Containing misinformation: Modeling spatial games of fake news.

The spread of fake news on social media is a pressing issue. Here, we develop a mathematical model on social networks in which news sharing is modeled as a coordination game. We use this model to study the effect of adding designated individuals who sanction fake news sharers (representing, for example, correction of false claims or public shaming of those who share such claims). By simulating our model on synthetic square lattices and small-world networks, we demonstrate that social network structure allows fake news spreaders to form echo chambers and more than doubles fake news' resistance to distributed sanctioning efforts. We confirm our results are robust to a wide range of coordination and sanctioning payoff parameters as well as initial conditions. Using a Twitter network dataset, we show that sanctioners can help contain fake news when placed strategically. Furthermore, we analytically determine the conditions required for peer sanctioning to be effective, including prevalence and enforcement levels. Our findings have implications for developing mitigation strategies to control misinformation and preserve the integrity of public discourse.

Outcomes of transcatheter pulmonary SAPIEN 3 valve implantation: an international registry.

BACKGROUND AND AIMS: Transcatheter pulmonary valve implantation (TPVI) is indicated to treat right-ventricular outflow tract (RVOT) dysfunction related to congenital heart disease (CHD). Outcomes of TPVI with the SAPIEN 3 valve that are insufficiently documented were investigated in the EUROPULMS3 registry of SAPIEN 3-TPVI. METHODS: Patient-related, procedural, and follow-up outcome data were retrospectively assessed in this observational cohort from 35 centres in 15 countries. RESULTS: Data for 840 consecutive patients treated in 2014-2021 at a median age of 29.2 (19.0-41.6) years were obtained. The most common diagnosis was conotruncal defect (70.5%), with a native or patched RVOT in 50.7% of all patients. Valve sizes were 20, 23, 26, and 29 mm in 0.4%, 25.5%, 32.1%, and 42.0% of patients, respectively. Valve implantation was successful in 98.5% [95% confidence interval (CI), 97.4%-99.2%] of patients. Median follow-up was 20.3 (7.1-38.4) months. Eight patients experienced infective endocarditis; 11 required pulmonary valve replacement, with a lower incidence for larger valves (P = .009), and four experienced pulmonary valve thrombosis, including one who died and three who recovered with anticoagulation. Cumulative incidences (95%CI) 1, 3, and 6 years after TPVI were as follows: infective endocarditis, 0.5% (0.0%-1.0%), 0.9% (0.2%-1.6%), and 3.8% (0.0%-8.4%); pulmonary valve replacement, 0.4% (0.0%-0.8%), 1.3% (0.2%-2.4%), and 8.0% (1.2%-14.8%); and pulmonary valve thrombosis, 0.4% (0.0%-0.9%), 0.7% (0.0%-1.3%), and 0.7% (0.0%-1.3%), respectively. CONCLUSIONS: Outcomes of SAPIEN 3 TPVI were favourable in patients with CHD, half of whom had native or patched RVOTs.

Transcatheter versus surgical treatment for isolated superior sinus venosus atrial septal defect.

BACKGROUND: The superior sinus venosus atrial septal defect is a congenital communication between the left and right atria. Open surgical approach by patch closure has historically been the only treatment option. Recently, a transcatheter approach has been developed. This study aims to compare the efficacy and safety of surgical and transcatheter approach in treatment of sinus venosus atrial septal defect. METHODS: Between March 2010 and December 2020, 58 patients (median age: 45.4, range 14.8-73.8) underwent either surgical or transcatheter correction of superior sinus venosus atrial septal defect with partial anomalous pulmonary venous drainage. RESULTS: Twenty-four patients (median age: 35.4, range 14.8-66.8) underwent surgery while 34 patients (median age: 46.8, range 15.5-73.8) had a transcatheter treatment. During the catheterization era, 41 patients was considered suitable for a transcatheter closure. In 5 patients, surgery was the patient's or referring physician's choice. In 2 cases, the procedure was unsuccessful; the remaining 34 were successfully closed (94.4% of cases). Intensive care unit stay (median of 1 day, range 0.5-4, vs. 0, range 0-2, p < 0.0001) and hospital stay (median 7 days, range 2-15 vs. 2 days, range 1-12, p < 0.0001), were significantly longer in the surgery group. Total early complication rate, consisted on procedural and in-hospital complication, were higher in the surgical group (62.5% vs. 23.5%; p = 0.005). However, complications in both groups were clinically mild. At follow-up, a small residual shunt was present in 6 patients (surgery group: 2 pts; catheterization group: 4 pts; p: NS). Imaging studies showed significant improvement of right ventricular size and unobstructed pulmonary venous return in all patients. No late complications occurred at follow-up. CONCLUSIONS: Transcatheter correction of sinus venosus atrial septal defect is effective and safe in selected patients and may be considered as a valid alternative to surgery.

Provocation and localization of atrial ectopy in patients with atrial septal defects.

BACKGROUND: Atrial fibrillation (AF) is associated with atrial septal defects (ASDs), but the mechanism of arrhythmia in these patients is poorly understood. We hypothesised that right-sided atrial ectopy may predominate in this cohort. Here, we aimed to localise the origin of spontaneous and provoked atrial ectopy in ASD patients. METHODS: Following invasive calibration of P-wave axes, 24-h Holter monitoring was used to determine the chamber of origin of spontaneous atrial ectopy. Simultaneous electrogram recording from multiple intra-cardiac catheters was used to determine the chamber of origin of isoprenaline-provoked ectopy. Comparison was made to a group of non-congenital heart disease AF patients. RESULTS: Amongst ASD patients, a right-sided origin for spontaneous atrial ectopy was significantly more prevalent than a left-sided origin (24/30 patients with right-sided ectopy vs. 14/30 with left-sided ectopy, P = 0.015). Amongst AF patients, there was no difference in the prevalence of spontaneous right vs. left-sided ectopy. For isoprenaline-provoked ectopy, there was no significant difference in the proportions of patients with right-sided or left-sided ectopy in either group. CONCLUSIONS: When spontaneous atrial ectopy occurs in ASD patients, it is significantly more prevalent from a right-sided than left-sided origin. Isoprenaline infusion did not reveal the predilection for right-sided ectopy during electrophysiology study.

Random choices facilitate solutions to collective network coloring problems by artificial agents.

Global coordination is required to solve a wide variety of challenging collective action problems from network colorings to the tragedy of the commons. Recent empirical study shows that the presence of a few noisy autonomous agents can greatly improve collective performance of humans in solving networked color coordination games. To provide analytical insights into the role of behavioral randomness, here we study myopic artificial agents attempting to solve similar network coloring problems using decision update rules that are only based on local information but allow random choices at various stages of their heuristic reasonings. We show that the resulting efficacy of resolving color conflicts is dependent on the implementation of random behavior of agents and specific population characteristics. Our work demonstrates that distributed greedy optimization algorithms exploiting local information should be deployed in combination with occasional exploration via random choices in order to overcome local minima and achieve global coordination.

Transcatheter creation of a pulmonary artery to left atrial fenestration in a failing Fontan circulation using the Atrial Flow Regulator (AFR).

Transcatheter creation of an interatrial communication using the Occlutech Atrial Flow Regulator Device for pulmonary hypertension or heart failure is well described. We report a case of an 8-year-old boy with a failing Fontan circulation, in whom the Atrial Flow Regulator was used to successfully create a fenestration between the pulmonary artery and left atrium, improving his clinical condition.

Melody Valve Fracture Causing Mitral Stenosis: Novel Solution for Transapical Valve-in-Valve.

The use of Melody valves in the mitral position has been introduced in clinical practice. Stent fracture is a recognized complication of Melody valve implantation in the pulmonary position; however, reports in the mitral position are rare. We present the case of an 8-year-old boy in whom complete fracture of the proximal stent struts occurred, causing acute severe mitral stenosis, and in whom urgent hybrid transapical Melody valve implantation in the fractured Melody valve was performed successfully using a novel modified technique. This modification simplified the implantation, led to reduced time of the procedure, and minimized hemodynamic instability.

Initial experience with a novel ePTFE-covered balloon expandable stent in patients with near-atretic or severe aortic coarctation and small femoral arterial access.

OBJECTIVES: We report our experience of using the Bentley BeGraft Aortic stent in patients with severe or near-atretic aortic coarctation and small femoral arterial access. BACKGROUND: Use of covered stent is recommended in some settings such as aortic coarctation with associated aneurysm, Turner syndrome, and coarctation with aortic atresia. However, currently available covered stents need larger sheaths that may limit their use in children and patients with smaller arterial access. Newer stents may overcome this limitation. METHODS: Single-centre retrospective study of patients with severe or near-atretic aortic coarctation and small femoral arterial access. RESULTS: Between July and October, 2019, five patients (median age 15 years) with near-atretic or severe coarctation were treated with a Bentley BeGraft Aortic stent. Long sheaths between 9 and 11 Fr were used to implant stents, which were dilated up to 12-16 mm. None of the patients had residual coarctation (gradient >20 mm of mercury) after stenting. None of the patients developed acute vascular injuries or local access related complications at the end of the procedure or during follow-up (range 6-10 months). CONCLUSIONS: Bentley BeGraft aortic stents are important to consider in patients with severe coarctation and provided acute procedural success in patients with small femoral arterial access and widen the applicability in this patient population.

The dual problems of coordination and anti-coordination on random bipartite graphs.

In some scenarios ("anti-coordination games"), individuals are better off choosing different actions than their neighbors while in other scenarios ("coordination games"), it is beneficial for individuals to choose the same strategy as their neighbors. Despite having different incentives and resulting population dynamics, it is largely unknown which collective outcome, anti-coordination or coordination, is easier to achieve. To address this issue, we focus on the distributed graph coloring problem on bipartite graphs. We show that with only two strategies, anti-coordination games (2-colorings) and coordination games (uniform colorings) are dual problems that are equally difficult to solve. To prove this, we construct an isomorphism between the Markov chains arising from the corresponding anti-coordination and coordination games under certain specific individual stochastic decision-making rules. Our results provide novel insights into solving collective action problems on networks.

Recent advances in transcatheter management of pulmonary regurgitation after surgical repair of tetralogy of Fallot.

Surgical repair of tetralogy of Fallot (ToF) in childhood is associated with generally good outcomes, and almost all children can be expected to survive until adulthood. However, significant pulmonary regurgitation leading to progressive right ventricular dilatation is common in teenagers or young adults because of the nature of the surgical intervention. In patients whose repair included placement of a right ventricle to pulmonary artery conduit, it has been possible to place a stented valve within the conduit to treat this. Pulmonary regurgitation after repair of ToF via a transannular patch technique has historically involved repeat surgery as the dimensions of the right ventricular outflow tract have been too large for commercially available valves. This review summarises the novel transcatheter valves available for management of pulmonary regurgitation after surgical repair of ToF in patients in whom the dimensions of the right ventricular outflow tract have previously been considered too large for transcatheter valve implantation.

Congenitally corrected transposition: complex anatomic repair or Fontan pathway?

Background Successful anatomic repair of congenitally corrected transposition of the great arteries achieves excellent outcomes. Several centers report excellent long-term survival with the Fontan pathway as well. We have selectively applied both approaches depending on individual patient morphology, with anatomic repair preferred but utilizing the Fontan pathway when high technical complexity or operative risk is anticipated. Methods Hospital records over an 18-year period (1998-2016) were reviewed to identify patients with congenitally corrected transposition of the great arteries who underwent surgical management. Physiological repairs and hypoplastic ventricles were excluded. Patient- and procedure-related variables were reviewed. Results We identified 19 patients. Group 1 consisted of 12 anatomic repairs, of which 10 (83.3%) required prior interim staging procedures. Mean age at anatomic repair was 2.6 ± 1.3 years, mean follow-up was 8.7 ± 5.3 years. Nine (75%) patients experienced important complications and 4 (33.3%) required reintervention during follow-up. There were no deaths; one patient required heart transplantation. Group 2 (7 patients) underwent Fontan palliation. Mean age at Fontan completion was 7.2 ± 3.8 years, mean follow-up was 6.3 ± 4 years. There was no reintervention, death, or transplant. Conclusion Patients with congenitally corrected transposition of the great arteries and two adequate-sized ventricles do well with both anatomic repair and the Fontan pathway in the medium term. Excellent outcomes with reduced early complication and reintervention rates can be achieved for this cohort of patients when a strategy of avoiding complex anatomic repair in favor of the Fontan pathway is used.

Infective endocarditis with co-existent acalculous cholecystitis: a rare but important association.

The authors present the case of an otherwise healthy retired male who presented with a history of fevers, rigors and right upper quadrant abdominal pain. Although haematological, biochemical and radiological investigations supported a diagnosis of acalculous cholecystitis, the underlying cause was not obviously apparent and the patient's clinical condition deteriorated rapidly over the course of a few hours despite appropriate medical treatment. Repeat clinical examination was consistent with acute pulmonary oedema in association with a new murmur throughout the whole of the cardiac cycle. Transthoracic echocardiography revealed the presence of severe aortic regurgitation, a presumptive diagnosis of infective endocarditis was made and medical therapy adjusted. Shortly after, the patient suffered a cardiac arrest and an attempt at resuscitation was unsuccessful. Postmortem examination revealed the presence of aortic valve cusp rupture secondary to bacterial endocarditis in addition to gallbladder appearances consistent with acute acalculous cholecystitis.