Voltage-gated potassium channel dysfunction in dorsal root ganglia contributes to the exaggerated exercise pressor reflex in rats with chronic heart failure

Neurocardiology: translational advancements and potential

In our original white paper published in the The Journal of Physiology in 2016, we set out our knowledge of the structural and functional organization of cardiac autonomic control, how it remodels during disease, and approaches to exploit such knowledge for autonomic regulation therapy. The aim of this update is to build on this original blueprint, highlighting the significant progress which has been made in the field since and major challenges and opportunities that exist with regard to translation. Imbalances in autonomic responses, while beneficial in the short term, ultimately contribute to the evolution of cardiac pathology. As our understanding emerges of where and how to target in terms of actuators (including the heart and intracardiac nervous system (ICNS), stellate ganglia, dorsal root ganglia (DRG), vagus nerve, brainstem, and even higher centres), there is also a need to develop sensor technology to respond to appropriate biomarkers (electrophysiological, mechanical, and molecular) such that closed-loop autonomic regulation therapies can evolve. The goal is to work with endogenous control systems, rather than in opposition to them, to improve outcomes.

Systemic mapping of organ plasma extravasation at multiple stages of chronic heart failure

Introduction: Chronic Heart failure (CHF) is a highly prevalent disease that leads to significant morbidity and mortality. Diffuse vasculopathy is a commonmorbidity associated with CHF. Increased vascular permeability leading to plasma extravasation (PEx) occurs in surrounding tissues following endothelial dysfunction. Such micro- and macrovascular complications develop over time and lead to edema, inflammation, and multi-organ dysfunction in CHF. However, a systemic examination of PEx in vital organs among different time windows of CHF has never been performed. In the present study, we investigated time-dependent PEx in several major visceral organs including heart, lung, liver, spleen, kidney, duodenum, ileum, cecum, and pancreas between sham-operated and CHF rats induced by myocardial infarction (MI). Methods: Plasma extravasation was determined by colorimetric evaluation of Evans Blue (EB) concentrations at 3 days, ∼10 weeks and 4 months following MI. Results: Data show that cardiac PEx was initially high at day 3 post MI and then gradually decreased but remained at a moderately high level at ∼10 weeks and 4 months post MI. Lung PEx began at day 3 and remained significantly elevated at both ∼10 weeks and 4 months post MI. Spleen PExwas significantly increased at ∼10 weeks and 4 months but not on day 3 post MI. Liver PEx occurred early at day 3 and remain significantly increased at ∼10 weeks and 4 months post MI. For the gastrointestinal (GI) organs including duodenum, ileum and cecum, there was a general trend that PEx level gradually increased following MI and reached statistical significance at either 10 weeks or 4 months post MI. Similar to GI PEx, renal PEx was significantly elevated at 4 months post MI. Discussion: In summary, we found that MI generally incites a timedependent PEx of multiple visceral organs. However, the PEx time window for individual organs in response to the MI challenge was different, suggesting that different mechanisms are involved in the pathogenesis of PEx in these vital organs during the development of CHF.

Consequences of group III/IV afferent feedback and respiratory muscle work on exercise tolerance in heart failure with reduced ejection fraction

Exercise intolerance and exertional dyspnoea are the cardinal symptoms of heart failure with reduced ejection fraction (HFrEF). In HFrEF, abnormal autonomic and cardiopulmonary responses arising from locomotor muscle group III/IV afferent feedback is one of the primary mechanisms contributing to exercise intolerance. HFrEF patients also have pulmonary system and respiratory muscle abnormalities that impair exercise tolerance. Thus, the primary impetus for this review was to describe the mechanistic consequences of locomotor muscle group III/IV afferent feedback and respiratory muscle work in HFrEF. To address this, we first discuss the abnormal autonomic and cardiopulmonary responses mediated by locomotor muscle afferent feedback in HFrEF. Next, we outline how respiratory muscle work impairs exercise tolerance in HFrEF through its effects on locomotor muscle O2 delivery. We then discuss the direct and indirect evidence supporting an interaction between locomotor muscle group III/IV afferent feedback and respiratory muscle work during exercise in HFrEF. Last, we outline future research directions related to locomotor and respiratory muscle abnormalities to progress the field forward in understanding the pathophysiology of exercise intolerance in HFrEF. NEW FINDINGS: What is the topic of this review? This review is focused on understanding the role that locomotor muscle group III/IV afferent feedback and respiratory muscle work play in the pathophysiology of exercise intolerance in patients with heart failure. What advances does it highlight? This review proposes that the concomitant effects of locomotor muscle afferent feedback and respiratory muscle work worsen exercise tolerance and exacerbate exertional dyspnoea in patients with heart failure.

Regulation of pain neurotransmitters and chondrocytes metabolism mediated by voltage-gated ion channels: A narrative review

Osteoarthritis (OA) is one of the leading causes of chronic pain and dysfunction. It is essential to comprehend the nature of pain and cartilage degeneration and its influencing factors on OA treatment. Voltage-gated ion channels (VGICs) are essential in chondrocytes and extracellular matrix (ECM) metabolism and regulate the pain neurotransmitters between the cartilage and the central nervous system. This narrative review focused primarily on the effects of VGICs regulating pain neurotransmitters and chondrocytes metabolism, and most studies have focused on voltage-sensitive calcium channels (VSCCs), voltage-gated sodium channels (VGSCs), acid-sensing ion channels (ASICs), voltage-gated potassium channels (VGKCs), voltage-gated chloride channels (VGCCs). Various ion channels coordinate to maintain the intracellular environment's homeostasis and jointly regulate metabolic and pain under normal circumstances. In the OA model, the ion channel transport of chondrocytes is abnormal, and calcium influx is increased, which leads to increased neuronal excitability. The changes in ion channels are strongly associated with the OA disease process and individual OA risk factors. Future studies should explore how VGICs affect the metabolism of chondrocytes and their surrounding tissues, which will help clinicians and pharmacists to develop more effective targeted drugs to alleviate the progression of OA disease.

miR-448 regulates potassium voltage-gated channel subfamily A member 4 (KCNA4) in ischemia and heart failure

BACKGROUND

MicroRNA miR-448 mediates some of the effects of ischemia on arrhythmic risk. Potassium voltage-gated channel subfamily A member 4 (KCNA4) encodes a Kv1.4 current that opens in response to membrane depolarization and is essential for regulating the action potential duration in heart. KCNA4 has a miR-448 binding site.

OBJECTIVE

We investigated whether miR-448 was involved in the regulation of KCNA4 messenger RNA expression in ischemia.

METHODS

Quantitative real-time reverse-transcriptase polymerase chain reaction was used to investigate the expression of KCNA4 and miR-448. Pull-down assays were used to examine the interaction between miR-448 and KCNA4. miR-448 decoy and binding site mutation were used to examine the specificity of the effect for KCNA4.

RESULTS

The expression of KCNA4 is diminished in ischemia and human heart failure tissues with ventricular tachycardia. Previously, we have shown that miR-448 is upregulated in ischemia and inhibition can prevent arrhythmic risk after myocardial infarction. The 3'-untranslated region of KCNA4 has a conserved miR-448 binding site. miR-448 bound to this site directly and reduced KCNA4 expression and the transient outward potassium current. Inhibition of miR-448 restored KCNA4.

CONCLUSION

These findings showed a link between Kv1.4 downregulation and miR-448-mediated upregulation in ischemia, suggesting a new mechanism for the antiarrhythmic effect of miR-448 inhibition.

Effect of ICD/CRT-D Implantation on Adverse Events and Readmission Rate in Patients with Chronic Heart Failure (CHF)

Objective

To explore the effect of implantable cardioverter defibrillator/cardiac resynchronization therapy defibrillator (ICD/CRT-D) implantation on adverse events and the readmission rate in patients with chronic heart failure (CHF).

Methods

Sixty patients with CHF treated in our hospital from April 2019 to July 2021 were enrolled. The patients were randomly assigned into the control group and study group. The control group received routine intervention, and the study group received remote management with ICD/CRT-D implantation.

Results

First of all, we compared the general data of the two groups. There was no significant difference in LVEF, NYHA grade, concomitant disease, and history of arrhythmia (P > 0.05). Secondly, we compared the end-point events. In the study group, 5 cases of heart failure were readmitted, 0 cases died, and 4 cases were admitted to hospital with arrhythmia and ICD events, with a total incidence of 30.0%, while in the control group, 12 cases were rehospitalized with heart failure, 3 cases died, 25 cases were admitted with arrhythmia and ICD events, and the total incidence rate was 56.67% (P < 0.05). In terms of the readmission rate of patients with heart failure in grade NYHAII and grade III, among the patients with grade NYHAII, the number of patients with heart failure less than once in the study group was higher compared to that in the control group and the number of patients with heart failure ≥ once in the study group was lower compared to that in the control group (P < 0.05). Among the patients with grade NYHAIII, the number of patients with heart failure less than once in the study group was higher compared to that in the control group and the number of patients with heart failure ≥ once in the study group was lower compared to that in the control group. There exhibited no significant difference in the data (P > 0.05). Considering the occurrence of VT and VF events, the study team reported that 14 patients recorded a total of 276 ventricular arrhythmias: 261 ventricular tachycardia and 15 ventricular fibrillations. Among them, 24 VT (9.2%) and 4 VF (26.7%) were determined to be misrecognition of the equipment. A total of 178 ventricular arrhythmias were recorded in 13 patients in the control group, including 152 ventricular tachycardia and 26 ventricular fibrillations. Among them, 10 VT (6.6%) and 8 VF (30.8%) were determined as misrecognition of the device. In regard to the treatment results of the two groups, after admission to the hospital for radio frequency, ablation, and adjustment of drug treatment to reprogram control, the patients did not reappear to have CRT-D misidentification and misdischarged. Finally, we compared the diagnosis time of VT/VE events. The time from VT/VE events to diagnosis in 14 patients in the study group was 2.55 ± 1.41 days, and that in 13 patients in the control group was 37.32 ± 15.31 days. The discovery of ICD events in the study group was significantly earlier compared to that in the routine follow-up group (P < 0.05). This gives doctors enough time to assess the patient's condition and determine a further diagnosis and treatment plan.

Conclusion

Using ICD/CRT-D implantation to remotely monitor patients with CHF, through remote monitoring of the 24-hour average heart rate and the heart rate at rest and patient activity and other parameters and early intervention, the readmission rate caused by the deterioration of heart failure can be reduced. Compared with routine follow-up, remote monitoring significantly reduced the diagnosis time of VT/VE events.