Analysis of age-related left ventricular collagen remodeling in living donors: Implications in arrhythmogenesis

Therapeutic potential and mechanistic insights of astragaloside IV in the treatment of arrhythmia: a comprehensive review

Arrhythmia, a common cardiovascular disorder, results from disturbances in cardiac impulse generation and conduction, leading to decreased cardiac output and myocardial oxygenation, with potentially life-threatening consequences. Despite advancements in therapeutic approaches, the incidence and mortality associated with arrhythmia remain high, and drug-related adverse effects continue to pose significant challenges. Traditional Chinese Medicine (TCM) has attracted considerable attention for its potential as a complementary and alternative approach in treating cardiovascular diseases, including arrhythmia. Astragalus, a prominent herb in TCM, is commonly used in clinical practice for its multi-faceted therapeutic properties, encompassing anti-arrhythmic, cardiotonic, anti-inflammatory, and immunomodulatory effects. Astragaloside IV, a primary active compound in Astragalus membranaceus, has demonstrated cardioprotective effects through mechanisms such as antioxidant, anti-inflammatory, and anti-apoptotic activities. Although evidence suggests that astragaloside IV holds promise in arrhythmia treatment, comprehensive reviews of its specific mechanisms and clinical applications in arrhythmia are scarce. This review systematically explores the pharmacological properties and underlying mechanisms of astragaloside IV in arrhythmia treatment. Utilizing a targeted search of databases including PubMed, Web of Science, Cochrane Library, Embase, CNKI, and Wanfang Data, we summarize recent findings and examine astragaloside IV's potential applications in arrhythmia prevention and treatment. Our analysis aims to provide a theoretical foundation for the development of novel arrhythmia treatment strategies, while offering insights into future research directions for clinical application.

Analysis of age-related changes in the left ventricular myocardium with multiphoton microscopy

Aging induces cardiac remodeling, resulting in an increase in the risk of suffering heart diseases, including heart failure. Collagen deposition increases with age and, together with sarcomeric changes in cardiomyocytes, may lead to ventricular stiffness. Multiphoton (MP) microscopy is a useful technique to visualize and detect variations in cardiac structures in a label free fashion. Here, we propose a method based on MP imaging (both two-photon excitation fluorescence (TPEF) and second harmonic generation (SHG) modalities) to explore and objectively quantify age-related structural differences in various components of cardiac tissues. Results in transmural porcine left ventricle (LV) sections reveal significant differences when comparing samples from young and old animals. Collagen and myosin SHG signals in old specimens are respectively 3.8x and >6-fold larger than in young ones. Differences in TPEF signals from cardiomyocyte were ∼3x. Moreover, the increased amount of collagen in old specimens results in a more organized pattern when compared to young LV tissues. Since changes in collagen and myosin are associated with cardiac dysfunction, the technique used herein might be a useful tool to accurately predict and measure changes associated with age-related myocardium fibrosis, tissue remodeling and sarcomeric alterations, with potential implications in preventing heart disease.

Automatic quantification of myocardial remodeling features in human ventricular tissue from label-free microscopy

The procedures used routinely for collagen and lipofuscin evaluation are, in many cases, qualitative, observer dependent, and disregard spatial distribution. Here, we present a protocol for automatic quantification and spatial characterization of collagen and lipofuscin from label-free microscopy images of human ventricular tissues. We describe the steps for sample collection, tissue processing, image acquisition, and quantification of collagen and lipofuscin. This protocol avoids discrepancies between observers and can be adapted to other tissues and species. For complete details on the use and execution of this protocol, please refer to García-Mendívil et al. (2022).1.

Interindividual Age-Independent Differences in Human CX43 Impact Ventricular Arrhythmic Risk

Connexin 43 (CX43) is one of the major components of gap junctions, the structures responsible for the intercellular communication and transmission of the electrical impulse in the left ventricle. There is limited information on the histological changes of CX43 with age and their effect on electrophysiology, especially in humans. Here, we analyzed left ventricular biopsies from living donors starting at midlife to characterize age-related CX43 remodeling. We assessed its quantity, degree of lateralization, and spatial heterogeneity together with fibrotic deposition. We observed no significant age-related remodeling of CX43. Only spatial heterogeneity increased slightly with age, and this increase was better explained by biological age than by chronological age. Importantly, we found that CX43 features varied considerably among individuals in our population with no relevant relationship to age or fibrosis content, in contrast to animal species. We used our experimental results to feed computational models of human ventricular electrophysiology and to assess the effects of interindividual differences in specific features of CX43 and fibrosis on conduction velocity, action potential duration, and arrhythmogenicity. We found that larger amounts of fibrosis were associated with the highest arrhythmic risk, with this risk being increased when fibrosis deposition was combined with a reduction in CX43 amount and/or with an increase in CX43 spatial heterogeneity. These mechanisms underlying high arrhythmic risk in some individuals were not associated with age in our study population. In conclusion, our data rule out CX43 remodeling as an age-related arrhythmic substrate in the population beyond midlife, but highlight its potential as a proarrhythmic factor at the individual level, especially when combined with increased fibrosis.

Potential Benefits of Sodium-Glucose Transporter-2 Inhibitors in the Symptomatic and Functional Status of Patients With Heart Failure: A Systematic Review and Meta-Analysis

This review evaluates the potential benefits of sodium-glucose transporter-2 (SGLT-2) inhibitors on symptom burden/health-related quality of life (HRQoL), functional improvement, hospitalization for heart failure (HHF), cardiovascular mortality (CVM), and all-cause mortality (ACM) in patients with heart failure (HF) with reduced or preserved ejection fraction (EF). We analyzed 12 randomized clinical trials (RCTs) accessed through 11 records and three secondary analyses from PubMed and Scopus following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) 2020 guidelines. These studies evaluated 23,389 patients treated with either an SGLT-2 inhibitor or placebo in addition to the standard of care. Four studies recruited diabetic patients, some of whom had HF at the baseline and were evaluated as a subgroup. One study had diabetes and HF present in all patients at the baseline. Ten studies recruited patients with HF at their baseline irrespective of diabetic status. Eight studies evaluated the SGLT-2 inhibitors for a composite of hospitalization for heart failure or cardiovascular mortality (HHF/CVM) and ACM. Five of these studies showed a decreased risk for HHF/CVM, and two showed a reduced risk for ACM. One trial showed benefits in patients with heart failure with reduced ejection fraction (HFrEF) only and not in heart failure with preserved ejection fraction (HFpEF). Other studies revealed benefits but did not reach statistical significance. Ten studies assessed the SGLT-2 inhibitors for improvement in symptoms and HRQoL; four demonstrated a significant improvement, three showed a slight improvement, and three did not find any benefit. Five trials evaluated participants' functional progress by assessing for a six-minute walk test (6MWT). Two studies showed a significant increase in the distance walked by the patient, while three others did not. The SGLT-2 inhibitors reduce the risk of HHF/CVM irrespective of ejection fraction and result in a symptomatic improvement.