Remote Ischemic Conditioning: Challenges and Opportunities

Stroke-heart syndrome: current progress and future outlook

Stroke can lead to cardiac complications such as arrhythmia, myocardial injury, and cardiac dysfunction, collectively termed stroke-heart syndrome (SHS). These cardiac alterations typically peak within 72 h of stroke onset and can have long-term effects on cardiac function. Post-stroke cardiac complications seriously affect prognosis and are the second most frequent cause of death in patients with stroke. Although traditional vascular risk factors contribute to SHS, other potential mechanisms indirectly induced by stroke have also been recognized. Accumulating clinical and experimental evidence has emphasized the role of central autonomic network disorders and inflammation as key pathophysiological mechanisms of SHS. Therefore, an assessment of post-stroke cardiac dysautonomia is necessary. Currently, the development of treatment strategies for SHS is a vital but challenging task. Identifying potential key mediators and signaling pathways of SHS is essential for developing therapeutic targets. Therapies targeting pathophysiological mechanisms may be promising. Remote ischemic conditioning exerts protective effects through humoral, nerve, and immune-inflammatory regulatory mechanisms, potentially preventing the development of SHS. In the future, well-designed trials are required to verify its clinical efficacy. This comprehensive review provides valuable insights for future research.

Re-evaluation of the cardioprotective effects of cannabinoids against ischemia-reperfusion injury according to the IMproving Preclinical Assessment of Cardioprotective Therapies (IMPACT) criteria

Ischemic heart disease, associated with high morbidity and mortality, represents a major challenge for the development of drug-based strategies to improve its prognosis. Results of pre-clinical studies suggest that agonists of cannabinoid CB2 receptors and multitarget cannabidiol might be potential cardioprotective strategies against ischemia-reperfusion injury. The aim of our study was to re-evaluate the cardioprotective effects of cannabinoids against ischemia-reperfusion injury according to the IMproving Preclinical Assessment of Cardioprotective Therapies (IMPACT) criteria published recently by the European Union (EU) CARDIOPROTECTION COST ACTION. To meet the minimum criteria of those guidelines, experiments should be performed (i) on healthy small animals subjected to ischemia with reperfusion lasting for at least 2 hours and (ii) confirmed in small animals with comorbidities and co-medications and (iii) in large animals. Our analysis revealed that the publications regarding cardioprotective effects of CB2 receptor agonists and cannabidiol did not meet all three strict steps of IMPACT. Thus, additional experiments are needed to confirm the cardioprotective activities of (endo)cannabinoids mainly on small animals with comorbidities and on large animals. Moreover, our publication underlines the significance of the IMPACT criteria for a proper planning of preclinical experiments regarding cardiac ischemia-reperfusion injury.

Remote Ischemic Conditioning to Reduce Perihematoma Edema in Patients with Intracerebral Hemorrhage (RICOCHET): A Randomized Control Trial

Background: Early perihematomal edema (PHE) growth is associated with worse functional outcomes at 90 days. Remote Ischemic conditioning (RIC) may reduce perihematomal inflammation if applied early to patients with intracerebral hemorrhage (ICH). We hypothesize that early RIC, delivered for seven days in patients with spontaneous ICH, may reduce PHE growth. Methods: ICH patients presenting within 6 h of symptom onset and hematoma volume < 60 milliliters (mL) were randomized to an RIC + standard care or standard care (SC) group. The primary outcome measure was calculated edema extension distance (EED), with the cm assessed on day seven. Results: Sixty patients were randomized with a mean  ±  SD age of 57.5  ±  10.8 years, and twenty-two (36.7%) were female. The relative baseline median PHE were similar (RIC group 0.75 (0.5-0.9) mL vs. SC group 0.91 (0.5-1.2) mL, p  =  0.30). The median EEDs at baseline were similar (RIC group 0.58 (0.3-0.8) cm vs. SC group 0.51 (0.3-0.8) cm, p  =  0.76). There was no difference in the median day 7 EED (RIC group 1.1 (0.6-1.2) cm vs. SC group 1 (0.9-1.2) cm, p  =  0.75). Conclusions: Early RIC therapy delivered daily for seven days was feasible. However, no decrease in EED was noted with the intervention.

Remote ischaemic preconditioning for transcatheter aortic valve replacement: a protocol for a systematic review with meta-analysis and trial sequential analysis

INTRODUCTION

Transcatheter aortic valve replacement (TAVR) has become an important treatment in patients with aortic valve disease with the continuous advancement of technology and the improvement of outcomes. However, TAVR-related complications still increase patient morbidity and mortality. Remote ischaemic preconditioning (RIPC) is a simple procedure that provides perioperative protection for many vital organs. However, the efficiency of RIPC on TAVR remains unclear based on inconsistent conclusions from different clinical studies. Therefore, we will perform a protocol for a systematic review and meta-analysis to identify the efficiency of RIPC on TAVR.

METHODS AND ANALYSIS

English databases (PubMed, Web of Science, Ovid Medline, Embase and Cochrane Library), Chinese electronic databases (Wanfang Database, VIP Database and China National Knowledge Infrastructure) and trial registry databases will be searched from inception to December 2023 to identify randomised controlled trials of RIPC on TAVR. We will calculate mean differences or standardised mean differences with 95% CIs for continuous data, and the risk ratio (RR) with 95% CIs for dichotomous data by Review Manager version 5.4. Fixed-effects model or random-effects model will be used according to the degree of statistical heterogeneity assessed by the I-square test. We will evaluate the risk of bias using the Cochrane risk-of-bias tool 2 and assess the evidence quality of each outcome by the Grading of Recommendations Assessment, Development and Evaluation. The robustness of outcomes will be evaluated by trial sequential analysis. In addition, we will evaluate the publication bias of outcomes by Funnel plots and Egger's regression test.

ETHICS AND DISSEMINATION

Ethical approval was not required for this systematic review protocol. The results will be disseminated through peer-reviewed publications.

PROSPERO REGISTRATION NUMBER

CRD42023462926.

Remote ischemic conditioning improves cerebral hemodynamics in symptomatic intracranial atherosclerosis: A PET/CT-guided randomized controlled study

Patients with symptomatic intracranial arterial stenosis (sICAS) suffer embarrassed hemodynamic status and acute ischemic stroke (AIS) recurrence. We aimed to assess the efficacy of remote ischemic conditioning (RIC) on improving this status by evaluating cerebral blood flow (CBF) and cerebral glucose metabolism (CGM) via PET/CT. Adult patients with unilateral sICAS in middle cerebral artery and/or intracranial segment of internal carotid artery-related AIS or transient ischemic attack within 6 months prior to randomization were enrolled. Individuals who received intravenous thrombolysis or endovascular treatment, or sICAS caused by cardiac embolism, small vessel occlusion, or other determined causes were excluded. Twenty-three eligible patients were randomly assigned to standard medical treatment (SMT) (n = 10) or RIC group (n = 13). The RIC protocol consisted of 5 cycles, each for 5-min bilateral upper limb ischemia and 5-min reperfusion period, twice a day, with a total duration of 3 months. Ten healthy volunteers were enrolled as healthy control group. We tested CBF and CGM at the rest stage and the methazolamide-induced stress stage. All patients received PET/CT at baseline and three-month followup. Both CBF and CGM in ipsilateral hemisphere of sICAS patients were significantly decreased at the rest stage and the stress stage (p < .05), which were improved by three-month RIC (p < .05). The lesions decreased notably in RIC group compared to SMT group (p < .05). RIC ameliorated the hemodynamic status and glucose metabolism in regions at high risk of infarction, which might improve the resistance capacity towards ischemic load in sICAS patients.

The hormesis principle of neuroplasticity and neuroprotection

Animals live in habitats fraught with a range of environmental challenges to their bodies and brains. Accordingly, cells and organ systems have evolved stress-responsive signaling pathways that enable them to not only withstand environmental challenges but also to prepare for future challenges and function more efficiently. These phylogenetically conserved processes are the foundation of the hormesis principle, in which single or repeated exposures to low levels of environmental challenges improve cellular and organismal fitness and raise the probability of survival. Hormetic principles have been most intensively studied in physical exercise but apply to numerous other challenges known to improve human health (e.g., intermittent fasting, cognitive stimulation, and dietary phytochemicals). Here we review the physiological mechanisms underlying hormesis-based neuroplasticity and neuroprotection. Approaching natural resilience from the lens of hormesis may reveal novel methods for optimizing brain function and lowering the burden of neurological disorders.

Changes in excitatory amino acid transporters in response to remote ischaemic preconditioning and glutamate excitotoxicity

The successful implementation of remote ischaemic conditioning as a clinical neuroprotective strategy requires a thorough understanding of its basic principles, which can be modified for each patient. The mechanisms of glutamate homeostasis appear to be a key component. In the current study, we focused on the brain-to-blood glutamate shift mediated by glutamate transporters (excitatory amino acid transports [EAATs]) and the effect of remote ischaemic preconditioning (RIPC) as a mediator of ischaemic tolerance. We used model mimicking ischaemia-mediated excitotoxicity (intracerebroventricular administration of glutamate) to avoid the indirect effect of ischaemia-triggered mechanisms. We found quantitative changes in EAAT2 and EAAT3 and altered membrane trafficking of EAAT1 on the cells of the choroid plexus. These changes could underlie the beneficial effects of ischaemic tolerance. There was reduced oxidative stress and increased glutathione level after RIPC treatment. Moreover, we determined the stimulus-specific response on EAATs. While glutamate overdose stimulated EAAT2 and EAAT3 overexpression, RIPC induced membrane trafficking of EAAT1 and EAAT2 rather than a change in their expression. Taken together, mechanisms related to glutamate homeostasis, especially EAAT-mediated transport, represents a powerful tool of ischaemic tolerance and allow a certain amount of flexibility based on the stimulus used.