American Journal of Physiology-Heart and Circulatory Physiology

AimMaternal iron deficiency (ID) during pregnancy induces cardiovascular adaptations, including reduced blood pressure and improved cardiac efficiency in hypertensive pregnancy. Iron is essential for mitochondrial function, particularly oxidative phosphorylation, where it serves as a cofactor within electron transfer complexes. Given the high metabolic demands of the maternal heart and irons central role in mitochondrial metabolism, we examined how maternal ID affects cardiac mitochondrial ultrastructure, respiration, dynamics, and redox status in pregnant spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Methods and ResultsFemale SHR and WKY rats were fed iron-replete or iron-restricted diets before and throughout gestation. On gestational day 21, cardiac mitochondrial ultrastructure was assessed by transmission electron microscopy (TEM), respiration by high-resolution respirometry, and the expression of proteins involved in fusion, fission, autophagy, and apoptosis markers by immunoblotting. Antioxidant gene expression was quantified by RT-qPCR. Data were analyzed by two-way ANOVA with Holm-Sidaks post hoc test. Maternal iron restriction reduced hemoglobin levels in both strains. TEM revealed enlarged, morphologically heterogeneous mitochondria with reduced and disrupted cristae architecture in ID dams of both strains. Iron restriction reduced succinate-supported respiration and tended to reduce NADH-supported respiration, in both strains. SHR dams exhibited reduced fusion signalling, reflected by a lower L-OPA1:S-OPA1 ratio. MFN1 expression was reduced by ID in both strains, whereas MFN2 expression was lower in SHR and further reduced by ID. In contrast, DRP1 phosphorylation increased selectively in ID-WKY dams. Iron restriction increased LC3-II:I ratio and BNIP3 in SHR, and increased PINK1 in both strains, while Parkin and p62 were unchanged. Antioxidant gene expression increased in ID-SHR but decreased in ID-WKY dams. Despite these alterations, markers of oxidative damage and apoptosis were unchanged by iron restriction. ConclusionMaternal ID induces marked remodeling of myocardial mitochondrial ultrastructure and selectively constrains iron-dependent respiration in hypertensive pregnancy without overt oxidative damage or apoptosis. These mitochondrial alterations occur alongside previously observed reductions in blood pressure and improved cardiac efficiency, suggesting favorable hemodynamic adaptations may coexist with underlying bioenergetic constraints in the maternal heart. Translational PerspectiveMaternal iron deficiency anemia (IDA) may alter the course of hypertensive pregnancy in ways not evident from hemodynamic indices alone. Here, IDA was associated with abnormal myocardial mitochondrial ultrastructure, selective reductions in respiratory capacity and stress response pathways, despite previously observed improvements in blood pressure and cardiac efficiency. These findings suggest that favourable hemodynamic changes may reflect reduced metabolic demand rather than enhanced bioenergetic capacity. If confirmed in human pregnancy, management of ID in women with underlying hypertension may need closer attention to cardiac metabolic health, as cardiovascular adaptions could coexist with myocardial stress and may vary with anemia severity and duration.

Drug-induced inhibition of the delayed rectifier potassium (IKr) current predisposes to early afterdepolarisations (EADs) and cardiac arrhythmias. Here, we sought to determine the contribution of action potential duration (APD), APD variability and spontaneous calcium release from the sarcoplasmic reticulum (SR) in the formation of EADs. In isolated sheep ventricular myocytes, EADs were induced by combined inhibition of IKr with dofetilide and {beta}-adrenergic stimulation. The onset of EADs was preceded by increased beat-to-beat variability of APD. To isolate the role of APD in EAD initiation, the sarcoplasmic reticulum (SR) was depleted of calcium with caffeine. The first beat post-caffeine was associated with prolonged APD but not an EAD. During {beta}-AR stimulation, increasing ryanodine receptor open probability had no effect on APD but increased APD variability and induced both EADs and delayed afterdepolarisations (DADs). Targeting RyR open probability with K201 reversibly abolished afterdepolarisations. APD variability was a better predictor of EADs than APD alone. During an EAD, changes in [Ca2+]i preceded those of membrane depolarisation and the changes in [Ca2+]i were in the form of calcium sparks. In silico modelling demonstrated that membrane time constant effects account for the delay between changes in [Ca2+]i and membrane potential. In summary, using a drug-induced model of action potential prolongation with {beta}-AR stimulation, EADs are preceded by increased APD variability and an increase in Ca2+ sparks. Targeting SR function abolishes EADs. These results suggest a key role for SR Ca2+ overload in the formation of EADs and indicate that EADs and DADs share common mechanisms. Key PointsO_LIDrugs that prolong the cardiac action potential and ECG QT interval are a major cause of early afterdepolarisations and dangerous ventricular arrhythmias initiated by early afterdepolarisations. C_LIO_LIProlongation of the action potential is widely assumed to be the primary driver of these events. C_LIO_LIWe show that early afterdepolarisations are instead preceded by increased beat-to-beat variability of action potential duration and that this variability has better sensitivity and specificity for early afterdepolarisations than action potential duration. C_LIO_LISmall, spontaneous calcium release events known as calcium sparks occur before membrane depolarisation driving early afterdepolarisations. C_LIO_LISuppressing calcium release from the sarcoplasmic reticulum abolishes early afterdepolarisations, identifying calcium handling instability as potentially a key mechanism of drug-induced arrhythmia. C_LI

AimsHeart failure with preserved ejection fraction (HFpEF) afflicts millions annually and current treatments provide symptomatic relief. Here, we investigate the therapeutic potential of synthetic human Relaxin-2 (RLX) at reversing diastolic dysfunction (DD) and reducing arrhythmia vulnerability. Methods and ResultsMale ZSF1 rats were placed on a normal diet (ND, N=10 controls) or a high-fat diet (HFD, N=11), resulting in the development of DD in 11-weeks, based on serial echocardiograms (enlarged left atrium (LA), wall thickness, doppler flow: E/e). Once HFpEF was confirmed, control and HFpEF rats were randomly treated with Relaxin (400{micro}g/kg/day RLX, N=6) or the vehicle (N=5) for 2-weeks using implanted minipumps. Echocardiograms were repeated at weeks 1 and 2, then hearts were isolated, optically mapped, subjected to programmed electrical stimulation (PES) and tissues dissected for immuno-fluorescence (IF), and qPCR analysis. Circulating levels of glucose, RLX and NT-pro-ANP were measured, pre- and post-treatment. Echocardiograms indicated that RLX reversed DD by reducing LA dimensions and E/e. Optical mapping revealed that 1/3 of HFpEF hearts exhibited sustained atrial and ventricular arrhythmia which were blocked by RLX as it tended to increase conduction velocity (CV). Based on IF, RLX increased Nav1.5, Connexin-43, {beta}-catenin and Wnt1 expression. There were no significant changes in fibrosis in this HFpEF model. NT-pro-ANP was elevated in HFpEF and reduced towards control values by RLX. qPCR analysis showed that RLX decreased DKK1 and MMP1A and increased SCN5A expression compared to Vehicle treatment (N=6 and 5, respectively). ConclusionsThe ZSF1 model showed clear signs of HFpEF, including DD, enlargement of the LA, enhanced hemodynamic stress, increased vulnerability to sustained AF and VF, and elevated glucose and blood pressure. RLX treatment largely reversed DD, hemodynamic stress, and suppressed sustained arrhythmias. RLX elicited cardiac genomic changes, most likely through Wnt/canonical signaling, demonstrating RLXs potential as a therapy for HFpEF.

BackgroundPeripheral artery disease is a major manifestation of atherosclerotic cardiovascular disease (ASCVD) that affects both men and women. In women, menopause increases the ASCVD risk. However, preclinical ASCVD research has historically been conducted predominantly in males, with relatively few studies focused on females and even fewer incorporating menopause models that more closely reflect human ASCVD pathobiology. Herein, we tested whether the chemical 4-vinylcyclohexene diepoxide (4-VCD)-induced ovarian failure or ovariectomy (OVX) would drive atherosclerotic development and worsen ischemic limb pathophysiology. MethodsFemale C57BL/6J mice were injected with adeno-associated virus-mediated encoding a gain-of-function mutant PCSK9 and fed an atherogenic diet for 23 weeks. Based on the baseline body weight, mice were randomly assigned to normally cycling controls (CON), 4-VCD, or OVX groups. Three weeks after the conformation of ovarian failure (4-VCD) or surgical ovarian removal (OVX), hindlimb ischemia (HLI) was induced via femoral artery ligation, and limb perfusion recovery and limb muscle performance were assessed. ResultsBoth 4-VCD treatment and OVX reduced uterus mass, without impacting body weight or composition, or circulating cholesterol levels compared to CON mice. Despite the similar metabolic and cholesterol profiles, atherosclerotic lesion areas were 1.5-1.7-fold greater in 4-VCD and OVX mice than CON mice. Perfusion recovery following HLI and plantar flexor muscle function in the ischemic limb were similar across groups, though muscle oxygenation was reduced in 4-VCD and OVX groups. ConclusionsOvarian failure and removal exacerbated atherosclerotic development but had minimal impacts on perfusion recovery and limb function following HLI. These findings confirm the inclusion of menopausal models, whether through ovarian failure or OVX, should be carefully considered to improve translatability of preclinical ASCVD studies, especially for womens health. Clinical PerspectiveO_ST_ABSWhat is New?C_ST_ABSWe demonstrate that both gradual ovarian failure (4-VCD) and surgical ovariectomy exacerbate atherosclerotic plaque development in a clinically relevant AAV-PCSK9 model, despite similar circulating lipid levels. In contrast, loss of ovarian function did not impair limb perfusion recovery or muscle functional outcomes following hindlimb ischemia, revealing a dissociation between atherosclerotic burden and limb functional recovery in experimental peripheral artery disease (PAD). What are the Clinical Implications?These findings provide new insight into why menopause increases atherosclerotic cardiovascular disease (ASCVD) risk while not necessarily demonstrating proportional impairments in limb recovery following ischemia. The data suggest that menopause-associated factors accelerate large-vessel atherosclerosis independent of circulating lipids, highlighting the need for targeted therapies beyond lipid lowering in postmenopausal women. Moreover, the dissociation between plaque burden and ischemic limb function underscores the importance of assessing functional outcomes in PAD independently of vascular imaging. Finally, these findings suggest that the incorporation of menopause-relevant models in preclinical research should be considered within the context of the specific biological endpoints and translational goals being evaluated.

The cardiac autonomic nervous system is a key driver of various cardiac disorders and arrhythmias. However, investigating neuronal regulation of the human heart has proven difficult due to immitted and reliable experimental models. Here, we present a novel microphysiological system utilizing a compartmentalized microfluidic device (MFD) to integrate co-cultured human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hiPSC-CMs) and sympathetic neurons (hiPSC-SNs). MFD is composed of two wide-open chambers separated by microfluidic microchannels. hiPSC-SNs were characterized by confocal imaging and RT-qPCR for the expression of peripherin, tyrosine hydroxylase, and {beta}-tubulin III, as well as high levels of dopamine {beta}-hydroxylase and nicotinic acetylcholine receptors. Furthermore, patch-clamp techniques confirmed their functional maturity, showing spontaneous action potentials and positive responses to nicotine (1{micro}M). Co-culturing hiPSC-CMs and hiPSC-SNs within the MFD facilitated axonal projection into the cardiomyocyte chamber, establishing a physical connection between the two cell types. After 10 days of co-culture, functional integration was confirmed by a significant increase in the action potential frequency and beating rate of hiPSC-CMs, as recorded by patch-clamp and video motion tracking, respectively. Notably, nicotine application in the neuronal chamber accelerated these rates in hiPSC-CMs chamber, whereas the administration of the {beta}-blocker, propranolol (5{micro}M), effectively decreased the beating rates. Collectively, these data demonstrate the feasibility of differentiating hiPSCs into functional sympathetic neurons and establishing a robust neuro-cardiac interface. This microphysiological system represents a powerful platform for investigating disorders characterized by impaired neuro-cardiac interactions, offering a valuable tool for both disease modeling and pharmacological screening.

The epidermal growth factor receptor (EGFR) family network comprises 4 receptors (EGFR, ERBB2, ERBB3, ERBB4) and numerous ligands, and is dysregulated in many cancers. Since anti-cancer drugs that target these receptors are cardiotoxic for some patients, it is important to understand the network in cardiac cells. Data from the Human Protein Atlas established that EGFR family members and their ligands are differentially expressed in cardiac cell types. Ligand expression was altered in human failing hearts and may contribute to disease. These ligands stimulated extracellular signal-regulated kinases 1/2 (ERK1/2) and Akt in rat cardiomyocytes but to different degrees. Afatinib (at a concentration to inhibit all EGF family receptors) was used to assess the role of the network in a mouse model of cardiac hypertrophy induced by angiotensin II (AngII). Echocardiography and segmental strain analysis demonstrated that afatinib reduced AngII-induced cardiac hypertrophy and caused cardiac dysfunction. This was associated with loss of cardiomyocyte hypertrophy, enhanced cardiac fibrosis, and reduced expression of Nrg1. NRG1 binds to ERBB4 in cardiomyocytes which homodimerizes or heterodimerises with ERBB2. The role of ERBB2 in the cardiomyocyte response to NRG1 compared with EGF was dissected using tucatinib (a selective ERBB2 inhibitor) and mRNA expression profiling. Most, but not necessarily all, of the response to NRG1 required ERBB2 signalling; most, but not all, of the response to EGF did not. Thus, the EGFR family network plays an important role in the heart. Understanding this network may identify therapeutic approaches to avoid cardiotoxicity associated with EGFR family anti-cancer drugs. Clinical perspectivesO_LIAnti-cancer drugs that target the epidermal growth factor receptor (EGFR) family are cardiotoxic for some patients; it is therefore important to understand the network in cardiac cells. C_LIO_LIThe EGFR family and their ligands are differentially expressed in cardiac cells with changes in ligand expression in heart failure; inhibition of all receptors in a mouse model of hypertrophy reduces cardiac hypertrophy and causes cardiac dysfunction with attenuation of cardiomyocyte hypertrophy and enhanced cardiac fibrosis and loss of neuregulin 1 (NRG1); in rat cardiomyocytes, NRG1 signalling to gene expression is largely mediated via ERBB2. C_LIO_LIThe EGFR family network plays an important role in the heart; understanding this network may identify therapeutic approaches to avoid cardiotoxicity associated with anti-cancer drugs targeted against it. C_LI

BACKGROUNDIn addition to lethal ventricular arrhythmias, arrhythmogenic cardiomyopathy (ACM) is associated with conduction abnormalities, bradycardias, and reduced expression of the scaffolding junctional protein zonula occludens-1 (ZO-1). Reduced ZO-1 expression is also seen in dilated cardiomyopathy, which is far more common than ACM. Conduction abnormalities are likewise a feature of ZO-1 cardiac-specific knockout (ZO-1cKO) mice. However, the role of ZO-1 in sinoatrial node (SAN) automaticity has not been studied. OBJECTIVETo investigate the role of ZO-1 in SAN automaticity and elucidate the mechanisms by which ZO-1 deficiency leads to SAN dysfunction. METHODSZO-1 cardiac-specific knockout (ZO-1cKO) mice were generated by crossing ZO-1 floxed mice with MHC-nuclear Cre mice. SAN/atrial tissue and isolated SAN cells were examined using optical mapping, single-cell patch clamp, and quantitative PCR techniques to assess functional alterations caused by ZO-1 loss. RESULTSZO-1cKO mice exhibited enlarged atria and SAN area compared to control mice, with normal left ventricular function. Electrocardiograms showed sinus bradycardia, sinus pauses and atrioventricular block. Optical mapping revealed a caudal shift in the SAN leading region and reduced intra-atrial conduction velocity in ZO-1cKO mice. Patch-clamp recordings from isolated SAN cells showed reduced spontaneous action potential frequency and diastolic depolarization rate, while voltage-clamp revealed a marked reduction in pacemaker current (If). CONCLUSIONZO-1 expression is essential for SAN automaticity. Its loss impairs SAN impulse generation by reducing pacemaker current and hampering atrial conduction, leading to bradyarrhythmia, conduction delay and block. These findings help explain impulse generation and conduction abnormalities in ACM and other cardiomyopathies.

Background. Adults with congenital heart disease (CHD) are a growing population and face unique challenges as they age. Unlike acquired diseases that disrupt a previously healthy baseline, CHD is developmentally embedded. Allostatic load, the multi-system biological "wear and tear" exacted by the continuous cost of coping, offers a framework for indexing this lifelong psychophysiological stress. Methods. We analyzed 14,469 adults from the All of Us Research Program: non-syndromic CHD (n = 6,810), acquired heart disease (AHD; n = 2,264), non-cardiac chronic illness (n = 4,331), and a general population comparison cohort (GP; n = 1,064). Using a standardized operationalization, allostatic load was scored across five biomarker domains (AL5, range 0-5). A pre-specified primary test compared adjusted AL5 between CHD and GP. Exploratory analyses examined clinical predictor of this gap and whether baseline subjective health predicted prospective AL5 change, utilizing strictly matched biomarkers across timepoints to prevent substitution artifacts. Results. Adults with CHD carried significantly higher allostatic load than the general population comparison cohort (adjusted difference +0.30 AL5 units, 95% CI 0.24-0.37, p < .001). Cumulative comorbidity and cardiac medication burden explained most of this gap. Congenital anatomical complexity did not independently predict this burden. In a prospective subsample (n = 8,031, mean follow-up 2.7 years), worse baseline mental health predicted increases in allostatic load over time in CHD. Baseline physical health showed no such prospective association. The general population and acquired heart disease cohorts demonstrated the inverse dissociation: subjective physical health predicted these longitudinal physiological changes. Conclusions. Adults with CHD carry an elevated allostatic burden dictated by the cumulative cost of acquired medical and treatment intensity. The original congenital anatomy does not predict this accumulation. Furthermore, subjective mental health prospectively tracks future increases in allostatic load in CHD. This dissociation is absent in adult-onset acquired heart disease, suggesting that the mental aspects of coping with CHD may impact outcomes above and beyond those with acquired heart disease. These findings position psychological care as a potentially physiologically consequential intervention.

Patients with Fontan circulation face evolving risk for cardiovascular morbidity and mortality, yet the interplay between cardiac function, vascular properties, and circulating proteins is incompletely defined. We hypothesized that biochemical biomarkers and multimodal cardiovascular profile differ significantly between Fontan patients and controls, and that selected markers may serve as predictors of reduced single ventricle function. We conducted a prospective observational study at a tertiary pediatric heart center including 31 individuals with Fontan circulation and 52 matched controls. Cardiac function was assessed by echocardiography; vascular phenotyping included carotid intima-media thickness, central and peripheral blood pressure, augmentation index corrected for heart rate, carotid-femoral pulse wave velocity, aging index, and reactive hyperemia index. Compared to controls, the Fontan group had increased pulse wave reflection and central systolic pressure as well as decreased echocardiographic markers of systolic and diastolic function, while pulse wave velocity and other vascular parameters were not significantly different between the groups. Levels of 92 circulating cardiovascular biomarkers were quantified in a subset of 25 of the Fontan cohort and 81 controls using a proximity extension assay. Twenty-two biomarkers differed significantly in the Fontan group compared to controls, including FGF23, REN, HAOX1, and IL17D. Levels of several of these biomarkers correlated with patient age. Most importantly, HAOX1 (a peroxisomal oxidase linked to redox metabolism) and FGF23 (a bone-derived hormone regulating phosphate and vitamin D homeostasis) correlated negatively with ejection fraction within the Fontan group. By contrast, BNP was not associated with cardiac function in the Fontan group. None of the biomarkers correlated with central arterial parameters. In summary, central arterial hemodynamics and biomarkers such as FGF23 and HOAX1 may improve monitoring of cardiovascular function in single ventricle patients with Fontan circulation.

Background: Hypertensive disorders of pregnancy (HDP) are a risk factor for early cardiovascular disease in women, perhaps related to adverse cardiovascular reactivity to physiologic stress. Objectives: To evaluate the association of HDP subtypes with exercise stress echocardiography parameters. Methods: This retrospective cohort study linked exercise stress echocardiograms with delivery records. HDP was classified as none, gestational hypertension (GH), and preeclampsia (PEC). We compared features of treadmill exercise stress echocardiography among HDP groups, adjusted for maternal demographic characteristics, time between delivery and stress testing, resting blood pressure (BP), and exercise duration. Results: Among 885 women with matching delivery and exercise echocardiography records (41.4plus-or-minus sign7.4 years at exercise exam), 92 (10.4%) experienced GH and 39 (4.4%) experienced PEC. Women with PEC were referred for exercise stress testing 3.1 years earlier following delivery (p<0.001) and had shorter exercise duration (lower case Greek beta]=-69.6 seconds [95% CI -115.9, -23.4], p=0.003) than those without HDP. Women with GH had higher peak exercise systolic BP (lower case Greek beta=8.96 mmHg [95% CI 4.89, 13.04], p<0.001), diastolic BP (lower case Greek beta=2.67 mmHg [95% CI 0.24, 5.10], p=0.031), and pulse pressure (lower case Greek beta=8.25 mmHg [95% CI 4.11, 12.39], p<0.001) than those without HDP. Women with GH and PEC were twice as likely to have concentric remodeling and more adverse diastolic parameters on echocardiography than those without HDP (p<0.05). Conclusions: Exercise stress echocardiography may detect subclinical cardiovascular dysfunction in midlife women following HDP, with adverse findings differing by subtype: GH was associated with higher peak exercise BP and PEC with lower exercise capacity.

PurposeLeft ventricular hypertrophy (LVH) is a major complication of chronic hypertension and an independent risk factor for cardiovascular morbidity and mortality. There are currently no clinically validated markers available to identify hypertensive individuals at risk for developing LVH. In hearts of hypertensive rats, we previously described metabolic changes that precede LVH development, including in branched-chain amino acid (BCAA) metabolism. This study investigated whether cardiac leucine uptake, measured with dynamic 5-[18F]fluoroleucine positron emission tomography-computed tomography ([18F]FLE-PET/CT), was impaired and could serve as an in vivo marker for hypertension-induced LVH development. ProceduresWe synthesized [18F]FLE following established radiochemistry protocols and performed dynamic [18F]FLE-PET/CT imaging in 3-month-old spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) control rats (n = 4 per group). Cardiac magnetic resonance (CMR) imaging was conducted on the same animals for structural co-registration. A dual-output reversible two-tissue compartment model with spill-over (SP) and partial volume (PV) corrections was developed to quantify the first-pass rate constant (K1) and total distribution volume (Vt = K1/k2) for [18F]FLE. Protein expression of L-type amino acid transporter 1 (LAT1) and branched-chain keto acid dehydrogenase (BCKDH) phosphorylation status were assessed by immunoblotting of isolated heart tissue. ResultsSHR demonstrated markedly lower first-pass leucine uptake rates (K1) and total distribution volumes (Vt) compared with WKY rats, consistent with reduced cardiac BCAA uptake. Concurrently, LAT1 (SLC7A5) expression was significantly reduced in SHR hearts compatible with decreased leucine uptake. Elevated BCKDH phosphorylation at Ser293 in SHR hearts indicated diminished BCKDH enzymatic activity and impaired BCAA catabolism. ConclusionsDynamic cardiac [18F]FLE-PET imaging successfully detects decreased leucine uptake in hypertensive rat hearts at 3 months of age, before LVH is established at 5 months. Reduced cardiac leucine uptake may thus serve as a surrogate marker for impaired cardiac BCAA metabolism and early in vivo indicator of cardiometabolic dysfunction that precedes LVH. The imaging approach holds translational potential for identifying hypertensive patients at risk for LVH progression.

Background: Left atrial (LA) stiffness index is a non-invasive echocardiographic parameter reflecting left ventricular filling pressure; however, its prognostic significance in hypertension remains unclear. We aimed to assess the prognostic value of the longitudinal change in LA stiffness index in patients with hypertension. Methods: We analyzed 1,442 hypertensive patients from the STRATS-HHD registry who underwent echocardiography including LA and left ventricular (LV) strain at baseline and 6-18 months. Patients were categorized into four groups according to longitudinal changes in LA stiffness index: normal-normal, improved, aggravated, and persistently stiff. The primary outcome was a composite of hospitalization for heart failure (HHF) and cardiovascular death, and secondary outcomes included HHF and incident atrial fibrillation. Results: Among 1,442 patients, 996 (69.1%) were classified as normal-normal, 173 (12.0%) as improved, 91 (6.3%) as aggravated, and 182 (12.6%) as persistently stiff. Over 5 years, aggravated (adjusted hazard ratio [aHR] 2.175, 95% confidence interval [CI] 1.048-4.515, P=0.037) and persistently stiff (aHR 2.935, 95% CI 1.697-5.076, P<0.001) groups were associated with a higher risk of the primary outcome, whereas the improved group showed a similar risk to the normal-normal group. Similar trends were observed for HHF and for incident atrial fibrillation. Adding LA stiffness index into a model including clinical factors and LV mass index improved risk prediction for composite outcomes. Conclusions: LA stiffness index was associated with clinical outcomes in hypertensive patients, with longitudinal changes providing additional prognostic information. Assessment of its trajectory may further refine risk stratification in patients with hypertension.

Background Atrial fibrillation (AF) is a leading cause of stroke, cardiovascular morbidity, and mortality. Atrial myopathy, characterized by progressive metabolic, electrical, and structural changes, creates the arrhythmogenic substrate that drives AF. Defining the key drivers of atrial myopathic processes is essential for targeted therapies that can mitigate AF progression. Here we explore how reduced ERBB4 expression contributes to the development of left atrial myopathy. Methods We analyzed the Cleveland Clinic Biobank to compare left atrial ERBB4 levels in patients grouped by AF diagnosis. To investigate the impact of reduced ERBB4 levels on atrial tissue substrate, we created mouse models of cardiac-specific Erbb4 deficiency using Mlc2a (myosin light chain 2a)-Cre. Comprehensive physiological assessments were performed. Transcriptomic analyses of the left atrium were performed in an Erbb4 haploinsufficient mouse model and compared with human atrial datasets. Molecular validation of key dysregulated pathways was performed. Results We found that left atrial ERBB4 levels are reduced in patients with AF. Adult cardiomyocyte-specific Erbb4 heterozygous (Erbb4fl/+;Mlc2a-Cre) mice exhibited prolonged P-wave duration in the absence of ventricular dysfunction. Left atrial transcriptomic analysis in Erbb4 haploinsufficient mice showed upregulation of pathways related to fibrosis, apoptosis, and coagulation, and downregulation of pathways related to fatty acid metabolism and mitochondrial function, mirroring changes observed in pressure overload mouse models. A cross-species transcriptomic comparison revealed significant overlap between ERBB4-correlated gene expression and functional pathways in adult human atria and mice with Erbb4 haploinsufficiency. Validating the transcriptomic data, protein and functional assays demonstrated increased fibrosis, apoptosis, and oxidative stress in the mutant left atrial tissue. Conclusion Left atrial ERBB4 levels are reduced in AF patients. A mouse model of Erbb4 deficiency and human atrial transcriptomic analyses highlight a role for ERBB4 in supporting normal atrial metabolism while protecting against inflammation, apoptosis, and fibrosis.

OBJECTIVEThis study aimed to explore the role and underlying mechanism of microRNA-128 (miR-128) in regulating vascular remodeling in spontaneously hypertensive rats (SHRs), focusing on its targeting of peroxisome proliferator-activated receptor {gamma} (PPAR-{gamma}) and modulation of the Toll-like receptor 4/nuclear factor-{kappa}B (TLR4/NF-{kappa}B) inflammatory pathway. METHODSAll experimental procedures were approved by the Animal Care and Use Committee of Fujian Medical University. In vivo, ten-week-old male SHRs were randomly assigned to three groups: renal denervation (RDN, n=6), sacubitril/valsartan (Sac/Val, n=6), and Sham (n=6). Age-matched Wistar-Kyoto (WKY) rats served as normotensive controls (n=6).Eight weeks after intervention, mesenteric arteries were harvested for histological, functional, and molecular analyses. Serum miR-128 levels were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The expression levels of key proteins in the vascular wall were assessed via immunofluorescence (IF), immunohistochemistry (IHC), and Western blotting (WB). Bioinformatics analysis and RNA sequencing (RNA-seq) were employed to identify core genes and signaling pathways associated with hypertension-induced pathological inflammation. RESULTSIn vivo, in the SHR sham-operated group, elevated blood pressure, severe vascular remodeling, and impaired vasodilatory function were observed, accompanied by downregulated miR-128 expression and upregulated TLR4/NF-{kappa}B signaling activity (all p < 0.0001).RDN postoperative, miR-128 expression was significantly restored, which in turn inhibited the TLR4/NF-{kappa}B pathway, reduced the production of pro-inflammatory cytokines (including IL-1{beta}, IL-6, and TNF-), and ameliorated vascular dilation dysfunction in SHRs (all p < 0.0001). Mechanistically, miR-128 negatively regulated the TLR4/NF-{kappa}B signaling pathway while upregulating the expression of PPAR-{gamma} (p < 0.05). CONCLUSIONRDN not only exerts a hypotensive effect but also improves hypertensive vascular remodeling. miR-128 inhibits excessive inflammation in vascular smooth muscle cells and alleviates vascular remodeling in SHRs via the PPAR-{gamma}/TLR4/NF-{kappa}B axis. These findings identify miR-128 as a potential therapeutic target for RDN in the treatment of hypertension, providing a novel regulatory strategy for the precision management of cardiovascular diseases.

Aortic dissection is life-threatening due to continued loss of medial integrity that may culminate in secondary rupture within hours to days. While pre-existing defects or hemodynamic loads compound structural deterioration of the aorta, pathological progression from symptomatic dissection channel to lethal transmural tear is poorly understood. We examined the structure of referent and acutely dissected ascending aortas by microscopy. Elastic, collagen, and cellular components of non-dissected media were intricately interconnected. Medial damage in dissection lesions was traced from ingress to central to peripheral areas. Entry tears broke cleanly through successive laminae leading to cavernous false lumens in which medial structure was destroyed. Nearby laminae with widening between flanking elastic lamellae (termed minor delaminations) were filled with blood and showed severe medial damage. Farther laminae without delamination but containing red blood cells (termed blood extravasation) displayed moderate medial damage. More distant, non-delaminated laminae with accumulation of albumin but not red blood cells (termed plasma extravasation) exhibited mild medial damage. Varying medial hemorrhage with scattered sloughing of laminae was observed along the entire false lumen. We conclude that hydraulic fracturing of residual dissected media by pressurized blood via communications from the false lumen contributes to further structural weakening of the aortic wall.

BACKGROUNDIn tetralogy of Fallot (ToF), changes to right ventricular (RV) function (as seen by strain or TAPSE) relate to altered myocardial structure. Direct three-dimensional anatomical evidence supporting these changes remains limited. OBJECTIVESTo non-destructively characterize myocardial architecture in pediatric ToF hearts using Hierarchical Phase-Contrast Tomography (HiP-CT) and structure tensor analysis. METHODSTwenty ToF and control pediatric hearts were imaged at the European Synchrotron, ESRF. Myocyte orientation was assessed through structure tensor analysis and distributed high-performance computing. A region-specific framework was developed for analysis of the RV. The predominant direction of myocardial aggregates (their helical angle) was compared across ventricular regions. RESULTSSignificant differences in orientation were found in all ToF segments vs controls (left ventricle, RV inlet, RV outflow tract, septum; p < 0.001). Myocytes in the ToF RV inlet were more circumferential overall, with regional heterogeneity. Contrary to traditional models, no discrete middle layer was found in the ToF RV, instead, a shift towards more circumferentially orientated myocytes and disrupted septal and outflow components was observed. RV contribution to the septum was greater in ToF (47.3% vs 34.0% ; p = 0.0026) with extension of ventricular insertion points disrupting septal architecture. There were more longitudinally oriented myocytes in the ToF RVOT, consistent with hypertrophied septo-parietal trabeculations. LV structure in ToF demonstrated a greater proportion of circumferentially oriented myocytes vs controls. CONCLUSIONSWe reveal profound alterations in ToF myocardial organization which broadly align with clinical observations and provide the first open-access HiP-CT congenital heart disease data as a basis for future computational modelling.

BackgroundWomen experience drug-induced Torsades de Pointes (TdP) at approximately twice the rate of men across more than 50 QT-prolonging drug classes, yet the quantitative ionic basis of this sex disparity remains incompletely characterised. The slow delayed rectifier current (IKs) is reduced by [~]45% in female compared with male human ventricular cardiomyocytes, reducing the repolarization reserve available to compensate pharmacological IKr block. MethodsWe implemented the OHara-Rudy (ORd) 2011 undiseased human ventricular epicardial action potential model in Python and parameterised sex variants using the most robustly established human ionic difference: GKs reduced by 45% in females [Kurokawa et al., 2016]. We simulated graded IKr blockade (0-95% in steps of 5%) at three physiologically relevant pacing rates (2 Hz, 1 Hz, 0.5 Hz) after 60 beats of warm-up to approach electrophysiological steady state. Action potential duration at 90% repolarization (APD90), triangulation (APD90-APD30), and repolarization failure (defined as APD90 > 500 ms, a conservative cellular risk marker informed by clinical QTc safety thresholds, or failure to repolarize within the cycle length) were quantified. All simulations used SciPys Radau solver (rtol = 10-, atol = 10-8) with a Numba-JIT-compiled right-hand side for computational efficiency. ResultsAt baseline (0% block), the female model exhibited longer APD90 than the male at all pacing rates (+2.8 ms at 2 Hz; +4.6 ms at 1 Hz; +4.6 ms at 0.5 Hz). Under progressive IKr blockade, the absolute sex difference in APD90 amplified non-linearly: at 85% block and 1 Hz pacing the female APD90 exceeded the male by 60.4 ms (versus 4.6 ms at baseline; 13-fold amplification). At slow pacing (0.5 Hz), the sex gap was most pronounced: at 85% block, female APD90 was 1127 ms versus 939 ms for the male (+188 ms; 20% more prolonged). The critical APD threshold (>500 ms) was reached by female cells at 5 percentage points lower IKr block than male cells at 1 Hz pacing (55% vs. 60% block), both reported at the first simulated 5%-grid block level exceeding the criterion. Repolarization failure occurred 5 percentage points earlier in females at 1 Hz (90% vs. 95% block). Action potential triangulation was consistently greater in the female model at all block levels and pacing rates. ConclusionA 45% reduction in IKs conductance is sufficient in this model to produce measurably greater APD90 prolongation under IKr blockade across all tested pacing rates. The non-linear amplification of the sex gap is consistent with the hypothesis that reduced IKs repolarization reserve contributes to greater female susceptibility to drug-induced QT prolongation, and supports testing sex-specific parameterizations in CiPA-style in silico cardiac safety workflows.

BackgroundPulmonary artery (PA) wave reflection is a key determinant of right ventricular (RV) afterload. RV function is the most important factor determining long-term prognosis in patients with surgically repaired tetralogy of Fallot (rTOF). This study aimed to evaluate PA wave reflection in rTOF using RV pressure phase plane (PPP) analysis, and to identify the clinical, morphological, and hemodynamic characteristics associated with increased PA wave reflection in patients with rTOF. MethodsAugmentation pressure (AugPr) during late systole was quantified using the inflection point of systolic dP/dt on the PPP. The ratio of AugPr to RV systolic pressure (RVSP) was defined as the AugPr index. The study included 87 patients with rTOF (mean age, 15.9 {+/-} 10.0 years), 17 control subjects (13.3 {+/-} 6.3 years), and seven patients with pulmonary arterial hypertension (PAH) (16.4 {+/-} 11.7 years). The rTOF cohort was categorized according to surgical procedure: pulmonary valve-sparing repair (PVS, n = 5), transannular patch repair (TAP, n = 34), and the Rastelli procedure (n = 48). ResultsThe prevalence of AugPr was 0% in the control group, 100% in the PAH group, and 26.4% in the rTOF group (p < 0.0001). Among the surgical subgroups, the prevalence was 0% in PVS, 14.7% in TAP, and 41.7% in the Rastelli group (p < 0.0027). AugPr and the AugPr index were significantly higher in the Rastelli group than in the other two groups (p = 0.0447 and 0.0433, respectively). In addition, AugPr showed significant correlations with RVSP, RV outflow tract obstruction, maximal dP/dt, and pulmonary regurgitation grade (all p < 0.05). ConclusionsPA wave reflection can be clearly visualized using PPP. The Rastelli group demonstrated a higher prevalence and magnitude of PA wave reflection, suggesting a greater increase in RV afterload compared with other surgical repair types.

Mice housed at room temperature (RT, 25{degrees}C) experience chronic mild cold stress compared with those housed at thermoneutrality (TN, 30{degrees}C). We hypothesized that cold stress suppresses circadian transcript expression in peripheral tissues. RNA-seq of hearts, livers, and diaphragms collected every 4 hours over 48 hours in constant darkness identified mRNA transcripts exhibiting {approx}24-hour rhythms (REGs). TN produced tissue-specific changes in REG number, identity, and phase without altering core circadian clock transcript levels. Cardiac REGs increased 4-fold, diaphragm REGs 1.5-fold, and hepatic REG identity shifted substantially. GO analysis revealed coordinated reorganization of rhythmic metabolic programs in the heart and liver. These data demonstrate that ambient housing temperature has tissue-specific effects on the number, identity, and temporal organization of rhythmically expressed transcripts in the heart, liver, and diaphragm.

BackgroundNeighborhood social vulnerability may shape cardiovascular health (CVH), but its association with Lifes Essential 8 (LE8), and whether changes in vulnerability track with changes in CVH during midlife, are unclear. We examined cross-sectional and longitudinal associations of the Social Vulnerability Index (SVI) with LE8 and assessed differences by SVI domain, LE8 component, race, and sex. MethodsWe analyzed CARDIA participants at Year 15 (Y15; 2000-2001; n = 3,168; mean age 40 years) and Year 30 (Y30; 2015-2016; n = 2,267; mean age 55 years). Residential addresses were geocoded and linked to 2000 and 2016 SVI. Participants were stratified by SVI quartiles. CVH scores were calculated from LE8 metrics (range 0-100; higher is better CVH), excluding sleep. Using multivariable linear regression adjusted for age, sex, race, and educational attainment, we estimated LE8 differences across SVI quartiles and associations of 15-year SVI change/residential mobility with change in LE8. Cox models estimated incident CVD associations. ResultsHigher SVI was associated with lower LE8 at both exams. Adjusted Q4 vs Q1 differences in overall LE8 were -5.34 points (95% CI, -6.90 to -3.78) at Y15 and -4.60 points (95% CI, -6.51 to -2.69) at Y30. Among the four SVI domains, SES and household characteristics drove most of the disparity in LE8 scores (Y30 Q4 vs. Q1: SES {Delta} = -6.98; household {Delta} = -6.56 points). Component-level differences across quartiles of SVI were largest for nicotine exposure at Y15 (-13.09 points) and physical activity at Y30 (-13.09 points). Changes in SVI and residential mobility were not significantly associated with change in LE8. ConclusionHigher social vulnerability was associated with significantly lower CVH. Socioeconomic and household factors, along with behavioral gaps in nicotine exposure and physical activity, may be key targets for community-level interventions to improve cardiovascular health equity.