Efficacy of Active Immunization With Attenuated α-Hemolysin and Panton-Valentine Leukocidin in a Rabbit Model of Staphylococcus aureus Necrotizing Pneumonia.

Staphylococcus aureus is a common pathogen causing infections in humans with various degrees of severity, with pneumonia being one of the most severe infections. In as much as staphylococcal pneumonia is a disease driven in large part by α-hemolysin (Hla) and Panton-Valentine leukocidin (PVL), we evaluated whether active immunization with attenuated forms of Hla (HlaH35L/H48L) alone, PVL components (LukS-PVT28F/K97A/S209A and LukF-PVK102A) alone, or combination of all 3 toxoids could prevent lethal challenge in a rabbit model of necrotizing pneumonia caused by the USA300 community-associated methicillin-resistant S. aureus (MRSA). Rabbits vaccinated with Hla toxoid alone or PVL components alone were only partially protected against lethal pneumonia, whereas those vaccinated with all 3 toxoids had 100% protection against lethality. Vaccine-mediated protection correlated with induction of polyclonal antibody response that neutralized not only α-hemolysin and PVL, but also other related toxins, produced by USA300 and other epidemic MRSA clones.

Avoiding oesophageal injury during cardiac ablation: insights gained from mediastinal anatomy.

Aims: This study investigates the lateral displacement of the oesophagus at the level of the left atrium (LA) in 11 cadavers. Methods and results: The study was conducted using human cadavers. An endotracheal stylet probe was inserted into the eosphagus. The pericardium overlying the posterior LA was fixed in place. The lateral movement of the oesophagus from side to side was recorded. The initial study method had the stylet probe extending to the gastroesophageal (GE) junction. A revised protocol had the distal end of the endotracheal stylet probe ∼4 cm cranial to the GE junction. In six cadavers using the initial study method, the oesophagus was displaced a mean of 1.8 ± 0.35 cm to the right and 2 ± 0.48 cm to the left. In five cadavers, using the revised method, the oesophagus was displaced by a mean of 2.26 ± 0.27 cm to the right and 2.3 ± 0.66 cm to the left. Conclusion: Mediastinal anatomy, specifically the presence of a loose connective tissue that attaches the oesophagus to the parietal pericardium overlying the posterior LA wall will allow for a lateral displacement of the oesophagus. This should decrease or eliminate the likelihood of thermal injury of the oesophagus. Using an endotracheal stylet, we investigated the lateral displacement of the oesophagus in 11 human cadavers. In six with the stylet extending to the GE junction, the oesophagus was displaced a mean of 3.8 cm. In five, with stylet 4 cm cranial to the junction, the displacement was 4.56 cm.

Targeting the programmed cell death 1: programmed cell death ligand 1 pathway reverses T cell exhaustion in patients with sepsis.

INTRODUCTION: A major pathophysiologic mechanism in sepsis is impaired host immunity which results in failure to eradicate invading pathogens and increased susceptibility to secondary infections. Although many immunosuppressive mechanisms exist, increased expression of the inhibitory receptor programmed cell death 1 (PD-1) and its ligand (PD-L1) are thought to play key roles. The newly recognized phenomenon of T cell exhaustion is mediated in part by PD-1 effects on T cells. This study tested the ability of anti-PD-1 and anti-PD-L1 antibodies to prevent apoptosis and improve lymphocyte function in septic patients. METHODS: Blood was obtained from 43 septic and 15 non-septic critically-ill patients. Effects of anti-PD-1, anti-PD-L1, or isotype-control antibody on lymphocyte apoptosis and interferon gamma (IFN-γ) and interleukin-2 (IL-2) production were quantitated by flow cytometry. RESULTS: Lymphocytes from septic patients produced decreased IFN-γ and IL-2 and had increased CD8 T cell expression of PD-1 and decreased PD-L1 expression compared to non-septic patients (P<0.05). Monocytes from septic patients had increased PD-L1 and decreased HLA-DR expression compared to non-septic patients (P<0.01). CD8 T cell expression of PD-1 increased over time in ICU as PD-L1, IFN-γ, and IL2 decreased. In addition, donors with the highest CD8 PD-1 expression together with the lowest CD8 PD-L1 expression also had lower levels of HLA-DR expression in monocytes, and an increased rate of secondary infections, suggestive of a more immune exhausted phenotype. Treatment of cells from septic patients with anti-PD-1 or anti-PD-L1 antibody decreased apoptosis and increased IFN-γ and IL-2 production in septic patients; (P<0.01). The percentage of CD4 T cells that were PD-1 positive correlated with the degree of cellular apoptosis (P<0.01). CONCLUSIONS: In vitro blockade of the PD-1:PD-L1 pathway decreases apoptosis and improves immune cell function in septic patients. The current results together with multiple positive studies of anti-PD-1 and anti-PD-L1 in animal models of bacterial and fungal infections and the relative safety profile of anti-PD-1/anti-PD-L1 in human oncology trials to date strongly support the initiation of clinical trials testing these antibodies in sepsis, a disorder with a high mortality.

Sepsis endotypes identified by host gene expression across global cohorts.

BACKGROUND: Sepsis from infection is a global health priority and clinical trials have failed to deliver effective therapeutic interventions. To address complicating heterogeneity in sepsis pathobiology, and improve outcomes, promising precision medicine approaches are helping identify disease endotypes, however, they require a more complete definition of sepsis subgroups. METHODS: Here, we use RNA sequencing from peripheral blood to interrogate the host response to sepsis from participants in a global observational study carried out in West Africa, Southeast Asia, and North America (N = 494). RESULTS: We identify four sepsis subtypes differentiated by 28-day mortality. A low mortality immunocompetent group is specified by features that describe the adaptive immune system. In contrast, the three high mortality groups show elevated clinical severity consistent with multiple organ dysfunction. The immunosuppressed group members show signs of a dysfunctional immune response, the acute-inflammation group is set apart by molecular features of the innate immune response, while the immunometabolic group is characterized by metabolic pathways such as heme biosynthesis. CONCLUSIONS: Our analysis reveals details of molecular endotypes in sepsis that support immunotherapeutic interventions and identifies biomarkers that predict outcomes in these groups.

Sepsis is a life-threatening multi-organ failure caused by the body's immune response to infection. Clinical symptoms of sepsis vary from one person to another likely due to differences in host factors, infecting pathogen, and comorbidities. This difference in clinical symptoms may contribute to the lack of effective interventions for sepsis. Therefore, approaches tailored to targeting groups of patients who present similarly are of great interest. This study analysed a large group of sepsis patients with diverse symptoms using laboratory markers and mathematical analysis. We report four patient groups that differ by risk of death and immune response profile. Targeting these defined groups with tailored interventions presents an exciting opportunity to improve the health outcomes of patients with sepsis.

Gene expression signatures in blood from a West African sepsis cohort define host response phenotypes.

Our limited understanding of the pathophysiological mechanisms that operate during sepsis is an obstacle to rational treatment and clinical trial design. There is a critical lack of data from low- and middle-income countries where the sepsis burden is increased which inhibits generalized strategies for therapeutic intervention. Here we perform RNA sequencing of whole blood to investigate longitudinal host response to sepsis in a Ghanaian cohort. Data dimensional reduction reveals dynamic gene expression patterns that describe cell type-specific molecular phenotypes including a dysregulated myeloid compartment shared between sepsis and COVID-19. The gene expression signatures reported here define a landscape of host response to sepsis that supports interventions via targeting immunophenotypes to improve outcomes.

RAGE inhibits human respiratory syncytial virus syncytium formation by interfering with F-protein function.

Human respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract infection. Infection is critically dependent on the RSV fusion (F) protein, which mediates fusion between the viral envelope and airway epithelial cells. The F protein is also expressed on infected cells and is responsible for fusion of infected cells with adjacent cells, resulting in the formation of multinucleate syncytia. The receptor for advanced glycation end products (RAGE) is a pattern-recognition receptor that is constitutively highly expressed by type I alveolar epithelial cells. Here, we report that RAGE protected HEK cells from RSV-induced cell death and reduced viral titres in vitro. RAGE appeared to interact directly with the F protein, but, rather than inhibiting RSV entry into host cells, virus replication and budding, membrane-expressed RAGE or soluble RAGE blocked F-protein-mediated syncytium formation and sloughing. These data indicate that RAGE may contribute to protecting the lower airways from RSV by inhibiting the formation of syncytia, viral spread, epithelial damage and airway obstruction.

Point-of-care biomarker assay for rapid multiplexed detection of CRP and IP-10.

Rapid and accurate measurements of immune protein markers are essential for diagnosis and treatment in all clinical settings. The recent pandemic has revealed a stark need for developing new tools and assays that could be rapidly used in diverse settings and provide useful information to clinicians. Here, we describe the development and test application of a novel one-step CRP/IP-10 duplex assay for the LightDeck platform capable of delivering reproducible and accurate measurements in under eight minutes. We used the optimized assay to measure CRP and IP-10 levels in human blood and serum samples from healthy, SARS-CoV-2 (COVID-19) positive, and influenza-like illness (ILI) presenting patients. Our results agreed with previously published analyte levels and enabled us to make statistically significant comparisons relevant to multiple clinical parameters. Our duplex assay is a simple and powerful tool for aiding prognostic decision-making in diverse settings.

Screening tools for predicting mortality of adults with suspected sepsis: an international sepsis cohort validation study.

OBJECTIVES: We evaluated the performance of commonly used sepsis screening tools across prospective sepsis cohorts in the USA, Cambodia and Ghana. DESIGN: Prospective cohort studies. SETTING AND PARTICIPANTS: From 2014 to 2021, participants with two or more SIRS (Systemic Inflammatory Response Syndrome) criteria and suspected infection were enrolled in emergency departments and medical wards at hospitals in Cambodia and Ghana and hospitalised participants with suspected infection were enrolled in the USA. Cox proportional hazards regression was performed, and Harrell's C-statistic calculated to determine 28-day mortality prediction performance of the quick Sequential Organ Failure Assessment (qSOFA) score ≥2, SIRS score ≥3, National Early Warning Score (NEWS) ≥5, Modified Early Warning Score (MEWS) ≥5 or Universal Vital Assessment (UVA) score ≥2. Screening tools were compared with baseline risk (age and sex) with the Wald test. RESULTS: The cohorts included 567 participants (42.9% women) including 187 participants from Kumasi, Ghana, 200 participants from Takeo, Cambodia and 180 participants from Durham, North Carolina in the USA. The pooled mortality was 16.4% at 28 days. The mortality prediction accuracy increased from baseline risk with the MEWS (C-statistic: 0.63, 95% CI 0.58 to 0.68; p=0.002), NEWS (C-statistic: 0.68; 95% CI 0.64 to 0.73; p<0.001), qSOFA (C-statistic: 0.70, 95% CI 0.64 to 0.75; p<0.001), UVA score (C-statistic: 0.73, 95% CI 0.69 to 0.78; p<0.001), but not with SIRS (0.60; 95% CI 0.54 to 0.65; p=0.13). Within individual cohorts, only the UVA score in Ghana performed better than baseline risk (C-statistic: 0.77; 95% CI 0.71 to 0.83; p<0.001). CONCLUSIONS: Among the cohorts, MEWS, NEWS, qSOFA and UVA scores performed better than baseline risk, largely driven by accuracy improvements in Ghana, while SIRS scores did not improve prognostication accuracy. Prognostication scores should be validated within the target population prior to clinical use.

Ontogeny of the immune response in the ovine lung.

Perinatal lambs are increasingly appreciated as a model to study respiratory infections of premature and newborn human infants. To explore the relationship between developmental age and immunological competence in the respiratory tract, the basal levels of expression of genes involved in innate and adaptive immune functions in the lung were examined in pre-term lambs (115 days and 130 days), at birth (145 days) and post-partum (15 days and 3 years old). Our results show that innate immune genes (TLRs-3, -4, -7, -8; SP-A, SP-D, and SBD1) were differentially expressed through development; cytokines (IFN-γ, IL-6, TNF-α) and chemokines (IL-8, MCP-1) were low during gestation and post-partum but maximal at birth; genes involved in adaptive immunity (PD-1, PD-L1, TGF-ß) were present in pre-term and newborn lung, but were lower in adult lung. The results suggest that pre-term and neonatal lambs may be able to mount an immune response following infection, but that the response may not be optimal. Our studies provide an important set of comparative data on the ontogeny of lung immunity in sheep and set a framework for studies on age-dependent susceptibility to respiratory pathogens.

Analysis of respiratory syncytial virus preclinical and clinical variants resistant to neutralization by monoclonal antibodies palivizumab and/or motavizumab.

BACKGROUND: Palivizumab is a US Food and Drug Administration-approved monoclonal antibody for the prevention of respiratory syncytial virus (RSV) lower respiratory disease in high-risk infants. Motavizumab, derived from palivizumab with enhanced antiviral activity, has recently been tested in humans. Although palivizumab escape mutants have been generated in the laboratory, the development of resistant RSV in patients receiving palivizumab has not been reported previously. METHODS: We generated palivizumab and motavizumab escape mutants in vitro and examined the development of resistant mutants in RSV-breakthrough patients receiving immunoprophylaxis. The effect of these mutations on neutralization by palivizumab and motavizumab and in vitro fitness was studied. RESULTS: Antibody-resistant RSV variants selected in vitro had mutations at position 272 of the fusion protein, from lysine to asparagine, methionine, threonine, glutamine, or glutamate. Variants containing mutations at positions 272 and 275 were detected in breakthrough patients. All these variants were resistant to palivizumab, but only the glutamate variant at position 272 demonstrated resistance to motavizumab. Mixtures of wild-type and variant RSV soon lost the resistant phenotype in the absence of selection. CONCLUSIONS: Resistant RSV variants were detected in a small subset (∼ 5%) of RSV breakthrough cases. The fitness of these variants was impaired, compared to wild-type RSV.

Assessing the use of a micro-sampling device for measuring blood protein levels in healthy subjects and COVID-19 patients.

BACKGROUND: Venous phlebotomy performed by trained personnel is critical for patient diagnosis and monitoring of chronic disease, but has limitations in resource-constrained settings, and represents an infection control challenge during outbreaks. Self-collection devices have the potential to shift phlebotomy closer to the point of care, supporting telemedicine strategies and virtual clinical trials. Here we assess a capillary blood micro-sampling device, the Tasso Serum Separator Tube (SST), for measuring blood protein levels in healthy subjects and non-hospitalized COVID-19 patients. METHODS: 57 healthy controls and 56 participants with mild/moderate COVID-19 were recruited at two U.S. military healthcare facilities. Healthy controls donated Tasso SST capillary serum, venous plasma and venous serum samples at multiple time points, while COVID-19 patients donated a single Tasso SST serum sample at enrolment. Concentrations of 17 protein inflammatory biomarkers were measured in all biospecimens by Ella multi-analyte immune-assay. RESULTS: Tasso SST serum protein measurements in healthy control subjects were highly reproducible, but their agreements with matched venous samples varied. Most of the selected proteins, including CRP, Ferritin, IL-6 and PCT, were well-correlated between Tasso SST and venous serum with little sample type bias, but concentrations of D-dimer, IL-1B and IL-1Ra were not. Self-collection at home with delayed sample processing was associated with significant concentrations differences for several analytes compared to supervised, in-clinic collection with rapid processing. Finally, Tasso SST serum protein concentrations were significantly elevated in in non-hospitalized COVID-19 patients compared with healthy controls. CONCLUSIONS: Self-collection of capillary blood with micro-sampling devices provides an attractive alternative to routine phlebotomy. However, concentrations of certain analytes may differ significantly from those in venous samples, and factors including user proficiency, temperature control and time lags between specimen collection and processing need to be considered for their effect on sample quality and reproducibility.

Respiratory syncytial virus is associated with an inflammatory response in lungs and architectural remodeling of lung-draining lymph nodes of newborn lambs.

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infection in children worldwide. The understanding of neonatal RSV pathogenesis depends on using an animal model that reproduces neonatal RSV disease. Previous studies from us and others demonstrated that the neonatal lamb model resembles human neonatal RSV infection. Here, we provide an extensive and detailed characterization of the histopathology, viral load, cellular infiltration, and cytokine production in lungs and tracheobronchial lymph nodes of lambs inoculated with human RSV strain A2 over the course of infection. In the lung, RSV titers were low at day 3 postinfection, increased significantly by day 6, and decreased to baseline levels at day 14. Infection in the lung was associated with an accumulation of macrophages, CD4(+) and CD8(+) T cells, and a transcriptional response of genes involved in inflammation, chemotaxis, and interferon response, characterized by increased IFNγ, IL-8, MCP-1, and PD-L1, and decreased IFNß, IL-10, and TGF-ß. Laser capture microdissection studies determined that lung macrophage-enriched populations were the source of MCP-1 but not IL-8. Immunoreactivity to caspase 3 occurred within bronchioles and alveoli of day 6-infected lambs. In lung-draining lymph nodes, RSV induced lymphoid hyperplasia, suggesting an ability of RSV to enhance lymphocytic proliferation and differentiation pathways. This study suggests that, in lambs with moderate clinical disease, RSV enhances the activation of caspase cell death and Th1-skewed inflammatory pathways, and complements previous observations that emphasize the role of inflammation in the pathogenesis of RSV disease.

Posterior interatrial muscular connection between the coronary sinus and left atrium: anatomic and functional study of the coronary sinus with multidetector CT.

PURPOSE: To demonstrate coronary sinus-left atrium connections and evaluate coronary sinus function and anatomy in detail by using multidetector computed tomography (CT). MATERIALS AND METHODS: In this institutional review board-approved retrospective study, the authors evaluated coronary CT angiograms obtained in 65 patients with normal sinus rhythm (normal group) and seven with atrial fibrillation at CT (atrial fibrillation group). Coronary sinus-right atrium muscle continuity was indirectly evaluated by measuring the length of the coronary sinus contraction during atrial systole. The length, number, and extent of coronary sinus-left atrium connections were recorded. The accuracy of CT was validated by comparing microscopic images of autopsied hearts with corresponding CT images. Comparisons were performed by using Student t tests for continuous variables. P ≤ .05 was considered indicative of a statistically significant difference. RESULTS: In the normal group, coronary sinus contraction was seen in 60 of the 65 patients (92%, mean length ± standard deviation, 25.7 mm ± 8.0). The coronary sinus narrowed 26% from middiastole to atrial systole (P < .0001). Coronary sinus-left atrium muscle connections were seen in 58 of the 65 patients (89%). A single connection was seen in 43 of the 65 patients (66%), with a mean length of 21.0 mm ± 14.0 within 12.0 mm ± 11.0 of the coronary sinus ostium. In 10 of the 43 patients (26%) with single connections, the connection extended to the coronary sinus ostium. In 10 of the 65 patients (15%), the entire coronary sinus was attached to the left atrial wall. Fifteen patients (23%) had two connections; distal connections measured 9 mm ± 2.4 in length within 2.2 mm ± 3.8 of the coronary sinus ostium, and proximal connections measured 15.4 mm ± 10.0 in length within 24.0 mm ± 8.0 of the coronary sinus ostium. In seven patients (11%), no coronary sinus-left atrium connection was seen; however, all showed a coronary sinus constriction during atrial systole, indicating that coronary sinus-right atrium muscle continuity is likely the primary cause for coronary sinus contractions. In the atrial fibrillation group, no coronary sinus contraction was seen. All images in the atrial fibrillation group showed a coronary sinus-left atrium connection, which was single in five patients and double in two. The area of the coronary sinus during diastole was larger in the atrial fibrillation group than in the normal group (114 mm(2) ± 37 vs 77 mm(2) ± 40, respectively; P = .02). CONCLUSION: CT can provide excellent information about coronary sinus function and coronary sinus-left atrium muscle connections.

Respiratory syncytial virus infection is associated with an altered innate immunity and a heightened pro-inflammatory response in the lungs of preterm lambs.

INTRODUCTION: Factors explaining the greater susceptibility of preterm infants to severe lower respiratory infections with respiratory syncytial virus (RSV) remain poorly understood. Fetal/newborn lambs are increasingly appreciated as a model to study key elements of RSV infection in newborn infants due to similarities in lung alveolar development, immune response, and susceptibility to RSV. Previously, our laboratory demonstrated that preterm lambs had elevated viral antigen and developed more severe lesions compared to full-term lambs at seven days post-infection. Here, we compared the pathogenesis and immunological response to RSV infection in lungs of preterm and full-term lambs. METHODS: Lambs were delivered preterm by Caesarian section or full-term by natural birth, then inoculated with bovine RSV (bRSV) via the intratracheal route. Seven days post-infection, lungs were collected for evaluation of cytokine production, histopathology and cellular infiltration. RESULTS: Compared to full-term lambs, lungs of preterm lambs had a heightened pro-inflammatory response after infection, with significantly increased MCP-1, MIP-1α, IFN-γ, TNF-α and PD-L1 mRNA. RSV infection in the preterm lung was characterized by increased epithelial thickening and periodic acid-Schiff staining, indicative of glycogen retention. Nitric oxide levels were decreased in lungs of infected preterm lambs compared to full-term lambs, indicating alternative macrophage activation. Although infection induced significant neutrophil recruitment into the lungs of preterm lambs, neutrophils produced less myeloperoxidase than those of full-term lambs, suggesting decreased functional activation. CONCLUSIONS: Taken together, our data suggest that increased RSV load and inadequate immune response may contribute to the enhanced disease severity observed in the lungs of preterm lambs.

Lessons learned from experimental models of cerebrovascular aneurysms to improve endocardial device occlusion of the left atrial appendage.

In patients with atrial fibrillation, left atrial appendage (LAA) occlusion devices represent an alternative to anticoagulation but are associated with residual peridevice leaks (PDLs) and device-related thrombi (DRT). Similarly, cerebrovascular aneurysms can be treated with coil embolization, but pericoil leaks represent a significant limitation. In experimental models of cerebrovascular aneurysms, endothelial denudation achieved independently with (1) embolization with radioactive coils, (2) mechanical removal of the endothelium, or (3) radiofrequency ablation was dramatically effective in preventing or eliminating pericoil leaks. Anatomical, physiological, and blood flow similarities exist between the LAA and saccular aneurysms. Concepts developed in treating aneurysm leaks can be used to treat similar problems in the LAA. Learning from aneurysms, we conceived of a novel technique to denude local endothelium and thus eliminate residual leaks around LAA-occlusion devices. We recently successfully tested this hypothesis in patients with a PDL in a prospective manner in a multicenter study. In this article, we expand on the rationale of the technique developed to close PDLs and potentially also prevent DRTs.

Multiplexed cytokine detection using electrochemical point-of-care sensing device towards rapid sepsis endotyping.

The implementation of endotype-driven effective intervention strategies is now considered as an essential component for sepsis management. Rapid screening and frequent monitoring of immune responses are critical for evidence-based informed decisions in the early hours of patient arrival. Current technologies focus on pathogen identification that lack rapid testing of the patient immune response, impeding clinicians from providing appropriate sepsis treatment. Herein, we demonstrate a first-of-its-kind novel point-of-care device that uses a unique approach by directly monitoring a panel of five cytokine biomarkers (IL-6, IL-8, IL-10, TRAIL & IP-10), that is attributed as a sign of the body's host immune response to sepsis. The developed point-of-care device encompasses a disposable sensor cartridge attached to an electrochemical reader. High sensitivity is achieved owing to the unique sensor design with an array of nanofilm semiconducting/metal electrode interface, functionalized with specific capture probes to measure target biomarkers simultaneously using non-faradaic electrochemical impedance spectroscopy. The sensor has a detection limit of ~1 pg/mL and provides results in less than five minutes from a single drop of undiluted plasma sample. Furthermore, the sensor demonstrates an excellent correlation (Pearson's r > 0.90) with the reference method for a total n = 40 clinical samples, and the sensor's performance is ~30 times faster compared to the standard reference technique. We have demonstrated the sensor's effectiveness to enhance diagnosis with a mechanistic biomarker-guided approach that can help disease endotypying for effective clinical management of sepsis at the patient bedside.

An approach to rapidly assess sepsis through multi-biomarker host response using machine learning algorithm.

Sepsis is a life-threatening condition and understanding the disease pathophysiology through the use of host immune response biomarkers is critical for patient stratification. Lack of accurate sepsis endotyping impedes clinicians from making timely decisions alongside insufficiencies in appropriate sepsis management. This work aims to demonstrate the potential feasibility of a data-driven validation model for supporting clinical decisions to predict sepsis host-immune response. Herein, we used a machine learning approach to determine the predictive potential of identifying sepsis host immune response for patient stratification by combining multiple biomarker measurements from a single plasma sample. Results were obtained using the following cytokines and chemokines IL-6, IL-8, IL-10, IP-10 and TRAIL where the test dataset was 70%. Supervised machine learning algorithm naïve Bayes and decision tree algorithm showed good accuracy of 96.64% and 94.64%. These promising findings indicate the proposed AI approach could be a valuable testing resource for promoting clinical decision making.

Radiofrequency Energy Applications Targeting Significant Residual Leaks After Watchman Implantation: A Prospective, Multicenter Experience.

OBJECTIVES: The aim of this study was to evaluate the efficacy of radiofrequency (RF) energy applications targeting the atrial side of a significant residual leak in patients with acute and chronic evidence of incomplete percutaneous left atrial appendage (LAA) occlusion. BACKGROUND: RF applications have been proved to prevent recanalization of intracranial aneurysms after coil embolization, thereby favoring complete sealing. From a mechanistic standpoint, in vitro and in vivo experiments have demonstrated that RF promotes collagen deposition and tissue retraction. METHODS: Forty-three patients (mean age 75 ± 7 years mean CHA2DS2-VASc score 4.6 ± 1.4, mean HAS-BLED score 4.0 ± 1.1) with residual leaks ≥4 mm after Watchman implantation were enrolled. Procedural success was defined as complete LAA occlusion or presence of a mild or minimal (1- to 2-mm) peridevice leak on follow-up transesophageal echocardiography (TEE), which was performed approximately 45 days after the procedure. RESULTS: RF-based leak closure was performed acutely after Watchman implantation in 19 patients (44.2%) or scheduled after evidence of significant leaks on follow-up TEE in 24 others (55.8%). The median leak size was 5 mm (range: 4-7 mm). On average, 18 ± 7 RF applications per patient (mean maximum contact force 16 ± 3 g, mean power 44 ± 2 W, mean RF time 5.1 ± 2.5 minutes) were performed targeting the atrial edge of the leak. Post-RF median leak size was 0 mm (range: 0-1 mm). A very low rate (2.3% [n = 1]) of major periprocedural complications was observed. Follow-up TEE revealed complete LAA sealing in 23 patients (53.5%) and negligible residual leaks in 15 (34.9%). CONCLUSIONS: RF applications targeting the atrial edge of a significant peri-Watchman leak may promote LAA sealing via tissue remodeling, without increasing complications. (RF Applications for Residual LAA Leaks [REACT]; NCT04726943).

Variations in Thebesian valve anatomy and coronary sinus ostium: implications for invasive electrophysiology procedures.

AIMS: The coronary sinus (CS) is a commonly cannulated structure in patients undergoing electrophysiology studies, catheter ablation of arrhythmias, implantation of resynchronization therapy devices and, more recently, percutaneous mitral valve repair. The advent of these procedures has led to a renewed interest in the anatomy of the coronary venous system including its various components. To improve our understanding of this structure, we studied the anatomy of the human CS, including the valve that guards its ostium, the Thebesian valve. METHODS AND RESULTS: In 75 randomly selected autopsied human hearts, we measured the transverse and craniocaudal dimensions of the CS ostium and characterized the shape, composition, per cent coverage, and attachment points of the Thebesian valve when present. Of the 75 hearts examined, 54 had organic heart disease including atherosclerotic coronary artery disease, left ventricular hypertrophy, dilated cardiomyopathy, rheumatic heart disease, infective endocarditis, and non-rheumatic valvular heart disease. A wide variety of Thebesian valve morphologies were seen, ranging from the absence of any valve to those where the valve was completely occluding the CS ostium. A Thebesian valve was present in the majority of the hearts examined (55/75 hearts-73%). The average transverse dimension of the CS ostium in hearts with Thebesian valves (7.3+/-2.8 mm) was significantly shorter than those without Thebesian valves (9.4+/-2.9 mm, P=0.005). Similarly, the average craniocaudal dimension of the CS ostium in hearts with Thebesian valves (7.9+/-2.7 mm) was also significantly shorter than those without Thebesian valves (9.3+/-2.9 mm, P=0.045). CONCLUSION: Our study shows that some form of Thebesian valve is present in the majority of hearts (>70%). Of these, a significant minority (16%) had a valve morphology (covering >75% of the ostium, a fibrous, fibromuscular, or muscular composition, and devoid of fenestrations) that makes them a 'potentially complicating' structure interfering with the cannulation of the CS.

Closure of foramen ovale triggered by injury to tunnel surfaces of septum primum and secundum.

INTRODUCTION: We investigated the feasibility to proactively stimulate subsequent closure of a patent foramen ovale (PFO) by injuring (mechanical trauma or radiofrequency [RF] energy) the opposing surfaces of the septum primum (SP) and septum secundum (SS). METHODS: 1. Mechanical Injury: The interatrial septum of patients who underwent multiple left atrial (LA) ablations over 6 years, where a PFO was used for LA access, were examined. Patients whose PFO was absent during a later procedure were identified. Eleven patients with LA accessed via a PFO also underwent subsequent LA procedures. 2. Ablation: Ten patients undergoing ablation for drug-resistant atrial fibrillation (AF), who also had a PFO, were studied. RF delivery was extended along the upper SP. Transthoracic echocardiogram (TTE) bubble study was repeated after 3 months. RESULTS: 1. Mechanical Injury: Seven were male with a mean age of 58.3 ± 9.99. LA size was 42.73 ± 3.52 mm. The mean left ventricular ejection fraction (EF) was 62 ± 7.4%. During the repeat procedure, in 4 patients, the PFO could not be visualized and the fossa ovalis (FO) was punctured. The fourth patient had three procedures. During the second procedure the PFO was accessed, but with difficulty. During the third procedure, it was no longer present. All four patients had subsequent TTE showing no PFO. 2. Ablation: Seven were male with a mean age of 61.1 ± 9.8 years. The mean EF and LA diameters were 55 ± 5% and 4.4 ± 0.8 cm respectively. The mean RF time was 5.4 ± 2.2 min. At 3 months, 9 patients out of 10 showed no interatrial communication. CONCLUSION: Injury of tunnel surfaces of the SP and SS by mechanical trauma or ablation can fuse the foramen ovale.