BACKGROUND:Supraventricular arrhythmia (SVA) is the most frequent complication after patent foramen ovale (PFO) percutaneous closure. AIM:To develop and validate a predictive score for SVA after PFO closure. METHODS:Patients with PFO closure and undergoing implantable loop recorder (ILR) monitoring were recruited in 15 French centres. The primary outcome was any SVA lasting ≥30 s within 3 months after the procedure. The score was derived from multivariable logistic regression from a training set of patients and was tested in an independent internal validation set. The score was then externally validated in a cohort of patients without ILR monitoring from the AIR FORCE registry. RESULTS:Overall, 338 patients undergoing ILR monitoring (270 in the training set; 68 in the internal validation set) and 2215 not undergoing ILR monitoring (external validation set) were included. Determinants of the prognostic score were age, male sex, RoPE score, septum secundum thickness, left atrial volume and device left disc diameter. In the internal validation set, the area under the curve was 0.72 (0.58-0.87). A threshold of 55 (fourth quartile of the training set score) had a specificity of 93.3% and a positive predicted value of 72.7%. In the external validation set, the score demonstrated a similar correlation, with an observed threefold increase in the symptomatic SVA rate between the first and fourth quartiles. CONCLUSIONS:This easily calculable score can be used to identify patients at high risk of developing SVA after PFO closure and may help detect candidates for a specific rhythm-monitoring strategy.
BACKGROUND:With the recent introduction of the extravascular implantable cardioverter-defibrillator (EV-ICD), clinicians now have three distinct devices for sudden cardiac death prevention: the transvenous implantable cardioverter-defibrillator (TV-ICD); the subcutaneous implantable cardioverter-defibrillator (S-ICD); and the EV-ICD. AIMS:To quantify intercentre heterogeneity in device choice, and identify patient characteristics independently associated with selecting a TV-ICD, an S-ICD or an EV-ICD. METHODS:We conducted a cross-sectional vignette-based survey across 15 French implanting centres. Centres selected a first-line implantable cardioverter-defibrillator for 21 standardized scenarios in which all three devices were feasible (315 centre-level decisions). RESULTS:Intercentre agreement on device choice was slight (κ=0.065), and the median per-vignette majority consensus was 53% (range: 40-93%), indicating substantial between-centre heterogeneity. Unsupervised clustering of centres identified three distinct selection strategies: a TV-ICD first cluster (5/15 centres; TV-ICD 51.4% of choices); an S-ICD first cluster (7/15 centres; S-ICD 68.7% of choices); and an EV-ICD forward cluster (3/15 centres; EV-ICD 81.0% of choices). In adjusted analyses, age<65years was associated with selection of both S-ICDs (odds ratio [OR]: 2.10, 95% confidence interval [95% CI]: 1.11-4.00; P=0.024) and EV-ICDs (OR: 2.27, 95% CI: 1.05-4.91; P=0.038) versus TV-ICDs. Low body mass index (17 vs. 25kg/m2) was associated with lower odds of selection of an S-ICD versus a TV-ICD (OR: 0.30, 95% CI: 0.09-0.94; P=0.039) and higher odds of selection of an EV-ICD versus an S-ICD (OR: 3.81, 95% CI: 1.27-11.44; P=0.017). Sex, heart disease and prevention setting were not independently associated with device selection. CONCLUSIONS:Implantable cardioverter-defibrillator selection showed a marked centre-level practice effect, and was also influenced by age and body mass index. These findings support harmonized selection pathways to reduce unwarranted variability, while preserving patient profile-oriented shared decision-making.
Introduction The heart rhythm (HR) is initiated by the sinoatrial node (SAN) cells, which spontaneously generate action potentials (AP). The automaticity of these cells is conferred by the diastolic depolarization (DD), which brings the membrane potential to the AP threshold, generating the next AP. The DD, and thus the firing rate (FR) depends on two-coupled clocks systems: the voltage clock (leaded by HCN4-dependent funny current and CaV1.3-dependent Ca2+ current), and the calcium (Ca2+) clock, leaded by RyR2-dependent Ca2+ release that activates an NCX-dependent depolarizing current (Fig. 1A). Under stress, SAN cells accelerate their FR due to β-adrenergic stimulation, which elevates cAMP levels (regulating HCN4) and activates PKA (which phosphorylates the Ca2+ channel and RyR2, among other proteins). While β-adrenergic effect on the voltage clock is well known, it is not clear whether PKA-dependent RyR2-phosphorylation has any effect on the SAN response to stress. We focused on the S2030 site, phosphorylated by PKA during β-adrenergic stimulation. Objective Therefore, we wanted to understand the role of the S2030 PKA-dependent phosphorylation site of the RyR2 in the β-adrenergic response of the SAN. Method We used mice mutated at the S2030 site: S2030A (serine replaced by a non-phosphorylable alanine), as the phosphoablation condition; and the S2030D mutant (serine replaced by a tryptophan (D)), as the phosphomimetic condition (Fig. 1B). We use a variety of experiments to study the SAN function in these mutants: RyR2 activity measured in vitro (single-channels recordings), HR measured in-vivo (ECG in telemetry). AP and Ca2+ transients measured ex-vivo (on a SAN preparation using optical mapping). HCN4-dependent funny current on isolated SAN cells (patch-clamp), and RyR2 and HCN4 distribution (immunohistochemistry). Results The S2030D mutants present an increased RyR2 open probability (Fig. 1B) and basal HR, with attenuated β-adrenergic response compared with WT but reaching same WT maximum HR. The S2030A mutants show a normal basal HR with attenuated chronotropic response that to not reach the WT maximum HR. In both mutants there is a strong decrease in funny currents and an altered SAN shift of the leading site during β-adrenergic stimulation. Conclusion In conclusion, we show that S2030 site have a role on SAN positive chronotropic β-adrenergic response, and in basal HR with a compensatory downregulation of voltage HR leader, the funny current.
Introduction The assessment of the severity of calcific aortic stenosis (AS) traditionally relies on transthoracic echocardiography (TTE). However, a non-negligible proportion of patients exhibit discordance between hemodynamic parameters and clinical severity, making interpretation challenging. Computed tomography (CT)–derived aortic valve calcium score (CS) (Agatston score) represents an independent structural marker and is recommended to refine diagnosis, particularly in moderate or discordant forms. Objective This study aimed to analyze the correlation between echocardiographic parameters and calcium burden, as well as the overall concordance between the two modalities. Method A prospective cohort of 20 patients with aortic stenosis was evaluated using TTE and non-contrast cardiac CT. Patients were classified into three categories (moderate, intermediate, severe) according to recommended sex-adjusted thresholds. Echo–CT concordance was assessed using a confusion matrix, complemented by an individual analysis of discordant cases. Correlations between calcium score, aortic valve area (AVA), mean transvalvular gradient, and peak aortic jet velocity (Vmax) were analyzed. Results The mean age was 69±11 years, with a male-to-female ratio of 1.5. Aortic stenosis was severe in patients, moderately severe in, and moderate in 6 patients. Mean values were as follows: AVA=1.07±0.40cm2, mean gradient=32±13mmHg, Vmax=3.1±0.8m/s, and left ventricular ejection fraction=54%±10%. The mean CS was 1980 AU (median: 1600 AU; range: 400–6000). An inverse correlation was observed between CS and AVA, while mean gradient and Vmax were positively correlated with calcium burden. Overall echo–CT concordance was 45% (9/20 patients), whereas 11 patients (55%) showed discordance (Fig. 1). These discrepancies were mainly observed in intermediate or low-flow forms, in which hemodynamic parameters were less discriminative. Conclusion This study demonstrates that 55% of patients exhibited discordance between echocardiography and computed tomography, particularly in intermediate forms of aortic stenosis. The CS appears to be a reliable, flow-independent tool for refining the true severity of calcific aortic stenosis. Its systematic integration in equivocal situations improves diagnostic accuracy and helps guide therapeutic decision-making.
Introduction Sinus node dysfunction (SND) is characterized by impaired cardiac automaticity, which plays a central role in heart rhythm generation. SND has been reported in patients with Brugada syndrome (BrS), a hereditary cardiac channelopathy associated with an increased risk of ventricular fibrillation, particularly in individuals carrying mutations in SCN5A gene, encoding the cardiac sodium channel Nav1.5. Differentiation of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) into sinoatrial node-like cells (SAN-hiPSCs) provides an innovative in vitro platform to study SND. Here, we characterized SAN-hiPSCs from a patient carrying the R893C-SCN5A mutation to elucidate the cellular mechanisms of SND. Objective Our objective is to generate R893C-SCN5A SAN-hiPSCs from the patient and perform a detailed electrophysiological characterization. Method hiPSCs from patient with SND and healthy donor were differentiated into SAN-hiPSCs using a 2D matrix sandwich protocol with Wnt pathway modulation. To promote functional maturation, including proper intracellular Ca2+ dynamics, cells were exposed to a triiodothyronine, dexamethasone, and cyclic AMP (DTA) cocktail. 40 days after differentiation, the electrophysiological activity of the SAN-hiPSCs was examined using patch-clamp recordings. Results SAN-hiPSCs derived from an R893C-SCN5A patient showed a significant reduction in spontaneous action potential frequency compared with control cells (Ctrl: 160±10bpm; R893C-SCN5A: 78±11bpm). The pacemaker funny current (If) was not altered at −85mV (Ctrl: −5.10±0.85 pA/pF; R893C-SCN5A: −5.08±1.07 pA/pF). Conclusion SAN-hiPSCs derived from the R893C-SCN5A patient display a clear bradycardic phenotype compared with SAN-hiPSCs from control, consistent with the patient's clinical phenotype. This bradycardia is not attributable to alterations in If. However, other key determinants of cardiac automaticity, including Na+ currents, Ca2+ currents, the G protein–gated inwardly rectifying potassium current (IKACh), and intracellular Ca2+ handling, remain to be investigated. Notably, recent studies have shown that genetic ablation or pharmacological inhibition of IKACh prevents SND-associated bradycardia. This therapeutic strategy could therefore be evaluated in the future to rescue the SND in R893C-SCN5A SAN-hiPSCs.
Introduction Metabolic dysfunction-associated steatotic liver disease (MASLD) affects approximately 30% of the general population. In this population, and especially in patients with steatohepatitis (MASH), the aggressive form of MASLD, cardiovascular disease (CVD) is the predominant cause of death rather than liver-related events. MASH is considered an independent risk factor for the development of CVD. Endothelial dysfunction, characterized by impaired regulation of vascular tone, is highly prevalent in patients with MASH and represents an early event preceding the clinical onset of CVD. However, the mechanisms linking MASH to CVD remain poorly understood. Objective Our objective was to characterize endothelial function in two independent models of MASH and to determine whether a liver-derived circulating factor could contribute to endothelial dysfunction. Method Two mouse models of MASH were used: a genetic diet-induced model (Foz mice) and a purely diet-induced model. Endothelial function and nitric oxide (NO) signalling were evaluated by wire myography, qPCR, and western blotting. NO production in the aorta was measured by electron paramagnetic resonance (EPR), and asymmetric dimethylarginine (ADMA) was quantified by LC-MS. Results Both MASH models exhibited endothelial dysfunction associated with alterations in the NO pathway. EPR analysis revealed a significant reduction in aortic NO production in Foz mice compared with controls. Consistently, plasma and hepatic levels of ADMA, an endogenous inhibitor of NO production, were elevated in the two MASH models compared with obese controls without MASH. This elevation was associated with hepatic overexpression of Prmt1, a key enzyme involved in ADMA synthesis, as well as upregulation of the y+LAT1 and y+LAT2 transporters, which mediate ADMA export from the liver into the circulation. Conclusion These results suggest a hepatic origin for the elevated circulating ADMA observed in MASH models and identify ADMA as a potential mediator of endothelial dysfunction in this context. In vivo and in vitro approaches involving modulation of Prmt1 expression are being conducted to further substantiate the proposed mechanism.
Introduction Anthracyclines, including doxorubicin (DOX), are highly effective chemotherapeutic agents, but their clinical use is hampered by late-onset cardiotoxicity, driven by poorly understood molecular mechanisms. Recently, metabolic impairments have been identified as a central feature of DOX-induced cardiotoxicity. Protein O-GlcNAcylation is a glucose-derived post-translational modification produced via the hexosamine biosynthetic pathway that couples nutrient availability to adaptive stress signalling during heart failure progression. Objective Here, we investigated whether protein O-GlcNAcylation is modified by DOX and could contribute to DOX-induced cardiotoxicity (DIC). Method C57BL/6N mice received DOX (4mg/kg) via 6 intraperitoneal injections over 2 weeks (cumulative dose 24mg/kg). Cardiac function was evaluated at baseline and 6 weeks after the first injection. In vitro, adult rat ventricular myocytes (ARVMs) were treated with DOX along with O-GlcNAc inhibitors (DON and AMPK agonists) and inducer (Thiamet-G) to modulate the O-GlcNAcylation pathway. Modulation of protein O-GlcNAcylation and of its regulatory enzymes (GFAT, OGT, and OGA), as well as AMPK activation were evaluated by western blot. Apoptosis was evaluated by examining the caspase-3 cleavage. Results Echocardiography revealed systolic dysfunction and cardiac atrophy 6 weeks after treatment, associated with increased cardiac protein O-GlcNAcylation. In ARVMs, DOX treatment promoted apoptosis and induced a dose- and time-dependent enhancement of protein O-GlcNAcylation, accompanied by reduced levels of OGA, the sole enzyme responsible for removing O-GlcNAc modifications, and by a decrease in AMPK signalling (reduced phosphoAMPK/AMPK ratio), known to negatively regulate O-GlcNAcylation. Pharmacological inhibition of O-GlcNAcylation (using DON or the AMPK agonist 991) attenuated DOX-induced apoptosis, while its stimulation (with Thiamet-G) promoted ARVM apoptosis. Conclusion Our findings implicate O-GlcNAcylation in DIC and highlight AMPK activation as a promising therapeutic avenue.
Introduction Organophosphate nerve agents (OPNA) remain a military and terrorist threat, which necessitate new complementary treatments for both acute intoxication and long-term complications. Besides, organophosphorus pesticides (OP) still remain a significant public health challenge, causing thousands of annual fatalities. Beyond direct cholinesterase inhibition, OPs cause several auxiliary effects arise that span from nuclear processes to physiological functions. The heart appears to be a target of these auxiliary effects. Long-term occurrences of arrhythmias and cardiac defects have been reported in individuals, regardless of whether they received a treatment. Objective This study aims to characterize the non-cholinergic electrophysiological and metabolic alterations induced by 24hours exposure of two organophosphorus agents: first, the pesticide “paraoxon”, and then the OPNA “VX” (or its surrogate “NEMP”) using an in vitro model of cardiomyocytes-derived from induced pluripotent stem cells. Method Electrophysiological alterations were monitored using a microelectrode array in conjunction with calcium optical mapping. Metabolic alterations were assayed using Seahorse technology in conjunction with Oroboros O2k. Additionally, mRNA and proteins expressions were evaluated by RT-qPCR and Western-blot, respectively. Results Sodium, calcium and potassium currents showed signs of dysfunction consistent with our observations of decreased depolarization spike slope and amplitude, a strong amplitude beat drop, a prolonged field potential duration and excitation-contraction delay, associated with a loss of heart rate variability, that all would have proarrhythmic properties. In conjunction, calcium waves revealed an increased amplitude of calcium transient and a faster calcium reuptake by sarcoplasmic reticulum. Moreover, overall cellular energy production tends to be decreased both from glycolysis and mitochondrial respiratory chain. Our biochemical and molecular analyses support the functional findings by showing that gene and protein expressions of previously implicated actors are dysregulated following intoxication. Conclusion These alterations were not correlated to cholinesterases inhibition, as these enzymes are absent in our model, suggesting potential long-term consequences of untreated OPNA and OP exposure underscoring the urgent need to integrate this knowledge for optimal long-term treatment for both military personnel and civilians.
Introduction Cardiac NAD(H) levels rapidly decline after myocardial infarction (MI), compromising energy metabolism and signaling pathways critical for mitochondrial function, ROS defense, and calcium handling, including CD38, a major NAD+ consumer enzyme that may exacerbate this depletion. The potential of therapeutic interventions to restore NAD(H) pools post-ischemia remain underexplored. Objective 1. To characterize NAD(H) biosynthetic fluxes in cardiomyocytes using isotope-assisted LC/MS. 2. To establish an ischemia-reperfusion injury (IRI) model in isolated adult rat ventricular cardiomyocytes (ARVC) to evaluate NAD(H) dynamics, ROS, and cell survival. 3. To assess the efficacy of either nicotinamide riboside (NR), a precursor of NAD or a CD38 inhibitor, alone or in combination, in preserving NAD(H) and improving outcomes post-IRI. Method ARVCs were isolated from rats and incubated with labeled NR or nicotinamide (NAM). NAD metabolites and high-energy phosphates were quantified. In vitro IRI was induced via chemical ischemia and reperfusion; NR and CD38 inhibitor were added at reperfusion onset. NAD(H) was measured enzymatically, and viability by fluorescein diacetate staining. We also started to assess the potential of NR treatment on infarct size and area of no-reflow in an ex vivo rat heart IRI model. Results LC/MS fluxomic assays reveal that NR proved to be more effective than NAM in enhancing NAD+ synthesis in ARVC. In vitro IRI caused a 40% drop in viability and 30% NAD(H) depletion in surviving cells at 2h reperfusion (P<0.05). Either NR or CD38 inhibition preserved NAD(H) levels, and the combination of the two treatments was not superior. In the ex vivo IRI model, NR treatment led to a 31% reduction in infarct size and a trend to reduce the area of no-reflow. Conclusion Collectively, these findings support NAD(H) restoration via NR or CD38 inhibition as a promising cardioprotective strategies post-IRI. Future work will further examine impacts on mitochondrial function, oxidative stress and NAD signaling.
Introduction In the cardiomyocyte, mitochondria belong to two main distinct subpopulations: the subsarcolemmal mitochondria (SSM) are located below the cell membrane while the interfibrillar mitochondria (IFM) are arranged in rows between the myofibrils. Structural and functional differences have been reported between them: IFM display higher mitochondrial respiration and calcium retention capacity than SSM. We hypothesized that the increased respiratory capacity of the IFM could be due to a higher mitochondrial Ca2+ content through a change in their mitochondrial Ca2+ uniporter (mtCU) composition/function, i.e. a lower ratio between the MICU1 regulator and the MCU pore-forming protein, to enhance mtCa2+ uptake. Objective We sought to determine whether the composition and/or function of the mtCU differs between SSM and IFM in the rat heart. Method SSM and IFM were isolated by differential centrifugation from Lewis male rat hearts. Oxygen consumption was quantified with the Oroboros by stimulating complexes I, II and IV respectively with glutamate/malate/pyruvate, succinate and TMPD/ascorbate. The mtCU-mediated mitochondrial Ca2+ uptake was evaluated fluorometrically by measuring the cytosolic Ca2+ clearance after a Ca2+ bolus, thanks to the ratiometric fluorescence of the Fura2 Ca2+ probe added to the mitochondrial suspension. Protein level of MCU and its regulators MICU1/2 was performed by immunoblotting. Results As expected, IFM exhibited higher respiratory rates compared to SSM, whatever the substrates used. mtCU functional evaluation revealed a lower threshold of Ca2+ uptake with a reduced cooperative activation in IFM versus SSM, as supported by the reduced slope in IFM, 1.740±0.029 versus 1.848±0.057 in SSM. Reduced MICU1 and MICU2 protein levels in IFM versus SSM led to a lower MICU1/2-MCU ratio. Conclusion Altogether, these data suggest that the lower MICU1/2-MCU ratio contributing to lower threshold of mitochondrial Ca2+ uptake in IFM may account for the increased respiratory capacity. Whether heart failure differentially alters the mtCU composition/function between SSM and IFM is ongoing in explanted patients’ hearts.
Introduction Cardiovascular diseases are the leading cause of mortality in patients with type 2 diabetes. In addition to vascular complications, these patients are at risk of developing diabetic cardiomyopathy (DCM), a cardiac dysfunction that can lead to heart failure. DCM is notably characterized by a metabolic shift in which the heart relies excessively on fatty acids at the expense of glucose. Existing literature suggests that protein acetylation may play a key role in this metabolic reprogramming. Our group previously showed that metabolic overload increases cardiomyocyte protein acetylation, which inhibits insulin-stimulated glucose uptake. However, the temporal relationship between protein acetylation, cardiac insulin resistance (IR), and cardiac dysfunction during DCM development remains unclear. Objective To determine the role of protein acetylation in the development of cardiac IR and dysfunction during DCM, and to investigate whether similar mechanisms occur in skeletal muscle. Method C57Bl/6N mice were fed a high-fat diet (HFD) for 1 or 2 months. Cardiac function was assessed by echocardiography. Insulin signaling and protein acetylation were analyzed in vivo and ex vivo in the heart and skeletal muscles (soleus and gastrocnemius). Glucose uptake was measured in cardiomyocytes by following the detritiation rate of [2-3H]-glucose. Results After 1 month of HFD, protein acetylation was increased in the heart and soleus but remained unchanged in the gastrocnemius, while insulin signaling was not altered in any of the tissues. After 2 months of HFD, insulin signaling was reduced in all three tissues and glucose uptake, assessed in cardiomyocytes derived from HFD mice, was also significantly reduced. Systolic cardiac function showed a gradual decline, with a trend toward reduction already apparent after 1 month of HFD. Conclusion Increased protein acetylation under HFD precedes the development of cardiac IR and dysfunction.
Introduction Purkinje Fibers (PF) play a critical role in cardiac function, but they have been identified to trigger lethal arrhythmias. Recently, PF ectopy have been inducible by sodium channel blockers (SCBs). Objective However, the mechanisms underlying drug-induced PF ectopies remain unknown. Method We investigated the effects of two SCBs, ajmaline (15μM) and flecainide (2μM) using optical mapping on ex-vivo coronary-perfused ovine left ventricles (n=8). We measured ventricular activation and repolarization properties at the Purkinje-Muscle Junctions (PMJ) vs ventricular myocardium under increased pacing frequencies (1 to 5Hz) and various pacing sites (His, PF and myocardium) before and after introduction of SCBs. We also quantified and characterized arrhythmias for these conditions. Finally, myocardial and PF samples were collected to investigate voltage-gated channels and regulatory subunits expression by RTqPCR. Results Ajmaline significantly increased activation times (AT, 57.1±18.2 vs 220.2±62.1ms, P<0.01) for all pacing sites. Furthermore, a significant increase in action potential duration (APD80, 254.7±11.2 vs 380.5±82.9ms, P<0.05) was observed specifically at the PMJs, which led to an increased heterogeneity of repolarization time (RT, 0.045±0.022ms/mm2 vs 0.157±0.069ms/mm2, P<0.01). Flecainide increased AT (64.5±10.6ms vs 148.9±32.4ms, P<0.05) but had no significant impact on APD or RT dispersion. An increase in spontaneous arrhythmias was observed at low pacing frequencies (≤2Hz) for ajmaline (0.13±0.35 episodes vs 2.25±2.12 episodes, P<0.05) with a lower dominant frequency (4.98±1.0 vs 1.71±0.57, P<0.0001) whereas for flecainide, arrhythmias only occurred at high pacing frequencies (2-3.5Hz, 0.0±0.0 vs 1.11±1.67, P=0.625). RTqPCR revealed a higher expression of SCN5A, KCNA4 and KCND2 (×4, ×11.37, ×11.32 respectively) and a 10-fold lower expression of the regulatory subunit KCNIP2 in PF, compared to cardiomyocytes. Conclusion In conclusion, despite its expected effect on AT like flecainide, we demonstrate that ajmaline prolongs APD and increase RT dispersion of the PMJs leading to arrhythmic events even at low heart rates. Our molecular biology screening suggests that inhibition of the Ito current mediated by potassium channels may underly the effect of ajmaline on repolarization. These findings open new perspectives in terms of risk stratification and prevention.
Introduction Congenitally corrected transposition of the great arteries (ccTGA) is a rare congenital heart disease characterized by atrioventricular and ventriculo-arterial discordance, frequently associated with complex structural and functional anomalies. Cardiac position—variable among patients (levocardia, mesocardia, or dextrocardia)—may influence anatomical features and clinical evolution. Objective The aim of this study was to assess the impact of cardiac position on associated anatomical abnormalities, systemic right ventricular function, severity of systemic atrioventricular valve regurgitation, conduction disorders, and overall prognosis. Method This was a retrospective descriptive study conducted in the Department of Cardiology at Hedi Chaker University Hospital in Sfax, including patients with ccTGA followed between 2010 and 2024. Clinical, electrocardiographic, and echocardiographic data were collected and compared according to cardiac position, categorized into two groups: levocardia versus mesocardia/dextrocardia. Results The study included 37 patients, of whom 25 had levocardia, 5 mesocardia, and 7 dextrocardia. Cardiac anatomical anomalies did not show marked variations according to cardiac position: ventricular septal defect was present in 12/25 in levocardia, 3/7 in dextrocardia, and 4/5 in mesocardia; atrial septal defect in 6/25, 3/7, and 2/5; patent ductus arteriosus in 3/25, 0/7, and 1/5; coarctation of the aorta in 3/25 and absent in the other groups; pulmonary stenosis in 7/25, 3/7, and 3/5, respectively. Functional parameters showed that systemic right ventricular dysfunction was observed in 9/25 in levocardia versus 3/12 in mesocardia/dextrocardia, with no significant difference (P=0.630). Severe systemic atrioventricular valve regurgitation was noted in 7/25 and 3/12, respectively (P=0.829). Complete atrioventricular block was present in 5/25 versus 1/12 (P=0.389). Death occurred in 6/25 patients with levocardia and 2/12 with other cardiac positions (P=0.643). None of the observed differences reached statistical significance. Conclusion In this cohort of patients with ccTGA, cardiac position did not appear to influence the presence of associated anatomical anomalies, systemic right ventricular function, severity of systemic atrioventricular valve regurgitation, or mortality.
Introduction Sex-related differences in calcific aortic stenosis (CAS) are increasingly recognized, with divergent clinical presentation, valve morphology, and calcification burden. Whether gut microbiota–derived metabolites contribute to these sex-specific differences remains largely unexplored. Objective To investigate sex-specific differences in gut-derived metabolite profiles in patients with CAS and to assess CAS×sex interactions. Method Among 55 patients with CAS (41 men, 14 women), targeted serum metabolomics quantified TRP-derived metabolites, bile acids, SCFAs, and TMA/TMAO-related metabolites and 16s RNA sequencing was performed. Sex-stratified analyses and CAS×sex interaction models were performed. Results Baseline characteristics revealed sex-specific differences in hemoglobin, lipid profile (total and HDL cholesterol), and aortic valve area. In males with CAS, inflammatory TRP metabolites—including kynurenine (P=0.040), 3-hydroxyanthranilic acid (P=0.045), and xanthurenic acid (P=0.015)—were significantly higher compared with non-CAS males. In contrast, females with CAS demonstrated higher TMAO levels compared with non-CAS females (P=0.087). Direct comparison between CAS females and males revealed lower picolinic acid and kynurenic acid, but higher indole-3-acetamide and indole-3-lactic acid in females (all P<0.05). Significant CAS×sex interactions were observed for cholic acid (P=0.016) and trimethylamine (P=0.019), indicating sex-dependent modulation of gut-derived metabolic pathways. At the taxonomic level, sex-specific differences in gut microbiota composition were modest but consistent. Females with CAS showed higher relative abundance or prevalence of Bifidobacterium and Lactobacillus/Leuconostoc, whereas males exhibited higher representation of Coriobacteriaceae and Actinobacteria, taxa previously associated with cardiometabolic risk. Notably, some taxa demonstrated differences in prevalence without corresponding differences in relative abundance, or vice versa, highlighting subtle sex-related microbial patterning rather than overt dysbiosis. The results are summarized in Fig. 1. Conclusion CAS is associated with sex-specific gut-derived metabolic signatures, with activation of inflammatory TRP pathways in males and enhanced TMAO-related signaling in females.
Introduction Septic shock is characterized by a systemic inflammatory response syndrome (SIRS) causing hypotension and systemic hypoperfusion leading to altered cellular metabolism. O-GlcNAcylation is a post-translational modification involved in the stress response dependent of cellular metabolism. We have shown in 2 simplified models of endotoxemic shock that the stimulation of O-GlcNAcylation improves hemodynamic and metabolic parameters in rat. Objective We designed this study to evaluate in a more relevant model how the hyper-O-GlcNAc could impact protein response and we hypothesize that metabolic response to septic shock is regulated by O-GlcNAcylation in response to circulation-dependent metabolic stress. Method Septic shock was induced in rats (n=8-14 per group) by cecal ligation and punction (CLP). Twenty-two hours post-surgery, CLP rats received fluid therapy with or without OGA inhibitor, NButGT (10mg/kg) to increase O-GlcNAc levels. Cardiovascular functions were assessed and heart were harvested and analyzed at 24h post-surgery. Total proteomic and O-GlcNAcylomic were done as validated in the team. O-GlcNAcylation level and identified metabolic target by mass spectrometry (hexokinase-1 and NADH dehydrogenase [ubiquinone] iron-sulfur protein 2) were assessed by western blot. Results Results showed an improved cardiovascular function in NButGT treated rats. pO2 was significantly decreased and cHCO3- levels were increased in LPC versus sham, NButGT treatment restored this parameter. The proteomic analysis revealed that HK1 and NDUFS2 as potential interesting as they presented a particular profile. Considering their key role in glucose metabolism and ATP production, these 2 enzymes will be studied extensively to understand how the hyper-O-GlcNAcylation could modulate their activity in shock situations. Conclusion These findings suggest that LPC induces cardiovascular, metabolic and systemic stress, and that O-GlcNAcylation may contribute to adaptive responses, in particular by modulating the metabolic response, highlighting its potential as a therapeutic target in early sepsis.
Introduction Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare inherited cardiac disorder that manifests as stress-induced syncope or sudden cardiac death in children and young adults. A novel CPVT-associated RyR2 mutation, R169Q, was identified in a young Taiwanese woman. However, the functional consequences of this mutation on the regulation of intracellular calcium concentration remain unclear. Objective The present study aims to elucidate the mechanisms underlying the RyR2-R169Q mutation. Method Male and female wild-type (WT) and heterozygous RyR2-R169Q knock-in (KI) mice were studied. In vivo ECGs were recorded by implantable telemetry in conscious mice under basal conditions and following pharmacological stress (isoproterenol 2mg/kg, norepinephrine 2mg/kg and caffeine 120mg/kg), emotional stress (hairdryer exposure), and autonomic blockade with atropine (2mg/kg) and propranolol (2mg/kg). Additional ECGs were obtained in Langendorff-perfused hearts±1μM isoproterenol. Intracellular Ca2+ handling was assessed in isolated cardiomyocytes by confocal microscopy using Fluo-4, and protein expression was analyzed by Western blot. Results In vivo, 100% of KI mice, under pharmacological and emotional stress exhibited various types of arrhythmias, whereas WT mice hearts displayed normal ECGs with heart rate acceleration upon isoproterenol (ISO). ISO triggered ventricular tachycardia in ∼70% of KI hearts and ectopic beats in the remaining hearts. To explore the underlying mechanisms, Ca2+-induced Ca2+ release was analyzed. While Ca2+ current was similar between groups, KI cardiomyocytes showed reduced Ca2+ transient amplitudes correlating with a lower sarcoplasmic reticulum (SR) Ca2+ load under ISO, likely due to enhanced SR Ca2+ leak via calcium sparks. Although detectable Ca2+ spark frequency in intact cells was unchanged, KI myocytes exhibited more proarrhythmogenic Ca2+ waves and shorter latency to the first wave after 4-Hz stimulation. In permeabilized KI myocytes, Ca2+ spark frequency was higher at low [Ca2+]i than WT, indicating an altered relationship between Ca2+ spark frequency and [Ca2+]i. Expression of major Ca2+-handling proteins including RyR2, SERCA, PLN, NCX, FKBP12, CSQ2, and JPH2 was unchanged between groups. Conclusion The R169Q mutation promotes ventricular arrhythmias by increasing RyR2 openings at lower [Ca2+]i. Further molecular studies are needed to elucidate the underlying mechanisms.
Introduction Living cardiac slices as models for testing physiological and pharmacological interventions are recognised to offer unique advantages over whole perfused organs or single isolated cardiomyocytes for several reasons. To name just a few, slices allow multiple experimental samples from biopsies; they can be maintained under culture conditions for several days; they consist of mature cells; and multicellularity and intercellular contacts as well as ECM are preserved. Thus, they provide a promising approach for short- and long-term drug (up to several weeks) screening. Objective Our aim is to assess the validity the model by testing the electrophysiological effects of well-known antiarrhythmic drugs: flecainide (class 1c) and dofetilide (class 3) in human slices. Method Cardiac tissue excised from patients was sliced into 400 μm thick sections, mounted in biomimetic chambers (MyoDish, InVitroSys) allowing us to record contraction forces, preloaded and paced electrically at a frequency of 1 Hz. Action potentials (AP) were recorded at 37°C using sharp intracellular microelectrodes pulled from borosilicate glass capillaries (tip resistance 15–25 MΩ when filled with 3 M KCl solution). Observations before and during drug interventions are all paired. All values are reported as mean±standard error. Results Left ventricular slices (N=8, n=27) and right atrial slices (N=7, n=23) had respectively resting membrane potentials (RMP) of −82.5±0.9 and −72.1±1.4mV, AP amplitudes (APA) of 113±1.3 and 90.2±1.9mV, maximum upstroke velocities (dV/dtmax) of 127.6±7.6 and 190.5±13.8V/s, AP durations at 90% of repolarization (APD90) of 452.8±14.3 and 327.4±23.4ms, contraction durations 90% (CD90) of 551.3±18.4 and 231.1±16.6ms. Flecainide significantly decreased dV/dtmax and APA in both left ventricular and right atrial slices, whereas dofetilide significantly increased APD90 in both tissues. Regarding contractions, both drugs induced a significant negative inotropic effect and an increase of CD90 only in left ventricular slices. Conclusion The living cardiac slice model produced consistent results with published results on trabeculae and whole mount tissues concerning AP and contraction parameters. Classic antiarrhythmic drugs produced the expected effects. The results of this study suggest that the slice model is suitable for assessing drug effects on key electrophysiological parameters, making this model promising for assessing novel antiarrhythmic compounds
Introduction Although 3/4 of patients with abdominal aortic aneurysm (AAA) develop intraluminal thrombus (ILT), the role of ILT in AAA progression and rupture remains poorly understood. Objective The goal of this study is to longitudinally evaluate how ILT formation relates to AAA growth, aortic wall remodeling, and hemodynamic changes using a murine AAA model. Method To evaluate ILT in AAAs, we induced AAAs in C57Bl6/J mice (n=27 male; n=7 female) via surgical application of topical elastase (5μL of 5–10mg/mL) to the abdominal aorta below the renal arteries and administration of β-aminopropionitrile (BAPN, 0.2%) in drinking water. High-resolution ultrasound images of these AAAs were collected longitudinally over a period of 56 days to evaluate AAA growth and ILT deposition over time (Figure 1). We semi-quantitatively assessed elastin degradation and inflammation from Movat's pentachrome and H&E-stained samples, respectively. Additionally, we assessed extracellular matrix composition and elastin quality through Movat's pentachrome stained samples. Results Mice subjected to the topical elastase surgery+oral BAPN additive exhibited continuous and significant AAA growth over time, with 48% of males and 100% of females developing ILT. Mice with ILT had more significant expansion over the length of the study (P<0.05). From histology, ILT samples showed more elastin damage, greater collagen and proteoglycan accumulation, and greater inflammation than aneurysms without ILT. From scanning electron microscopy, we were able to confirm the presence of fibrin sheets and abnormally shaped red blood cells (polyhedrocytes) within the ILT. We also observed that tissue samples with greater acute-on-chronic inflammation were correlated with more elastin damage, and therefore greater aortic expansion. Further, larger aortic expansions were correlated with slower blood flow due to increased cross-sectional area. Conclusion Increased aortic expansion and damage to the aortic wall may create hemodynamic conditions that are conducive to the initiation of ILT deposition: endothelial damage and reduced blood flow. Understanding the relationship between ILT formation, aortic wall degradation, and inflammation could help refine clinical strategies for monitoring and treating AAAs. These data suggest that work focused on modulating inflammation and ILT formation could offer promising pathways for non-surgical intervention in AAA treatment.Aortic wall remodeling is induced via BAPN-mediated reduction in collagen crosslinking and elastase-driven elastin damage, promoting inflammation and aneurysm progression.
Introduction The spontaneous activity of pacemaker cells in the sinoatrial node (SAN) controls the heart rythm under physiological conditions. Recent studies by our group shows the importance of the L-type Ca2+ channel Cav1.3 on the generation pacemaker activity. Cav1.3 channel takes an important place in cardiac conduction system. Sustained atrial arrhyhtmias leads to chronic cardiac pathologies. Progressive electrical remodelling is an important part of atrial arrhythmias generation in the heart. Objective Here we evaluate if Cav1.3 selective deletion in the cardiac conduction system is suffisent to increase atrial arrhythmias susceptibility. Method We generated mice carrying conditional floxed Cav1.3 allele (Cav1.3 Flex eGFP/Flex eGFP) and crossed with HCN4 CreERT2 line allowing deletion of Cav1.3 in cardiac HCN4 expressing (HCN4+) cells upon tamoxifen injection (Cav1.3 eGFP/eGFP mice). We confirmed transgenic expression in our mice model by using patch clamp and immunostaining on transparized heart. We investigated the effect of Cav1.3 deletion on heart automaticity by telemetric ECGs and Langendorff-perfused hearts. Then, susceptibility to atrial arrhythmias was studied by using Langendorff-perfused heart coupled to optical mapping. Stimulation protocols were used to trigger and increase atrial arrhythmias susceptibility on our mice models. Results Cav1.3 eGFP/eGFP pacemaker cells shows significant bradycardia (201±36 AP/min vs 244±24 AP/min in untreated group), associated with a strong decrease of ICal (-69%). Cav1.3 eGFP/eGFP mice diplayed significant bradycardia (278±78 BPM vs 411±50 BPM in untreated group associated with an increase of atrial arrhythmias susceptibility (56%) compared to untreated group (22%). Conclusion To summarize, our datas shows that deletion of Cav1.3 leads to impairements in conduction system and heart rate generation. Loss of Cav1.3 causes important rythm troubles such as an increase of heart rate variability, AV blocks, strong bradycardia and seems to increase significantly atrial arrhythmias susceptibility. This study underscores the major role of Cav1.3 in cardiac conduction system. Thus, Cav1.3 channel could be an interesting target to improve atrial arrhythmias treatment.
