Gut microbiota and cardiac arrhythmia

New Insights of Cardiac Arrhythmias Associated with Sleep-Disordered Breathing: From Mechanisms to Clinical Implications-A Narrative Review

Although most research has concentrated on the link between sleep apnea and atrial fibrillation, obstructive sleep apnea (OSA) is also associated with ventricular arrhythmias. These cardiac arrhythmias can be triggered by repeated episodes of hypoxemia, hypercapnia, acidosis, intrathoracic pressure fluctuations, reoxygenation, and other mechanisms that occur during apnea and hypopnea. Studies show that OSA reduces the effectiveness of arrhythmia treatments, such as antiarrhythmic medications and radiofrequency current ablation. Several non-randomized studies indicate that treating sleep apnea syndrome with continuous positive airway pressure (CPAP) may help maintain sinus rhythm following electrical cardioversion and increase the success rates of catheter ablation. This review aims to thoroughly examine the role of OSA in the development of cardiac arrhythmias. Screening for OSA and arrhythmias in patients with OSA provides vital information on the need for additional interventions, such as CPAP therapy, anticoagulation, antiarrhythmic drug therapy, catheter ablation for specific arrhythmias, or device therapy. New therapies for OSA treatment have the potential to significantly influence arrhythmia development in patients with sleep-disordered breathing. However, further research is required to validate these findings and formulate comprehensive treatment protocols.

Gut microbiome and inflammation in cardiovascular drug response: trends in therapeutic success and commercial focus

The intricate Gut microbiome is evolving as an important system and is hypothesized to be a "metabolic organ" within the host. Alterations in Gut microbiota and inflammation associated with several diseases play a crucial role in drug transformation through microbiota-host co-metabolism, modified pharmacokinetic and pharmacodynamics profiles, and may result in the formation of toxic metabolites with interference in drug response. In recent studies, a large number of drugs are reported that are co-metabolized by the host and the Gut microbial enzymes. we summarize the direct and indirect involvement of Gut microbiome promotion or inhibition of cardiovascular diseases, mechanisms on bioavailability, and therapeutic outcomes of cardiovascular drugs, particularly pharmacokinetics and pharmacodynamics profiles in light of AUC, Tmax, Cmax, and bioavailability and drug transportation via immune cells, inter-individual variations in intestinal microbial taxonomy, influence of drugs on diversity and richness of microflora, high lightening limitations and significance of in personalized medicine. Recent advances in target-drug delivery by nanoparticles with limitations and challenges in application are discussed. The cross-talk between Gut microbiota and cardiovascular drugs signifies a better understanding and rationale for targeting the Gut microbiota to improve the therapeutic outcome for cardiovascular diseases, with present-day limitations.

Remodelling of T-Tubules and Associated Calcium Handling Dysfunction in Heart Failure: Mechanisms and Therapeutic Insights

In cardiomyocytes, transverse tubules (T-tubules) are sarcolemmal invaginations that facilitate excitation-contraction coupling and diastolic function. The clinical significance of T-tubules has become evident in that their remodelling is recognised as a hallmark feature of heart failure (HF) and a key contributor to disrupted Ca2+ homeostasis, compromised cardiac function, and arrhythmogenesis. Further investigations have revealed that T-tubule remodelling is particularly pronounced in HF with reduced ejection fraction (HFrEF), but not in HF with preserved ejection fraction, implying that T-tubule remodelling may play a crucial pathophysiologic role in HFrEF. While research on the functional importance of T-tubules is ongoing, T-tubule remodelling has been found to be reversible. That finding has triggered a surge in studies aimed at identifying specific therapeutic approaches for HFrEF. This review discusses the functional importance of T-tubules and their microdomains, the pathophysiology of T-tubule remodelling, and the potential mechanisms of current HFrEF therapeutic approaches in reversing T-tubule alterations. We also highlight discrepancies regarding the roles of T-tubule proteins in the recovery process across studies to offer valuable insights for future research.

Aged gut microbiota promotes arrhythmia susceptibility via oxidative stress

Arrhythmias and sudden cardiac death (SCD) impose a significant burden. Their prevalence rises with age and is linked to gut dysbiosis. Our study aimed to determine whether aged gut microbiota affects arrhythmogenesis. Here, we demonstrated that arrhythmia susceptibility in aged mice could be transmitted to young mice using fecal microbiota transplantation (FMT). Mechanistically, increased intestinal reactive oxygen species (ROS) in aged mice reduced ion channel protein expression and promoted arrhythmias. Gut microbiota depletion by an antibiotic cocktail reduced ROS and arrhythmia in aged mice. Interestingly, oxidative stress in heart induced by hydrogen peroxide (H2O2) increased arrhythmia. Moreover, aged gut microbiota could induce oxidative stress in young mice colon by gut microbiota metabolites transplantation. Vitexin could reduce aging and arrhythmia through OLA1-Nrf2 signaling pathway. Overall, our study demonstrated that the gut microbiota of aged mice reduced cardiac ion channel protein expression through systemic oxidative stress, thereby increased the risk of arrhythmias.

A coordinated adaptive multiscale enhanced spatio-temporal fusion network for multi-lead electrocardiogram arrhythmia detection

The multi-lead electrocardiogram (ECG) is widely utilized in clinical diagnosis and monitoring of cardiac conditions. The advancement of deep learning has led to the emergence of automated multi-lead ECG diagnostic networks, which have become essential in the fields of biomedical engineering and clinical cardiac disease diagnosis. Intelligent ECG diagnosis techniques encompass Recurrent Neural Networks (RNN), Transformers, and Convolutional Neural Networks (CNN). While CNN is capable of extracting local spatial information from images, it lacks the ability to learn global spatial features and temporal memory features. Conversely, RNN relies on time and can retain significant sequential features. However, they are not proficient in extracting lengthy dependencies of sequence data in practical scenarios. The self-attention mechanism in the Transformer model has the capability of global feature extraction, but it does not adequately prioritize local features and cannot extract spatial and channel features. This paper proposes STFAC-ECGNet, a model that incorporates CAMV-RNN block, CBMV-CNN block, and TSEF block to enhance the performance of the model by integrating the strengths of CNN, RNN, and Transformer. The CAMV-RNN block incorporates a coordinated adaptive simplified self-attention module that adaptively carries out global sequence feature retention and enhances spatial-temporal information. The CBMV-CNN block integrates spatial and channel attentional mechanism modules in a skip connection, enabling the fusion of spatial and channel information. The TSEF block implements enhanced multi-scale fusion of image spatial and sequence temporal features. In this study, comprehensive experiments were conducted using the PTB-XL large publicly available ECG dataset and the China Physiological Signal Challenge 2018 (CPSC2018) database. The results indicate that STFAC-ECGNet surpasses other cutting-edge techniques in multiple tasks, showcasing robustness and generalization.

Updated Progress on Polysaccharides with Anti-Diabetic Effects through the Regulation of Gut Microbiota: Sources, Mechanisms, and Structure-Activity Relationships

Diabetes mellitus (DM) is a common chronic metabolic disease worldwide. The disturbance of the gut microbiota has a complex influence on the development of DM. Polysaccharides are one type of the most important natural components with anti-diabetic effects. Gut microbiota can participate in the fermentation of polysaccharides, and through this, polysaccharides regulate the gut microbiota and improve DM. This review begins by a summary of the sources, anti-diabetic effects and the gut microbiota regulation functions of natural polysaccharides. Then, the mechanisms of polysaccharides in regulating the gut microbiota to exert anti-diabetic effects and the structure-activity relationship are summarized. It is found that polysaccharides from plants, fungi, and marine organisms show great hypoglycemic activities and the gut microbiota regulation functions. The mechanisms mainly include repairing the gut burrier, reshaping gut microbiota composition, changing the metabolites, regulating anti-inflammatory activity and immune function, and regulating the signal pathways. Structural characteristics of polysaccharides, such as monosaccharide composition, molecular weight, and type of glycosidic linkage, show great influence on the anti-diabetic activity of polysaccharides. This review provides a reference for the exploration and development of the anti-diabetic effects of polysaccharides.

Putative causal relations among gut flora, serums metabolites and arrhythmia: a Mendelian randomization study

BACKGROUND

The pathogenesis of cardiac arrhythmias is multifaceted, encompassing genetic, environmental, hemodynamic, and various causative factors. Emerging evidence underscores a plausible connection between gut flora, serum metabolites, and specific types of arrhythmias. Recognizing the role of host genetics in shaping the microbiota, we employed two-sample Mendelian randomization analyses to investigate potential causal associations between gut flora, serum metabolites, and distinct arrhythmias.

METHODS

Mendelian randomization methods were deployed to ascertain causal relationships between 211 gut flora, 575 serum metabolites, and various types of arrhythmias. To ensure the reliability of the findings, five complementary Mendelian randomization methods, including inverse variance weighting methods, were employed. The robustness of the results was scrutinized through a battery of sensitivity analyses, incorporating the Cochran Q test, leave-one-out test, and MR-Egger intercept analysis.

RESULTS

Eighteen gut flora and twenty-six serum metabolites demonstrated associations with the risk of developing atrial fibrillation. Moreover, ten gut flora and fifty-two serum metabolites were linked to the risk of developing supraventricular tachycardia, while eight gut flora and twenty-five serum metabolites were associated with the risk of developing tachycardia. Additionally, six gut flora and twenty-one serum metabolites exhibited associations with the risk of developing bradycardia.

CONCLUSION

This study revealed the potential causal relationship that may exist between gut flora, serum metabolites and different cardiac arrhythmias and highlights the need for further exploration. This study provides new perspectives to enhance diagnostic and therapeutic strategies in the field of cardiac arrhythmias.

Gut microbiota dysbiosis -associated obesity and its involvement in cardiovascular diseases and type 2 diabetes. A systematic review

INTRODUCTION

Obesity is a complex, multifactorial disease caused by various factors. Recently, the role of the gut microbiota in the development of obesity and its complications has attracted increasing interest.

PURPOSE

This article focuses on the mechanisms by which gut microbiota dysbiosis induces insulin resistance, type 2 diabetes, and cardiovascular diseases linked to obesity, highlighting the mechanisms explaining the role of gut microbiota dysbiosis-associated inflammation in the onset of these pathologies.

METHODS

A systematic study was carried out to understand and summarize the published results on this topic. More than 150 articles were included in this search, including different types of studies, consulted by an online search in English using various electronic search databases and predefined keywords related to the objectives of our study.

RESULTS

We have summarized the data from the articles consulted in this search, and we have found a major gut microbiota alteration in obesity, characterized by a specific decrease in butyrate-producing bacteria and the production of metabolites and components that lead to metabolic impairments and affect the progression of various diseases associated with obesity through distinct signaling pathways, including insulin resistance, type 2 diabetes, and cardiovascular diseases (CVD). We have also focused on the major role of inflammation as a link between gut microbiota dysbiosis and obesity-associated metabolic complications by explaining the mechanisms involved.

CONCLUSION

Gut microbiota dysbiosis plays a crucial role in the development of various obesity-related metabolic abnormalities, among them type 2 diabetes and CVD, and represents a major challenge for chronic disease prevention and health. Indeed, the intestinal microbiota appears to be a promising target for the nutritional or therapeutic management of these diseases.

Non-Coding RNAs and Gut Microbiota in the Pathogenesis of Cardiac Arrhythmias: The Latest Update

Non-coding RNAs (ncRNAs) are indispensable for adjusting gene expression and genetic programming throughout development and for health as well as cardiovascular diseases. Cardiac arrhythmia is a frequent cardiovascular disease that has a complex pathology. Recent studies have shown that ncRNAs are also associated with cardiac arrhythmias. Many non-coding RNAs and/or genomes have been reported as genetic background for cardiac arrhythmias. In general, arrhythmias may be affected by several functional and structural changes in the myocardium of the heart. Therefore, ncRNAs might be indispensable regulators of gene expression in cardiomyocytes, which could play a dynamic role in regulating the stability of cardiac conduction and/or in the remodeling process. Although it remains almost unclear how ncRNAs regulate the expression of molecules for controlling cardiac conduction and/or the remodeling process, the gut microbiota and immune system within the intricate networks might be involved in the regulatory mechanisms. This study would discuss them and provide a research basis for ncRNA modulation, which might support the development of emerging innovative therapies against cardiac arrhythmias.