The Hybrid Approach to Intervention of Chronic Total Occlusions

The "hybrid" approach to chronic total occlusion (CTO) percutaneous coronary intervention (PCI) was developed to provide guidance on optimal crossing strategy selection. Dual angiography remains the cornerstone of clinical decision making in CTO PCI. Four angiographic parameters are assessed: (a) morphology of the proximal cap (clear-cut or ambiguous); (b) occlusion length; (c) distal vessel size and presence of bifurcations beyond the distal cap; and (d) location and suitability of location and suitability of a retrograde conduit (collateral channels or bypass grafts) for retrograde access. Antegrade wire escalation is favored for short (<20 mm) occlusions, usually escalating rapidly from a soft tapered-tip polymer-jacketed guidewire to a stiff polymer-jacketed or tapered-tip guidewire. Antegrade dissection/re-entry is favored in long (≥20 mm long) occlusions, trying to minimize the dissection length by re-entering into the distal true lumen immediately after the occlusion. Primary retrograde approach is preferred for lesions with an ambiguous proximal cap, poor distal target, good interventional collaterals, and heavy calcification,as well as chronic kidney disease. The "hybrid" approach advocates early change between strategies to enable CTO crossing in the most efficacious, efficient, and safe way. Several early studies are demonstrating high success and low complication rates with use of the "hybrid" approach, supporting its expanding use in CTO PCI

In-Stent Restenosis in Saphenous Vein Grafts (from the DIVA Trial)

Saphenous vein grafts (SVGs) have high rates of in-stent restenosis (ISR). We compared the baseline clinical and angiographic characteristics of patients and lesions that did develop ISR with those who did not develop ISR during a median follow-up of 2.7 years in the DIVA study (NCT01121224). We also examined the ISR types using the Mehran classification. ISR developed in 119 out of the 575 DIVA patients (21%), with similar incidence among patients with drug-eluting stents and bare-metal stents (BMS) (21% vs 21%, p = 0.957). Patients in the ISR group were younger (67 ± 7 vs 69 ± 8 years, p = 0.04) and less likely to have heart failure (27% vs 38%, p = 0.03) and SVG lesions with Thrombolysis In Myocardial Infarction 3 flow before the intervention (77% vs 83%, p <0.01), but had a higher number of target SVG lesions (1.33 ± 0.64 vs 1.16 ± 0.42, p <0.01), more stents implanted in the target SVG lesions (1.52 ± 0.80 vs 1.31 ± 0.66, p <0.01), and longer total stent length (31.37 ± 22.11 vs 25.64 ± 17.42 mm, p = 0.01). The incidence of diffuse ISR was similar in patients who received drug-eluting-stents and BMS (57% vs 54%, p = 0.94), but BMS patients were more likely to develop occlusive restenosis (17% vs 33%, p = 0.05). © 202

Conceptualizing Social Responsibility in Operations via Stakeholder Resource-Based View

We seek to conceptualize social responsibility for operations management (OM) research to develop a social responsibility lens through which to view operations. To do so, we first consider the corporate social responsibility, sustainability, as well as the bottom-ofthe-pyramid and shared value approaches and identify three challenges to developing such a lens: selecting the level of analysis, tackling the huge multitude of objectives, and developing theoretical underpinnings. We then propose a ‘stakeholder resource-based view’ (SRBV) building on resource-based view, stakeholder theory, and utility theory to address these challenges. Under SRBV, all stakeholders are treated on a par with each other. These different stakeholders are all presumed to seek maximizing their respective (expected) utility, with different drivers shaping their preferences and do so they use their respective resources, routines and dynamic capabilities. SRBV provides (a) a descriptive framework for qualitative research, (b) an instrumental framework for empirical research, and (c) a normative framework for analytical research. It enables tackling many opportunities for OM research to do with social responsibility and we outline some of these in each of the three types of research methodologies

Stent-Only Versus Adjunctive Balloon Angioplasty Approach for Saphenous Vein Graft Percutaneous Coronary Intervention

BACKGROUND: Direct stenting without pre-dilation or post-dilation has been advocated for saphenous vein graft percutaneous coronary intervention to decrease the incidence of distal embolization, periprocedural myocardial infarction, and target lesion revascularization. METHODS: We performed a post hoc analysis of patients enrolled in the DIVA (Drug-Eluting Stents Versus Bare Metal Stents in Saphenous Vein Graft Angioplasty; ) prospective, double-blind, randomized controlled trial. Patients were stratified into stent-only and balloon-stent groups. Primary end point was 12-month incidence of target vessel failure (defined as the composite of cardiac death, target vessel myocardial infarction, or target vessel revascularization). Secondary end points included all-cause death, stent thrombosis, myocardial infarction, and target lesion revascularization during follow-up. RESULTS: Of the 575 patients included in this substudy, 185 (32%) patients underwent stent-only percutaneous coronary intervention. Patients in the stent-only versus balloon-stent group had similar baseline characteristics and similar incidence of target vessel failure at 12-months (15% versus 19%; hazard ratio, 1.34 [95% CI, 0.86–2.08]; P=0.19). During long-term follow-up (median of 2.7 years), the incidence of definite stent thrombosis (1% versus 5%; hazard ratio, 9.20 [95% CI, 1.23–68.92]; P=0.0085), the composite of definite or probable stent thrombosis (5% versus 11%; hazard ratio, 2.52 [95% CI, 1.23–5.18]; P=0.009), and target vessel myocardial infarction (8% versus 14%; hazard ratio, 1.92 [95% CI, 1.08–3.40]; P=0.023) was lower in the stent-only group. Multivariable analysis showed that a higher number of years since coronary artery bypass grafting and >1 target saphenous vein graft lesions were associated with increased target vessel failure during entire follow-up, while preintervention Thrombolysis in Myocardial Infarction-3 flow was protective. CONCLUSIONS: In patients undergoing percutaneous coronary intervention of de novo saphenous vein graft lesions, there was no difference in target vessel failure at 12 months and long-term follow-up in the stent-only versus the balloon-stent group; however, the incidence of stent thrombosis was lower in the stent-only group, as was target vessel myocardial infarction

Use of Intravascular Imaging During Chronic Total Occlusion Percutaneous Coronary Intervention: Insights From a Contemporary Multicenter Registry

Background: Intravascular imaging can facilitate chronic total occlusion (CTO) percutaneous coronary intervention. Methods and Results: We examined the frequency of use and outcomes of intravascular imaging among 619 CTO percutaneous coronary interventions performed between 2012 and 2015 at 7 US centers. Mean age was 65.4±10 years and 85% of the patients were men. Intravascular imaging was used in 38%: intravascular ultrasound in 36%, optical coherence tomography in 3%, and both in 1.45%. Intravascular imaging was used for stent sizing (26.3%), stent optimization (38.0%), and CTO crossing (35.7%, antegrade in 27.9%, and retrograde in 7.8%). Intravascular imaging to facilitate crossing was used more frequently in lesions with proximal cap ambiguity (49% versus 26%, P<0.0001) and with retrograde as compared with antegrade‐only cases (67% versus 31%, P<0.0001). Despite higher complexity (Japanese CTO score: 2.86±1.19 versus 2.43±1.19, P=0.001), cases in which imaging was used for crossing had similar technical and procedural success (92.8% versus 89.6%, P=0.302 and 90.1% versus 88.3%, P=0.588, respectively) and similar incidence of major cardiac adverse events (2.7% versus 3.2%, P=0.772). Use of intravascular imaging was associated with longer procedure (192 minutes [interquartile range 130, 255] versus 131 minutes [90, 192], P<0.0001) and fluoroscopy (71 minutes [44, 93] versus 39 minutes [25, 69], P<0.0001) time. Conclusions: Intravascular imaging is frequently performed during CTO percutaneous coronary intervention both for crossing and for stent selection/optimization. Despite its use in more complex lesion subsets, intravascular imaging was associated with similar rates of technical and procedural success for CTO percutaneous coronary intervention. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT02061436

Life cycle energy and carbon footprint analysis of large MW scale grid connected wind power systems in India

The centralized grid is the main electrical supply to the country. About 80% of the installed generation capacity is fossil fuel fired power plants, though there is increase in share of renewable generation over the years. India has significant wind potential, and a major share in the renewable generation of the country. The energy and carbon footprint sustainability of wind power systems in Indian conditions is the focus of this research. This paper presents a study of large grid connected wind storage systems with reference to the cradle to grave primary energy requirements and carbon emissions in an Indian scenario

An approach for building design optimization using design of experiments

Building simulation based optimization involves direct coupling of the optimization algorithm to a simulation model, making it computationally intensive. To overcome this issue, an approach is proposed using a combination of experimental design techniques (fractional factorial design and response surface methodology). These techniques approximate the simulation model behavior using surrogate models, which are several orders of magnitude faster than the simulation model. Fractional factorial design is used to identify the significant design variables. Response surface methodology is used to create surrogate models for the annual cooling and lighting energy with the screened significant variables. The error for these models is less than 10%, validating their effectiveness. These surrogate models speed up optimization with genetic algorithms, for single- and multi-objective optimization problems and scenario analyses, resulting in a better solution. Thus, optimization becomes possible within reasonable computational time with the proposed methodology. This framework is illustrated using the case study of a three-storey office building for New Delhi