Perpulmonary Device Closure of Patent Ductus Arteriosus with Minimum Diameter More Than 4 mm in Infants

Background:Closure of large patent ductus arteriosus(PDA)in older children has been accomplished using surgical and percutaneous techniques with remarkable outcomes.However,outcomes amongst infants have been variable with several drawbacks.Here we describe a novel minimally invasive technique,a product of mini-thoracotomy and traditional percutaneous technique skills,accomplished exclusively under echocardiography guidance.Methods:Symptomatic infants with a significant left-to-right shunt from PDA measuring more than 4 mm were selected.The symptoms were varying degrees of tachypnea,tachycardia,heart failure,failure to thrive,recurrent respiratory tract infections,or intensive care unit treatment for a longer duration.Through a left parasternal mini-thoracotomy,two parallel purse-string sutures were placed on the pulmonary trunk.After purse-string circle puncture,under exclusively transesophageal echocardiography guidance,a device secured to the safety-suture was implanted on the ascending aorta via pulmonary trunk using a specially designed set.The safety-suture prevented device migration in case of dislocation.The basic demographics,PDA size,device size and type,intrapulmonary manipulation time,operation time,PDA parameters(length,diameter,type of duct),redeployment of the device,residual shunt,and retention of safety-suture were all recorded and analyzed.The follow-up was done with transthoracic echocardiography on the 2^(nd)postoperative day,1,3,6,and 12 months,and yearly thereafter.Results:Fifty-two infants with a mean age of 8 months±2.8 months(Interquartile range=0)underwent Perpulmonary device closure of PDA.Successful PDA occlusion was accomplished event-free in all subjects.The mean PDA,mean device,and mean operation time were 5.6 mm±1.4 mm,7.9 mm±1.7 mm,and 61.2 min±12.9 min,respectively.The immediate acceptable residual shunt was noted among 3 subjects and disappeared at a 1-month follow-up.Eighteen infants had retained safety-suture for added safety.There were no reports of the device or procedure-related complications.Conclusion:Perpulmonary device closure is an effective and safe approach to PDA with a diameter measuring>4 mm among infants.The safety-suture,in case of dislocation,prevents migration and associated complications.

Two-dimensional transition metal MXene-based gas sensors:A review

As an emerging star in the family of two-dimensional(2D)materials,2D transition metal carbides,carbonitrides and nitrides,collectively referred to as MXenes,have large specific surface area,rich active sites,metallic conductivity and adjustable surface chemical properties.These features make MXenes promising candidates for gas-sensing materials.For the past few years,MXene-based sensors have drawn increasing attention due to their enhanced sensor performance.Based on this,this review systematically represents the structure,synthesis methods and properties of MXenes,and summarizes their applications in gas sensors.Firstly,the types,structure,main synthesis methods and properties of MXenes are introduced in a comprehensive way.Next,the corresponding design principle and working mechanism of MXene-based gas sensor are clarified.Subsequently,the sensing performances of pristine MXenes and the MXene-based nanocomposite are discussed.Finally,some future opportunities and challenges of MXene-based sensors are pointed out.

Mechanical and antibacterial properties of tannic acid-encapsulated carboxymethyl chitosan/polyvinyl alcohol hydrogels

The objective of this study was to develop an effective,potential wound dressing,which was constructed with a composite hydrogel of poly(vinyl alcohol)(PVA),carboxymethyl chitosan(CMC)and tannic acid(TA)by cryogenic treatment and freeze-drying method.The as-prepared TA-crosslinked PVA/CMC hydrogels exhibited interconnected pore structure with the mean pore size of roughly 3.7𝜇m.We found that the compressive strength and stiffness of composite hydrogel increased when the TA component was introduced.However,the PVA/CMC-TA hydrogel possessed obviously lower swell property than that of the TA-free PVA/CMC hydrogel.We also found that the TA addition significantly improved the antibacterial capacity of the as-prepared hydrogel.Moreover,the inhibition zone test showed that the antibacterial activity of PVA/CMC-TA against S.aureus bacteria was greater than that against E.coli.The biological results indicated that the PVA/CMC-TA hydrogel exhibited good cytocompatibility to natural human dermal fibroblasts.In summary,our PVA/CMC-TA composite hydrogel exhibited promising mechanical and antibacterial properties,which showed great potential application as wound healing materials.

Long-term outcomes of brainstem arteriovenous malformations after different management modalities: a single-centre experience

Objective The aims of this study are to clarify the long-term outcomes of brainstem arteriovenous malformations(AVMs)after different management modalities.Methods The authors retrospectively reviewed 61 brainstem AVMs in their institution between 2011 and 2017.The rupture risk was represented by annualised haemorrhagic rate.Patients were divided into five groups:conservation,microsurgery,embolisation,stereotactic radiosurgery(SRS)and embolisation+SRS.Neurofunctional outcomes were evaluated by the modified Rankin Scale(mRS).Subgroup analysis was conducted between different management modalities to compare the long-term outcomes in rupture or unruptured cohorts.Results All of 61 brainstem AVMs(12 unruptured and 49 ruptured)were followed up for an average of 4.5 years.The natural annualised rupture risk was 7.3%,and the natural annualised reruptured risk in the ruptured cohort was 8.9%.13 cases were conservative managed and 48 cases underwent intervention(including 6 microsurgery,12 embolisation,21 SRS and 9 embolisation+SRS).In the selection of interventional indication,diffuse nidus were often suggested conservative management(p=0.004)and nidus involving the midbrain were more likely to be recommended for intervention(p=0.034).The risk of subsequent haemorrhage was significantly increased in partial occlusion compared with complete occlusion and conservative management(p<0.001,p=0.036,respectively).In the subgroup analysis,the follow-up mRS scores of different management modalities were similar whether in the rupture cohort(p=0.064)or the unruptured cohort(p=0.391),as well as the haemorrhage-free survival(p=0.145).In the adjusted Bonferroni correction analysis of the ruptured cohort,microsurgery and SRS could significantly improve the obliteration rate compared with conservation(p<0.001,p=0.001,respectively)and SRS may have positive effect on avoiding new-onset neurofunctional deficit compared with microsurgery and embolisation(p=0.003,p=0.003,respectively).Conclusions Intervention has similar neurofunctional outcomes as conservation in these brainstem AVM cohorts.If intervention is adopted,partial obliteration should be avoided because of the high subsequent rupture risk.

Electrospun chitosan nanofibers for wound healing application

Electrospun nanofibers have been considered as relatively ideal material system for the design and construction of surgical wound dressings in the past few decades.Although there are lots of other biopolymers employed for electrospinning,chitosan is one of the most important biopolymers for the fabrication of electrospun nanofibers,due to its nontoxic,antibacterial,biocompatible as well as biodegradable properties.Electrospun chitosan nanofibers with random or aligned fiber structure can further be cross-linked by physical,chemical and ionic crosslinking methods.The as-crosslinked electrospun chitosan nanofibrous membranes possess enhanced wet stability,improved mechanical property and good biocompatibility,which are necessary for wound healing application.The present work reviews the recent studies on the design and development of electrospun chitosan nanofibers and their applications for wound healing,such as antibacterial materials,hemostatic dressings,angiogenesis and immune regulation.