A benefit-cost analysis of different response scenarios to COVID-19: A case study.

BACKGROUND: This paper compares the direct benefits to the State of Western Australia from employing a "suppression" policy response to the COVID-19 pandemic rather than a "herd immunity" approach. METHODS: An S-I-R (susceptible-infectious-resolved) model is used to estimate the likely benefits of a suppression COVID-19 response compared to a herd immunity alternative. Direct impacts of the virus are calculated on the basis of sick leave, hospitalizations, and fatalities, while indirect impacts related to response actions are excluded. RESULTS: Preliminary modeling indicates that approximately 1700 vulnerable person deaths are likely to have been prevented over 1 year from adopting a suppression response rather than a herd immunity response, and approximately 4500 hospitalizations. These benefits are valued at around AUD4.7 billion. If a do nothing policy had been adopted, the number of people in need of hospitalization is likely to have overwhelmed the hospital system within 50 days of the virus being introduced. Maximum hospital capacity is unlikely to be reached in either a suppression policy or a herd immunity policy. CONCLUSION: Using early international estimates to represent the negative impact each type of policy response is likely to have on gross state product, results suggest the benefit-cost ratio for the suppression policy is slightly higher than that of the herd immunity policy, but both benefit-cost ratios are less than one.

Repeat transcatheter aortic valve implantation and implications for transcatheter heart valve performance: insights from bench testing.

BACKGROUND: THV implantation within failed surgical valves is well established. However, the implications of THV implantation within failed THVs are poorly understood. AIMS: This study aimed to assess the impact of different transcatheter heart valve (THV) designs and implant positioning strategies on hydrodynamic performance after redo transcatheter aortic valve implantation (TAVI). METHODS: THVs of varying design (SAPIEN 3, Evolut PRO, ACURATE neo, ALLEGRA, and Portico) and size were implanted inside SAPIEN XT and Evolut R THVs. Hydrodynamic function as per International Organization for Standardization (ISO) specifications was evaluated using a pulse duplicator, and multi-modality imaging was performed. RESULTS: The majority of tested THV-in-THV combinations resulted in stable anchoring of the new implant. However, some combinations resulted in unstable anchoring with the potential for dislodgement or embolisation. Hydrodynamic function was favourable for all tested THV designs implanted in the intra-annular SAPIEN XT THV. SAPIEN 3 implantation within an Evolut THV with supra-annular leaflets must be appropriately sized to ensure adequate anchoring. Avoidance of an intra-annular deployment mitigated leaflet overhang of the Evolut leaflets and optimised hydrodynamic performance. CONCLUSIONS: This study demonstrates that most THV designs and implantation strategies can result in favourable hydrodynamic performance following redo TAVI. Whether the leaflets of a failed THV are intra- or supra-annular may have important implications for the positioning of a redo-THV implant. Certain THV designs or implantation positions may be more desirable when performing redo TAVI.

The Role of Digital Technologies in Responding to the Grand Challenges of the Natural Environment: The Windermere Accord.

Digital technology is having a major impact on many areas of society, and there is equal opportunity for impact on science. This is particularly true in the environmental sciences as we seek to understand the complexities of the natural environment under climate change. This perspective presents the outcomes of a summit in this area, a unique cross-disciplinary gathering bringing together environmental scientists, data scientists, computer scientists, social scientists, and representatives of the creative arts. The key output of this workshop is an agreed vision in the form of a framework and associated roadmap, captured in the Windermere Accord. This accord envisions a new kind of environmental science underpinned by unprecedented amounts of data, with technological advances leading to breakthroughs in taming uncertainty and complexity, and also supporting openness, transparency, and reproducibility in science. The perspective also includes a call to build an international community working in this important area.

A bench test study of bioprosthetic valve fracture performed before versus after transcatheter valve-in-valve intervention.

AIMS: Bioprosthetic valve fracture (BVF) may improve transvalvular gradients and transcatheter heart valve (THV) expansion during VIV interventions. However, the optimal timing of BVF is unknown. We assessed the impact of timing of BVF (before versus after) for valve-in-valve (VIV) intervention, on hydrodynamic function and THV expansion. METHODS AND RESULTS: Three THV designs were assessed, a 23 mm SAPIEN 3 (S3), small ACURATE neo (ACn) and 23 mm Evolut R, deployed into 21 mm Mitroflow bioprosthetic surgical valves. We evaluated each THV in three groups: 1) no BVF, 2) BVF before VIV, and 3) BVF after VIV. Hydrodynamic testing was performed using a pulse duplicator to ISO 5840:2013 standard. Transvalvular gradients were lower when BVF was performed after VIV for the S3 (no BVF 15.5 mmHg, BVF before VIV 8.0 mmHg, BVF after VIV 5.6 mmHg), and the ACn (no BVF 9.8 mmHg, BVF before VIV 8.4 mmHg, BVF after VIV 5.1 mmHg). Transvalvular gradients were similar for the Evolut R, irrespective of performance of BVF or timing of BVF. BVF performed after VIV resulted in better expansion in all three THV designs. The ACn and Evolut R samples all had a mild degree of pinwheeling, and BVF timing did not impact on pinwheeling severity. The S3 samples had severe pinwheeling with no BVF, and significant improvement in pinwheeling when BVF was performed after VIV. CONCLUSIONS: BVF performed after VIV was associated with superior THV expansion in all three THV designs tested, with lower residual transvalvular gradients in the S3 and ACn THVs. The Evolut R had similar hydrodynamic performance irrespective of BVF timing. Timing of BVF has potential implications on THV function.

Impact of implant depth on hydrodynamic function of the ALLEGRA bioprosthesis in valve-in-valve interventions.

AIMS: We aimed to assess the impact of implant depth on hydrodynamic function following valve-in-valve (VIV) intervention using the ALLEGRA transcatheter heart valve (THV) in three different surgical valve designs. METHODS AND RESULTS: Multiple implantation depths (+2 mm, -2 mm and -6 mm) were tested using a 23 mm ALLEGRA THV for VIV intervention in 19 mm, 21 mm, 23 mm, and 25 mm Epic, Mitroflow and Magna Ease bioprosthetic valves. Multimodality imaging and hydrodynamic evaluation was performed at each implantation depth. The 23 mm ALLEGRA valve had gradients <20 mmHg in the Mitroflow and Epic valves sized ≥21 mm, and in all sizes of the Magna Ease valve. Gradients did not increase significantly at lower implantation depths. The 19 mm Epic (+2 mm: 20.1±0.6 mmHg, -2 mm: 18.8±0.5 mmHg, -6 mm: 22.8±0.3 mmHg) and 19 mm Mitroflow (+2 mm: 24.1±0.2 mmHg, -2 mm: 31.5±0.3 mmHg, -6 mm: 25.6±0.2 mmHg) valves had elevated mean gradients. In larger sized surgical valves (≥23 mm) the regurgitant fraction was higher at low implantation depths. Pinwheeling was significantly worse in the smaller sized (≤21 mm) surgical valves and also at low (<-2 mm) implantation depth. CONCLUSIONS: The 23 mm ALLEGRA valve had favourable (<20 mmHg) gradients in all surgical valves sized ≥21 mm, even when the THV was implanted low. In 19 mm sized Mitroflow and Epic valves, gradients were elevated (>20 mmHg). While there was no major difference in mean transvalvular gradients, leaflet pinwheeling was worse at lower implantation depths.

Implications of hydrodynamic testing to guide sizing of self-expanding transcatheter heart valves for valve-in-valve procedures.

AIMS: The commonly used valve-in-valve (VIV) app recommends sizing based on dimensions of both the transcatheter heart valve (THV) and bioprosthetic surgical valve. The implications of hydrodynamic testing to guide VIV sizing are poorly understood. This bench study assessed the hydrodynamic performance of different sizes of self-expanding supra-annular THVs in three different surgical aortic bioprostheses at different implantation depths. METHODS: A small versus medium ACURATE neo (ACn), and a 26 mm versus 29 mm Evolut R were assessed after VIV implantation in 25 mm Mitroflow, Mosaic, and Magna Ease aortic surgical bioprostheses, at three implantation depths (+2 mm, -2 mm, and -6 mm). RESULTS: The medium-sized ACn had lower gradients compared to the small ACn when the THV was implanted high (+2 mm, or -2 mm). The 29 mm Evolut R had lower gradients compared to a 26 mm Evolut R for all implantation depths, except for a depth of -2 mm in the 25 mm Mitroflow. The medium ACn and 29 mm Evolut R had larger effective orifice areas compared to the small ACn and 26 mm Evolut R, respectively. Both Evolut R sizes had acceptable regurgitant fractions (<15%), while both ACn sizes were above the acceptable performance criteria (>15%), at all implantation depths. CONCLUSIONS: Use of a larger self-expanding THV was associated with superior hydrodynamic performance if the THV was implanted high. Hydrodynamic testing can provide additional information to the VIV app to help guide VIV sizing.

In-Vitro Pulsatile Flow Testing of Prosthetic Heart Valves: A Round-Robin Study by the ISO Cardiac Valves Working Group.

PURPOSE: Hydrodynamic performance testing is one of the core in vitro assessments required by the ISO 5840 series of standards for all prosthetic heart valves. A round-robin study carried out in 2005 in accordance with ISO 5840:2005 revealed significant variabilities in prosthetic heart valve hydrodynamic performance measurements among the participating laboratories. In order to re-examine the inter-laboratory variability based on the "state-of-the-art" under ISO 5840-1 and 5840-2:2015, the ISO Cardiac Valve Working Groups decided in 2016 to repeat the round-robin study. METHODS: A total of 13 international laboratories participated in the study. The test valves were chosen to be the St. Jude Medical Masters Series mechanical valves (19 mm aortic, 25 mm aortic, 25 mm mitral, and 31 mm mitral), which were circulated among the laboratories. The testing was conducted according to a common test run sequence, with prespecified flow conditions. RESULTS: The study revealed improved, yet still significant variability among different laboratories as compared to the 2005 study. The coefficient of variation ranged from 7.7 to 21.6% for the effective orifice area, from 10.1 to 32.8% for the total regurgitant fraction, and from 14.7 to 45.5% for the mean transvalvular pressure gradient. CONCLUSIONS: The study revealed the ambiguities in the current versions of the ISO 5840 series of standards and the shortcomings of some participating laboratories. This information has allowed the ISO Working Group to incorporate additional clarifying language into the ISO 5840-1, -2, and -3 standards that are currently under revision to improve in vitro assessments. The results presented here can also be used by the testing laboratories to benchmark pulse duplicator systems and to train and certify testing personnel.

Valve-in-Valve Transcatheter Aortic Valve Replacement and Bioprosthetic Valve Fracture Comparing Different Transcatheter Heart Valve Designs: An Ex Vivo Bench Study.

OBJECTIVES: The authors assessed the effect of valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) followed by bioprosthetic valve fracture (BVF), testing different transcatheter heart valve (THV) designs in an ex vivo bench study. BACKGROUND: Bioprosthetic valve fracture can be performed to improve residual transvalvular gradients following VIV TAVR. METHODS: The authors evaluated VIV TAVR and BVF with the SAPIEN 3 (S3) (Edwards Lifesciences, Irvine, California) and ACURATE neo (Boston Scientific Corporation, Natick, Massachusetts) THVs. A 20-mm and 23-mm S3 were deployed in a 19-mm and 21-mm Mitroflow (Sorin Group USA, Arvada, Colorado), respectively. A small ACURATE neo was deployed in both sizes of Mitroflow tested. VIV TAVR samples underwent multimodality imaging, and hydrodynamic evaluation before and after BVF. RESULTS: A high implantation was required to enable full expansion of the upper crown of the ACURATE neo and allow optimal leaflet function. Marked underexpansion of the lower crown of the THV within the surgical valve was also observed. Before BVF, VIV TAVR in the 19-mm Mitroflow had high transvalvular gradients using either THV design (22.0 mm Hg S3, and 19.1 mm Hg ACURATE neo). After BVF, gradients improved and were similar for both THVs (14.2 mm Hg S3, and 13.8 mm Hg ACURATE neo). The effective orifice area increased with BVF from 1.2 to 1.6 cm2 with the S3 and from 1.4 to 1.6 cm2 with the ACURATE neo. Before BVF, VIV TAVR with the ACURATE neo in the 21-mm Mitroflow had lower gradients compared with S3 (11.3 mm Hg vs. 16 mm Hg). However, after BVF valve gradients were similar for both THVs (8.4 mm Hg ACURATE neo vs. 7.8 mm Hg S3). The effective orifice area increased from 1.5 to 2.1 cm2 with the S3 and from 1.8 to 2.2 cm2 with the ACURATE neo. CONCLUSIONS: BVF performed after VIV TAVR results in improved residual gradients. Following BVF, residual gradients were similar irrespective of THV design. Use of a small ACURATE neo for VIV TAVR in small (≤21 mm) surgical valves may be associated with challenges in achieving optimum THV position and expansion. BVF could be considered in selected clinical cases.

Impact of implant depth on hydrodynamic function with the ACURATE neo transcatheter heart valve following valve-in-valve transcatheter aortic valve replacement in Mitroflow bioprosthetic valves: an ex vivo bench study.

AIMS: We aimed to assess the impact of implant depth on hydrodynamic function following valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) using the ACURATE neo transcatheter heart valve (THV) through an ex vivo bench study. METHODS AND RESULTS: Multiple implantation depths were tested at incremental depths of 2 mm using a small size ACURATE neo valve for VIV TAVR in 19 mm, 21 mm, 23 mm, and 25 mm Mitroflow bioprosthetic valves. Multimodality imaging and hydrodynamic evaluation was performed at each implantation depth. A low implantation was associated with higher transvalvular gradients. The highest transvalvular gradient was observed at -10 mm depth for 19 mm (40.0±0.5 mmHg), -8 mm for 21 mm (15.3±0.2 mmHg), -6 mm for 23 mm (14.7±0.3 mmHg) and -8 mm for 25 mm (8.4±0.2 mmHg) surgical valves. The lowest transvalvular gradient was observed at 0 mm depth for the 19 mm (14.9±0.2 mmHg)/21 mm (7.2±0.1 mmHg), and +2 mm depth for the 23 mm (5.7±0.1 mmHg)/25 mm (5.8±0.1 mmHg) surgical valves. At low implantation depth, there was worse leaflet pin-wheeling and also evidence of interaction of THV leaflets with those of the surgical valve that impaired leaflet coaptation, resulting in a high regurgitant fraction (42.5% in the 21 mm and 83.3% in the 23 mm surgical valve at -10 mm depths). CONCLUSIONS: A high implant is desirable to facilitate favourable hydrodynamic function when performing VIV TAVR using the ACURATE neo THV for Mitroflow aortic bioprostheses sized ±25 mm. In a 19 mm Mitroflow valve, positioning the upper crown of the ACURATE neo THV above the posts of the surgical valve is desirable to facilitate favourable transvalvular gradients. Low implantation results in higher transvalvular gradients and worse pin-wheeling, and THV leaflet dysfunction can be severe due to interaction with the surgical valve.

Overexpansion of the SAPIEN 3 Transcatheter Heart Valve: An Ex Vivo Bench Study.

OBJECTIVES: This study assessed the effect of overexpansion beyond labeled size (diameter) of transcatheter heart valves through an ex vivo bench study. BACKGROUND: Transcatheter heart valves function optimally when expanded to specific dimensions. However, clinicians may sometimes wish to overexpand balloon-expandable valves to address specific clinical challenges. The implications of overexpansion have assumed considerable importance, and objective information to guide practice is limited. METHODS: We evaluated SAPIEN 3 transcatheter heart valves (Edwards Lifesciences, Irvine, California). Valves (diameters of 23, 26, and 29 mm) were expanded to nominal dimensions, and then incrementally overexpanded with balloons sized 1-, 2-, and 3-mm larger than the recommended diameter. Valves underwent visual, microcomputed tomography, and hydrodynamic evaluation at various degrees of overexpansion. RESULTS: SAPIEN 3 valves with labeled diameters of 23, 26, and 29 mm could be incrementally overexpanded to midvalve diameters of 26.4, 28.4, and 31.2 mm, respectively. With overexpansion, there was visible restriction of the valve leaflets, which was particularly evident with the smaller valves. After maximal overexpansion of a 26-mm valve a leaflet tear was observed. High-speed video demonstrated impaired leaflet motion of both the 23- and 26-mm valves and hydrodynamic testing documented a regurgitant fraction for the 23- and 26-mm valves above accepted international standards. The maximally overexpanded 29-mm SAPIEN 3 still had relatively normal leaflet motion and excellent hydrodynamic function. Durability was not specifically evaluated. CONCLUSIONS: Overexpansion of balloon-expandable valves is possible. However, excessive overexpansion may be associated with impaired hydrodynamic function, acute leaflet failure, and reduced durability. Smaller valves may be at greater risk with overexpansion than larger valves. Overexpansion is best avoided unless clinical circumstances are compelling.

Commentary: Nurses' positive impact across the continuum.

Leaders need to look far ahead, setting a course that "excites and engages" others in improving nurses' positive impact on health, throughout life and at the time of death.

Investigating some of the factors that influence "consumer" choice when adopting a shelter dog in the United kingdom.

This study examined which characteristics of dogs available at a large rehoming organization in the United Kingdom influenced prospective adopters' choices. The revealed preference data used to model "consumer" choice were from the Dogs Trust rehoming web pages. The analysis of the probability of adoption involved a logistic regression model with multiple imputation. The factors that had a significant impact on the adopters' choices were age, size, pedigree status, coat length, behavior (e.g., fearfulness, adjustment issues), friendliness (toward children, dogs, and other pets), and training. This study offers a quantitative analysis of adopters' preferences that could prove to be useful for shelter personnel and researchers interested in the analysis of companion animal markets.

Biosecurity and yield improvement technologies are strategic complements in the fight against food insecurity.

The delivery of food security via continued crop yield improvement alone is not an effective food security strategy, and must be supported by pre- and post-border biosecurity policies to guard against perverse outcomes. In the wake of the green revolution, yield gains have been in steady decline, while post-harvest crop losses have increased as a result of insufficiently resourced and uncoordinated efforts to control spoilage throughout global transport and storage networks. This paper focuses on the role that biosecurity is set to play in future food security by preventing both pre- and post-harvest losses, thereby protecting crop yield. We model biosecurity as a food security technology that may complement conventional yield improvement policies if the gains in global farm profits are sufficient to offset the costs of implementation and maintenance. Using phytosanitary measures that slow global spread of the Ug99 strain of wheat stem rust as an example of pre-border biosecurity risk mitigation and combining it with post-border surveillance and invasive alien species control efforts, we estimate global farm profitability may be improved by over US$4.5 billion per annum.

Similar effects of foods high in protein, carbohydrate and fat on subsequent spontaneous food intake in healthy individuals.

Pre-loads high in protein, as compared to carbohydrate and fat, produce greater satiety and reduce food intake after a fixed time interval. This study investigated the effect of macronutrient composition on spontaneous eating behaviour. On four separate occasions, 16 fasted, healthy, non-obese men, blinded to the true purpose of the study, consumed iso-energetic ( approximately 3MJ) yoghurt-based pre-loads of equivalent weight ( approximately 0.5 kg), high in fat (40%) [HF], carbohydrate (60%) [HC] or protein (29%) [HP], and no pre-load in a randomized, single-blind fashion. Subjects ate at will from a selection of food items for the remainder of the day (7 h) with the time of food requests (h) and energy content (kJ) and macronutrient distribution (%) of food eaten recorded. The three pre-loads delayed the first spontaneous request for food by 1.5-1.8 h relative to no pre-load. Total spontaneous food intake was suppressed 29% [HP], 20% [HF] and 17% [HC] by the pre-loads. Neither the amount of food eaten per spontaneous eating episode, nor the spontaneous eating frequency differed statistically following ingestion of the different pre-loads or no pre-load. In this study, in subjects who were free to choose when as well as how much they ate, a high-protein pre-load exerted similar effects on satiety as did iso-energetic high-fat and high-carbohydrate pre-loads.