Fully automated cardiac MRI segmentation using dilated residual network.

PURPOSE: Cardiac ventricle segmentation from cine magnetic resonance imaging (CMRI) is a recognized modality for the noninvasive assessment of cardiovascular pathologies. Deep learning based algorithms achieved state-of-the-art result performance from CMRI cardiac ventricle segmentation. However, most approaches received less attention at the bottom layer of UNet, where main features are lost due to pixel degradation. To increase performance, it is important to handle the bottleneck layer of UNet properly. Considering this problem, we enhanced the performance of main features at the bottom layer of network. METHOD: We developed a fully automatic pipeline for segmenting the right ventricle (RV), myocardium (MYO), and left ventricle (LV) by incorporating short-axis CMRI sequence images. We propose a dilated residual network (DRN) to capture the features at full resolution in the bottleneck of UNet. Thus, it significantly increases spatial and temporal information and maintains the localization accuracy. A data-augmentation technique is employed to avoid overfitting and class imbalance problems. Finally, output from each expanding path is added pixel-wise to improve the training response. RESULTS: We used and evaluated our proposed method on automatic cardiac diagnosis challenge (ACDC). The test set consists of 50 patient records. The overall dice similarity coefficient (DSC) we achieved for our model is 0.924 ± 0.03, 0.907 ± 0.01, and 0.949 ± 0.05 for RV, MYO, and LV, respectively. Similarly, we obtained hausdorff distance (HD) scores of 10.09 ± 0.01, 7.25 ± 0.05, and 6.86 ± 0.02 mm for RV, MYO, and LV, respectively. The results show superior performance and outperformed state-of-the-art methods in terms of accuracy and reached expert-level segmentation. Consequently, the overall DSC and HD result improved by 1.0% and 1.5%, respectively. CONCLUSION: We designed a dilated residual UNet (DRN) for cardiac ventricle segmentation using short-axis CMRI. Our method has the advantage of restoring and capturing spatial and temporal information by expanding the receptive field without degrading the image main features in the bottleneck of UNet. Our method is highly accurate and quick, taking 0.28 s on average to process 2D MR images. Also, the network was designed to work on predictions of individual MR images to segment the ventricular region, for which our model outperforms many state-of-the-art methods.

Atypically Shaped Cardiomyocytes (ACMs): The Identification, Characterization and New Insights into a Subpopulation of Cardiomyocytes.

In the adult mammalian heart, no data have yet shown the existence of cardiomyocyte-differentiable stem cells that can be used to practically repair the injured myocardium. Atypically shaped cardiomyocytes (ACMs) are found in cultures of the cardiomyocyte-removed fraction obtained from cardiac ventricles from neonatal to aged mice. ACMs are thought to be a subpopulation of cardiomyocytes or immature cardiomyocytes, most closely resembling cardiomyocytes due to their spontaneous beating, well-organized sarcomere and the expression of cardiac-specific proteins, including some fetal cardiac gene proteins. In this review, we focus on the characteristics of ACMs compared with ventricular myocytes and discuss whether these cells can be substitutes for damaged cardiomyocytes. ACMs reside in the interstitial spaces among ventricular myocytes and survive under severely hypoxic conditions fatal to ventricular myocytes. ACMs have not been observed to divide or proliferate, similar to cardiomyocytes, but they maintain their ability to fuse with each other. Thus, it is worthwhile to understand the role of ACMs and especially how these cells perform cell fusion or function independently in vivo. It may aid in the development of new approaches to cell therapy to protect the injured heart or the clarification of the pathogenesis underlying arrhythmia in the injured heart.

Endolysosomal calcium release and cardiac physiology.

Calcium ions play a central role in determining the timing and magnitude of the pumping action of heart muscle in a process which couples electrical activity of action potentials to muscle contraction. Regulation of this excitation-contraction coupling is achieved by Ca2+ signalling mechanisms that include activation of Ca2+ mobilising agents which influence the movement of Ca2+ between intracellular membrane-bound compartments. Research discussed here concerns endolysosomes, which play diverse signalling roles throughout the body. In the heart, a population of endolysosomes is strategically placed close to two other important membrane bound organelles, sarcoplasmic reticulum (SR) and mitochondria. In each case this proximity provides a structural basis for highly localised Ca2+ signalling in nanodomains between endolysosomes and the organelle. Ca2+ is released from endolysosomes via at least two varieties of two-pore domain channels (TPCs) in mammalian cardiac cells, TPC1 determining the interaction with mitochondria, while TPC2 controls the influence on SR. Ca2+ release via both TPC1 and TPC2 is enhanced by the Ca2+ mobilising agent, nicotinic acid adenine dinucleotide phosphate (NAADP) which is synthesised in the heart primarily by CD38. In normal physiology, NAADP plays an important regulatory role in which Ca2+ is released from endolysosomes via TPC2 channels into a nanodomain next to SR, and an amplification mechanism resulting from Ca2+ activation of CaMKII enhances SR Ca2+ uptake by the enzyme SERCA to increase the amplitude of the Ca2+ transient accompanying action potentials. A separate mechanism underlies pathology associated with reperfusion after ischaemia, when NAADP-mediated endolysosomal calcium release via TPC1 acts on nearby mitochondria resulting in abnormal SR Ca2+ release and extreme disruption to the normal excitation-contraction coupling process, causing muscle damage. There are different roles for PKA in the two pathways dependant on TPC1 or TPC2. Oxidising conditions during reperfusion following ischaemia promote disulphide bond formation in PKAIalpha causing accumulation of PKAI holoenzyme in endolysosomes and cardioprotective inhibition of TPC1 channels. In the case of TPC2, PKAII actions are thought to enhance NAADP synthesis by CD38 therefore promoting the endolysosomal influence on SR Ca2+. Excessive activation of this pathway leads to cardiac arrhythmias and hypertrophy.

Persistent Ventricle Partitioning in the Adult Zebrafish Heart.

The vertebrate heart integrates cells from the early-differentiating first heart field (FHF) and the later-differentiating second heart field (SHF), both emerging from the lateral plate mesoderm. In mammals, this process forms the basis for the development of the left and right ventricle chambers and subsequent chamber septation. The single ventricle-forming zebrafish heart also integrates FHF and SHF lineages during embryogenesis, yet the contributions of these two myocardial lineages to the adult zebrafish heart remain incompletely understood. Here, we characterize the myocardial labeling of FHF descendants in both the developing and adult zebrafish ventricle. Expanding previous findings, late gastrulation-stage labeling using drl-driven CreERT2 recombinase with a myocardium-specific, myl7-controlled, loxP reporter results in the predominant labeling of FHF-derived outer curvature and the right side of the embryonic ventricle. Raised to adulthood, such lineage-labeled hearts retain broad areas of FHF cardiomyocytes in a region of the ventricle that is positioned at the opposite side to the atrium and encompasses the apex. Our data add to the increasing evidence for a persisting cell-based compartmentalization of the adult zebrafish ventricle even in the absence of any physical boundary.

The control of cardiac ventricular excitability by autonomic pathways.

Central to the genesis of ventricular cardiac arrhythmia are variations in determinants of excitability. These involve individual ionic channels and transporters in cardiac myocytes but also tissue factors such as variable conduction of the excitation wave, fibrosis and source-sink mismatch. It is also known that in certain diseases and particularly the channelopathies critical events occur with specific stressors. For example, in hereditary long QT syndrome due to mutations in KCNQ1 arrhythmic episodes are provoked by exercise and in particular swimming. Thus not only is the static substrate important but also how this is modified by dynamic signalling events associated with common physiological responses. In this review, we examine the regulation of ventricular excitability by signalling pathways from a cellular and tissue perspective in an effort to identify key processes, effectors and potential therapeutic approaches. We specifically focus on the autonomic nervous system and related signalling pathways.

Cinnamon intake reduces serum T3 level and modulates tissue-specific expression of thyroid hormone receptor and target genes in rats.

BACKGROUND: Cinnamon has several effects on energy metabolism. However, no data exist on the impact of cinnamon intake on thyroid hormone serum concentrations and action, since thyroid hormones (THs) play a major role in metabolism. RESULTS: Male rats were treated with cinnamon water extract (400 mg kg(-1) body weight, 25 days). Cinnamon supplementation resulted in a lower serum total T3 level accompanied by normal serum T4 and TSH levels. The cinnamon-treated rats did not exhibit significant differences in TSHß subunit, TRß or deiodinase type 2 mRNA expression in the pituitary. In the liver, cinnamon did not change the TRß protein expression or the deiodinase type 1 mRNA expression, suggesting that there were no changes in T3 signaling or metabolism in this organ. However, mitochondrial GPDH, a target gene for T3 in the liver, exhibited no changes in mRNA expression, although its activity level was reduced by cinnamon. In the cardiac ventricle, T3 action was markedly reduced by cinnamon, as demonstrated by the lower TRα mRNA and protein levels, reduced SERCA2a and RyR2 and increased phospholamban mRNA expression. CONCLUSION: This study has revealed that TH action is a novel target of cinnamon, demonstrating impairment of T3 signaling in the cardiac ventricles. © 2015 Society of Chemical Industry.

Miocardiocitos conducentes ventriculares / Leading ventricular cardiomyocytes

Objetivo: Exponer las características histológicas y funcionales que se presentan en el tejido muscular estriado cardíaco especializado en la conducción del estímulo eléctrico y sus implicaciones actuales en las arritmias cardíacas. Materiales y métodos: Se seleccionaron publicaciones en revistas indexadas en las bases PubMed, Wiley, Ovid-Medline y Science Direct. Los descriptores MESH utilizados para la búsqueda fueron cardiac myocytes, myocardium, heart conduction system. Se acoplaron los conceptos histology y arrhythmia. Se revisaron artículos publicados entre 1990 a 2014, originales, reportes de caso y revisiones, relacionados con los conceptos de desarrollo embrionario, diferenciación celular, morfología normal y alteración de los miocardiocitos conducentes ventriculares. Se revisó el resumen de 317 artículos, de los que se clasificaron 75 para lectura completa y de estos, 52 se seleccionaron para la redacción del presente artículo. Conclusión: Los estudios actuales se encaminan hacia las simulaciones del sistema de conducción para establecer otras causas de arritmia y opciones de tratamiento. La terapia con células indiferenciadas y las técnicas moleculares de modificación genética hacen parte de estos estudios, así como la implementación de terapias alternativas no invasivas en el tratamiento de las arritmias cardíacas.

Objective: To expose the histological and functional characteristics that occur in heart striated muscle tissue specialized in the conduction of electrical stimulation and its current implications for cardiac arrhythmias. Materials and methods: Publications in indexed journals in PubMed, Wiley, Ovid-Medline and Science Direct databases were selected. The MESH descriptors used for the search were cardiac myocytes, myocardium and heart conduction system. The concepts of histology and arrhythmia were mated. Articles published from 1990 to 2014 were reviewed as well as the original ones, case reports and reviews related to the concepts of embryonic development, cell differentiation and normal morphology alteration of the leading ventricular cardiomyocytes. The summary of 317 articles were read, from which 75 were classified to complete reading and finally 52 were selected for the drafting of this article. Conclusion: Current studies are directed towards the driving system simulation to establish other causes of arrhythmia and its treatment options. Not only therapies with undifferentiated cells and molecular genetic modification techniques are part of these studies but also the implementation of alternative therapies that are not invasive in the treatment of cardiac arrhythmias.

Comparison of right ventricular measurements and SFRV in fetuses with and without tricuspid regurgitation at 11+0 and 13+6 weeks' gestation.

OBJECTIVES: To compare right ventricular dimensions and systolic shortening fraction of the right ventricle (SFRV) in fetuses with tricuspid regurgitation (TR [+]) to those without tricuspid regurgitation (TR [-]). METHODS: Unselected patients presenting for first trimester screening between 11 + 0 and 13 + 6 weeks' gestation were examined for the presence or absence of fetal tricuspid regurgitation using a standard approach. Only euploid fetuses without structural anomalies were included in the study. The heart was examined with the aid of M-mode using a previously described method. The right ventricular diastolic diameter (RVDD) and right ventricular systolic diameter (RVSD) were measured on stored M-mode images and the SFRV was calculated using the following formula [(RVDD-RVSD)/RVDD] × 100. RESULTS: A total of 69 fetuses (n = 44 (TR [-]); n = 25 (TR [+])) were examined. The two groups were similar in maternal age, gestational age and nuchal translucency (NT) measurements. The SFRV was noted not to change with gestational age and there was no statistical difference between the two groups. Both the RVDD and the RVSD increased with gestational age. The calculated delta RVDD was statistically larger in the TR [+] group (mean: 0.29, CI 95%: 0.054-0.532) than the TR [-] group (mean: 0.013, CI 95%: -0.128 to 0.154) (p < 0.05). This was not true for the delta RVSD: TR [+] (mean: 0.17, CI 95%: 0.015-0.325) versus TR [-] group (mean: 0.035, CI 95%: -0.061 to 0.131). However, there was a trend towards larger RVSD in the TR [+] group (p = 0.13). CONCLUSIONS: The presence of TR appears to be associated with an increased RVDD in normal fetuses between 11 + 0 and 13 + 6 weeks' gestation.

Study of the cardiac left atrioventricular valvar complex in water buffaloes (Bubalus bubalis) of the Jafarabadi breed / Estudo do complexo valvar atrioventricular cardíaco esquerdo em búfalos (Bubalus bubalis) da raça Jafarabadi

Atrioventricular valve complex of 30 Jafarabadi water buffaloes, adult males were studied in this research with no heart diseases. The animals were obtained from a slaughterhouse in Brazilian State of Parana. The hearts were opened at the third portion affording access to the valve complex. The complexes had its area, number and type of tendinous cords submitted to analysis. The results showed that the complex is composed by two cusps and four accessory cusps, two or three papillary muscles in which 10-25 tendinous cords fix on the cusps that face the ventricle wall. The total area of the complex was on average 38.56cm², with a minimum of 24.96cm² and a maximum of 55.54cm². Statistically, no relation between the number of cords and the cusps' area where they are inserted or with the number of papillary muscle where they originated from was observed.

Foram estudados os complexos valvares atrioventricular esquerdo de 30 búfalos da raça Jafarabadi, machos e adultos, sem alterações cardíacas, provenientes de abatedouros do Estado do Paraná. Os corações foram examinados em seu terço médio para acesso ao complexo valvar, que foi submetido a estudos de área, número e tipificação de cordas tendíneas. Os resultados demonstram que este complexo é formado por duas cúspides principais e quatro cúspides acessórias, apresentam em sua formação de 2-3 músculos papilares, nos quais se inserem de 10-25 cordas tendíneas, que se fixam em cúspides voltadas para a parede do ventrículo. A área total deste complexo apresenta uma média de 38,56cm² com um mínimo de 24,96cm² e um máximo de 55,54cm². Estatisticamente não há relação entre número de cordas e a área da cúspide onde estas estão inseridas, nem com o número de músculos papilares dos quais elas provem.

Effects of Rh2 on cardiac hemodynamics and electrophysiological parameters in anesthetic rats / 中国药理学通报

Aim To observe the effects of Rh2 on the hemodynamics and electrophysiological parameters in anesthetic rats. Methods The changes of hemodynamics and electrophysiological parameters in anesthetic rats were tested after administration with Rh2, such as SAP, DAP, MAP, LVSP, LVDP, LVEDP, ?dp/dt_ max,HR,RRP and ERP. Results Rh2 increased SAP,DAP,MAP,LVSP,?dp/dt_ max with the decrease of LVEDP. It had no distinct effects on HR, ECG, RRP and ERP. Conclusion Rh2 has the effects of increasing SAP,DAP and MAP in anesthetic rats and has no influence on HR, ECG and cardiac ventricle electrophysiological parameter, suggesting that the effect of increasing blood pressure could be related to the increases of peripheral resistance.