Continuous synthesis of high-entropy alloy nanoparticles by in-flight alloying of elemental metals.

High-entropy alloy (HEA) nanoparticles (NPs) exhibit unusual combinations of functional properties. However, their scalable synthesis remains a significant challenge requiring extreme fabrication conditions. Metal salts are often employed as precursors because of their low decomposition temperatures, yet contain potential impurities. Here, we propose an ultrafast (< 100 ms), one-step method that enables the continuous synthesis of HEA NPs directly from elemental metal powders via in-flight alloying. A high-temperature plasma jet ( > 5000 K) is employed for rapid heating/cooling (103 - 105 K s-1), and demonstrates the synthesis of CrFeCoNiMo HEA NPs ( ~ 50 nm) at a high rate approaching 35 g h-1 with a conversion efficiency of 42%. Our thermofluid simulation reveals that the properties of HEA NPs can be tailored by the plasma gas which affects the thermal history of NPs. The HEA NPs demonstrate an excellent light absorption of > 96% over a wide spectrum, representing great potential for photothermal conversion of solar energy at large scales. Our work shows that the thermal plasma process developed could provide a promising route towards industrial scale production of HEA NPs.

Does the pattern of bicuspid aortic valve leaflet fusion determine the success of the Ross procedure?

BACKGROUND: In addition to being associated with aortopathy, a bicuspid aortic valve (BAV) has been posed to be a risk factor for the dilation of the pulmonary autograft in the aortic position. The aim of this study is to assess the association between the subtype of native aortic valve leaflet fusion (right and noncoronary leaflets [R/N] vs right and left leaflets [R/L]) and autograft dilation and valve dysfunction after the Ross procedure. METHODS: We performed a retrospective review of 43 patients with BAV who underwent a Ross procedure in our center from 1993 to 2013. Serial transthoracic echocardiography was used to measure changes in autograft and ascending aortic diameter over time. The aortic diameter was measured at four levels, and Z values were computed. Aortic dilation was defined as a Z value greater than 3. RESULTS: The mean age at the time of the Ross procedure was 13.5 ± 9.2 years. R/L was the most prevalent native aortic valve subtype (R/L, n = 26, 61% vs R/N, n = 17, 39%). PreRoss procedure, aortic dilation was more frequent in patients with R/N fusion (P = .02), whereas the initial aortic valve gradient and grade of aortic insufficiency (AI) did not differ between the subgroups. At follow-up, (mean = 9.6 ± 4.3 years) dilation of the autograft and ascending aorta was seen more often in patients with R/N leaflet fusion (P = .03). Conversely, the prevalence of more than moderate AI was significantly higher in patients with R/L leaflet fusion (P = .03). There was no significant difference between groups among numbers of late reintervention on the aortic valve or root (P = .75); however the type of intervention varied by morphologic subtype. Patients with R/L fusion underwent more aortic valve replacements (AVRs) while patients with R/N fusion underwent more valve-sparing aortic root replacements. CONCLUSIONS: After Ross procedure, both groups of patients were likely to have a combination of dilation of the aortic root and the tubular portion of the ascending aorta at follow-up. Patients with R/L fusion were more likely to have a prevalence of root dilation, while patients with R/N fusion were more likely to have tubular ascending aorta dilation. The R/L phenotype is associated with a slightly more rapid dilation at follow-up and is more likely to have postoperative autograft insufficiency. This information may serve to guide patient and procedure selection for AVR.

The World Database for Pediatric and Congenital Heart Surgery "A Call to Service for North American Congenital Heart Surgery Programs".

The World Society for Pediatric and Congenital Heart Surgery has endorsed the establishment of an international platform for the exchange of knowledge and experience for those that treat patients with a congenital heart defect. On January 1, 2017, the release of the World Database for Pediatric and Congenital Heart Surgery opened a new era in evaluation of treatment with congenital heart defects. The contribution of data from countries with established congenital surgical databases will greatly enhance the efforts to provide the most accurate measure of overall surgical outcomes across the globe.

Role of Hydrogen in High-Yield Growth of Boron Nitride Nanotubes at Atmospheric Pressure by Induction Thermal Plasma.

We recently demonstrated scalable manufacturing of boron nitride nanotubes (BNNTs) directly from hexagonal BN (hBN) powder by using induction thermal plasma, with a high-yield rate approaching 20 g/h. The main finding was that the presence of hydrogen is crucial for the high-yield growth of BNNTs. Here we investigate the detailed role of hydrogen by numerical modeling and in situ optical emission spectroscopy (OES) and reveal that both the thermofluidic fields and chemical pathways are significantly altered by hydrogen in favor of rapid growth of BNNTs. The numerical simulation indicated improved particle heating and quenching rates (∼105 K/s) due to the high thermal conductivity of hydrogen over the temperature range of 3500-4000 K. These are crucial for the complete vaporization of the hBN feedstock and rapid formation of nanosized B droplets for the subsequent BNNT growth. Hydrogen is also found to extend the active BNNT growth zone toward the reactor downstream, maintaining the gas temperature above the B solidification limit (∼2300 K) by releasing the recombination heat of H atoms, which starts at 3800 K. The OES study revealed that H radicals also stabilize B or N radicals from dissociation of the feedstock as BH and NH radicals while suppressing the formation of N2 or N2+ species. Our density functional theory calculations showed that such radicals can provide faster chemical pathways for the formation of BN compared with relatively inert N2.

Management of an associated ventricular septal defect at the time of coarctation repair.

BACKGROUND: Management of a ventricular septal defect (VSD) at time of coarctation of the aorta (CoA) repair remains controversial, with recent studies advocating concomitant repair of both defects. We evaluated the surgical management and mortality for patients undergoing CoA repair associated with a VSD. METHODS: We retrospectively reviewed data submitted to the Pediatric Cardiac Care Consortium of patients undergoing repair of CoA from 1982 to 2007. The cohort was divided into three groups: CoA repair plus VSD closure (group 1); CoA repair plus pulmonary artery band (group 2); and CoA repair without repair of VSD (group 3). Variables reviewed included era, age, and weight at repair, and in-hospital mortality. RESULTS: There were 7,860 patients who underwent repair of CoA, of whom 2,022 had an associated VSD (25.7%). Mortality after CoA repair with and without an associated diagnosis of VSD was 8.3% versus 2.1% (p < 0.001). Mean age at repair for group 1 (n = 286) and group 2 (n = 472) was 87.4 days and 21.6 days, respectively (p = 0.004), and median weight was 3.31 kg and 3.30 kg, respectively (p = 0.130). Discharge mortality for group 1 and group 2 was similar, at 8.7% and 9.1%, respectively (p = 0.852). Patients with CoA/VSD who had neither VSD closure nor pulmonary artery banding (group 3) had a hospital mortality of 7.9%. CONCLUSIONS: The association of CoA and VSD is common. A strategy of concomitant VSD closure at CoA repair does not result in worse discharge mortality when compared with pulmonary banding with anticipated staged repair of the VSD. These outcomes support continued evaluation of a one-stage approach.

A paired membrane umbrella double-lumen cannula ensures consistent cavopulmonary assistance in a Fontan sheep model.

OBJECTIVES: The Avalon Elite (Macquet, Rastatt, Germany) double-lumen cannula can provide effective cavopulmonary assistance in a Fontan (total cavopulmonary connection) sheep model, but it requires strict alignment. The objective was to fabricate and test a newly designed paired umbrella double-lumen cannula without alignment requirement. METHODS: The paired membrane umbrellas were designed on the double-lumen cannula to bracket infusion blood flow toward the pulmonary artery. Two umbrellas were attached, one 4 cm above and one 4 cm below the infusion opening. Umbrellas were temporarily wrapped and glued to the double-lumen cannula body to facilitate insertion. A total cavopulmonary connection mock loop was used to test cavopulmonary assistance performance and reliability with double-lumen cannula rotation and displacement. The paired umbrella double-lumen cannula also was tested in a total cavopulmonary connection adult sheep model (n = 6). RESULTS: The bench test showed up to 4.5 L/min pumping flow and approximately 90% pumping flow efficiency at 360° rotation and 8-cm displacement of double-lumen cannula. The total cavopulmonary connection model with compromised hemodynamics was successfully created in all 6 sheep. The cavopulmonary assistance double-lumen cannula with paired umbrellas was smoothly inserted into the superior vena cava and extracardiac conduit in all sheep. At 3.5 to 4.0 L/min pump flow, the systolic arterial blood pressure and central venous pressure returned to normal baseline and remained stable throughout the 90-minute experiment, demonstrating effective cavopulmonary assistance support. Double-lumen cannula rotation and displacement did not affect performance. Autopsy revealed well-opened and positioned paired umbrellas, and double-lumen cannulas were easily removed from the right jugular vein. CONCLUSIONS: Our double-lumen cannula with paired umbrellas is easy to insert and remove. The paired umbrellas eliminated the strict alignment requirement and ensured consistent cavopulmonary assistance performance.

Hydrogen-catalyzed, pilot-scale production of small-diameter boron nitride nanotubes and their macroscopic assemblies.

Boron nitride nanotubes (BNNTs) exhibit a range of properties that are as compelling as those of carbon nanotubes (CNTs); however, very low production volumes have prevented the science and technology of BNNTs from evolving at even a fraction of the pace of CNTs. Here we report the high-yield production of small-diameter BNNTs from pure hexagonal boron nitride powder in an induction thermal plasma process. Few-walled, highly crystalline small-diameter BNNTs (∼5 nm) are produced exclusively and at an unprecedentedly high rate approaching 20 g/h, without the need for metal catalysts. An exceptionally high cooling rate (∼10(5) K/s) in the induction plasma provides a strong driving force for the abundant nucleation of small-sized B droplets, which are known as effective precursors for small-diameter BNNTs. It is also found that the addition of hydrogen to the reactant gases is crucial for achieving such high-quality, high-yield growth of BNNTs. In the plasma process, hydrogen inhibits the formation of N2 from N radicals and promotes the creation of B-N-H intermediate species, which provide faster chemical pathways to the re-formation of a h-BN-like phase in comparison to nitridation from N2. We also demonstrate the fabrication of macroscopic BNNT assemblies such as yarns, sheets, buckypapers, and transparent thin films at large scales. These findings represent a seminal milestone toward the exploitation of BNNTs in real-world applications.

A practical and less invasive total cavopulmonary connection sheep model.

Our goal was to develop a less invasive total cavopulmonary connection (TCPC) sheep model for testing total cavopulmonary assist (CPA) devices. Thirteen sheep underwent a right fourth intercostal lateral thoracotomy. In series I (n = 6), a polytetrafluoroethylene (PTFE) extracardiac conduit (ECC) was connected to inferior vena cava (IVC) and superior vena cava (SVC) by end-to-side anastomosis. The SVC/IVC remained connected to right atrium (RA). A PTFE graft bridged ECC to right pulmonary artery (RPA). Clamps between SVC/IVC anastomoses and RA diverted total venous blood to pulmonary circulation. In series II (n = 7), temporary bypasses between SVC/IVC and RA allowed SVC/IVC to be cut off from RA for better RPA exposure. The ECC-SVC/IVC were end-end anastomosed and ECC-RPA side-side anastomosed for total SVC/IVC to pulmonary artery (PA) conversion. In each series, one sheep died of bleeding. In five sheep in series I and six sheep in series II, the TCPC model was successfully created with significantly increased central venous pressure and significantly decreased PA pressure/arterial blood pressure. Our acute TCPC sheep model has a less traumatic right thoracotomy with no cardiopulmonary bypass and less blood loss with no blood transfusion, facilitating future long-term CPA device evaluation.

Death by late-presenting Bochdalek hernia in infant soon after congenital cardiac repair.

Congenital diaphragmatic hernia (CDH) presenting beyond the neonatal period is commonly perceived to be rare. With reported frequencies of 2.6% to 20% of all CDH, it may be an overlooked cause of mortality. Variable symptomatology makes its diagnosis challenging. We report the sudden death of a 3-month-old patient shortly after hospital discharge following congenital heart surgery. Autopsy findings associated the patient's demise with migrated abdominal contents in the chest through a Bochdalek hernia defect. No indications of CDH existed before hospital discharge. Relevant issues pertaining to congenital heart disease, CDH, and importance of autopsy in this context are discussed.

AngioJet rheolytic thrombectomy for thrombotic myocardial injury in a 15-year-old cystic fibrosis patient during lung transplantation.

We report on an acute myocardial injury caused by thrombotic emboli during off-pump bilateral sequential lung transplantation in a 15-year-old female patient with end-stage cystic fibrosis. A few minutes after reperfusion of the right (second sequential) allograft, the patient developed hemodynamic collapse, including hypotension, acute akinesis of the anterior and lateral myocardial walls, and severe mitral regurgitation. Thrombus was noted within the left atrium and ventricle on intraoperative transesophageal echocardiogram. After emergent cannulation for cardiopulmonary bypass, the patient underwent left cardiac catheterization with AngioJet rheolytic thrombectomy and removal of the clot from the distal left anterior descending coronary artery. Reperfusion was established without the need for stent placement or further intervention. The patient required short-term life support with venoarterial extracorporeal membrane oxygenation.

Successful use of a pneumatic biventricular assist device as a bridge to transplantation in cardiogenic shock.

BACKGROUND: Mechanical circulatory support is a highly effective technology to maintain organ perfusion in patients with cardiogenic shock as a bridge to transplantation. Although implantation of a left ventricular assist device alone is often the preferred configuration, patients with biventricular failure and significant end-organ dysfunction often require biventricular assistance. METHODS: Between January 2000 and September 2008, 80 patients with severe biventricular failure were accepted for heart transplantation and received a pneumatic biventricular assist devices as a bridge to transplant. Patients were retrospectively divided into 2 groups: those successfully bridged to transplant (Group A) and those who died (Group B). Patients were also divided into 2 periods of implantation: Group X (2000-2005) and Group Y (2006-2008, which used a multidiscipline selection process). RESULTS: Overall success rate to transplantation was 71.3%, with Group Y demonstrating an 82% success to transplant rate vs 63% in Group X. One-year actuarial survival after transplant was 89% compared with 92% in patients without a ventricular assist device. There were no statistically significant laboratory parameters between Groups A and B identifying potential risk factors for poor outcome. CONCLUSION: Biventricular assist device therapy represents an effective and reliable means of supporting selected Interagency Registry for Mechanically Assisted Circulatory Support profile 1 patients as a bridge to transplantation, with excellent success to transplant rates and post-transplant survival.

Wang-Zwische double-lumen cannula leads to total cavopulmonary support in a failing Fontan sheep model.

BACKGROUND: We are developing a total cavopulmonary support system for failing Fontan physiology using the percutaneous Wang-Zwische double-lumen cannula (DLC). METHODS: We developed a sheep model of failing Fontan physiology through a right thoracotomy in 5 sheep. An extracardiac conduit was anastomosed to the inferior vena cava and superior vena cava, and a graft was applied to connect the conduit and the right pulmonary artery (PA) to create total vena cava-to-PA diversion, excluding the right heart. The DLC (commercialized as AvalonElite, Avalon Laboratories LLC, Rancho Dominguez, CA) was coupled with a CentriMag pump (Levitronix Waltham, MA) to form a cavopulmonary support system. The DLC was inserted through the right jugular vein and the superior vena cava into the extracardiac conduit with the infusion lumen opening aligned with the right PA bridge. Blood was withdrawn from the superior vena cava and the inferior vena cava through the drainage lumen and pumped into the right PA through the infusion lumen, with flow adjusted to 4.0±0.5 L/min. RESULTS: A successful Fontan model was created without cardiopulmonary bypass. After total venous blood diversion from the vena cava to the right PA artery, failing Fontan physiology developed, evidenced by elevated central venous pressure and dropping mean PA pressure and systolic arterial pressure. The DLC was successfully inserted, and hemodynamics were normalized in all 5 sheep for the duration of the 2-hour study. CONCLUSIONS: We created a model of failing Fontan circulation in sheep without cardiopulmonary bypass. The DLC system achieved total cavopulmonary support for 2 hours in our failing Fontan sheep model.

Arrhythmia recurrence in adult patients with single ventricle physiology following surgical Fontan conversion.

OBJECTIVES: To evaluate the incidence of atrial tachy-arrhythmia (AT) recurrence following conversion from right atrial-pulmonary artery (RA-PA) Fontan to total cavopulmonary connection (TCPC) in adults. BACKGROUND: AT is a recognized sequel of Fontan palliation, especially in RA-PA Fontans, and is associated with significant morbidity. While catheter ablation achieves fairly reliable short-term success with low morbidity, conversion to TCPC with arrhythmia surgery is a highly effective treatment option for the classical Fontan patients with incessant AT. METHODS: Single center retrospective review. RESULTS: Twenty-seven adults underwent Fontan conversion from RA-PA to TCPC, mostly for AT indications (n = 24). Nine (33%) underwent conversion to a lateral tunnel (LT) and 18 (67%) to an extracardiac (EC) Fontan. Two patients died <30 days post-operatively. Both had liver failure and had been turned down for cardiac/liver transplantation. In-hospital complications occurred in 15/27 patients (55%), including recurrence of AT requiring cardioversion in six patients (22%) and persistent pleural effusions in 4 (15%). Mean follow-up was 4.2 years (range 3 months-14 years). Functional capacity improved from mean New York Heart Association (NYHA) class 1.8 pre-conversion to 1.2 post-conversion (P= 0.008). Twenty-one patients had concomitant arrhythmia surgery (MAZE in 12 patients with IART and Cox-MAZE in nine patients with A-Fib +/- IART). Of these, 3/21 (14%) had AT recurrence >3 months following conversion. CONCLUSIONS: Conversion from RA-PA Fontan to TCPC, with arrhythmia surgery, decreases AT recurrence and improves functional capacity. The risk of peri-operative mortality is highest in patients with cirrhosis. AT recurred in 14% of patients.

Repair of anomalous origin of right pulmonary artery from ascending aorta without cardiopulmonary bypass.

Anomalous origin of a pulmonary artery from the ascending aorta (AORPA) is a rare congenital cardiac malformation that needs prompt surgical repair; otherwise it is associated with poor prognosis. We describe 3 cases of AORPA that successfully underwent complete surgical correction without extracorporeal circulation.

Influence of ionic strength changes on the structure of pre-adsorbed salivary films. A response of a natural multi-component layer.

Salivary films coating oral surfaces are critically important for oral health. This study focuses on determining the underlying nature of this adsorbed film and how it responds to departures from physiological conditions due to changes in ionic strength. Under physiological conditions, it is found that pre-adsorbed in vitro salivary film on hydrophobic surfaces is present as a highly hydrated viscoelastic layer. We follow the evolution of this film in terms of its effective thickness, hydration and viscoelastic properties, as well as adsorbed mass of proteins, using complementary surface characterisation methods: a Surface Plasmon Resonance (SPR) and a Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D). Our results support a heterogeneous model for the structure of the salivary film with an inner dense anchoring layer and an outer highly extended hydrated layer. Further swelling of the film was observed upon decreasing the salt concentration down to 1mM NaCl. However, upon exposure to deionised water, a collapse of the film occurs that was associated with the loss of water contained within the adsorbed layer. We suggest that the collapse in deionised water is driven by an onset of electrostatic attraction between different parts of the multi-component salivary film. It is anticipated that such changes could also occur when the oral cavity is exposed to food, beverage, oral care and pharmaceutical formulations where drastic changes to the structural integrity of the film is likely to have implications on oral health, sensory perception and product performance.

Truncal valve repair in neonates using pericardial leaflet extension.

Truncal valve insufficiency is a significant risk factor for post-operative mortality following repair of truncus arteriosus. The surgical management of dysplastic and insufficient truncal valves remains an operative challenge. We report the cases of two infants with type 2 truncus arteriosus and severely dysplastic and insufficient quadricuspid truncal valves. At primary repair, their truncal valves were successfully repaired using pericardial leaflet extensions. This technique may be used in neonates with truncal valve insufficiency as part of the primary repair of truncus arteriosus.