Re-repair for mitral insufficiency.

BACKGROUND: Mitral valve repair provides superior outcomes to replacement for primary MR. Whether this is true following previous repair is unknown. We present the results of a strategy of re-repair for failed mitral valve repair. We examine patients who were brought to the operating room for an intended mitral valve re-repair. METHODS: We reviewed the last one decade of our institutional mitral valve databases at The University of Pennsylvania and Plano Heart Hospital and identified patients undergoing repeat mitral valve repair, in whom the index operation was mitral valve repair. We analyzed their operative details, clinical and echocardiographic outcomes. RESULTS: Between 2008 and 2021, 71 patients (aged 61.5 ±10.7 years, 20% female) underwent mitral valve reoperation at an mean of 6.24 ±7.62 years following index mitral repair. 20% of patients presented with NYHA class III/IV symptoms. At index operation, 34 (47.9%) had repair through a right mini-thoracotomy. 15 patients (21.1%) required the reoperation within one year. There were 0 early and 8 late deaths. One patient who underwent mitral replacement instead of repair, required reoperation for paravalvular leak during the follow-up period. Three patients required mitral valve replacement at an average of 2.28 ±2.03 years following initial mitral valve re-repair. CONCLUSIONS: Mitral re-repair can be performed with acceptable results at a valve reference center. Durability and functional advantages of this approach remain to be proven.

Transaortic TAVR and Mitral Repair Under Deep Hypothermic Circulatory Arrest in a Porcelain Aorta Patient.

Vascular and valvular calcifications, commonly seen in renal patients, increase operative mortality and can preclude conventional valvular management. We show a novel approach to treat aortic stenosis and degenerative mitral regurgitation under hypothermic circulatory arrest in a hemodialysis patient with aortic, mitral disease and porcelain aorta with surgical and transcatheter contraindications.

Evaluating the effect of poly (amidoamine) treated bioactive glass nanoparticle incorporated in universal adhesive on bonding to artificially induced caries affected dentin.

BACKGROUND: The purpose of this study was to evaluate remineralisation and its effect on microtensile bond-strength of artificially induced caries affected dentin (CAD) when treated with a commercial universal adhesive modified with poly(amidoamine) dendrimer (PAMAM) loaded mesoporous bioactive glass nanoparticles (A-PMBG). MATERIAL AND METHODS: Mesoporous bioactive glass nanoparticles (MBG) were synthesised using sol-gel process, where PAMAM was loaded (P-MBG) and added to commercial adhesive at different weight percentages (0.2, 0.5, 1 and 2 wt%). First, rheological properties of commercial and modified adhesives were evaluated. The effect of remineralization/hardness and microtensile bond-strength (MTBs) of those samples that mimicked the rheological properties of commercial adhesives were evaluated using Vickers hardness tester and universal testing machine respectively. Scanning-Electron microscope was used to visualize failed samples of MTBs and remineralization samples. Both evaluations were carried out at 1-,3 and 6-month intervals, samples being stored in stimulated salivary fluid during each time interval. RESULTS: Addition of nanoparticles altered the rheological properties. With increase in the weight percentage of nanoparticles in commercial adhesive, there was significant increase in degree of conversion, viscosity and sedimentation rate (p < 0.05). The 0.2 and 0.5 wgt% groups closely mimicked the properties of commercial adhesive and were evaluated for remineralization and MTBs. After 6 months, 0.2wgt% group showed increased MTBs (p < 0.05) and 0.5wgt% group increased remineralization/hardness (p < 0.05). CONCLUSION: The complex of PAMAM-MBG-Universal adhesive can remineralize the demineralised CAD thereby improving its bond-strength when evaluated for up to 6-months.

Oligopoly competition between satellite constellations will reduce economic welfare from orbit use.

Orbital space enables many essential services, such as weather forecasting, global communication, navigation, Earth observation for environmental and agricultural management, and national security applications. Orbit use is increasingly defined by firms launching coordinated fleets-"constellations"-of satellites into low-Earth orbit. These firms operate in markets with few or no competitors, such as the market for broadband internet provision to rural areas. How will oligopolistic competition shape the allocation of orbital space? We analyze orbital-use patterns and economic welfare when two profit-maximizing firms operate satellite constellations with sophisticated collision avoidance systems. We compare this duopoly equilibrium to public utility constellations designed and regulated to maximize economic welfare from orbit use. We show that imperfect competition reduces economic welfare from orbit use by up to 12%-$1.1 billion USD-per year and distorts the allocation of orbital space. The nature of the distortion depends on the magnitude of constellation-related environmental damages. When damages are low, economic welfare is maximized by larger-than-equilibrium constellations. When damages are high, economic welfare is maximized by smaller-than-equilibrium constellations. Between the growing commercial and national interests in outer space and the importance of low-Earth orbit to space exploration, orbit-use management is likely to be a fruitful and policy-relevant area for economic research. We conclude with a discussion of future research directions in orbit-use management relevant to policymakers around the world.

Robotic and endoscopic mitral valve repair for degenerative disease.

Background: Minimally invasive mitral valve repair has been proven to be a safe alternative to open sternotomy and may be accomplished through classic endoscopic and robotic endoscopic approaches. Outcomes across different minimally invasive techniques have been insufficiently described. We compare early and late clinical outcomes across matched patients undergoing robotic endoscopic and classic endoscopic repair. Methods: From 2011 to 2020, 786 patients underwent minimally invasive mitral surgery, from which we were able to generate 124 matched patients (62 patients in each cohort). Clinical results were then compared between the two matched populations. Survival analysis was used to compare freedom from mortality to 10 years among matched classic endoscopic and robotic endoscopic mitral valve repair cohorts and to calculate freedom from moderate or severe mitral insufficiency at latest follow-up. Histograms of cardiopulmonary bypass (CPB) and aortic cross-clamp times were constructed, and mean bypass and cross-clamp times were compared between classic endoscopic and robotic endoscopic cohorts. Results: There was no difference in early or late mortality at 10 years in either cohort. Freedom from moderate or severe mitral regurgitation or mitral valve replacement at last echocardiogram was 86.4% vs. 73.5% at 10 years, P=0.97. Patients undergoing robotic endoscopic mitral repair had a significantly longer CPB run when compared to the classic endoscopic cohort, with 148 min of CPB in the robotic endoscopic cohort compared to 133 min in the classic endoscopic group, P=0.03. Overall post-operative length of stay was not statistically significant between the robotic endoscopic and classic endoscopic groups, 6.3±0.5 and 6.0±0.3 days, respectively. No patients in either cohort developed renal failure or wound infection. The classic endoscopic group had a slightly higher risk of prolonged ventilation when compared to the robotic endoscopic group, with three classic endoscopic patients remaining intubated >8 hours post-operatively, compared to a single patient in the robotic endoscopic group. There were no unplanned reoperations in either group. Rates of postoperative stroke were comparable between groups (three in the classic endoscopic cohort, and two in the robotic endoscopic cohort). Conclusions: Index mitral valve surgery via a classic endoscopic approach yields similar clinical outcomes when compared to robotic endoscopic surgery. We demonstrate that both classic endoscopic and robotic endoscopic approaches allow repair of degenerative mitral valves with excellent short- and medium-term outcomes in a tertiary referral center.

Evaluating the Effect of Tideglusib-Loaded Bioactive Glass Nanoparticles as a Potential Dentine Regenerative Material.

Dental pulp treatment is the least intrusive procedure currently available for preserving the vitality of the pulp. Several studies are underway to improve the bioactivity of pulp capping materials. Tideglusib isa potent anti-inflammatory, antioxidant, and a regenerative drug developed against Alzheimer's disease and has been shown to be effective in the treatment of dental cavities. However, its bioactive properties encapsulated within the nanoparticles as a component of pulp capping material are largely unknown. In this study, tideglusib-loaded bioactive glass nanoparticles were synthesized (tideglusib-BgNPs) and mixed at various concentrations into the calcium silicate cement to testits physiomechanical and bioactivitiescompared with biodentine (control). The calcium silicate cement with 10wgt% tideglusib-BgNPs showed comparable physiomechanical properties to that of biodentine. Additionally, the assessment of cytotoxicity and bioactivity (cell proliferation, wound healing, and cell migration assays) showed increased bioactivity in terms of better wound healing, increased proliferation, and better migration of human dental pulp stem cells than biodentine. These findings suggest new opportunities to use tideglusib-BgNPs in pulp therapy.

Disease-economy trade-offs under alternative epidemic control strategies.

Public policy and academic debates regarding pandemic control strategies note disease-economy trade-offs, often prioritizing one outcome over the other. Using a calibrated, coupled epi-economic model of individual behavior embedded within the broader economy during a novel epidemic, we show that targeted isolation strategies can avert up to 91% of economic losses relative to voluntary isolation strategies. Unlike widely-used blanket lockdowns, economic savings of targeted isolation do not impose additional disease burdens, avoiding disease-economy trade-offs. Targeted isolation achieves this by addressing the fundamental coordination failure between infectious and susceptible individuals that drives the recession. Importantly, we show testing and compliance frictions can erode some of the gains from targeted isolation, but improving test quality unlocks the majority of the benefits of targeted isolation.

Patients with Atrial Fibrillation Benefit from SAVR with Surgical Ablation Compared to TAVR Alone.

INTRODUCTION: In patients with preoperative atrial fibrillation (AF) undergoing aortic valve replacement, the addition of surgical ablation to surgical aortic valve replacement (SAVR-SA) is efficacious and a Class I guideline. We hypothesized that this subgroup may benefit from SAVR-SA compared to transcatheter aortic valve replacement (TAVR) alone. METHODS: Medicare beneficiaries with persistent non-valvular AF who underwent SAVR-SA or TAVR alone between 2012 and 2018 were included. Patients with high-risk surgical comorbidities were excluded. Groups were matched using inverse probability weighting. The primary outcome was all-cause mortality. Secondary outcomes were stroke, transient ischemic attack, permanent pacemaker implantation, bleeding, rehospitalization for atrial arrhythmias, and rehospitalization for heart failure. Kaplan-Meier estimates and Cox proportional-hazards regression were used to compare outcomes. Outcomes were adjusted for variables with a standardized mean difference greater than 0.1. RESULTS: Of 439,492 patients who underwent aortic valve replacement, 2591 underwent SAVR-SA and 1494 underwent TAVR alone. Weighting resulted in adequately matched groups. Compared to TAVR alone, SAVR-SA was associated with a significant reduction in all-cause mortality (HR 0.65, 95% CI 0.53-0.79), permanent pacemaker implantation (HR 0.62, 95% CI 0.44-0.87), bleeding (HR 0.63, 95% CI 0.39-1.00), and rehospitalization for heart failure (HR 0.49 (0.36-0.65). There was no difference in the incidence of stroke (HR 1.07, 95% CI 0.74-1.54), transient ischemic attack (HR 1.05, 95% CI 0.75-1.47), or rehospitalization for atrial arrhythmia. CONCLUSION: Select patients with persistent non-valvular AF may benefit from SAVR-SA compared to TAVR alone.

Populational Perceptions Regarding Decision to Visit the Emergency Room with Chest Pain During COVID-19.

INTRODUCTION: A significant decrease in emergency presentations of acute cardiac conditions has been observed during the COVID-19 pandemic. We aimed to understand perceptions that influence people's decisions whether to present to the emergency department (ED) with symptoms related to acute cardiovascular events to inform necessary medical communication. METHODS: We recruited users of Amazon Mechanical Turk (Seattle, WA) to participate in a survey to elucidate perceptions of COVID-19 risk associated with a visit to the ED. A conjoint analysis was designed based on commonly reported factors associated with people's decisions to present to the ED during the pandemic to calculate preference utilities. RESULTS: After exclusions, 1003 participants completed the survey between 12/5/2020 and 12/6/2020. Participants ranked the perceived risk of contracting COVID-19 at the ED as one of the highest, only second to that at bars and restaurants. Only 68% (685/1003) were willing to present to the ED immediately with severe chest pain. Fear of further transmitting the virus to loved ones was the most frequently cited reason for not presenting. Conjoint analysis demonstrated severe chest pain to be the dominant factor in the decision to present to the ED. CONCLUSIONS: The risk of contracting COVID-19 while presenting to the ED for a life-threatening cardiovascular symptom is overestimated and is strongly affected by social factors.

How Should ECMO Be Used Under Conditions of Severe Scarcity? A Population Study of Public Perception.

OBJECTIVE: To assess societal preferences regarding allocation of extracorporeal membrane oxygenation (ECMO) as a rescue option for select patients with coronavirus disease 2019 (COVID-19). DESIGN: Cross-sectional survey of a nationally representative sample. SETTING: Amazon Mechanical Turk platform. PARTICIPANTS: In total, responses from 1,041 members of Amazon Mechanical Turk crowd-sourcing platform were included. Participants were 37.9 ± 12.6 years old, generally white (65%), and college-educated (66.1%). Many reported working in a healthcare setting (22.5%) and having a friend or family member who was admitted to the hospital (43.8%) or died from COVID-19 (29.9%). MEASUREMENTS AND MAIN RESULTS: Although most reported an unwillingness to stay on ECMO for >one week without signs of recovery, participants were highly supportive of ECMO utilization as a life-preserving technique on a policy level. The majority (96.7%) advocated for continued use of ECMO to treat COVID patients during periods of resource scarcity but would prioritize those with highest likelihood of recovery (50%) followed by those who were sickest regardless of survival chances (31.7%). Patients >40 years old were more likely to prefer distributing ECMO on a first-come first-served basis (21.5% v 13.3%, p < 0.05). CONCLUSION: Even though participants expressed hesitation regarding ECMO in personal circumstances, they were uniformly in support of using ECMO to treat COVID patients at a policy level for others who might need it, even in the setting of severe scarcity.

Prevalence of Complications Following Unifocalization and Pulmonary Artery Reconstruction Procedures.

BACKGROUND: Unifocalization and pulmonary artery reconstructions have been developed to treat complex disorders of pulmonary artery development. These procedures require extremely long periods of cardiopulmonary bypass (CPB) to facilitate surgical repair. The objective of this study was to document the prevalence of complications in patients undergoing unifocalization or pulmonary artery reconstructions associated with prolonged periods of CPB. METHODS: This was a retrospective review of 100 consecutive patients who underwent unifocalization (n = 66) or pulmonary artery reconstructions (n = 34) with CPB times in excess of five hours. Thirty-eight of these operations were primary procedures, whereas 62 were reoperations. RESULTS: The median age at surgery was 15 months, median duration of CPB was 473 minutes, median number of postoperative complications was 5, and the median length of hospital stay was 24 days. The most frequently encountered complications were low cardiac output (43%), open sternum (40%), reintubation (24%), arrhythmia (17%), and bronchoscopy (17%). There was a correlation between the total number of complications and overall length of hospital stay (R2 = 0.64). Major adverse cardiac events (MACE) occurred in 11 patients with one hospital mortality. Patients who experienced MACE had a median length of stay that was 35 days longer (56 vs 21 days) than patients who did not experience MACE. CONCLUSIONS: The data demonstrate that complications were relatively frequent in this cohort of patients and had a linear association with hospital length of stay. Major adverse cardiac events were encountered at a modest prevalence but had a profound impact on measures of outcome.

Orbital-use fees could more than quadruple the value of the space industry.

The space industry's rapid recent growth represents the latest tragedy of the commons. Satellites launched into orbit contribute to-and risk damage from-a growing buildup of space debris and other satellites. Collision risk from this orbital congestion is costly to satellite operators. Technological and managerial solutions-such as active debris removal or end-of-life satellite deorbit guidelines-are currently being explored by regulatory authorities. However, none of these approaches address the underlying incentive problem: satellite operators do not account for costs they impose on each other via collision risk. Here, we show that an internationally harmonized orbital-use fee can correct these incentives and substantially increase the value of the space industry. We construct and analyze a coupled physical-economic model of commercial launches and debris accumulation in low-Earth orbit. Similar to carbon taxes, our model projects an optimal fee that rises at a rate of 14% per year, equal to roughly $235,000 per satellite-year in 2040. The long-run value of the satellite industry would more than quadruple by 2040-increasing from around $600 billion under business as usual to around $3 trillion. In contrast, we project that purely technological solutions are unlikely to fully address the problem of orbital congestion. Indeed, we find debris removal sometimes worsens economic damages from congestion by increasing launch incentives. In other sectors, addressing the tragedy of the commons has often been a game of catch-up with substantial social costs. The infant space industry can avert these costs before they escalate.

Study of the factors that promoted the implementation of electronic medical record on iPads at two emergency departments.

The purpose of this study was to understand the factors which promoted the demand for iPads by physicians in two Emergency departments (ED) prior to a system wide implementation of an electronic medical record (EMR). A grounded theory design was employed and 14 semi-structured interviews conducted with ED physicians. Analysis of the interview transcripts was completed using Atlas.ti qualitative software, which revealed that physicians' perceptions of iPad use in the ED stemmed from their personal use of iPads along with three perceived ease of use factors. Physicians perceived that improved patient physician interaction, improved workflow and structural iPad benefits promoted their demand. Physicians perceived the structural benefits of iPads would improve patient physician interaction and improve workflow in the ED. As interest in handheld devices such as iPads increases, these findings could direct and encourage other iPad implementations at other hospital EDs'.