Normal Heart Research Articles

High Density Isochronal Repolarisation Mapping (iREM) and Reentry Vulnerability Estimation for Scar-related VT Ablation: Mechanistic Basis, Clinical Application and Challenges.

Alterations in repolarisation gradients and increased heterogeneity are key electrophysiological determinants of ventricular arrhythmogenesis across a variety of aetiologies with and without structural heart disease. High-density repolarisation mapping to localise these repolarisation abnormalities could improve characterisation of the individual arrhythmogenic substrate and inform more targeted ablation. Yet, due to challenges posed by intrinsic features of human cardiac repolarisation itself as well as technical and practical limitations, they are not routinely assessed, and traditional substrate mapping techniques remain strictly limited to determining conduction abnormalities. Here, we provide an overview of the mechanistic role of repolarisation alterations in ventricular re-entry arrhythmias followed by a description of a clinical workflow that enables high-density repolarisation mapping during VT ablations using existing clinical tools. We describe step-by-step guidance of how-to set-up and generate repolarisation maps illustrating the approach in case examples of structural normal and abnormal hearts. Furthermore, we discuss how repolarisation mapping could be combined with existing substrate mapping approaches, including isochronal late activation mapping, to delineate sites of increased re-entry vulnerability, that may represent targets for ablation without the requirement for VT induction. Finally, we review challenges and pitfalls and ongoing controversies in relation to repolarisation mapping and discuss the need for future technical and analytical improvements in repolarisation mapping to integrate into ventricular substrate mapping strategies. Repolarisation mapping remains investigational and future research efforts need to be focused on prospective trials to establish the additional diagnostic value and its role in clinical ablation procedures.

True-MAD and pseudo-MAD in consecutive patients undergoing cardiovascular magnetic resonance

Abstract Background Mitral annulus disjunction (MAD) is a controversial imaging entity with uncertain clinical significance, which has been either considered a pathological entity potentially related to mitral valve prolapse (MVP) and sudden cardiac death or, on the contrary, a benign finding in normal hearts. Cardiovascular magnetic resonance (CMR) is poised to be the ideal imaging modality to assess MAD. Recently, a distinction between pseudo-MAD, present only in systole and secondary to juxtaposition of the billowing posterior leaflet on the adjacent left atrial wall, and true-MAD, where the insertion of the posterior leaflet is clearly displaced on the atrial wall either in diastole or in systole, has been suggested. Purpose We aimed to investigate the prevalence of pseudo-MAD and true-MAD in consecutive patients undergoing clinically-referred CMR. Methods This was a single-center retrospective study including consecutive patients referred to CMR from September 2023 to November 2023. Patients with feasible MAD assessment were included. MAD was defined as a ≥1 mm displacement between the left atrial wall-mitral valve leaflet junction hinge and the top of the left ventricular wall, measured from cine-CMR images in the three long-axis views. Pseudo-MAD and true-MAD were defined according to the presence of MAD only in systole or both in systole and diastole, respectively. MVP was defined as a systolic displacement ≥2 mm of one or both mitral valve leaflets above the annulus in 3-chamber view. Results Two-hundred-ninety patients (mean age 57±18 years; 181 men, 62%) were included. MVP and MAD were respectively found in 24 (8%) and 145 (50%) patients, of which 98 (34%) with true-MAD and 47 (16%) with pseudo-MAD. In all measurements, systolic MAD (2.6±1.3 mm) resulted equal to or greater than diastolic MAD (2.2±1.1 mm). The most frequent MAD location was the inferior wall in the two-chamber view (42%), whereas the rarest one was the inferolateral wall in the three-chamber view (17%). In patients with MVP, the prevalence of MAD was higher when considering all long-axis views (22 patients, 92%), of which 50% presented with true-MAD and 50% with pseudo-MAD. The extent of pseudo-MAD and true-MAD were both greater in patients with MVP (4.2±1.5 mm and 3.0±1.6 mm, respectively) than in those without MVP (2.3±1.0 and 2.1±0.9 mm; p<0.001 and p=0.007, respectively) in all locations. At the level of the inferolateral wall, the prevalence of MAD was 71% vs. 12% (p<0.001) in patients with vs. without MVP. Conclusions The presence of true-MAD was a common imaging finding in consecutive patients undergoing CMR, thus not resulting in a distinctive abnormal feature related to MVP or sudden cardiac death. Patients with MVP showed higher prevalence and extent of true-MAD and pseudo-MAD in all locations, in line with greater degeneration of the mitral annulus. Larger studies are needed to identify potential malignant characteristics of MAD.True-MAD (A,B) and pseudo-MAD (C,D).

Hypertensive myocardial disease screening in low-income settings using smartphone-based technologies: a prospective multicenter trial

Abstract Background Mobile health technologies are revolutionizing cardiovascular (CV) medicine. However, more than 80% of heart disease related deaths occur in low-income settings, that are unable to take advantage of such technologies for healthcare awareness and prevention. Purpose To assess the feasibility of a pilot telemedicine-based CV screening campaign with D-Heart, a validated low-cost 8-lead smartphone portable ECG, coupled with blood-pressure (BP) monitoring in three regions of Africa. Methods A total of 950 patients (60%) men, age 29±21) were enrolled at 5 African rural dispensaries, 2 in Kenya, 2 in Senegal and at a hospital (Uganda). ECGs recording were obtained by community health workers with D- Heart smartphone ECG; BP was measured with a validated smartphone BP recorder. Global burden of ECG abnormalities was defined by a semi-quantitative score based on the sum of 9 criteria, identifying four classes of increasing severity. ECGs that were moderately and severely abnormal and from patients with severe hypertension, were sent for consultation via smartphone to D-Heart tele-cardiology centre: an advice on how to manage the patient was sent back to the community health worker’s smartphone within 15 minutes. If referral was needed, patients were sent to the local hospital. Results Mean BMI was 26.2 ± 8.5 (men 22.3±1.5 vs women 27.2±1.1, p<0.01). Active/recent history of smoking and alcohol intake were 327 (45%, 298 men) and 232/590 (40%, 198 men) respectively. A total of 142 (15%) patients had been previously diagnosed with diabetes, 199(25%) had known hypertension of whom 95/199 on treatment), whereas 43(4%) had a previous myocardial infarction. A total of 487 (51%) patients never had their blood pressure measured, whereas 798(91%) never received an ECG. Mean SBP/DBP were 138±31/71±12 mmHg respectively. Patients with normal BP were 304(32%), whereas 380(40%) were mildly-moderately hypertensive (SBP/DBP 148±7/91±5 mmHg) and 130 (29%) with severe hypertension (SBP/DBP 162±8/99±6 mmHg). D-Heart ECGs tracings were respectively classified as: normal: 361(38%); mildly abnormal: 332(35%); moderately abnormal: 199 (21%) and severely abnormal 58(6%). Most common ECG abnormality was a positive Romhilt-Estes index in 361, 38%. For 174(18%) patients smartphone tele-report advised referral to the local hospital, but only 121 69%) presented to the visit: 9 (8%) were found to have normal hearts, 57(47%) with hypertensive heart disease, 35 (29%) with rheumatic heart disease, 20 (16%) with HFrEF. Visit time was 8±2 minutes; cost of screening per patient was 1.10€: 0,30€ for consumable electrodes, 0.80€ for the community health worker visit time. Conclusions D-Heart ECG screening combined with smartphone BP measurement proved feasible and cost-effective. This should encourage to develop and extend low-cost/high-technology community-based CV screening programs in low-income settings.

Fabry cardiomyopathy: myocardial fibrosis, inflammation and reduced mannose6phosphate receptors cause low accessibility to enzyme therapy

Abstract Background Clinical impact of enzyme replacement therapy (ERT) on advanced Fabry disease cardiomyopathy (FDCM) appears limited. Purpose Clarify the pathologic mechanisms responsible of ERT inefficacy in the advanced FDCM. Methods Ten male patients with advanced FDCM (echocardiographic maximal wall thickness 19.3 ± 2.1 mm) underwent left ventricular endomyocardial biopsy before and 4 hours after beta-agalsidase infusion. Comparative studies between pre and post infusion samples included: histology and electron microscopy; assessment of myocardial alpha-galactosidase A activity; immunohistochemistry for alpha-galactosidase A and semiquantitative evaluation (from 0 to 3) of its cardiomyocyte content; Ultrastructural immunogold analysis with anti-alpha-galactosidase A ab. Western Blot (WB) quantification of mannose-6-phosphate receptors (M6Pr). Controls were surgical left ventricular biopsies from patients with mitral stenosis. Results Histologic and Ultrastructural evaluation showed no removal of storage material while myocardial fibrosis was 9.8 ± 6.8 vs 3.8 ± 2.0 of controls and virus-negative lymphocytic inflammation was observed in 7 out of 10 patients. At Ultrastructural immunogold analysis, Myocardial alpha-galactosidase A activity increased in post infusion samples by overall 1.89-fold. Alpha-galactosidase A immunostaining in cardiomyocytes was absent at baseline in all patients and did not significantly improve in post-infusion samples. Immunogold particles increased by 1.33-fold remaining far from normal controls (86.9 ± 6.6). Protein analysis showed M6Pr in advanced FDCM to be 81% lower than in normal heart. Conclusions Our study shows a low accessibility to ERT of cardiomyocytes affected by advanced FDCM. It is sustained by myocardial fibrosis, inflammation and severe down-regulation of M6Pr. Figure Legend Histologic and ultrastructural and mannose6phosphate receptors characteristics of patients with severe Fabry Disease Cardiomyopathy. Panel A shows severe cellular glycolipid infiltration associated with diffuse interstitial fibrosis (Masson trichrome, 100x). Panel B reveals an overlapping lymphocytic CD45Ro+ myocardial inflammation with focal necrosis of adjacent cardiomyocytes. Insert(i), Ultrastructural detail showing vacuoles (black arrows) to consist of myelin bodies,( scale bar=3μm). Panel C (upper) Western blot analysis of all 10 patients of Mannose-6-phosphate Receptor, molecular weight 275 Kd. Alpha sarcomeric actin (43 kDa) was used as a loading control. (Panel C -lower) Panel D: Graphs document western blot of Mannose-6-phosphate Receptor, in all 10 patients with severe FDCM showing 3-fold lower of Mannose-6-phosphate Receptor values in patients versus normal heart (4.830 ± 1116,724 vs 14.737± 1145,386; p < 0.001).

What characterizes normotensive individuals with obesity and normal systolic heart function? A descriptive study from the SCAPIS cohort

Abstract Background Heart failure and cardiovascular disease are strongly related to obesity, and the incidence of these conditions shows a linear relationship with increasing body mass index (BMI). Despite these known facts, some individuals with obesity show no clinical signs of heart disease or arterial hypertension (AH). Purpose We aimed to investigate the characteristics of individuals with obesity without impaired left ventricular function and left ventricular hypertrophy (termed systolic heart function, SHF) and AH, compared to individuals with obesity with signs of impaired SHF or AH, and individuals without obesity with and without signs of impaired SHF or AH. Method A cross-sectional analysis was performed of the 4,692 individuals who had undergone a transthoracic echocardiography within the Swedish CArdioPulmonary bioImage Study (SCAPIS). Participants were divided into four groups: 1) individuals with obesity (BMI³30 kg/m2) without impaired SHF (normal left ventricular systolic function and left ventricular mass) and no AH (based upon the absence of antihypertensive treatment) (ObSHF/AH-, n=623; 13%), 2) individuals with obesity with impaired SHF or AH (ObSHF/AH+, n=252; 5%), 3) individuals without obesity and without impaired SHF and no AH (NObSHF/AH-, n=3179; 68%) and 4) individuals without obesity with impaired left ventricular systolic function, left ventricular hypertrophy or AH (NObSHF/AH+, n=638; 14%). Individuals in group 1 (ObSHF/AH-;) were compared to those in groups 2-4 through descriptive analyses. Results Compared to ObSHF/AH+ individuals, ObSHF/AH- subjects showed significantly lower HbA1c (p<0.001), fasting plasma glucose (p<0.001), triglyceride (p<0.001), NT-proBNP (p=0.035) and troponin I (p<0.001) levels. Furthermore, no significant differences between the two obese groups could be seen regarding BMI (p=0.074), whereas waist-to-hip ratio was lower in ObSHF/AH- subjects (p<0.001). ObSHF/AH- individuals had higher glucose and lipid levels as well as higher blood pressure than individuals without obesity. Interestingly, no differences were seen between ObSHF/AH- and NObSHF/AF- subjects regarding NT-proBNP (p=0.864) and troponin I levels (p=0.110). Furthermore, left ventricular mass index (LVMI) was significantly higher in ObSHF/AH- subjects compared to NObSHF/AH- individuals (73.8 vs. 72.1 g/m2, p=0.015) and the ejection fraction was significantly lower (57.4 vs. 59.6 %, p<0.001). Conclusion When ObSHF/AH- and NObSHF/AH- subjects were compared, markers of cardiac damage/remodeling did not differ significantly, indicating that heart function might be preserved despite a worsened metabolic profile and an obese phenotype, through putative protective mechanisms yet to be explored. However, parameters of SHF were unfavorable for ObSHF/AH- when compared to NObSHF/AH-, further implicating preclinical cardiac impairment in individuals with obesity.

A patient with unexplained hypoxemia after a fall diagnosed with platypnea orthodeoxia syndrome: approaches to resolving discrepancies between level of hypoxemia and clinical presentation.

Platypnea orthodeoxia syndrome (POS) is a rare cause of hypoxemia. Diagnosis of POS is challenging, requiring a high index of clinical suspicion, special investigations, and collaboration with multiple specialists. We describe an 86-yr-old male who presented to the emergency department with hip pain after a witnessed fall. He was noted to be hypoxemic at presentation with a peripheral oxygen saturation (SpO2) of 84% on room air, with an inadequate increase in oxygenation after administration of a fractional concentration of inspired oxygen (FIO2) of 1.00. A chest radiograph, computed tomography pulmonary angiogram, and Doppler ultrasound of the liver were unremarkable. In the supine position with an FIO2 of 0.65, his SpO2 and arterial partial pressure of oxygen (PaO2) (96% and 74mm Hg, respectively) increased significantly relative to the seated position (84% and 50mm Hg, respectively). Contrast transthoracic echocardiography (TTE) showed a large patent foramen ovale (PFO) with right-to-left shunt. Transthoracic echocardiography showed rotation of the patient's heart, enabling direct alignment of the inferior vena cava with the PFO, creating a large anatomical right-to-left shunt in the seated position. Right heart catheterization confirmed a large PFO with normal right-sided heart pressures. He was treated with a septal occlusion and his SpO2 in the seated position improved immediately. The patient was discharged home without requiring supplemental oxygen. Platypnea orthodeoxia syndrome is a rare presentation of hypoxemia. Positional changes in oxygenation are the cardinal feature of POS. Discordance between lung imaging and the severity of hypoxemia should prompt investigation for an intracardiac shunt, which can occur in POS even in the absence of increased right-sided heart pressures. Either contrast TTE or transesophageal echocardiography is necessary to make this diagnosis.

The myocardium of human dilated nonischemic cardiomyopathy harbors unique tissue-resident lymphocyte subsets

Abstract Purpose The etiology of dilated nonischemic cardiomyopathy (NICM) is often unclear, but thought to be multifactorial, involving an interplay between genetic factors and direct myocardial damage caused by infection, autoimmunity, or toxins. Tissue-resident lymphocytes are non-circulating immune cells which are retained within various tissues and play integral roles in maintaining homeostasis, responding to infection, regulating inflammation, and mediating tissue repair. Despite their likely involvement in various cardiac pathologies, the presence of tissue-resident lymphocytes in the human heart has not yet been well-characterized, neither in health nor in disease. Methods Human left ventricular tissue and paired peripheral blood samples were obtained from six adult organ donors with normal heart function who died of noncardiac causes and from the explants of six adult patients with end-stage nonischemic cardiomyopathy. Heart tissue was processed using mechanical and enzymatic digestion. Mononuclear cells were isolated from both heart and paired blood by density centrifugation. Isolated mononuclear cells were surface stained with an antibody cocktail and interrogated using multidimensional flow cytometry. Results The adult human heart contains a diverse immune cell population (Fig 1A). Both healthy and NICM cardiac lymphocytes express distinct phenotypic profiles which resemble those of resident lymphocytes found across various tissues, distinct from those isolated from paired blood. Frequencies of effector memory T (Tem) cells (CD45RA- CCR7-) were higher in heart than in blood among both CD4+ and CD8+ T-cells. In heart compared to blood, significantly more Tem expressed CD69, a canonical marker of tissue-resident memory T (Trm) cells (Fig 1B). Cardiac Trm, especially CD8+ Trm, expressed classical Trm signature markers including integrins CD103 (epithelial binding) and CD49a (collagen binding). NICM Trm expressed more CD49a than healthy heart Trm (Fig 1C). NK-cells also demonstrated higher CD69 expression (trNK) in heart than in blood, with associated expression of CD103, CD49a, and CXCR6 (Fig 1D). Compared to healthy hearts, NICM trNK were predominantly CD56bright/CD16- (Fig 1E and 1F) and expressed less CD57 (Fig 1D), overall indicating a less mature state with lower cytotoxic potential. Confocal imaging of cardiac tissue revealed CD69-expressing tissue-resident lymphocytes within the cardiac interstitium. Conclusions The adult human heart contains diverse populations of lymphocytes which express canonical markers of tissue residency, similar to lymphocytes resident in other tissues. Compared to healthy hearts, NICM hearts have more CD49a+ Trm, perhaps related to greater fibrosis, and also harbor a distinct subset of immature tissue-resident NK cells which may shed light on pathophysiology. Future work is focused on better exploring the functional phenotypes of these resident cells and better localizing them within the myocardium.FA - Figure 1

Resting heart rate and outcomes in patients with heart failure: impact of AF from the Thai-Heat Failure Registry (THFR - HRAF study)

Abstract Introduction Heart rate (HR) is a significant prognosis factor and target of the treatment in patients with heart failure (HF) but this relationship in heart failure patients with atrial fibrillation (AF) is uncertain. Methods A total of 2,996 patients with HF were enroll in the Thai-Heart Failure registry between 2023 to 2024, from 37 heart failure clinics in Thailand. Patients were classified by resting HR and whether having AF or not. The primary outcomes are all-cause death and/or HF. The continuous prognostic relationship and interaction were determined by Cubic-spline model. Results Total of 2,932 patients with available resting heart rate and AF status were analyzed (mean age 59.3±14.5 years, 67.9% male, mean LVEF 31.9%, 12.4% having AF). There were 273, 1,497, 895 and 267 patients have HR <60, 60-80, 80-100 and >100 bpm, respectively. From the lowest HR to the highest group, the all-cause death and/or HF were 16.5%, 10.4% 13.7% and 14.0%. Interestingly, the patients in the lowest, high and highest HR group were associated with poorer outcomes when compared to patients with normal HR (60-80 bpm). (p <0.001, 0.004 and 0.033, respectively). There were no statistic significances in patient with LVEF >40% (p= 0.37, 0.48 and 0.41, respectively). The hazard ratio is lowest between 64 to 91 bpm. The relationship is the same in patient with AF (p for interaction 0.071) but higher hazard ratio at any giving heart rate. Conclusion The normal heart rate (between 60-80 bpm) is associated with the best outcomes, not lower is better. HR is a significant prognosis factor whether having AF or not. The relationship is mainly in patient with HFrEF.Figure

Vector Field Heterogeneity (VFH) as a novel quantitative marker of electrical disarray in Arrhythmogenic CardioMyopathy (ACM) with ventricular tachycardia

Abstract Background ACM is a hereditary condition characterized by fibrofatty infiltration and replacement of cardiac myocytes predominantly presenting with ventricular arrhythmias (VA). Cardiac imaging allows for detailed structural phenotyping of scar patterns in ACM. Yet, there is a lack of tools to objectively quantify the electrical substrate alterations that may enable a more precise identification of critical sites that predispose to VA. Purpose To quantify locally disorganized cardiac electrical propagation wavefronts using the Vector Field Heterogeneity (VFH) metric from high-density multi-electrodes in patients with ACM with VT and compare to healthy controls. Methods High density epicardial substrate maps acquired with a 16-pole grid catheter during SR or RV pacing in patients with ACM with VA, who underwent clinically indicated catheter ablation, were retrospectively reviewed. Patients with structurally normal heart and idiopathic VA with epicardial ablation were analysed as a control group. Unipolar contact mapping data was exported & processed offline. From the 4×4 electrode array EGMs, vector maps of the directions of electrical propagation for recorded sites were computed. The VFH was then computed as a quantitative measure of local heterogeneity of propagation, with higher VFH expected to correlate with sites of (micro)structural tissue alterations. VFH was compared between ACM and control patients as well as at sites of normal, border zone & scar based on omnipolar voltage in ACM patients (>1.5mV, 0.5mV–1.5mV, <0.5mV, respectively). Results 10 patients with ACM (70% male, aged 52 ±18 years, ARVC 70%, biventricular 30%, RVEF 40.7±4.7%, LVEF 66±12%) and 2 patients with structurally normal heart (female, 38 & 61 years) were included. Epicardial maps had an average of 9258 ±5412 EGM points. Median VFH was statistically significantly higher in the ACM cohort compared to control for global maps (0.33±0.33 vs 0.13±0.22, p<0.001) and at sites with voltage >1.5mV (i.e. greater disorganization in ACM, p<0.001). In ACM, assessment of VFH according to omnipolar voltage sites (as a surrogate of scar) showed a quantifiable statistically significant increase in electrical disorganized propagation at sites of lower voltage (<0.5mV, median VFH 0.53±0.36) compared to borderzone (0.5-1.5mV, VFH 0.29±0.41) and normal voltage (>1.5mV, VFH 0.15±0.26), p <0.001 respectively. Conclusion Heterogenous electrical propagation as quantified by VFH is significantly increased in patients with ACM at sites of scar, but importantly also in areas of normal voltages when compared to non-ACM controls, possibly indicating microstructural alterations that are missed in traditional assessments of the arrhythmogenic substrate. Identifying and quantifying disorganized conduction patterns by VFH is a promising new mapping approach that could allow improved substrate characterization. Its diagnostic value to guide ablation therapy is currently being validated.VFH Metric ACM and ControlVFH Map Examples

Sudden cardiac death in acute coronary occlusion: potential roles of sino-atrial nodal artery and conus artery

Abstract An estimated 80% of sudden cardiac death (SCD) is due to coronary artery disease1. Ventricular arrhythmia (VA) is most commonly associated with LAD infarctions, likely due to the larger extent of affected myocardium, but non-LAD territory infarctions also present with VA. We propose two potential contributors, the sinoatrial nodal artery (SANa) and conus artery (CA). We retrospectively analyzed 2 cohorts of patients presenting with STEMI complicated by SCD due to VA, and whether these arteries were compromised in non-LAD territory STEMI, compared with uncomplicated STEMI. In the first, cohort A, we compared 127 consecutive STEMI patients presenting with cardiac arrest, with 100 uncomplicated STEMI. SANa and CA involvement was assessed in patients presenting with non-LAD territory STEMI. In the second, cohort B, we looked at patients presenting with inferior STEMI involving the RCA only, 20 complicated by aborted SCD due to VA compared with 24 uncomplicated patients. Cohort A (see table) showed a preponderance of single vessel and proximal LAD culprits in the arrest group and a significant number of non-LAD culprits. The extent and complexity of coronary disease and amount of myocardium at risk, reflected in SYNTAX and modified Jeopardy scores, were not significantly different between arrest and non-arrest groups. In those with RCA or Circumflex culprits, 77% in the Arrest group had the SANa arising from the culprit vessel, with only 33% of patients in the Control group, p<0.005. In cohort B, 70% of arrest and 21% of non-arrest patients had SANa involvement, p<0.005. In this cohort, we also observed that 74% of the arrest patients had CA involvement, compared with only 21% of Control patients, p<0.005. There were no significant differences in heart rate nor incidence of complete heart block and atrial arrhythmia in either cohort. There was significantly more ST elevation in standard leads V1-V2, suggesting RVOT ischemia, in those with aborted SCD and RCA culprit in both cohorts (cohort B: Arrests 85% vs non-arrest 21%, p<0.005. The SANa arises from the proximal RCA in 60% of people, and 40% from the left system. Transient ischemia leading to sinus bradycardia may not result in as marked QT prolongation compared with AV block at comparable heart rates, but in the ischemic environment, with hypotension provoking sympathetic upregulation, may lead to enough repolarization heterogeneity to induce VA. The CA arises from the RCA in 50% or more, and otherwise from the right coronary sinus, supplying the RVOT, a region prone to arrhythmogenesis, even in structurally normal hearts, more so if ischemic. Recognizing the potential role of these arterial branches in the VA mechanism would alert operators into preserving their patency. Transient disturbances may not translate into long term adverse outcomes, but whereas permanent damage to the SAN is more readily remedied, further study is needed to assess any long-term sequelae of RVOT infarction.

Intronic regulatory sequences regulate epicardial gene expression and EMT during heart development

Abstract Background During organogenesis, cells from the outer layer of the heart, the epicardium, undergo epithelial-to-mesenchymal transition (EMT), contributing essential paracrine signals and different cell types to the growing heart. Epicardial cells are integral to heart regeneration in lower vertebrates and neonatal mammalian injured hearts. That said, prospects to harness the epicardium for therapeutic applications to effect adult heart repair, heavily depend on improved insight into its intrinsic properties during heart development. Purpose Cell fate decisions underpinning EMT are directed by transcription factors such as Wilms’ tumour 1 (WT1). Whilst a requirement for Wt1 in heart development is widely accepted, the upstream regulatory mechanisms underpinning its activation remain elusive. Our previous research has led to the identification of two intronic evolutionary conserved regions (ECRs) shared between mouse and human, located within intron 1 of the Wt1 locus, i.e. +4.0kbECR and +5.8kbECR. We hypothesised these regulatory sequences direct locus activation and EMT to support normal heart development. Methods & Results Here, we used CRISPR/Cas9 gene-editing technology to generate mice carrying a sequence deletion containing one ECR (Wt1Δ+4.0kbECR and Wt1Δ+5.8kbECR mice) or a deletion comprising both ECRs (Wt1Δ+4-5.8kbECR mouse). Extensive survival analysis, high-resolution episcopic microscopy (HREM), qPCR, immunostaining, confocal microscopy and epicardial explants were used to characterise heart formation in these models. Mendelian ratios indicated an overall underrepresentation of Wt1ΔECR/ΔECR mutants recovered in the offspring arising from heterozygous inter-crosses. HREM revealed smaller hearts, incidence of myocardial non-compaction and spongy interventricular septum with muscular or membranous ventricular septum defects, tricuspid hypoplasia and enlarged aortic valves, as well as abnormal formation/patterning of coronary artery stems in ΔECR/ΔECR hearts. Expression of Wt1 was markedly reduced in ΔECR/ΔECR hearts, but not in the kidneys, suggesting intronic enhancers are cardiac-specific. Whole-mount and tissue-section immunostaining combined with confocal microscopy revealed abnormal coronary vessel and innervation extension and patterning along the subepicardial space, as well as reduced epicardial EMT and myocardial non-compaction/hyper-trabeculation in Wt1ΔECR/ΔECR hearts. Conclusions Together, we demonstrated a requirement for novel intronic enhancers regulating Wt1 locus activity and impacting on essential epicardial EMT and associated biological processes during normal heart development. Importantly, observation of septum and aortic valve defects in ΔECR mutants suggests an hitherto unrecognised role for WT1/epicardial EMT and opens new avenues of research to improve our understanding of congenital heart disease that affects at least 1:150 live births, with remarkably two thirds of cases having unknown aetiology.

Heart sound classification algorithm based on bispectral feature extraction and convolutional neural networks

Cardiovascular disease (CVD) is one of the leading causes of death worldwide. Heart sound classification plays a key role in the early detection of CVD. The difference between normal and abnormal heart sounds is not obvious. In this paper, in order to improve the accuracy of the heart sound classification model, we propose a heart sound feature extraction method based on bispectral analysis and combine it with convolutional neural network (CNN) to classify heart sounds. The model can effectively suppress Gaussian noise by using bispectral analysis and can effectively extract the features of heart sound signals without relying on the accurate segmentation of heart sound signals. At the same time, the model combines with the strong classification performance of convolutional neural network and finally achieves the accurate classification of heart sound. According to the experimental results, the proposed algorithm achieves 0.910, 0.884 and 0.940 in terms of accuracy, sensitivity and specificity under the same data and experimental conditions, respectively. Compared with other heart sound classification algorithms, the proposed algorithm shows a significant improvement and strong robustness and generalization ability, so it is expected to be applied to the auxiliary detection of congenital heart disease.

How to auscultate for heart sounds in infants and children.

This article provides an introduction to performing cardiac auscultation in infants and children aged 0-16 years, with the aim of improving children's nurses' knowledge and confidence in this procedure. Nurses wishing to develop competence in cardiac auscultation can use this article as a guide to complement supervised practical experience; however, it is not intended to determine an individual's competence. • Cardiac auscultation is a component of a structured cardiac assessment rather than a standalone tool. • It is important to auscultate all four main heart valve areas, listening for normal heart sounds and any additional sounds. • Several differences should be considered when auscultating heart sounds in infants and children compared with adults, including heart rate ranges and the potential need to use distraction techniques for those who are distressed. REFLECTIVE ACTIVITY: 'How to' articles can help to update your practice and ensure it remains evidence based. Apply this article to your practice. Reflect on and write a short account of: • How you think this article might help improve your practice when undertaking cardiac auscultation in infants and children. • How you could use this information to develop your own knowledge and skills before educating others on the appropriate technique and evidence base behind auscultating heart sounds in infants and children.

Outcomes in infective endocarditis among adults with CHD: a comparative national study.

Given increased survival for adults with CHD, we aim to determine outcome differences of infective endocarditis compared to patients with structurally normal hearts in the general population. We conducted a retrospective cross-sectional study identifying infective endocarditis hospitalisations in patients 18 years and older from the National Inpatient Sample database between 2001 and 2016 using International Classification of Disease diagnosis and procedure codes. Weighting was used to create national annual estimates indexed to the United States population, and multivariable logistic regression analysis determined variable associations. Outcome variables were mortality and surgery. The primary predictor variable was the presence or absence of CHD. We identified 1,096,858 estimated infective endocarditis hospitalisations, of which 17,729 (1.6%) were adults with CHD. A 125% increase in infective endocarditis hospitalisations occurred for adult CHD patients during the studied time period (p < 0.001). Adults with CHD were significantly less likely to experience mortality (5.4% vs. 9.5%, OR 0.54, CI 0.47-0.63, p < 0.001) and more likely to undergo in-hospital surgery (31.6% vs. 6.7%, OR 6.49, CI 6.03-6.98, p < 0.001) compared to the general population. CHD severity was not associated with increased mortality (p = 0.53). Microbiologic aetiology of infective endocarditis varied between groups (p < 0.001) with Streptococcus identified more commonly in adults with CHD compared to patients with structurally normal hearts (36.2% vs. 14.4%). Adults with CHD hospitalised for infective endocarditis are less likely to experience mortality and more likely to undergo surgery than the general population.

Acute toxicity of trypsin inhibitor from tamarind seeds in embryo and adult zebrafish (Danio rerio)

The trypsin inhibitor isolated from tamarind seeds (TTI) is being investigated for potential applications in the treatment of noncommunicable diseases (NCD), such as hypertension, obesity, and diabetes. This study aimed to assess TTI embryotoxicity and acute toxicity in adult zebrafish (Danio rerio). TTI was extracted and isolated from tamarind seeds. Embryonic and adult zebrafish were exposed for 96 hours to three concentrations of TTI (12.5, 25, and 50 mg/L). Zebrafish embryos (n=60 per group) were evaluated for survival, hatching, malformations, and potential developmental marker alterations, in addition to cardiotoxicity and neurotoxicity tests. For acute toxicity assessment in adults (n=20 per group), survival and locomotor and anxiety-like behaviors were assessed, along with genotoxicity (micronucleus) evaluation. Embryos exposed to TTI showed no significant adverse effects, presented normal heart rates and positive reflex response in the neurotoxicity tests. In adult fish, TTI did not cause mortality or significant behavioral changes, suggesting no neurotoxicity and no genotoxicity. Histopathological analyses of the whole body showed only changes in the liver and spinal cord, similar to those observed in the control group not exposed to TTI. These findings indicate TTI's biosafety and therapeutic potential in complex organisms. Further research is required to evaluate its long-term effects and efficacy in treating non-communicable diseases.

Morphological Changes Of The Heart In Sudden Death Psychiatric Patients

Although sudden cardiac death is often reported in epileptic or psychiatric patients, the etiologyis not fully understood. The aim of this study was to examine whether morphological changes of the heart contribute to sudden cardiac death in epileptic or psychiatric patients, compared with control decedents.Cases of sudden cardiac deathsdue to fatal arrhythmia in patients with epilepsy or psychiatric disease were selected from forensic autopsies performed at the Shiga Prefecture from 2014 to 2021.As the control group, autopsied healthy decedents were selected. The heart weight to normal heart weight ratio, ventricular wall thickness, cardiomyocyte width, nuclear diameter and nuclear density of the left and right ventricle and interventricular septum were examined. The left and right ventricular wall thickness and cardiomyocyte to be smaller in epileptic patients, however, no significant differences were found. The nuclear diameter/body surface area of the left ventricle was significantly smaller in epileptic and psychiatric patients than in control patients.The smaller nuclei of cardiomyocytes in epileptic and psychiatric patients may relate to the etiology of sudden cardiac death.

Glucocorticoid chrono-pharmacology promotes glucose metabolism in heart through a cardiomyocyte-autonomous transactivation program.

Circadian time-of-intake gates the cardioprotective effects of glucocorticoid administration in both healthy and infarcted hearts. The cardiomyocyte-specific glucocorticoid receptor (GR) and its co-factor, Krüppel-like factor (Klf15), play critical roles in maintaining normal heart function in the long-term and serve as pleiotropic regulators of cardiac metabolism. Despite this understanding, the cardiomyocyte-autonomous metabolic targets influenced by the concerted epigenetic action of GR-Klf15 axis remain undefined. Here, we demonstrate the critical roles of the cardiomyocyte-specific GR and Klf15 in orchestrating a circadian-dependent glucose oxidation program within the heart. Combining integrated transcriptomics and epigenomics with cardiomyocyte-specific inducible ablation of GR or Klf15, we identified their synergistic role in the activation of adiponectin receptor expression (Adipor1) and the mitochondrial pyruvate complex (Mpc1/2), thereby enhancing insulin-stimulated glucose uptake and pyruvate oxidation. Furthermore, in obese diabetic (db/db) mice exhibiting insulin resistance and impaired glucose oxidation, light-phase prednisone administration, as opposed to dark-phase prednisone dosing, effectively restored cardiomyocyte glucose oxidation and improved diastolic function towards control-like levels in a sex-independent manner. Collectively, our findings uncover novel cardiomyocyte-autonomous metabolic targets of the GR-Klf15 axis. This study highlights the circadian-dependent cardioprotective effects of glucocorticoids on cardiomyocyte glucose metabolism, providing critical insights into chrono-pharmacological strategies for glucocorticoid therapy in cardiovascular disease.

8278 Myxedema Coma With COVID-19 Infection

Abstract Disclosure: R. Kalas: None. V. Manohar: None. N.S. Bapat: None. Y. Kim: None. Myxedema coma is a rare medical emergency that occurs in severe hypothyroidism with a mortality rate reaching 60%. The hallmarks include depressed mental status and hypothermia, but hypotension, hyponatremia, bradycardia, and hypoventilation can also occur. This complication can occur in patients with a longstanding history of severe hypothyroidism especially when precipitated by an acute event such as infection, myocardial infarction, or surgery. Prompt recognition and treatment of the condition is important to prevent fatal outcomes. We present a case of myxedema coma in the setting of COVID-19 infection and nonadherence to medication. A 91-year-old woman with history of hypothyroidism, hypertension, coronary artery disease, cardiomyopathy, and chronic obstructive pulmonary disease presented with dyspnea. Her home medications included levothyroxine 75 mcg daily, which she reported not taking for at least 3 weeks. Vital signs revealed a normal heart rate and blood pressure of 84 beats/min and 137/78 mmHg, but the patient was hypothermic to 35.7 °C. On exam, she was somnolent. Labs were notable for markedly elevated TSH level of 111 (0.380 - 4.700 uIU/mL), low free T4 level of 0.57 (0.93 - 1.70 ng/dL), random cortisol level of 25.5 (6.2-18.4 ug/dL), and positive SARS-COV-2 PCR test. Chest x-ray revealed bilateral lower lung parenchymal consolidations and arterial blood gas revealed a pH of 7.29 and pCO2 of 52.5 (35-45 mm Hg), indicating hypercapnia. She was treated for COVID pneumonia and given concern for COVID induced myxedema coma she was given IV levothyroxine 100 mcg for 2 days, after which the patient’s hypothermia and somnolence improved, with an improved repeat free T4 level 0.87 ng/dL. She was subsequently transitioned to oral levothyroxine 112 mcg daily and discharged after improvement of her COVID symptoms. Myxedema coma is a rare complication of decompensated hypothyroidism, frequently triggered by an infection. Thyroid hormone plays an important role in regulating both the innate and adaptive immune systems. As a result, individuals with hypothyroidism are at increased risk of acquiring infections, which can further lead to myxedema coma. COVID-19 infection has been associated with thyrotoxicosis, thyroiditis and hypothyroidism. Given the associated high mortality rate, regardless of the underlying precipitant, prompt diagnosis and early administration of thyroid hormone replacement therapy is crucial to improve outcomes. Presentation: 6/3/2024

A Feasibility Study of [18F]F-AraG Positron Emission Tomography (PET) for Cardiac Imaging-Myocardial Viability in Ischemia-Reperfusion Injury Model.

Myocardial infarction (MI) with subsequent inflammation is one of the most common heart conditions leading to progressive tissue damage. A reliable imaging marker to assess tissue viability after MI would help determine the risks and benefits of any intervention. In this study, we investigate whether a new mitochondria-targeted imaging agent, 18F-labeled 2'-deoxy-2'-18F-fluoro-9-β-d-arabinofuranosylguanine ([18F]F-AraG), a positron emission tomography (PET) agent developed for imaging activated T cells, is suitable for cardiac imaging and to test the myocardial viability after MI. To test whether the myocardial [18F]-F-AraG signal is coming from cardiomyocytes or immune infiltrates, we compared cardiac signal in wild-type (WT) mice with that of T cell deficient Rag1 knockout (Rag1 KO) mice. We assessed the effect of dietary nucleotides on myocardial [18F]F-AraG uptake in normal heart by comparing [18F]F-AraG signals between mice fed with purified diet and those fed with purified diet supplemented with nucleotides. The myocardial viability was investigated in rodent model by imaging rat with [18F]F-AraG and 2-deoxy-2[18F]fluoro-D-glucose ([18F]FDG) before and after MI. All PET signals were quantified in terms of the percent injected dose per cc (%ID/cc). We also explored [18F]FDG signal variability and potential T cell infiltration into fibrotic area in the affected myocardium with H&E analysis. The difference in %ID/cc for Rag1 KO and WT mice was not significant (p = ns) indicating that the [18F]F-AraG signal in the myocardium was primarily coming from cardiomyocytes. No difference in myocardial uptake was observed between [18F]F-AraG signals in mice fed with purified diet and with purified diet supplemented with nucleotides (p = ns). The [18F]FDG signals showed wider variability at different time points. Noticeable [18F]F-AraG signals were observed in the affected MI regions. There were T cells in the fibrotic area in the H&E analysis, but they did not constitute the predominant infiltrates. Our preliminary preclinical data show that [18F]F-AraG accumulates in cardiomyocytes indicating that it may be suitable for cardiac imaging and to evaluate the myocardial viability after MI.

The Subtle Signs Of Neonatal Grave’s Disease- ACase Report And Review

A newborn male is born via caesarean section at 37 weeks of gestation to a 25-year-old primigravida mother. Mother was a known case of Grave’s disease (TSH receptor antibody positive) on Carbimazole with gestational diabetes mellitus on Insulin, her antenatal course was otherwise uneventful, with normal fetal heart rate monitoring and appropriate fetal growth. She was admitted with complaints of pain abdomen and decreased fetal movement. She was planned for emergency section and a live, healthy male baby was born with a birth weight of 2.962 kg, appropriate for gestation age with APGAR 8/9. Postnatal examination was negative for congenital anomalies and no systemic involvement was noticed. The baby was discharged on close follow-up. On day 7th of life, the baby was re-admitted for phototherapy. In this admission, the baby was noticed to have a resting tachycardia heart rate of 170-180/min, no murmur or abnormal heart sound was noticed on examination. The baby had no significant weight loss or history of feeding difficulties. In consideration of maternal grave disease, a further workup for the baby was planned, which revealed a Cord TSH (0.007microIU/ml) range (2.30-13.20) and free T4 1.52 ng/dl (Range 1.10-2.00). Further, the workup revealed TSH receptor antibody positive 23.76 IU/L range (less than 1.22), free T4 7.77 ng/dl (1.120-2.00), TSH less than 0.005 microIU/ml. However, As per the paediatric Endocrinologist's opinion, the baby was started on propranolol and propylthiouracil. The resting tachycardia resolved upon starting the drug. On subsequent follow-up, the baby had an improving thyroid profile