Numerical analysis of flow non-uniformity in the hot gas manifold of the Space Shuttle main engine

Three-dimensional viscous flow in a conceptual hot gas manifold (HGM) for the Space Shuttle Main Engine High Pressure Fuel Turbopump (SSME HPFTP) was numerically analyzed. A finite difference scheme was used to solve the Navier-Stokes equations. The exact geometry of the SSME HGM was modeled using boundary fitted curvilinear coordinates and the General Interpolants Method (GIM) code. Slight compressibility of the subsonic flow was modeled using a linearized equation of state with artificial compressibility. A time relaxation method was used to obtain a steady state solution. The feasibility and potential usefulness of computational methods in assisting the design of SSME components which involves the flow of fluids within complex geometrical shapes is demonstrated

Development of the general interpolants method for the CYBER 200 series of supercomputers

The General Interpolants Method (GIM) is a 3-D, time-dependent, hybrid procedure for generating numerical analogs of the conservation laws. This study is directed toward the development and application of the GIM computer code for fluid dynamic research applications as implemented for the Cyber 200 series of supercomputers. An elliptic and quasi-parabolic version of the GIM code are discussed. Turbulence models, algebraic and differential equations, were added to the basic viscous code. An equilibrium reacting chemistry model and an implicit finite difference scheme are also included

Prevalence of albuminuria and cardiovascular risk profile in a referred cohort of patients with type 2 diabetes: An Asian perspective

Background: Microalbuminuria (MA) is a risk marker for diabetic nephropathy and cardiovascular (CV) disease (CVD) in patients with diabetes. This study aimed to describe the prevalence of albuminuria, CV risk factors, and treatments for renal and CV protection in an Asian population with type 2 diabetes. Methods: This cross-sectional study conducted in eight Asian countries enrolled normotensive/hypertensive adults with type 2 diabetes without known proteinuria and/or non-diabetic kidney disease. Exclusion criteria were type 1 diabetes, menstruation, pregnancy, and acute fever. A single random urinary albumin/creatinine test was carried out in all patients. Results: Of 8,561 patients, 14% had diabetic retinopathy, and 17% and 21% had history of CV disease and smoking, respectively. Normoalbuminuria was seen in 44%, MA in 44%, and macroalbuminuria in 12%. Target glycosylated hemoglobin (HbA1c) (<7%) was reached in only 37% of 3,834 patients with available values. Diabetes was managed by diet alone in 6%, while others received oral hypoglycemic drugs and/or insulin. In total, 75% did not reach target blood pressure (BP) of ≤130/80 mm Hg. Antihypertensive drugs were prescribed to 52%, with the number of drugs increasing as the level of systolic BP increased. Drugs blocking the renin-angiotensin system were most commonly prescribed, followed by calcium channel blockers. Lipid-lowering drugs and anticoagulant/antiplatelet agents were used in about 30% and 25% of patients, respectively. Conclusions: Asian patients with type 2 diabetes had a high prevalence of MA and reduced kidney function. Furthermore, BP and HbA1c control was only achieved in a minority of patients. Aggressive risk management by administration of reno- and cardioprotective treatments is urgently needed. © 2008 Mary Ann Liebert, Inc.published_or_final_versio

Electronic health records to facilitate clinical research

Electronic health records (EHRs) provide opportunities to enhance patient care, embed performance measures in clinical practice, and facilitate clinical research. Concerns have been raised about the increasing recruitment challenges in trials, burdensome and obtrusive data collection, and uncertain generalizability of the results. Leveraging electronic health records to counterbalance these trends is an area of intense interest. The initial applications of electronic health records, as the primary data source is envisioned for observational studies, embedded pragmatic or post-marketing registry-based randomized studies, or comparative effectiveness studies. Advancing this approach to randomized clinical trials, electronic health records may potentially be used to assess study feasibility, to facilitate patient recruitment, and streamline data collection at baseline and follow-up. Ensuring data security and privacy, overcoming the challenges associated with linking diverse systems and maintaining infrastructure for repeat use of high quality data, are some of the challenges associated with using electronic health records in clinical research. Collaboration between academia, industry, regulatory bodies, policy makers, patients, and electronic health record vendors is critical for the greater use of electronic health records in clinical research. This manuscript identifies the key steps required to advance the role of electronic health records in cardiovascular clinical research

Prespecified Risk Criteria Facilitate Adequate Discharge and Long-Term Outcomes After Transfemoral Transcatheter Aortic Valve Implantation

Background Despite the availability of guidelines for the performance of transcatheter aortic valve implantation (TAVI), current treatment pathways vary between countries and institutions, which impact on the mean duration of postprocedure hospitalization. Methods and Results This was a prospective, multicenter registry of 502 patients to validate the appropriateness of discharge timing after transfemoral TAVI, using prespecified risk criteria from FAST-TAVI (Feasibility and Safety of Early Discharge After Transfemoral [TF] Transcatheter Aortic Valve Implantation), based on hospital events within 1-year after discharge. The end point-a composite of all-cause mortality, vascular access-related complications, permanent pacemaker implantation, stroke, cardiac rehospitalization, kidney failure, and major bleeding-was reached in 27.0% of patients (95% CI, 23.3-31.2) within 1 year after intervention; 7.5% (95% CI, 5.5-10.2) had in-hospital complications before discharge and 19.6% (95% CI, 16.3-23.4) within 1 year after discharge. Overall mortality within 1 year after discharge was 7.3% and rates of cardiac rehospitalization 13.5%, permanent pacemaker implantation 4.2%, any stroke 1.8%, vascular-access-related complications 0.7%, life-threatening bleeding 0.7%, and kidney failure 0.4%. Composite events within 1 year after discharge were observed in 18.8% and 24.3% of patients with low risk of complications/early (≤3&nbsp;days) discharge and high risk and discharged late (&gt;3&nbsp;days) (concordant discharge), respectively. Event rate in patients with discordant discharge was 14.3% with low risk but discharged late and increased to 50.0% in patients with high risk but discharged in ≤3&nbsp;days. Conclusions The FAST-TAVI risk assessment provides a tool for appropriate, risk-based discharge that was validated with the 1-year event rate after transfemoral TAVI. Registration URL: https://www.ClinicalTrials.gov; Unique identifier: NCT02404467

Prespecified Risk Criteria Facilitate Adequate Discharge and Long‐Term Outcomes After Transfemoral Transcatheter Aortic Valve Implantation

Background Despite the availability of guidelines for the performance of transcatheter aortic valve implantation (TAVI), current treatment pathways vary between countries and institutions, which impact on the mean duration of postprocedure hospitalization. Methods and Results This was a prospective, multicenter registry of 502 patients to validate the appropriateness of discharge timing after transfemoral TAVI, using prespecified risk criteria from FAST‐TAVI (Feasibility and Safety of Early Discharge After Transfemoral [TF] Transcatheter Aortic Valve Implantation), based on hospital events within 1‐year after discharge. The end point—a composite of all‐cause mortality, vascular access–related complications, permanent pacemaker implantation, stroke, cardiac rehospitalization, kidney failure, and major bleeding—was reached in 27.0% of patients (95% CI, 23.3–31.2) within 1 year after intervention; 7.5% (95% CI, 5.5–10.2) had in‐hospital complications before discharge and 19.6% (95% CI, 16.3–23.4) within 1 year after discharge. Overall mortality within 1 year after discharge was 7.3% and rates of cardiac rehospitalization 13.5%, permanent pacemaker implantation 4.2%, any stroke 1.8%, vascular‐access–related complications 0.7%, life‐threatening bleeding 0.7%, and kidney failure 0.4%. Composite events within 1 year after discharge were observed in 18.8% and 24.3% of patients with low risk of complications/early (≤3 days) discharge and high risk and discharged late (>3 days) (concordant discharge), respectively. Event rate in patients with discordant discharge was 14.3% with low risk but discharged late and increased to 50.0% in patients with high risk but discharged in ≤3 days. Conclusions The FAST‐TAVI risk assessment provides a tool for appropriate, risk‐based discharge that was validated with the 1‐year event rate after transfemoral TAVI. Registration URL: https://www.ClinicalTrials.gov ; Unique identifier: NCT02404467

Non-manifesting AHI1 truncations indicate localized loss-of-function tolerance in a severe Mendelian disease gene

Determination of variant pathogenicity represents a major challenge in the era of high-throughput sequencing. Erroneous categorization may result if variants affect genes that are in fact dispensable. We demonstrate that this also applies to rare, apparently unambiguous truncating mutations of an established disease gene. By whole-exome sequencing (WES) in a consanguineous family with congenital non-syndromic deafness, we unexpectedly identified a homozygous nonsense variant, p.Arg1066*, in AHI1, a gene associated with Joubert syndrome (JBTS), a severe recessive ciliopathy. None of four homozygotes expressed any signs of JBTS, and one of them had normal hearing, which also ruled out p.Arg1066* as the cause of deafness. Homozygosity mapping and WES in the only other reported JBTS family with a homozygous C-terminal truncation (p.Trp1088Leufs*16) confirmed AHI1 as disease gene, but based on a more N-terminal missense mutation impairing WD40-repeat formation. Morpholinos against N-terminal zebrafish Ahi1, orthologous to where human mutations cluster, produced a ciliopathy, but targeting near human p.Arg1066 and p.Trp1088 did not. Most AHI1 mutations in JBTS patients result in truncated protein lacking WD40-repeats and the SH3 domain; disease was hitherto attributed to loss of these protein interaction modules. Our findings indicate that normal development does not require the C-terminal SH3 domain. This has far-reaching implications, considering that variants like p.Glu984* identified by preconception screening (‘Kingsmore panel') do not necessarily indicate JBTS carriership. Genomes of individuals with consanguineous background are enriched for homozygous variants that may unmask dispensable regions of disease genes and unrecognized false positives in diagnostic large-scale sequencing and preconception carrier screenin

IMPULSE: The impact of gender on the presentation and management of aortic stenosis across Europe

Aims There is an increasing awareness of gender-related differences in patients with severe aortic stenosis and their outcomes after surgical aortic valve replacement (SAVR) and transcatheter aortic valve implantation (TAVI). Methods Data from the IMPULSE registry were analysed. Patients with severe aortic stenosis (AS) were enrolled between March 2015 and April 2017 and stratified by gender. A subgroup analysis was performed to assess the impact of age. Results Overall, 2171 patients were enrolled, and 48.0% were female. Women were characterised by a higher rate of renal impairment (31.7 vs 23.3%; p&lt;0.001), were at higher surgical risk (EuroSCORE II: 4.5 vs 3.6%; p=0.001) and more often in a critical preoperative state (7.0vs 4.2%; p=0.003). Men had an increased rate of previous cardiac surgery (9.4 vs 4.7%; p&lt;0.001) and a reduced left ventricular ejection fraction (4.9 vs 1.3%; p&lt;0.001). Concomitant mitral and tricuspid valve disease was substantially more common among women. Symptoms were highly prevalent in both women and men (83.6 vs 77.3%; p&lt;0.001). AVR was planned in 1379 cases. Women were more frequently scheduled to undergo TAVI (49.3 vs 41.0%; p&lt;0.001) and less frequently for SAVR (20.3 vs 27.5%; p&lt;0.001). Conclusions The present data show that female patients with severe AS have a distinct patient profile and are managed in a different way to males. Gender-based differences in the management of patients with severe AS need to be taken into account more systematically to improve outcomes, especially for women

Impact of selected comorbidities on the presentation and management of aortic stenosis

Background Contemporary data regarding the impact of comorbidities on the clinical presentation and management of patients with severe aortic stenosis (AS) are scarce. Methods Prospective registry of severe patients with AS across 23 centres in nine European countries. Results Of the 2171 patients, chronic kidney disease (CKD 27.3%), left ventricular ejection fraction (LVEF) &lt;50% (22.0%), atrial fibrillation (15.9%) and chronic obstructive pulmonary disease (11.4%) were the most prevalent comorbidities (49.3% none, 33.9% one and 16.8% ≥2 of these). The decision to perform aortic valve replacement (AVR) was taken in a comparable proportion (67%, 72% and 69%, in patients with 0, 1 and ≥2 comorbidities; p=0.186). However, the decision for TAVI was more common with more comorbidities (35.4%, 54.0% and 57.0% for no, 1 and ≥2; p&lt;0.001), while the decision for surgical AVR (SAVR) was decreased with increasing comorbidity burden (31.9%, 17.4% and 12.3%; p&lt;0.001). The proportion of patients with planned AVRs that were performed within 3 months was significantly higher in patients with 1 or ≥2 comorbidities than in those without (8.7%, 10.0% and 15.7%; p&lt;0.001). Furthermore, the mean time to AVR was significantly shorter in patients with one (30.5 days) or ≥2 comorbidities (30.8 days) than in those without (35.7 days; p=0.012). Patients with reduced LVEF tended to be offered an AVR more frequently and with a shorter delay while patients with CKD were less frequently treated. Conclusions Comorbidities in severe patients with AS affect the presentation and management of patients with severe AS. TAVI was offered more often than SAVR and performed within a shorter time period

Management of patients with severe aortic stenosis in the TAVI-era: How recent recommendations are translated into clinical practice

Objective Approximately 3.4% of adults aged &gt;75 years suffer from aortic stenosis (AS). Guideline indications for aortic valve replacement (AVR) distinguish between patients with symptomatic and asymptomatic severe AS. The present analysis aims to assess contemporary practice in the treatment of severe AS across Europe and identify characteristics associated with treatment decisions, namely denial of AVR in symptomatic patients and assignment of asymptomatic patients to AVR. Methods Participants of the prospective, multinational IMPULSE database of patients with severe AS were grouped according to AS symptoms, and stratified into subgroups based on assignment to/denial of AVR. Results Of 1608 symptomatic patients, 23.8% did not undergo AVR and underwent medical treatment. Denial was independently associated with multiple factors, including severe frailty (p=0.024); mitral (p=0.002) or tricuspid (p=0.004) regurgitation grade III/IV, and the presence of renal impairment (p=0.017). Of 392 asymptomatic patients, 86.5% had no prespecified indication for AVR. Regardless, 36.3% were assigned to valve replacement. Those with an indexed aortic valve area (AVA; p=0.045) or left ventricular ejection fraction (LVEF; p&lt;0.001) below the study median; or with a left ventricular end systolic diameter above the study median (p=0.007) were more likely to be assigned to AVR. Conclusions There may be considerable discrepancies between guideline-based recommendations and clinical practice decision-making in the treatment of AS. It appears that guidelines may not fully capture the complete clinical spectrum of patients with AS. Thus, there is a need to find ways to increase their acceptance and the rate of adoption