A streamlined pathway for transcatheter aortic valve implantation: the BENCHMARK study.

BACKGROUND AND AIMS: There is significant potential to streamline the clinical pathway for patients undergoing transcatheter aortic valve implantation (TAVI). The purpose of this study was to evaluate the effect of implementing BENCHMARK best practices on the efficiency and safety of TAVI in 28 sites in 7 European countries. METHODS: This was a study of patients with severe symptomatic aortic stenosis (AS) undergoing TAVI with balloon-expandable valves before and after implementation of BENCHMARK best practices. Principal objectives were to reduce hospital length of stay (LoS) and duration of intensive care stay. Secondary objective was to document patient safety. RESULTS: Between January 2020 and March 2023, 897 patients were documented prior to and 1491 patients after the implementation of BENCHMARK practices. Patient characteristics were consistent with a known older TAVI population and only minor differences. Mean LoS was reduced from 7.7 ± 7.0 to 5.8 ± 5.6 days (median 6 vs. 4 days; P < .001). Duration of intensive care was reduced from 1.8 to 1.3 days (median 1.1 vs. 0.9 days; P < .001). Adoption of peri-procedure best practices led to increased use of local anaesthesia (96.1% vs. 84.3%; P < .001) and decreased procedure (median 47 vs. 60 min; P < .001) and intervention times (85 vs. 95 min; P < .001). Thirty-day patient safety did not appear to be compromised with no differences in all-cause mortality (0.6% in both groups combined), stroke/transient ischaemic attack (1.4%), life-threatening bleeding (1.3%), stage 2/3 acute kidney injury (0.7%), and valve-related readmission (1.2%). CONCLUSIONS: Broad implementation of BENCHMARK practices contributes to improving efficiency of TAVI pathway reducing LoS and costs without compromising patient safety.

Trends in transcatheter aortic valve implantation practice and clinical outcomes at an Irish tertiary referral centre.

OBJECTIVE: A paucity of data exists on how transcatheter aortic valve implantation (TAVI) practice has evolved in Ireland. This study sought to analyse temporal trends in patient demographics, procedural characteristics, and clinical outcomes at an Irish tertiary referral centre. METHODS: The prospective Mater TAVI database was divided into time tertiles based on when TAVI was performed: Group A, November 2008-April 2013; Group B, April 2013-September 2017; and Group C, September 2017-February 2022. Patient and procedural characteristics and clinical outcomes were compared across groups. RESULTS: A total of 1063 (Group A, 59; Group B, 268; and Group C:, 736) patients were treated with TAVI during the study period (mean age 81.1±7.4, mean Society of Thoracic Surgeons score 5.9±5.1).Conscious sedation (Group A, 0%; Group B, 59.9%; and Group C, 90.2%, p<0.001) and femoral artery access (Group A, 76.3%; Group B, 90.7%; and Group C, 96.6%, p<0.001) were used more frequently over time. The median length of hospital stay reduced from 9 days (IQR 7, 18) in Group A to 2 days (IQR 2, 3) in Group C. In-hospital death was numerically higher in Group A compared with Group C (6.8% vs 1.9%, p=0.078). At 1-year follow-up, the rate of death and/or stroke was similar in Group A and Group C (20.3% vs 12.0%, adjusted HR 1.49, 95% CI (0.59 to 3.74)). CONCLUSION: There was exponential growth in TAVI procedural volume during the study period. A minimalist approach to TAVI emerged, and this was associated with significantly shorter procedure duration and hospital stay. Clinical outcomes at 1-year follow-up did not change significantly over time.

Impact of the COVID-19 Pandemic on Global TAVR Activity: The COVID-TAVI Study.

BACKGROUND: The COVID-19 pandemic adversely affected health care systems. Patients in need of transcatheter aortic valve replacement (TAVR) are especially susceptible to treatment delays. OBJECTIVES: This study sought to evaluate the impact of the COVID-19 pandemic on global TAVR activity. METHODS: This international registry reported monthly TAVR case volume in participating institutions prior to and during the COVID-19 pandemic (January 2018 to December 2021). Hospital-level information on public vs private, urban vs rural, and TAVR volume was collected, as was country-level information on socioeconomic status, COVID-19 incidence, and governmental public health responses. RESULTS: We included 130 centers from 61 countries, including 65,980 TAVR procedures. The first and second pandemic waves were associated with a significant reduction of 15% (P < 0.001) and 7% (P < 0.001) in monthly TAVR case volume, respectively, compared with the prepandemic period. The third pandemic wave was not associated with reduced TAVR activity. A greater reduction in TAVR activity was observed in Africa (-52%; P = 0.001), Central-South America (-33%; P < 0.001), and Asia (-29%; P < 0.001). Private hospitals (P = 0.005), urban areas (P = 0.011), low-volume centers (P = 0.002), countries with lower development (P < 0.001) and economic status (P < 0.001), higher COVID-19 incidence (P < 0.001), and more stringent public health restrictions (P < 0.001) experienced a greater reduction in TAVR activity. CONCLUSIONS: TAVR procedural volume declined substantially during the first and second waves of the COVID-19 pandemic, especially in Africa, Central-South America, and Asia. National socioeconomic status, COVID-19 incidence, and public health responses were associated with treatment delays. This information should inform public health policy in case of future global health crises.

Risk assessment-based verification of the CertiPURTM limit values for toluene diamine and methylene dianiline in flexible polyurethane foam.

Flexible polyurethane foams (PUF) are used in many consumer products. PUF may contain trace levels of aromatic diamine impurities that could represent a potential health risk. The risk associated with sleeping on a PUF mattress was evaluated. Toxicity benchmarks for sensitization and non-cancer endpoints were derived from the respective points-of-departure using standard assessment factors. For the cancer endpoints, toxicity benchmarks were derived from the 25th-percentile values of animal studies. Recently published emission and migration data allowed to link exposure with the CertiPURTM voluntary quality limits of ≤5 mg.kg-1 for 2,4-toluene diamine and 4,4'-methylene dianiline in PUF. Using conservative exposure scenarios, lifetime-average daily internal doses from the combined inhalation and dermal exposures were calculated. Margins of safety for non-cancer and sensitization endpoints were >104. The theoretical excess cancer risk was ≤1.5 × 10-7. It is concluded that sleeping on a mattress that satisfies the CertiPUR limit value does not pose undue risk to consumers.

Stepwise provisional versus systematic culotte for stenting of true coronary bifurcation lesions: five-year follow-up of the multicentre randomised EBC TWO Trial.

BACKGROUND: The multicentre European Bifurcation Club Trial (EBC TWO) showed no significant differences in 12-month clinical outcomes between patients randomised to a provisional stenting strategy or systematic culotte stenting in non-left main true bifurcations. AIMS: This study aimed to investigate the 5-year clinical results of the EBC TWO Trial. METHODS: A total of 200 patients undergoing stent implantation for non-left main bifurcation lesions were recruited into EBC TWO. Inclusion criteria required a side branch diameter ≥2.5 mm and side branch lesion length >5 mm. Five-year follow-up was completed for 197 patients. The primary endpoint was the composite of all-cause mortality, myocardial infarction, or target vessel revascularisation. RESULTS: The mean side branch stent diameter was 2.7±0.3 mm and mean side branch lesion length was 10.3±7.2 mm. At 5-year follow-up, the primary endpoint occurred in 18.4% of provisional and 23.7% of systematic culotte patients (hazard ratio [HR] 0.75, 95% confidence interval [CI]: 0.41-1.38). No significant differences were identified individually for all-cause mortality (7.8% vs 7.2%, HR 1.11, 95% CI: 0.40-3.05), myocardial infarction (8.7% vs 13.4%, HR 0.64, 95% CI: 0.27-1.50) or target vessel revascularisation (6.8% vs 9.3%, HR 1.12, 95% CI: 0.37-3.34). Stent thrombosis rates were also similar (1.9% vs 3.1%, HR 0.63, 95% CI: 0.11-3.75). There was no significant interaction between the extent of side branch disease and the primary outcome (p=0.34). CONCLUSIONS: In large non-left main true bifurcation lesions, the use of a systematic culotte strategy showed no benefit over provisional stenting for the composite outcome of all-cause mortality, myocardial infarction, or target vessel revascularisation at 5 years. The stepwise provisional approach may be considered preferable for the majority of true coronary bifurcation lesions. CLINICALTRIALS: gov: NCT01560455.

An Update on Anti-thrombotic Therapy Following Transcatheter Aortic Valve Implantation: Expert Cardiologist Opinion from a UK and Ireland Delphi Group.

Transcatheter aortic valve implantation (TAVI) is an effective and established treatment for symptomatic aortic stenosis. However, there is a lack of consensus concerning the need for peri- and post-procedural anti-thrombotic medication. Contemporary guidelines recommend that anti-thrombotic therapy is balanced against a patient's bleeding risk following TAVI, but do not fully consider the evolving evidence base. The purpose of the Delphi panel recommendations presented here is to provide a consensus elicited from a panel of experts who regularly prescribe anti-thrombotic therapy post-TAVI. The goal was to address evidence gaps across four key topics: anti-thrombotic therapy (anti-platelet and/or anti-coagulant) in TAVI patients in sinus rhythm; anti-thrombotic therapy in TAVI patients with AF; direct oral anti-coagulants versus vitamin K antagonists; and the need for UK/Ireland specific guidance. This consensus statement aims to inform clinical decision-making by providing a concise, evidence-based summary of best practice for prescribing anti-thrombotic therapies following TAVI and highlights areas where further research is needed.

Glu298Asp variant of the endothelial nitric oxide synthase gene and acute coronary syndrome or premature coronary artery disease: A systematic review and meta-analysis.

INTRODUCTION: Several published studies have reported an association between the Glu298Asp polymorphism (rs1799983), residing in the endothelial nitric oxide synthase (NOS3) gene, and lower levels of circulating nitric oxide, as well as an increased risk of coronary artery disease (CAD). However, association status of this genetic variant with acute coronary syndrome (ACS) or premature CAD (PCAD) is still unclear. Against this background, we conducted a systematic review and study level meta-analysis to assess the association of the NOS3 Glu298Asp polymorphism with ACS or PCAD. MATERIALS AND METHODS: A comprehensive online search to identify relevant studies was performed on several databases including PubMed, EMBASE, MEDLINE, Scopus, Cochrane library and Web of Science. The identified studies were stratified into two ancestral subgroups: 'European ancestry' and 'All other ancestries combined'. Study level odds ratios (ORs) and their 95% confidence intervals (CI) were pooled using random/fixed effects employing a Z test. RESULTS: Out of a total of 195 distinct records identified through online search, 37 articles with 39 different studies, with a total sample size of 27,441 (11,516 cases/15,925 controls) were included for quantitative synthesis. Pooled results suggested significant associations of the NOS3 Glu298Asp polymorphism with ACS or PCAD through dominant as well as allelic genetic models (p ≤ 0.002), primarily driven by the 'All other ancestries combined' subgroup. The 'All other ancestries combined' subgroup demonstrated an additional risk of 36% for ACS or PCAD, through both dominant and allelic genetic models (OR = 1.36, 95%CI = 1.13, 1.63, p = 0.001 and OR = 1.36, 95%CI = 1.14, 1.61, p = 0.0005 respectively). On the other hand, the 'European ancestry' subgroup did not show any significant associations. Sensitivity analysis and a sub-analysis for the myocardial infarction endpoint further supported these observed associations. CONCLUSIONS: This meta-analysis indicates towards an association between the NOS3 Glu298Asp polymorphism and ACS or PCAD, predominantly driven by 'All other ancestries combined' subgroup. In contrast, the 'European ancestry' subgroup did not demonstrate any significant association. Further large-scale investigations are required to confirm our derived results.

Methylene diphenyl diisocyanate occupational exposure data in industry (1998-2020): A descriptive summary from an industrial hygiene perspective.

This paper provides an overview of airborne methylene diphenyl diisocyanate (MDI) concentrations in workplaces across North America and Europe. A total of 7649 samples were collected between 1998 and 2020 by producers of MDI during product stewardship activities at customer sites, primarily using validated OSHA or ISO sampling and analysis techniques. As would be expected from the low vapor pressure of MDI, 80% of the concentrations were less than 0.01 mg/m3 (1 ppb) and 93% were less than 0.05 mg/m3 (5 ppb). Respiratory protection is an integral part of Industrial Hygiene practices; therefore, its use was studied and summarized. While covering a variety of MDI applications, a large number of samples was obtained from composite wood manufacturing facilities, offering specific insight into potential exposures associated with different process sections and job types in this industry sector. Given the potential presence in industrial processes of MDI-containing dust or aerosols, future work should place increased emphasis on also investigating dermal exposure. The data reported in this paper provide valuable information for product stewardship and industrial hygiene purposes throughout the MDI-processing industry.

Emission and time-resolved migration rates of aromatic diamines from two flexible polyurethane foams.

Performing risk assessments (RA) on household use of flexible polyurethane (PU) foams requires access to reliable data about emission and migration of potential diamine impurities. A toluene diisocyanate (TDI) and a methylene diphenyl diisocyanate (MDI) based foam were thermally treated to enable measurements on samples with defined concentrations of the corresponding diamines, toluene diamine (TDA), and methylene dianiline (MDA). The thermally treated foams used for emission testing contained up to 15 mg.kg-1 of TDA and 27 mg.kg-1 of MDA. Those used for migration testing contained 5.1 mg.kg-1 of TDA and 14.1 mg.kg-1 of MDA. Stability of the thermally generated diamines was sufficient for testing over a 37-day period. Analytical techniques that did not decompose the polymer matrix were applied. Emission rates for TDA and MDA isomers were less than the limit of quantitation (LOQ) of 0.008-0.07 µg.m-2.h-1. Migration was studied using samples of the same thermally treated foams over a 35-day period. Quantifiable migration of MDA from the MDI-based foam was only observed on Days 1 and 2. From Day 3 onward, migration rates were less than the LOQ. Quantifiable migration of TDA from the TDI-based foam rapidly decreased with time and was only observed on Days 1 thru 3. From Day 4 onward, migration rates were less than the LOQ. Theoretically, the migration rate should be inversely proportional to the square root of time (t) as t-0.5. This relationship was confirmed by the experimental data and enables extrapolating migration values to more extended time periods to conduct RAs.

Redo aortic valve replacement versus valve-in-valve trans-catheter aortic valve implantation: a UK propensity-matched analysis.

This study sought to compare the morbidity and mortality of redo aortic valve replacement (redo-AVR) versus valve-in-valve trans-catheter aortic valve implantation (valve-in-valve TAVI) for patients with a failing bioprosthetic valve. A multicenter UK retrospective study of redo-AVR or valve-in-valve TAVI for patients referred for redo aortic valve intervention due to a degenerated aortic bioprosthesis. Propensity score matching was performed for confounding factors. From July 2005 to April 2021, 911 patients underwent redo-AVR and 411 patients underwent valve-in-valve TAVI. There were 125 pairs for analysis after propensity score matching. The mean age was 75.2±8.5 years. In-hospital mortality was 7.2% (n=9) for redo-AVR versus 0 for valve-in-valve TAVI, p=0.002. Surgical patients suffered more post-operative complications, including intra-aortic balloon pump support (p=0.02), early re-operation (p<0.001), arrhythmias (p<0.001), respiratory and neurological complications (p=0.02 and p=0.03) and multi-organ failure (p=0.01). The valve-in-valve TAVI group had a shorter intensive care unit and hospital stay (p<0.001 for both). However, moderate aortic regurgitation at discharge and higher post-procedural gradients were more common after valve-in-valve TAVI (p<0.001 for both). Survival probabilities in patients who were successfully discharged from the hospital were similar after valve-in-valve TAVI and redo-AVR over the 6-year follow-up (log-rank p=0.26). In elderly patients with a degenerated aortic bioprosthesis, valve-in-valve TAVI provides better early outcomes as opposed to redo-AVR, although there was no difference in mid-term survival in patients successfully discharged from the hospital.

Long-term durability of self-expanding and balloon-expandable transcatheter aortic valve prostheses: UK TAVI registry.

BACKGROUND: With expansion of transcatheter aortic valve implantation (TAVI) into younger patients, valve durability is critically important. AIMS: We aimed to evaluate long-term valve function and incidence of severe structural valve deterioration (SVD) among patients ≥ 10-years post-TAVI and with echocardiographic follow-up at least 5-years postprocedure. METHODS: Data on patients who underwent TAVI from 2007 to 2011 were obtained from the UK TAVI registry. Patients with paired echocardiograms postprocedure and ≥5-years post-TAVI were included. Severe SVD was determined according to European task force guidelines. RESULTS: 221 patients (79.4 ± 7.3 years; 53% male) were included with median echocardiographic follow-up 7.0 years (range 5-13 years). Follow-up exceeded 10 years in 43 patients (19.5%). Valve types were the supra-annular self-expanding CoreValve (SEV; n = 143, 67%), balloon-expandable SAPIEN/XT (BEV; n = 67, 31%), Portico (n = 4, 5%) and unknown (n = 7, 3%). There was no difference between postprocedure and follow-up peak gradient in the overall cohort (19.3 vs. 18.4 mmHg; p = NS) or in those with ≥10-years follow-up (21.1 vs. 21.1 mmHg; p = NS). Severe SVD occurred in 13 patients (5.9%; median 7.8-years post-TAVI). Three cases (23.1%) were due to regurgitation and 10 (76.9%) to stenosis. Valve-related reintervention/death occurred in 5 patients (2.3%). Severe SVD was more frequent with BEV than SEV (11.9% vs. 3.5%; p = 0.02), driven by a difference in patients treated with small valves (BEV 28.6% vs. SEV 3.0%; p < 0.01). CONCLUSIONS: Hemodynamic function of transcatheter heart valves remains stable up to more than 10 years post-TAVI. Severe SVD occurred in 5.9%, and valve-related death/reintervention in 2.3%. Severe SVD was more common with BEV than SEV.

Assessment of hemodynamic indices of conjunctival microvascular function in patients with coronary microvascular dysfunction.

OBJECTIVE: Coronary microvascular dysfunction (CMD) is a cause of ischaemia with non-obstructive coronary arteries (INOCA). It is notoriously underdiagnosed due to the need for invasive microvascular function testing. We hypothesized that systemic microvascular dysfunction could be demonstrated non-invasively in the microcirculation of the bulbar conjunctiva in patients with CMD. METHODS: Patients undergoing coronary angiography for the investigation of chest pain or dyspnoea, with physiologically insignificant epicardial disease (fractional flow reserve ≥0.80) were recruited. All patients underwent invasive coronary microvascular function testing. We compared a cohort of patients with evidence of CMD (IMR ≥25 or CFR <2.0); to a group of controls (IMR <25 and CFR ≥2.0). Conjunctival imaging was performed using a previously validated combination of a smartphone and slit-lamp biomicroscope. This technique allows measurement of vessel diameter and other indices of microvascular function by tracking erythrocyte motion. RESULTS: A total of 111 patients were included (43 CMD and 68 controls). There were no differences in baseline demographics, co-morbidities or epicardial coronary disease severity. The mean number of vessel segments analysed per patient was 21.0 ± 12.8 (3.2 ± 3.5 arterioles and 14.8 ± 10.8 venules). In the CMD cohort, significant reductions were observed in axial/cross-sectional velocity, blood flow, wall shear rate and stress. CONCLUSION: The changes in microvascular function linked to CMD can be observed non-invasively in the bulbar conjunctiva. Conjunctival vascular imaging may have utility as a non-invasive tool to both diagnose CMD and augment conventional cardiovascular risk assessment.

Impact of technique on bifurcation stent outcomes in the European Bifurcation Club Left Main Coronary Trial.

BACKGROUND: Techniques for provisional and dual-stent left main bifurcation stenting require optimization. AIM: To identify technical variables influencing procedural outcomes and periprocedural myocardial infarction following left main bifurcation intervention. METHODS: Procedural and outcome data were analyzed in 438 patients from the per-protocol cohort of the European Bifurcation Club Left Main Trial (EBC MAIN). These patients were randomized to the provisional strategy or a compatible dual-stent extension (T, T-and-protrude, or culotte). RESULTS: Mean age was 71 years and 37.4% presented with an acute coronary syndrome. Transient reduction of side vessel thrombolysis in myocardial infarction flow occurred after initial stent placement in 5% of procedures but was not associated with periprocedural myocardial infarction. Failure to rewire a jailed vessel during any strategy was more common when jailed wires were not used (9.5% vs. 2.5%, odds ratio [OR]: 6.4, p = 0.002). In the provisional cohort, the use of the proximal optimization technique was associated with less subsequent side vessel intervention (23.3% vs. 41.9%, OR: 0.4, p = 0.048). Side vessel stenting was predominantly required for dissection, which occurred more often following side vessel preparation (15.3% vs. 4.4%, OR: 3.1, p = 0.040). Exclusive use of noncompliant balloons for kissing balloon inflation was associated with reduced need for side vessel intervention in provisional cases (20.5% vs. 38.5%, OR: 0.4, p = 0.013), and a reduced risk of periprocedural myocardial infarction across all strategies (2.9% vs. 7.7%, OR: 0.2, p = 0.020). CONCLUSION: When performing provisional or compatible dual-stent left main bifurcation intervention, jailed wire use is associated with successful jailed vessel rewiring. Side vessel preparation in provisional patients is linked to increased side vessel dissection requiring stenting. Use of the proximal optimization technique may reduce the need for additional side vessel intervention, and noncompliant balloon use for kissing balloon inflation is associated with a reduction in both side vessel stenting and periprocedural myocardial infarction. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT02497014.

Assessment of Indices of Conjunctival Microvascular Function in Patients With and Without Obstructive Coronary Artery Disease.

BACKGROUND: Atherosclerotic heart disease often remains asymptomatic until presentation with a major adverse cardiovascular event. Primary preventive therapies improve outcomes, but conventional screening often misattributes risk. Vascular imaging can be utilised to detect atherosclerosis, but often involves ionising radiation. The conjunctiva is a readily accessible vascular network allowing non-invasive hemodynamic evaluation. AIM: To compare conjunctival microcirculatory function in patients with and without obstructive coronary artery disease. METHODS: We compared the conjunctival microcirculation of myocardial infarction patients (MI-cohort) to controls with no obstructive coronary artery disease (NO-CAD cohort). Conjunctival imaging was performed using a smartphone and slit-lamp biomicroscope combination. Microvascular indices of axial (Va) and cross-sectional (Vcs) velocity; blood flow rate (Q); and wall shear rate (WSR) were compared in all conjunctival vessels between 5 and 45 µm in diameter. RESULTS: A total of 127 patients were recruited (66 MI vs 61 NO-CAD) and 3602 conjunctival vessels analysed (2414 MI vs 1188 NO-CAD). Mean Va, Vcs and Q were significantly lower in the MI vs NO-CAD cohort (Va 0.50 ± 0.17 mm/s vs 0.55 ± 0.15 mm/s, p < 0.001; Vcs 0.35 ± 0.12 mm/s vs 0.38 ± 0.10 mm/s, p < 0.001; Q 154 ± 116 pl/s vs 198 ± 130 pl/s, p < 0.001). To correct for differences in mean vessel diameter, WSR was compared in 10-36 µm vessels (3268/3602 vessels) and was lower in the MI-cohort (134 ± 64 s-1 vs 140 ± 63 s-1, p = 0.002). CONCLUSIONS: Conjunctival microcirculatory alterations can be observed in patients with obstructive coronary artery disease. The conjunctival microvasculature merits further evaluation in cardiovascular risk screening.

Toluene diisocyanate occupational exposure data in the polyurethane industry (2005-2020): A descriptive summary from an industrial hygiene perspective.

This article provides an overview of toluene diisocyanate (TDI) workplace air concentration data. Data were collected between 2005-2020 in workplaces across the United States, Canada, and the European Union by a number of different organizations, primarily using the sampling procedures published in OSHA Methods 42 and 5002. The data were then collated and organized by the International Isocyanate Institute. Air samples were collected from several market segments, with a large portion of the data (87%) from the flexible foam industry. The air samples (2534 in total) were categorized into "area" or "personal," and the personal samples were subcategorized into "task," "short term," and "long term." Most of the air sample concentrations (87%) were less than 5 ppb. However, the presence of airborne TDI greater than 5 ppb indicated the importance of respiratory protection in some situations; therefore, respirator use patterns were studied and summarized. Additionally, this article provides a summary of air sample concentrations at different flexible foam manufacturing job roles. The information on air sampling concentrations and respiratory protection during TDI applications collected in this paper could be useful for product stewardship and industrial hygiene purposes in the industries studied.

Exploring structure/property relationships to health and environmental hazards of polymeric polyisocyanate prepolymer substances-1. Design of experiments, aquatic exposure, and acute aquatic toxicity.

Polymeric polyisocyanate prepolymer substances are reactive intermediates used in the manufacture of various polyurethane products. Knowledge of their occupational and environmental hazard properties is essential for product stewardship and industrial hygiene purposes. This work reports on the systematic design of a program to explore how structural features (i.e., types of polymeric polyol and diisocyanate reactants, functionality) and physical-chemical properties (i.e., octanol-water partition coefficient [log Kow], viscosity, molecular weight) of a group of 10 toluene diisocyanate (TDI)- and methylene diphenyl diisocyanate (MDI)-based monomer-depleted prepolymer substances can be related to their exposure and hazard potentials. The revelation of trends or thresholds in such relationships could form a basis for regulatory screening of existing or new prepolymer substances, while also informing the design of substances having reduced exposure and/or hazard profiles. As a first step, the aquatic exposure and hazard potentials of these 10 substances were investigated. The results of this investigation showed that yields of dissolved reaction products (derived from non-purgeable organic carbon measurements and carbon contents of the parent prepolymers) were inversely correlated with the calculated log Kow of the substances. For prepolymer loading rates of both 100 and 1000 mg/L in water, the average dissolved reaction product yields ranged from ≤1% to 32% and from ≤0.1% to 25%, respectively, over calculated log Kow values ranging from -4.8 to 45. For both loading rates, dissolved reaction products were not quantifiable where the calculated log Kow value was >10. Yet, none of the 10 prepolymers and tested loading rates exhibited acute adverse effects on the aquatic invertebrate, Daphnia magna, in the 48-h acute immobilization test. From a product stewardship perspective, polymeric prepolymers of TDI and MDI within the investigated domain and concentration range are not expected to be hazardous in the aquatic environment.

A brief overview of properties and reactions of diisocyanates.

By way of introduction to the special issue on diisocyanates and their corresponding diamines, this brief overview presents, for the most commonly used diisocyanate monomers, a selection of physical-chemical properties that are relevant to exposure in the workplace and in the general environment, as well as a concise overview of diisocyanate reactions and some of their toxicological implications.

Concomitant use of Sapien 3 transcatheter valve for severe MAC with Intuity Elite rapid deployment valve for aortic stenosis.

BACKGROUND: Concomitant double valve pathology in the presence of severe MAC poses significant technical challenges when planning surgical intervention. With continued evolution of valve prosthesis, innovative techniques can be considered with the potential for additional therapeutic benefit. CASE PRESENTATION: We present a novel technique of using a rapid deployment surgical aortic valve in combination with open surgical transcatheter mitral valve implantation (TMVI) for severe Mitral Annular Calcification (MAC). The Intuity Elite rapid deployment prosthesis (Edwards Lifesciences, Irvine, CA) was used concomitantly with the Sapien 3 (Edwards Lifesciences, Irvine, CA) transcatheter prosthesis trans-atrially on cardiopulmonary bypass in a patient with critical aortic stenosis and moderate-severe mixed mitral valve disease in the setting of severe MAC (off-label use). CONCLUSIONS: We demonstrate how both technologies can, not only be accommodated, but indeed complement each other achieving an excellent outcome in a high-risk patient.