 ± 16.48% and 25.5 ± 20.85, and mode 9 explained 12.1 ± 8.74% and 13.54 ± 16.91% of the variances of mechanics and pressure-derived phenotypes, respectively. Electrophysiological biomarkers were explained by the interaction of 3 ± 1 modes. In the healthy adult human heart, shape modes that explain large portions of anatomical variance do not explain equivalent levels of electromechanical functional variation. As a result, in cardiac models, representing patient anatomy using a limited number of modes of anatomical variation can cause a loss in accuracy of simulated electromechanical function.

A Review of Ex Vivo X-ray Microfocus Computed Tomography-Based Characterization of the Cardiovascular System

Cardiovascular malformations and diseases are common but complex and often not yet fully understood. To better understand the effects of structural and microstructural changes of the heart and the vasculature on their proper functioning, a detailed characterization of the microstructure is crucial. In vivo imaging approaches are noninvasive and allow visualizing the heart and the vasculature in 3D. However, their spatial image resolution is often too limited for microstructural analyses, and hence, ex vivo imaging is preferred for this purpose. Ex vivo X-ray microfocus computed tomography (microCT) is a rapidly emerging high-resolution 3D structural imaging technique often used for the assessment of calcified tissues. Contrast-enhanced microCT (CE-CT) or phase-contrast microCT (PC-CT) improve this technique by additionally allowing the distinction of different low X-ray-absorbing soft tissues. In this review, we present the strengths of ex vivo microCT, CE-CT and PC-CT for quantitative 3D imaging of the structure and/or microstructure of the heart, the vasculature and their substructures in healthy and diseased state. We also discuss their current limitations, mainly with regard to the contrasting methods and the tissue preparation.

Fast calculation software for modified Look-Locker inversion recovery (MOLLI) T1 mapping

BACKGROUND

The purpose of this study was to develop a software tool and evaluate different T1 map calculation methods in terms of computation time in cardiac magnetic resonance imaging.

METHODS

The modified Look-Locker inversion recovery (MOLLI) sequence was used to acquire multiple inversion time (TI) images for pre- and post-contrast T1 mapping. The T1 map calculation involved pixel-wise curve fitting based on the T1 relaxation model. A variety of methods were evaluated using data from 30 subjects for computational efficiency: MRmap, python Levenberg-Marquardt (LM), python reduced-dimension (RD) non-linear least square, C++ single- and multi-core LM, and C++ single- and multi-core RD.

RESULTS

Median (interquartile range) computation time was 126 s (98-141) for the publicly available software MRmap, 261 s (249-282) for python LM, 77 s (74-80) for python RD, 3.4 s (3.1-3.6) for C++ multi-core LM, and 1.9 s (1.9-2.0) for C++ multi-core RD. The fastest C++ multi-core RD and the publicly available MRmap showed good agreement of myocardial T1 values, resulting in 95% Bland-Altman limits of agreement of (- 0.83 to 0.58 ms) and (- 6.57 to 7.36 ms) with mean differences of - 0.13 ms and 0.39 ms, for the pre- and post-contrast, respectively.

CONCLUSION

The C++ multi-core RD was the fastest method on a regular eight-core personal computer for pre- or post-contrast T1 map calculation. The presented software tool (fT1fit) facilitated rapid T1 map and extracellular volume fraction map calculations.

Safety of natural anthraquinone emodin: an assessment in mice

BACKGROUND

Emodin, a natural anthraquinone, has shown potential as an effective therapeutic agent in the treatment of many diseases including cancer. However, its clinical development is hindered by uncertainties surrounding its potential toxicity. The primary purpose of this study was to uncover any potential toxic properties of emodin in mice at doses that have been shown to have efficacy in our cancer studies. In addition, we sought to assess the time course of emodin clearance when administered both intraperitoneally (I.P.) and orally (P.O.) in order to begin to establish effective dosing intervals.

METHODS

We performed a subchronic (12 week) toxicity study using 3 different doses of emodin (~ 20 mg/kg, 40 mg/kg, and 80 mg/kg) infused into the AIN-76A diet of male and female C57BL/6 mice (n = 5/group/sex). Body weight and composition were assessed following the 12-week feeding regime. Tissues were harvested and assessed for gross pathological changes and blood was collected for a complete blood count and evaluation of alanine transaminase (ALT), aspartate transaminase (AST) and creatinine. For the pharmacokinetic study, emodin was delivered intraperitoneally I.P. or P.O. at 20 mg/kg or 40 mg/kg doses to male and female mice (n = 4/group/sex/time-point) and circulating levels of emodin were determined at 1, 4 and 12 h following administration via liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis.

RESULTS

We found that 12 weeks of low (20 mg/kg), medium (40 mg/kg), or high (80 mg/kg) emodin feeding did not cause pathophysiological perturbations in major organs. We also found that glucuronidated emodin peaks at 1 h for both I.P. and P.O. administered emodin and is eliminated by 12 h. Interestingly, female mice appear to metabolize emodin at a faster rate than male mice as evidenced by greater levels of glucuronidated emodin at the 1 h time-point (40 mg/kg for both I.P. and P.O. and 20 mg/kg I.P.) and the 4-h time-point (20 mg/kg I.P.).

CONCLUSIONS

In summary, our studies establish that 1) emodin is safe for use in both male and female mice when given at 20, 40, and 80 mg/kg doses for 12 weeks and 2) sex differences should be considered when establishing dosing intervals for emodin treatment.

Evaluation of a delineation software for cardiac atlas-based autosegmentation: An example of the use of artificial intelligence in modern radiotherapy

PURPOSE

The primary objective of this work was to implement and evaluate a cardiac atlas-based autosegmentation technique based on the "Workflow Box" software (Mirada Medical, Oxford UK), in order to delineate cardiac substructures according to European Society of Therapeutic Radiation Oncology (ESTRO) guidelines; review and comparison with other cardiac atlas-based autosegmentation algorithms published to date.

MATERIALS AND METHODS

Of an atlas of data set from 20 breast cancer patients' CT scans with recontoured cardiac substructures creation according to the ESTRO guidelines. Performance evaluation on a validation data set consisting of 20 others CT scans acquired in the same treatment position: cardiac substructure were automatically contoured by the Mirada system, using the implemented cardiac atlas, and simultaneously manually contoured by a radiation oncologist. The Dice similarity coefficient was used to evaluate the concordance level between the manual and the automatic segmentations.

RESULTS

Dice similarity coefficient value was 0.95 for the whole heart and 0.80 for the four cardiac chambers. Average Dice similarity coefficient value for the left ventricle walls was 0.50, ranging between 0.34 for the apical wall and 0.70 for the lateral wall. Compared to manual contours, autosegmented substructure volumes were significantly smaller, with the exception of the left ventricle. Coronary artery segmentation was unsuccessful. Performances were overall similar to other published cardiac atlas-based autosegmentation algorithms.

CONCLUSION

The evaluated cardiac atlas-based autosegmentation technique, using the Mirada software, demonstrated acceptable performance for cardiac cavities delineation. However, algorithm improvement is still needed in order to develop efficient and trusted cardiac autosegmentation working tools for daily practice.

A Hands-On Organ-Slicing Activity to Teach the Cross-Sectional Anatomy

The presentation of pre-sliced specimens is a frequently used method in the laboratory teaching of cross-sectional anatomy. In the present study, a new teaching method based on a hands-on slicing activity was introduced into the teaching of brain, heart, and liver cross-sectional anatomy. A randomized, controlled trial was performed. A total of 182 third-year medical students were randomized into a control group taught with the prosection mode (pre-sliced organ viewing) and an experimental group taught with the dissection mode (hands-on organ slicing). These teaching methods were assessed by testing the students' knowledge of cross-sectional specimens and cross-sectional radiological images, and analyzing students' feedback. Using a specimen test on three organs (brain, heart, and liver), significant differences were observed in the mean scores of the control and experimental groups: for brain 59.6% (±14.2) vs. 70.1% (±15.5), (P < 0.001, Cohen's d = 0.17); for heart: 57.6% (±12.5) vs. 75.6% (±15.3), (P < 0.001, d = 0.30); and for liver: 60.4% (±14.5) vs. 81.7% (±14.2), (P < 0.001, d = 0.46). In a cross-sectional radiological image test, better performance was also found in the experimental group (P < 0.001). The mean scores of the control vs. experimental groups were as follows: for brain imaging 63.9% (±15.1) vs. 71.1% (±16.1); for heart imaging 64.7% (±14.5) vs. 75.2% (±15.5); and for liver imaging 61.1% (±15.5) vs. 81.2% (±14.6), respectively. The effect sizes (Cohen's d) were 0.05, 0.23, and 0.52, respectively. Students in the lower tertile benefited the most from the slicing experiences. Students' feedback was generally positive. Hands-on slicing activity can increase the effectiveness of anatomy teaching and increase students' ability to interpret radiological images.

Effects of single-dose protons or oxygen ions on function and structure of the cardiovascular system in male Long Evans rats

PURPOSE

Studies are required to determine whether exposures to radiation encountered during manned missions in deep space may have adverse effects on the cardiovascular system. Most of the prior studies on effects of simulated space radiation on the heart and vasculature have been performed in mouse models. To provide data from a second animal species, two studies were performed to assess effects of high-energy charged particle radiation on the heart and abdominal aorta in a rat model.

MATERIALS AND METHODS

In study A, male Long Evans rats were exposed to whole-body protons (250 MeV, 0.5 Gy) or oxygen ions (¹⁶O, 600 MeV/n, 0.5 Gy), and ultrasonography was used to measure in vivo cardiac function and blood flow parameters at 3, 5, 9 and 12 months after radiation, followed by tissue collection at 12 months. In study B, male Long Evans rats were exposed to ¹⁶O (1 GeV/n, 0.01-0.25 Gy), and hearts collected at 6 to 7 and 12 months for histology and western-blots.

RESULTS

Both protons (250 MeV) and ¹⁶O (600 MeV/n) caused a decrease in left ventricular posterior wall thickness at 3-5 months, but did not change echocardiographic measures of cardiac function. In Pulsed-wave Doppler assessment of the abdominal aorta, an increase was seen in mean velocity, peak velocity, and velocity time integral at 12 months after ¹⁶O (600 MeV/n), suggesting a change in vascular function. There were no significant changes in histopathology or histological quantification of total collagens in heart or aorta. On the other hand, an increase was seen in a 75 kDa peptide of collagen type III in the left ventricle of rats exposed to protons (250 MeV) and ¹⁶O (600 MeV/n and 1 GeV/n), suggesting that radiation caused remodeling of existing collagens in the heart. ¹⁶O (600 MeV/n and 1 GeV/n) caused increases in left ventricular protein levels of immune cell markers CD2, CD4, CD8, and CD68.

CONCLUSION

A single low dose of whole body protons or ¹⁶O in male Long Evans rats did not change cardiac function or induce gross pathological changes in the heart or aorta, but induced mild changes in vascular function and remodeling of existing collagens in the heart. Altogether, studies in prior mouse models and the current work in rats indicate minor changes in cardiac function and structure after a low dose of single-ion radiation.

Elastohydrodynamic Scaling Law for Heart Rates

Animal hearts are soft shells that actively pump blood to oxygenate tissues. Here, we propose an allometric scaling law for the heart rate based on the idea of elastohydrodynamic resonance of a fluid-loaded soft active elastic shell that buckles and contracts axially when twisted periodically. We show that this picture is consistent with numerical simulations of soft cylindrical shells that twist-buckle while pumping a viscous fluid, yielding optimum ejection fractions of 35%-40% when driven resonantly. Our scaling law is consistent with experimental measurements of heart rates over 2 orders of magnitude, and provides a mechanistic basis for how metabolism scales with organism size. In addition to providing a physical rationale for the heart rate and metabolism of an organism, our results suggest a simple design principle for soft fluidic pumps.

Medical decision making for 5D cardiac model: Template matching technique and simulation of the fifth dimension

The purpose of this paper is to develop a 5D cardiac model which is inspired from the 5D model for the lungs. This model depends on five variables: the anatomical structure of the 3D heart, temporal dimension and the function of blood flow as the fifth dimension. To test this hypothesis, we took the same mathematical modeling as a reference for the fifth dimension of pulmonary flow where r→_ρ(t)=r→_v(t)+r_f→(t) wherer→_v(t) is the displacement vectors with approximate magnitudes by linear functions of the tidal volume and r_f→(t) is the blood flow. The scans were acquired for 10 patients,in the 404 series for a total of 18,483 images studied in three cases: healthy patient, case of heart failure and aortic stenosis. Where r→_vand r→_f are the unit vectors along the volume of ejection and the blood flow axes, indicating the direction of motion of the object due to heart volume ejection and blood flow variations, respectively. The quantities of α and β coefficients are determined from real-time patient image data. The alpha and beta coefficients are derived from the following dimension equations[mm / ml] [mm*ms / ml] . Since the cardiac system has two diastolic and systolic phases, we have calculated α₁ and β₁ for telediatolic volume and α₂ and β₂ for telesystolic volume throughout the cardiac cycle as a function of the location of the cuts chosen randomly. Fifth-dimensional experiments are used to track, simulate the behavior of blood flow to detect preliminary indications for the identification of stenosis or valve leakage. The average discrepancy was tabulated as the global fraction of systolic ejection. The results shown in Fig. 3 detect a correspondence between the hunting chamber cut and the flow sequence through the orifice of aorta for this patient with suspicious of having an aortic stenosis disease and an ejection fraction about 71% with a maximum of velocity (Vmax) detected=250 (cm / ms) = 2.5 (m / 10-3 s). In this case this patient has a minor stenosis in the aorta. It should be referred that the normalization of this measures is classified such as : Minor stenosis: area 1.5 cm2, Vmax <3 m / moderate stenosis: area 1.0 - 1.5 cm2, Vmax 3 - 4 m / severe stenosis: area <1.0 cm2, Vmax> 4 m / s. For a patient who has an aortic stenosis the cloud of the points is accumulated comparing to the origin of the axis while the patient with a symptom of insufficiency the points are widened with a remarkable gap in the trajectory. To solve the issue of the bad prediction, the inaccuracy of the clouds points of the model 5D, the lack of the exact measurements to estimate the degree of cardiac insufficiency (leakage or stenosis), a solution of 5D imagery was depicted. Our main contribution is to test the validity of the template-matching algorithm and the fifth dimension simulation to provide more clues to detect the aortic stenosis and cardiac insufficiency in the context of medical decision support.

Allometric scaling patterns among the human coronary artery tree, myocardial mass, and coronary artery flow

Human coronary artery tree is a physiological transport system for oxygen and vital materials through a hierarchical vascular network to match the energy demands of myocardium, which has the highest oxygen extraction ratio among body organs and heavily depends on the blood flow for its energy supply. Therefore, it would be reasonable to expect that the key design principle of this arterial network is to minimize energy expenditure, which can be described by allometric scaling law. We enrolled patients who underwent coronary computed tomography angiography without obstructive lesion. The cumulative arterial length (L), volume (V), and diameter (D) in relation to the artery-specific myocardial mass (M) were assessed. Flow rate (Q) was computed using quantitative flow ratio (QFR) measurement in patients who underwent invasive angiography. A total of 638 arteries from 43 patients (mean age 61 years, male gender 65%) were analyzed. A significant power-law relationship was found among L-M, V-M, D-M, V-L, D-L, and V-D, and also among Q-M, Q-L, Q-V, and Q-D in 106 arteries interrogated with QFR (p < .001, all). Our results suggest that the fundamental design principle of the human coronary arterial network may follow allometric scaling law.

Random effects inducing heart pathological dynamics: An approach based on mathematical models

This work deals with an investigation of randomness effects on heart rhythm analysis. A mathematical model composed by three-coupled nonlinear oscillators coupled by time-delayed connections is employed for this aim. In this regard, heart rhythm is governed by delayed-differential equations. Nondeterministic aspects are incorporated considering random connections among oscillators. The main idea is to show that nonlinearities and randomness define together the great variety of possibilities in the heart dynamical system. In general, results corroborate that the model is able to capture the main behaviors of the cardiac system showing that pathological behaviors can evolve from normal rhythms due to random couplings. Experimental data corroborate this argues pointing that nonlinear dynamical analysis is useful for a proper physiological comprehension.

Cardiac function modulates endocardial cell dynamics to shape the cardiac outflow tract

Physical forces are important participants in the cellular dynamics that shape developing organs. During heart formation, for example, contractility and blood flow generate biomechanical cues that influence patterns of cell behavior. Here, we address the interplay between function and form during the assembly of the cardiac outflow tract (OFT), a crucial connection between the heart and vasculature that develops while circulation is under way. In zebrafish, we find that the OFT expands via accrual of both endocardial and myocardial cells. However, when cardiac function is disrupted, OFT endocardial growth ceases, accompanied by reduced proliferation and reduced addition of cells from adjacent vessels. The flow-responsive TGFβ receptor Acvrl1 is required for addition of endocardial cells, but not for their proliferation, indicating distinct modes of function-dependent regulation for each of these essential cell behaviors. Together, our results indicate that cardiac function modulates OFT morphogenesis by triggering endocardial cell accumulation that induces OFT lumen expansion and shapes OFT dimensions. Moreover, these morphogenetic mechanisms provide new perspectives regarding the potential causes of cardiac birth defects.

Left ventricular assist device recovery: does duration of mechanical support matter?

Heart failure is a widespread condition in the United States that is predicted to significantly increase in prevalence in the next decade. Many heart failure patients are given a left ventricular assist device (LVAD) while they wait for a heart transplant, while those that are not able to undergo a heart transplant may be given an LVAD permanently. However, past studies have observed a small subset of heart failure patients that recovered cardiac function of their native heart after being placed on an LVAD. As a result, some patients have been able to have their LVAD explanted and no longer needed a heart transplant. In this review, we analyzed the data of 15 studies that observed recovery of cardiac function in LVAD patients in order to investigate the effects that duration of LVAD support has on patient outcomes. From our review, we identified that there may be negative consequences of prolonged duration of mechanical support such as myocardial atrophy and abnormal calcium cycling as well as circumstances that may allow for a longer duration of LVAD support such as in patients using a continuous-flow LVAD, non-ischemic cardiomyopathy patients, and the specific pharmacological therapy.

Measurement method of optical properties of ex vivo biological tissues of rats in the near-infrared range

An optical fiber-based supercontinuum setup and a custom-made spectrophotometer that can measure spectra from 1100 to 2300 nm, are used to describe attenuation properties from different ex vivo rat tissues. Our method is able to differentiate between scattering and absorption coefficients in biological tissues. Theoretical assumptions combined with experimental measurements demonstrate that, in this infrared range, tissue attenuation and absorption can be accurately measured, and scattering can be described as the difference between both magnitudes. Attenuation, absorption, and scattering spectral coefficients of heart, brain, spleen, retina, and kidney are given by applying these theoretical and experimental methods. Light through these tissues is affected by high scattering, resulting in multiple absorption events, and longer wavelengths should be used to obtain lower attenuation values. It can be observed that the absorption coefficient has a similar behavior in the samples under study, with two main zones of absorption due to the water absorption bands at 1450 and 1950 nm, and with different absolute absorption values depending on the constituents of each tissue. The scattering coefficient can be determined, showing slight differences between retina and brain samples, and among heart, spleen and kidney tissues.

A smaller heart-aorta-angle associates with ascending aortic dilatation and increases wall shear stress

OBJECTIVES

The aim of this study was to evaluate whether the orientation of the heart, measured as an angle between the long axis of the heart and ascending aorta midline (heart-aorta-angle, HAA), associates with ascending aortic (AA) dilatation. Furthermore, the association between HAA and wall shear stress (WSS) was studied.

METHODS

HAA was retrospectively measured in 1000 consecutive coronary artery computed tomographic angiography (CCTA) images in patients with low-to-moderate pretest probability for coronary artery disease (CAD). To evaluate the effects of HAA on AA flow, 4D flow MRI was performed for 28 patients with AA dilatation (> 40 mm) and WSS was analyzed.

RESULTS

The mean age of patients undergoing CCTA was 52.9 ± 9.8 years; 66.5% were women. Their median HAA was 128.7° and interquartile range 123.3-134.1°. HAA was significantly smaller in patients with dilated AA (median 126.7° [121.3-130.8°]) compared with the patients with normal AA (median 129.5° [124.3-135.3°], p < 0.001). HAA was smaller in males (p < 0.001) and in patients with diabetes (p = 0.016), hypertension (p = 0.001), CAD (p = 0.003), hypercholesterolemia (p < 0.001), and bicuspid aortic valve (p = 0.025) than without these factors. In a subpopulation without any of these underlying diseases (n = 233), HAA was still significantly smaller in the patients with dilated AA (median 127.9° [124.3-134.3°]) compared with patients with normal AA (median 131.9° [127.6-136.9°], p = 0.013). In 4D flow MRI, a smaller HAA correlated with increased total WSS in the outer curvature of the proximal AA (r = - 0.510, p = 0.006).

CONCLUSION

A smaller HAA associates with AA dilatation and affects the blood flow in the proximal AA.

KEY POINTS

• A smaller angle between the long axis of the heart and ascending aorta midline associated with ascending aortic dilatation. • A smaller heart-aorta-angle correlated with increased total wall shear stress in the outer curvature of the proximal ascending aorta.

Seasonal variation in body composition in an Afrotropical passerine bird: increases in pectoral muscle mass are, unexpectedly, associated with lower thermogenic capacity

Phenotypic flexibility in avian metabolic rates and body composition have been well-studied in high-latitude species, which typically increase basal metabolic rate (BMR) and summit metabolism (M_sum) when acclimatized to winter conditions. Patterns of seasonal metabolic acclimatization are more variable in lower-latitude birds that experience milder winters, with fewer studies investigating adjustments in avian organ and muscle masses in the context of metabolic flexibility in these regions. We quantified seasonal variation (summer vs winter) in the masses of organs and muscles frequently associated with changes in BMR (gizzard, intestines and liver) and M_sum (heart and pectoral muscles), in white-browed sparrow-weavers (Plocepasser mahali). We also measured pectoral muscle thickness using a portable ultrasound system to determine whether we could non-lethally estimate muscle size. A concurrent study measured seasonal changes in BMR and M_sum in the same population of sparrow-weavers, but different individuals. There was no seasonal variation in the dry masses of the gizzard, intestines or liver of sparrow-weavers, and during the same period, BMR did not vary seasonally. We found significantly higher heart (~ 18% higher) and pectoral muscle (~ 9% higher) dry mass during winter, although ultrasound measurements did not detect seasonal changes in pectoral muscle size. Despite winter increases in pectoral muscle mass, M_sum was ~ 26% lower in winter compared to summer. To the best of our knowledge, this is the first study to report an increase in avian pectoral muscle mass but a concomitant decrease in thermogenic capacity.

Evaluation of the Toxicity of Sugammadex in Zebrafish Larvae

BACKGROUND

Sugammadex is a new neuromuscular blockade reversal agent. Recently, it has been used in patients under general anesthesia. However, sugammadex could be toxic to fetuses and pediatric patients under 3 years of age. In this study, we demonstrated the safety of sugammadex in fetuses, using zebrafish larvae. Furthermore, its neurotoxicity was evaluated using neuronal cell lines.

METHODS

We used SH-SY5Y cells to determine the viability of neuronal cells treated with sugammadex. Zebrafish larvae were used to determine the teratogenic effects of sugammadex.

RESULTS

Sugammadex showed no adverse effects on neuronal cells and zebrafish larvae. The survival rates of neuronal cells were not different in all concentrations. In addition, the heart formation of zebrafish embryos, which were exposed to various concentrations of sugammadex, were not different.

CONCLUSION

This study demonstrated the feasibility of using sugammadex during pregnancy. However, further clinical studies will be required to extrapolate these results to humans.

Evaluating the Portability of an NLP System for Processing Echocardiograms: A Retrospective, Multi-site Observational Study

While natural language processing (NLP) of unstructured clinical narratives holds the potential for patient care and clinical research, portability of NLP approaches across multiple sites remains a major challenge. This study investigated the portability of an NLP system developed initially at the Department of Veterans Affairs (VA) to extract 27 key cardiac concepts from free-text or semi-structured echocardiograms from three academic edical centers: Weill Cornell Medicine, Mayo Clinic and Northwestern Medicine. While the NLP system showed high precision and recall easurements for four target concepts (aortic valve regurgitation, left atrium size at end systole, mitral valve regurgitation, tricuspid valve regurgitation) across all sites, we found moderate or poor results for the remaining concepts and the NLP system performance varied between individual sites.

Accelerated coronary MRI with sRAKI: A database-free self-consistent neural network k-space reconstruction for arbitrary undersampling

Purpose

To accelerate coronary MRI acquisitions with arbitrary undersampling patterns by using a novel reconstruction algorithm that applies coil self-consistency using subject-specific neural networks.

Methods

Self-consistent robust artificial-neural-networks for k-space interpolation (sRAKI) performs iterative parallel imaging reconstruction by enforcing self-consistency among coils. The approach bears similarity to SPIRiT, but extends the linear convolutions in SPIRiT to nonlinear interpolation using convolutional neural networks (CNNs). These CNNs are trained individually for each scan using the scan-specific autocalibrating signal (ACS) data. Reconstruction is performed by imposing the learned self-consistency and data-consistency, which enables sRAKI to support random undersampling patterns. Fully-sampled targeted right coronary artery MRI was acquired in six healthy subjects. The data were retrospectively undersampled, and reconstructed using SPIRiT, l₁-SPIRiT and sRAKI for acceleration rates of 2 to 5. Additionally, prospectively undersampled whole-heart coronary MRI was acquired to further evaluate reconstruction performance.

Results

sRAKI reduces noise amplification and blurring artifacts compared with SPIRiT and l₁-SPIRiT, especially at high acceleration rates in targeted coronary MRI. Quantitative analysis shows that sRAKI outperforms these techniques in terms of normalized mean-squared-error (~44% and ~21% over SPIRiT and l1-SPIRiT at rate 5) and vessel sharpness (~10% and ~20% over SPIRiT and l₁-SPIRiT at rate 5). Whole-heart data shows the sharpest coronary arteries when resolved using sRAKI, with 11% and 15% improvement in vessel sharpness over SPIRiT and l₁-SPIRiT, respectively.

Conclusion

sRAKI is a database-free neural network-based reconstruction technique that may further accelerate coronary MRI with arbitrary undersampling patterns, while improving noise resilience over linear parallel imaging and image sharpness over l₁ regularization techniques.

Toward Noninvasive Mapping of Diffuse Scattering in the Presence of Motion

Ultrasonic coda wave analysis techniques localize defects in fields such as seismography and nondestructive testing. In medical ultrasound, these techniques might provide novel mapping of tissue properties in diseases characterized by local fibrosis. In this work, we present an approach for localizing variation in scattering properties in the diffuse regime with an array transducer in medical ultrasound. This approach estimates coda wave decorrelation as the array is displaced by 0.5 mm, allowing data acquisition at two slightly different spatial locations. An inverse problem is solved as in nondestructive testing based on coda wave decorrelation estimates and a locally-estimated diffusion constant. The developed approach is demonstrated in a tissue-mimicking phantom to assess sensitivity to variation in scattering properties. Next, the ability of the approach for localizing regions of increased multiple scattering in biological tissues is assessed with a large multiple scattering bead in an ex vivo porcine cardiac sample. Through these experiments, the ability to map variation in multiple scattering is demonstrated for the first time, with a mean localization error of 1.42 ± 3.5 mm for this low-resolution mapping technique. While the goal of this technique is to map defects in the diffuse regime rather than to develop a conventional image, contrast ratios in the resulting images were in good agreement with scattering concentrations in phantom studies: 1.98 ± 0.05 for a 2× scattering target, 1.37 ± 0.02 for a 1.4× scattering target, 0.65 ± 0.02 for a 0.7× scattering target, and 0.49 ± 0.03 for a 0.5× scattering targets.

WHAT ANATOMIC FEATURES GOVERN PERSONAL LONG-TERM HEALTH RISKS FROM BREAST CANCER RADIOTHERAPY?

Breast cancer radiotherapy may in the long term lead to radiation-induced secondary cancer or heart disease. These health risks hugely vary among patients, partially due to anatomy-driven differences in doses deposited to the heart, ipsilateral lung and contralateral breast. We identify four anatomic features that largely cover these dosimetric variations to enable personalized risk estimates. For three exemplary, very different risk scenarios, the given parameter set reproduces 63-74% of the individual risk variability for left-sided breast cancer patients. These anatomic features will be used in the PASSOS software to support decision processes in breast-cancer therapy.

Evaluation of algorithms for Multi-Modality Whole Heart Segmentation: An open-access grand challenge

Knowledge of whole heart anatomy is a prerequisite for many clinical applications. Whole heart segmentation (WHS), which delineates substructures of the heart, can be very valuable for modeling and analysis of the anatomy and functions of the heart. However, automating this segmentation can be challenging due to the large variation of the heart shape, and different image qualities of the clinical data. To achieve this goal, an initial set of training data is generally needed for constructing priors or for training. Furthermore, it is difficult to perform comparisons between different methods, largely due to differences in the datasets and evaluation metrics used. This manuscript presents the methodologies and evaluation results for the WHS algorithms selected from the submissions to the Multi-Modality Whole Heart Segmentation (MM-WHS) challenge, in conjunction with MICCAI 2017. The challenge provided 120 three-dimensional cardiac images covering the whole heart, including 60 CT and 60 MRI volumes, all acquired in clinical environments with manual delineation. Ten algorithms for CT data and eleven algorithms for MRI data, submitted from twelve groups, have been evaluated. The results showed that the performance of CT WHS was generally better than that of MRI WHS. The segmentation of the substructures for different categories of patients could present different levels of challenge due to the difference in imaging and variations of heart shapes. The deep learning (DL)-based methods demonstrated great potential, though several of them reported poor results in the blinded evaluation. Their performance could vary greatly across different network structures and training strategies. The conventional algorithms, mainly based on multi-atlas segmentation, demonstrated good performance, though the accuracy and computational efficiency could be limited. The challenge, including provision of the annotated training data and the blinded evaluation for submitted algorithms on the test data, continues as an ongoing benchmarking resource via its homepage (www.sdspeople.fudan.edu.cn/zhuangxiahai/0/mmwhs/).

Furcellaran-Coated Microcapsules as Carriers of Cyprinus carpio Skin-Derived Antioxidant Hydrolysate: An In Vitro and In Vivo Study

Carp skin gelatine hydrolysate (CSGH) may be a possible bioactive peptide source, as promising antioxidant properties have been noted during in vivo testing. Hence, the present study focused on improving the bioavailability of the antioxidant peptides from CSGH and on the use of furcellaran (FUR), which can protect the biopeptides during digestion in the gastrointestinal tract. Therefore, in this study, microcapsules coated with furcellaran and containing CSGH cores were prepared. The structural properties of the sample were determined using FT-IR and SEM analysis. The antioxidant properties of hydrolysate, uncoated, and encapsulated samples were investigated. In vivo analysis included determination of its safety in an animal organism and evaluation of the lipid profile, antioxidant blood status, and mRNA expression of some genes involved in antioxidant status in Wistar rats. The results showed no adverse effects of microencapsulated protein hydrolysates in laboratory animals. Nonetheless, there was a statistically significant rise in the level of total antioxidant status blood serum among animals consuming CSGH and not inducing oxidative stress. This can be viewed as a promising indication of the positive effects of antioxidant properties tested in vivo. The process of CSGH microencapsulation in FUR cause a decrease in antioxidant hydrolysate activity, both in vitro, as well as in healthy Wistar rats. When considering the results of the presented diverse therapeutic potential, further research on CSGH being a potential bioactive peptide source used as a functional food or nutraceutical, but with a different microencapsulation coating, is encouraged.

An Overview of the Cardiac Catheterization Lab

The role of the cardiac catheterization lab technologist differs from other radiologic technologist roles. This article demystifies the cardiac catheterization lab by explaining commonly performed procedures. The anatomy and pathology that might require treatment in the catheterization lab also are discussed.

Myocardial Fiber Mapping of Rat Hearts, Using Apparent Backscatter, with Histologic Validation

Myocardial fiber architecture is a physiologically important regulator of ejection fraction, strain and pressure development. Apparent ultrasonic backscatter has been shown to be a useful method for recreating the myocardial fiber architecture in human-sized sheep hearts because of the dependence of its amplitude on the relative orientation of a myofiber to the angle of ultrasonic insonification. Thus, the anisotropy of the backscatter signal is linked to and provides information about the fiber orientation. In this study, we sought to determine whether apparent backscatter could be used to measure myofiber orientation in rodent hearts. Fixed adult-rat hearts were imaged intact, and both a transmural cylindrical core and transmural wedge of the left ventricular free wall were imaged. Cylindrical core samples confirmed that backscatter anisotropy could be measured in rat hearts. Ultrasound and histologic analysis of transmural myocardial wedge samples confirmed that the apparent backscatter could be reproducibly mapped to fiber orientation (angle of the fiber relative to the direction of insonification). These data provided a quantitative relationship between the apparent backscatter and fiber angle that was applied to whole-heart images. Myocardial fiber architecture was successfully measured in rat hearts. Quantifying myocardial fiber architecture, using apparent backscatter, provides a number of advantages, including its scalable use from rodents to man, its rapid low-cost acquisition and minimal contraindications. The method outlined in this study provides a method for investigators to begin detailed assessments of how the myocardial fiber architecture changes in preclinical disease models, which can be immediately translated into the clinic.

Cardiac structure and function characterized across age groups and between sexes in healthy wild-born captive chimpanzees (Pan troglodytes) living in sanctuaries

OBJECTIVE

To comprehensively characterize cardiac structure and function, from infancy to adulthood, in male and female wild-born captive chimpanzees (Pan troglodytes) living in sanctuaries.

ANIMALS

290 wild-born captive chimpanzees.

PROCEDURES

Physical and echocardiographic examinations were performed on anesthetized chimpanzees in 3 sanctuaries in Africa between October 2013 and May 2017. Results were evaluated across age groups and between sexes, and potential differences were assessed with multiple 1-way independent Kruskal-Wallis tests.

RESULTS

Results indicated that left ventricular diastolic and systolic function declined at a younger age in males than in females. Although differences in right ventricular diastolic function were not identified among age groups, right ventricular systolic function was lower in adult chimpanzees (> 12 years old), compared with subadult (8 to 12 years old) and juvenile (5 to 7 years old) chimpanzees. In addition, male subadult and adult chimpanzees had larger cardiac wall dimensions and chamber volumes than did their female counterparts.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of the present study provided useful reference intervals for cardiac structure and function in captive chimpanzees categorized on the basis of age and sex; however, further research is warranted to examine isolated and combined impacts of blood pressure, age, body weight, and anesthetic agents on cardiac structure and function in chimpanzees.