Metal-free photocatalysts for hydrogen evolution.

This review focuses on the discussion of the latest progress and remaining challenges in selected metal-free photocatalysts for hydrogen production. The scope of this review is limited to the metal-free elemental photocatalysts (i.e. B, C, P, S, Si, Se etc.), binary photocatalysts (i.e. BC3, B4C, CxNy, h-BN etc.) and their heterojunction, ternary photocatalysts (i.e. BCN) and their heterojunction, and different types of organic photocatalysts (i.e. linear, covalent organic frameworks, microporous polymer, covalent triazine frameworks etc.) and their heterostructures. Following a succinct depiction of the latest progress in hydrogen evolution on these photocatalysts, discussion has been extended to the potential strategies that are deemed necessary to attain high quantum efficiency and high solar-to-hydrogen (STH) conversion efficiency. Issues with reproducibility and the disputes in reporting the hydrogen evolution rate have been also discussed with recommendations to overcome them. A few key factors are highlighted that may facilitate the scalability of the photocatalyst from microscale to macroscale production in meeting the targeted 10% STH. This review is concluded with additional perspectives regarding future research in fundamental materials aspects of high efficiency photocatalysts followed by six open questions that may need to be resolved by forming a global hydrogen taskforce in order to translate bench-top research into large-scale production of hydrogen.

SCAI expert consensus statement for advanced training programs in pediatric and congenital interventional cardiac catheterization.

Pediatric and Congenital Interventional Cardiology is the practice of catheter-based techniques that improve cardiac physiology and circulation through the treatment of heart disease in children and adults with congenital or acquired heart defects. Over the last decade, and since last published training guidelines for pediatric cardiac catheterization and interventional cardiology were published in 2005 [1] the field of Pediatric and Congenital Cardiac Catheterization has evolved into a predominantly interventional discipline. As there is no sub-specialty certification for interventional cardiac catheterization in pediatrics, the Congenital Heart Disease Committee of the Society of Cardiovascular Angiography and Interventions has put together this consensus statement for advanced training in pediatric and congenital interventional cardiac catheterization. The statement puts forth recommendations for program infrastructure in terms of teaching, personnel, equipment, facilities, conferences, patient volume and trainee assessment. This is meant to set a standard for training programs as well as giving applicants a basis on which to judge and compare programs.

Balloon catheter delivery of helper-dependent adenoviral vector results in sustained, therapeutic hFIX expression in rhesus macaques.

Hemophilia B is an excellent candidate for gene therapy because low levels of factor IX (FIX) (≥1%) result in clinically significant improvement of the bleeding diathesis. Helper-dependent adenoviral (HDAd) vectors can mediate long-term transgene expression without chronic toxicity. To determine the potential for HDAd-mediated liver-directed hemophilia B gene therapy, we administered an HDAd expressing hFIX into rhesus macaques through a novel and minimally invasive balloon occlusion catheter-based method that permits preferential, high-efficiency hepatocyte transduction with low, subtoxic vector doses. Animals given 1 × 10(12) and 1 × 10(11) virus particle (vp)/kg achieved therapeutic hFIX levels for the entire observation period (up to 1,029 days). At 3 × 10(10) and 1 × 10(10) vp/kg, only subtherapeutic hFIX levels were achieved which were not sustained long-term. Balloon occlusion administration of HDAd was well tolerated with negligible toxicity. Five of six animals developed inhibitors to hFIX. These results provide important information in assessing the clinical utility of HDAd for hemophilia B gene therapy.

Diminished left ventricular function is associated with poor mid-term outcomes in neonates after balloon aortic valvuloplasty.

OBJECTIVES: We studied outcomes of neonatal aortic valvuloplasty to determine the risk factors for poor outcomes. BACKGROUND: Balloon aortic valvuloplasty (BAV) is the primary therapy for neonates with severe aortic stenosis (AS). Limited data are available on the mid-term and long-term outcomes in this population, and reported risk factors for poor outcomes vary among studies. METHODS: We reviewed all cases of BAV in neonates in our institution between 1998 and 2009. We reviewed patient characteristics, preintervention echocardiographic, and procedural details. We tracked repeat BAV, aortic valve replacement (AVR), and death/transplant. Kaplan-Meier and Cox regression analyses were performed. Changes in dimensions of left heart structures post-BAV were also studied. RESULTS: Forty-eight neonates were included-of these, 30 (62%) had critical AS. There was one procedural death. The remaining 47 neonates were followed for 4.8 ± 4.4 years. Repeat BAV was performed in 19 (40%) neonates; AVR was performed in 9 (19%), and death/transplant occurred in 4 (8%) neonates. Multivariate analysis revealed that lower LV shortening fraction pre-BAV, higher pre-BAV and final valve gradient, and need for inotropes were associated with poor long-term outcomes. LV diastolic and systolic dimensions normalized over time, and left heart structures improved in size early and late after BAV. CONCLUSIONS: Neonatal BAV is associated with low mortality. Lower LV shortening fraction pre-BAV is associated with risk of future interventions, while repeat valvuloplasty is safe and effective for recurrent AS. There is significant improvement in dimensions of the LV and aortic valve annulus following BAV.

The outcome of pulmonary artery stents following surgical manipulation.

BACKGROUND: Pulmonary artery (PA) stents are utilized to treat branch pulmonary stenosis (BPS). Often patients with PA stents undergo subsequent cardiac surgery for other indications, and the stents can be manipulated during the procedure. OBJECTIVE: The purpose of this study was to evaluate the outcome of branch PA stenoses following surgical manipulation of previously implanted PA stents and to determine factors associated with future reintervention. METHODS: Catheterization data, operative reports, and clinical summaries were reviewed on patients with PA stents placed between September 1989 and December 2006 undergoing subsequent cardiac surgery. Surgical manipulation was recorded as removed, trimmed, or longitudinally transected, and patched. Those that were not manipulated were defined as untouched. RESULTS: 459 patients had branch PA stents placed. About 54 patients, with 70 stents in branch PA's. subsequently had further cardiac surgery. The median age of stent placement was 7.5 (0.5-32.4) years with a median age of surgery of 12.7 (5.1-39.6) years. Surgical manipulation was performed in 23 (33%) PA's and 47 (66%) stents were untouched. Stent removal occurred in 11 (16%), with transecting longitudinally and patching in 5 (7%), and trimming in 7 (10%). Comparing the surgical manipulation and the untouched groups, there was no difference in median age of stent placement [7.2 (0.5-30.2) versus 7.6 (1.8-32.4) years, p=0.40], wt [21.0 (5.3-86.5) versus 24.7 (9.0-96.0) kg, p=0.42], or residual catheterization gradient across the stent [3 (0-59) versus 4 (0-50) mmHg, p=0.81]. Catheter reintervention (stent n=6 or balloon dilation n=14) on the previously stented PAs was similar between the surgically manipulated (median 7.5 years) and untouched groups (median 11.5 years) (p=0.31). In multivariate analysis, the factors associated with future catheter reintervention were having the stent transected longitudinally and patched (p=0.003) and a lower weight (p=0.006) at the time of stent placement. CONCLUSIONS: Surgical stent manipulation is often performed in patients who have PA stents. Surgical manipulation does not alter the need for future reintervention and catheter re-intervention may be more likely when the stents are transected longitudinally and patched.

Pulmonary artery stents: long-term follow-up.

OBJECTIVES: Determine the long-term outcomes of branch pulmonary artery (PA) stents. BACKGROUND: PA stents in congenital heart disease effectively relieve stenoses in the short-term. Published long-term data are limited. METHODS: Patients enrolled in an FDA IDE protocol from 1989-92 were included. Clinical follow-up and catheterization data were evaluated. Patients were included if >5 year follow-up data was available or if mortality occurred following the initial procedure. RESULTS: There were five deaths: four due to progression of their underlying heart disease, and one from a complication during a follow-up catheterization. Clinical data for 43 surviving patients demonstrated 39 patients (91%) are in NYHA class I or II. Seven patients underwent surgical intervention during the follow-up period (five RV-PA conduit, two Fontan revisions), but none addressed PA stenosis. Final repeat catheterizations were performed in 36 patients (55 stents) 7.2 +/- 4.3 years post stent insertion with 1.2 +/- 0.9 further procedures with stent dilations. In this subgroup, the minimum vessel diameter increased from 4.7 +/- 1.8 to 13.4 +/- 2.4 mm (P < 0.001), and the pressure gradient improved from 41 +/- 25 to 9 +/- 11 mm Hg (P < 0.001). Higher initial gradient and smaller balloons were associated with a final stent diameter of <14 mm (P = 0.030 and 0.046). Jailed vessels occurred in 49% of stents with abnormal angiographic flow in 18/55. Six repeat catheterizations resulted in complications, including the one procedural death. CONCLUSION: Stents implants for PA stenoses provide effective improvement in vessel caliber in the long-term. Although repeat interventions are necessary, this procedure reduces RV pressure and provides an important alternative to surgery for residual PA obstruction.

Efficient, long-term hepatic gene transfer using clinically relevant HDAd doses by balloon occlusion catheter delivery in nonhuman primates.

Helper-dependent adenoviral vectors (HDAd) are devoid of all viral coding sequences and are thus an improvement over early generation Ad because they can provide long-term transgene expression in vivo without chronic toxicity. However, high vector doses are required to achieve efficient hepatic transduction by systemic intravenous injection, and this unfortunately results in dose-dependent acute toxicity. To overcome this important obstacle, we have developed a minimally invasive method to preferentially deliver HDAd into the liver of nonhuman primates. Briefly, a balloon occlusion catheter was percutaneously positioned in the inferior vena cava to occlude hepatic venous outflow. HDAd was injected directly into the occluded liver via a percutaneously placed hepatic artery catheter. Compared to systemic vector injection, this approach resulted in substantially higher hepatic transduction efficiency using clinically relevant low vector doses and was accompanied by mild-to-moderate acute but transient toxicities. Transgene expression was sustained for up to 964 days. These results suggest that our minimally invasive method of delivery can significantly improve the vector's therapeutic index and may be a first step toward clinical application of HDAd for liver-directed gene therapy.

Use of Intracardiac Echocardiography in the Evaluation and Management of Iatrogenic Aortopulmonary Communication After Percutaneous Intervention in Postoperative Patients With Congenital Heart Disease.

Iatrogenic aortopulmonary communications (IAPCs) are an uncommon but important complication after percutaneous intervention in postoperative patients. Iatrogenic aortopulmonary communications typically occur after balloon angioplasty or other interventions of the pulmonary outflow tract in certain anatomic configurations in which there is a denuded tissue plane between the pulmonary artery and aorta. They can present with signs and symptoms ranging from subtle clues which are difficult to recognize to near immediate hemodynamic instability. Once recognized, these lesions can become management dilemmas, and intraprocedural interventions can be complicated by complex anatomy and inadequate visualization by standard imaging techniques. We report cases where intracardiac echocardiography (ICE) was integral in the evaluation and management of IAPC as complications of prior transcatheter interventions. We found using ICE safely and effectively identified IAPCs and reduced the technical difficulty of intervention after IAPC discovery.

Modulating Charge Transfer Efficiency of Hematite Photoanode with Hybrid Dual-Metal-Organic Frameworks for Boosting Photoelectrochemical Water Oxidation.

The glorious charge transfer efficiency of photoanode is an important factor for efficient photoelectrochemical (PEC) water oxidation. However, it is often limited by slow kinetics of oxygen evolution reaction. Herein, a dual transition metal-based metal-organic frameworks (MOF) cocatalyst, Fe@Ni-MOF, is introduced into a titanium-doped hematite (Fe2O3:Ti) photoanode. The combination of Ni and Fe can optimize the filling of 3d orbitals. Moreover, the introduction of Fe donates electrons to Ni in the MOF structure, thus, suppressing the irreversible (long-life-time) oxidation of Ni2+ into Ni3+. The resulting Fe@Ni-MOF/Fe2O3:Ti photoanode exhibits ∼threefold enhancement in the photocurrent density at 1.23 V versus the reversible hydrogen electrode. Kinetic analysis of the PEC water oxidation processes indicates that this performance improvement is primarily due to modulating the charge transfer efficiency of hematite photoanode. Further results show that a single transition metal-based MOF cocatalyst, Ni-MOF, exhibits slow charge transfer in spite of a reduction in surface charge recombination, resulting in a smaller charge transfer efficiency. These findings provide new insights for the development of photoelectrodes decorated with MOFs.

Simultaneous stent implantation to treat bifurcation stenoses in the pulmonary arteries: Initial results and long-term follow up.

BACKGROUND: Balloon angioplasty of bifurcating pulmonary artery (PA) stenoses is often inadequate, and stent treatment often requires simultaneous implantation of two stents. This study evaluates initial results and long-term follow up of transcatheter stent placement in bifurcating PAs. METHODS: This is a retrospective review of patients (pts) who had bifurcating PA stents placed in main and lobar branches from 1993 to 2007. RESULTS: Forty-nine pts had bifurcating PA stents placed at a median age of 10.9 years (range 1-43 years). The mean minimum vessel diameter increased from 5.7 +/- 2.5 mm to 11.0 +/- 3.6 mm (P < 0.001), the mean gradient across the stenoses decreased from 37.0 +/- 26.9 to 9.2 +/- 13 mm Hg (P < 0.001), whereas the mean RV:FA ratio decreased from 0.76 +/- 0.29 to 0.53 +/- 0.24 (P < 0.001). There was one death due to severe pulmonary hemorrhage. F/U data were available in 38 pts (mean duration 6.3 +/- 4.1 years, range 1.2-13.1 years). Thirty pts underwent repeat catheterizations (mean 2.3 +/- 2.2 years poststent), with 26 requiring further interventions: Fifteen had balloon angioplasty alone and 11 had additional stents placed. There were no complications at f/u catheterization. Six pts underwent further palliative surgeries, although none for repair of branch PA stenoses. CONCLUSIONS: Simultaneous transcatheter placement of bifurcating PA stents provides immediate gradient relief of bifurcating stenoses in the proximal or lobar branch PAs and reduces RV systolic pressure. Further interventions can be safely performed in future procedures, and the presence of stents does not complicate future surgeries.

Stent fractures in congenital heart disease.

OBJECTIVE: To describe incidence, characteristics, predictive factors, and sequelae of stent fractures in congenital heart disease. BACKGROUND: Stent fracture in congenital heart disease patients is rarely reported. METHODS: Patients with stents implanted from 1990 to 2006, with subsequent fluoroscopy were enrolled. Information obtained included: stent type, location, balloon diameter, and residual narrowing. Fracture characteristics, radiographic appearance, and clinical sequelae were also obtained in those with fractures identified. RESULTS: : Two hundred and sixty-five patients (583 stents) had fluoroscopy 4.2 +/- 3.3 years after stent implantation. The majority of stents (395, 67.7%) were placed in a pulmonary artery (PA) or its branches. Sixteen stents (2.7%) were placed in a right ventricle to pulmonary artery (RV-PA) conduit. Fourteen fractures (2.4%) were identified 5.0 +/- 3.2 years after implantation: RV-PA conduit 4/16, proximal right PA 4/135, proximal left PA 6/184 (P = 0.003). Identification was primarily made on lateral fluoroscopy. Review of chest radiographs demonstrated fractures in only 71%. In fractured PA stents, five were redilated and three had additional stents placed. Of the four conduit stent fractures: one underwent redilation, one had embolized segments, and one was reinforced with a second stent that also fractured and embolized a segment during redilation at a later catheterization. All fractures were asymptomatic. CONCLUSIONS: With the exception of RV-PA conduit stents, fracture is rare and asymptomatic. PA stent fractures occurred in 2.5% and did not embolize, whereas RV-PA conduit stent fractures were significantly more common and may embolize.

Recent advances in managing vascular occlusions in the cardiac catheterization laboratory.

Vascular occlusions continue to be a significant cause of morbidity and mortality. The management of vascular occlusions in patients is complex, requiring specialized expertise in the cardiac catheterization laboratory and from other disciplines. Knowledge of currently available tools at the operator's disposal is important to optimize the success of these procedures. In this review, we discuss some of the recent advances in recanalization procedures of vascular occlusions and thrombotic lesions in the cardiac catheterization laboratory.

Outcomes after Balloon Pulmonary Valvuloplasty for Critical Pulmonary Stenosis and Incidence of Coronary Artery Fistulas.

Outcome data for neonates with critical pulmonary stenosis (PS) is limited. We aimed to review the outcomes after balloon pulmonary valvuloplasty (BPV) for neonates with critical PS at our institution. All neonates with critical PS who underwent BPV from 1990 to 2017 were included. A total of 44 neonates underwent BPV for critical PS. Nonright ventricular dependent coronary artery fistulas was seen in 6/44 (13.6%) patients. Tricuspid valve z-scores were -1.9 (interquartile range [IQR] -3.04, -0.48) in those with coronary artery fistulas as compared with -0.27 (IQR -0.5, 0.8) in those without (p = 0.03). Fifteen of forty-four subjects (34.1%) patients underwent reintervention with 10 patients (22.7%) requiring an alternate source of pulmonary blood flow (3 patients subsequently underwent right ventricular overhaul, 2 underwent Glenn operations, and 1 underwent repeat BPV). Five patients underwent reintervention for right ventricular outflow tract obstruction. Pulmonary valve annulus z-score was significantly smaller in those who needed reintervention -2.4 (IQR -2.9 to -0.95) versus -0.59 (IQR -1.3, -0.15); p = 0.02. At a median follow-up of 8.2 (IQR 3.4 to 13.1) years, moderate or severe pulmonary regurgitation was seen in 22/42 (53.7 %) patients with biventricular circulation, 3 requiring pulmonary valve repair/replacement. In conclusion, coronary artery fistulas occur in a significant number of patients with critical pulmonary stenosis, occurring more frequently in patients with small tricuspid valves. Reintervention is required for 1/3 of patients. Patients with small pulmonary valve annuli are more likely to undergo reintervention for right ventricular outflow tract obstruction. Significant pulmonary regurgitation is common and may require eventual pulmonary valve replacement.

Atrial septostomy improves survival in select patients with pulmonary hypertension.

BACKGROUND: Atrial septostomy is a palliative treatment for patients with pulmonary hypertension (PHTN) refractory to vasodilator therapy. Limited data exist in the pediatric population and in patients with repaired congenital heart defects. METHODS: We performed a retrospective analysis of hemodynamic and symptomatic changes in patients with PHTN who underwent an atrial septostomy at our institution. RESULTS: Forty-six atrial septostomies were performed on 43 patients. Patient ages ranged from 0.3 to 30 years (median 12.5). Of 43 patients, 29 had primary PHTN, 10 had PHTN associated with repaired congenital heart defects, and 4 had other secondary causes of PHTN. Mean baseline pulmonary vascular resistance was 35 +/- 17 Wood units, and mean pulmonary artery pressure was 74 +/- 19 mm Hg. Patients surviving > or = 30 days had immediate improvement in cardiac index (from 2.3 to 2.9 L x min(-1) x m(-2), P < .0001), right atrial pressure (RAp) (from 9.9 to 8.3 mm Hg, P < .05), and oxygen delivery (from 424 to 491 mL O2 per minute, P < .01), with a decrease in systemic oxygen saturation (from 93% to 86%, P < .001). Pulmonary artery pressure was unchanged (P = .3). New York Heart Association class and symptoms of syncope improved (P < .01). Event-free survival at 1, 2, and 3 years was 84%, 77%, and 69%, respectively. Using the National Institutes of Health Registry model, predicted survival probability significantly improved (P < .001). Ten patients (22%) died within 30 days of catheterization. Mortality was associated with preceding decompensations in the intensive care unit (6/10, P < .001) and a higher RAp (21.4 vs 9.8 mm Hg, P < .001). CONCLUSIONS: Atrial septostomy provides symptomatic and hemodynamic improvement in cardiac index and RAp. Risk of septostomy is increased in patients with preceding decompensation or a RAp > 18 mm Hg.

Self-Assembled Cu-Sn-S Nanotubes with High (De)Lithiation Performance.

Through a gelation-solvothermal method without heteroadditives, Cu-Sn-S composites self-assemble to form nanotubes, sub-nanotubes, and nanoparticles. The nanotubes with a Cu3-4SnS4 core and Cu2SnS3 shell can tolerate long cycles of expansion/contraction upon lithiation/delithiation, retaining a charge capacity of 774 mAh g-1 after 200 cycles with a high initial Coulombic efficiency of 82.5%. The importance of the Cu component for mitigation of the volume expansion and structural evolution upon lithiation is informed by density functional theory calculations. The self-generated template and calculated results can inspire the design of analogous Cu-M-S (M = metal) nanotubes for lithium batteries or other energy storage systems.