Assessment of accuracy of the Doppler pressure half-time method in the estimation of the mitral valve area immediately after balloon mitral valvuloplasty

AIM: The reliability of Doppler echocardiography in determining the mitral valve area after balloon mitral valvuloplasty has been questioned, as discrepancies were noted between measurements obtained by the pressure half-time method and those derived haemodynamically, immediately following completion of the procedure. Recent investigations, however, have indicated that these discrepancies may be attributable to the over-estimation of the mitral valve area by haemodynamic measurements, caused by the presence of the iatrogenic atrial septal defect complicating transseptal catheterization. The aim of the present study was to further test this hypothesis. METHODS AND RESULTS: Measurements of the mitral valve area by the Doppler pressure half-time method and the Gorlin formula were obtained and compared in 238 consecutive patients before and immediately after retrograde non-transseptal balloon mitral valvuloplasty, which does not involve puncture and/or dilatation of the inter-atrial septum. No significant difference was found between Doppler- and Gorlin-derived measurements, neither before (1.04 +/- 0.23 vs 1.03 +/- 0.23 cm2, P = ns) nor immediately after (2.14 +/- 0.47 vs 2.12 +/- 0.49 cm2, P = ns) valvuloplasty. Linear regression analysis demonstrated a high degree of correlation between Doppler and Gorlin measurements before (r = 0.778) and after (r = 0.886) the procedure. Good agreement was confirmed by the Bland-Altman method. CONCLUSION: Doppler echocardiography yields accurate measurements of the mitral valve area immediately after retrograde non-transseptal balloon mitral valvuloplasty. This finding supports the hypothesis that the creation of an iatrogenic atrial septal defect during transseptal catheterization may contribute to the poor agreement between Doppler and Gorlin data after balloon mitral valvuloplasty.     

Hydrogen infrastructure strategic planning using multi-objective optimization

Increasingly, hydrogen is being promoted as an alternative energy carrier for a sustainable future. Many argue that its use as a transportation fuel in fuel cell vehicles offers a number of attractive advantages over existing energy sources, especially in terms of well-to-wheel greenhouse gas emissions. Following this interest, several of the leading energy companies, like BP, have started investigating strategies for its introduction. The challenge of developing a future commercial hydrogen economy clearly still remains, though: what are the energy efficient, environmentally benign and cost effective pathways to deliver hydrogen to the consumer? Establishing what these “best” pathways may be is not trivial, given that a large number of technological options exist and are still in development for its manufacturing, storage, distribution and dispensing. Cost, operability, reliability, environmental impacts, safety and social implications are all performance measures that should be considered when assessing the different pathways as viable long-term alternatives. To aid this decision-making process, we present a generic optimization-based model for the strategic long-range investment planning and design of future hydrogen supply chains. By utilizing Mixed Integer Linear Programming (MILP) techniques, the model is capable of identifying optimal investment strategies and integrated supply chain configurations from the many alternatives. Realizing also that multiple performance criteria are of interest, the optimization is conducted in terms of both investment and environmental criteria, with the ultimate outcome being a set of optimal trade-off solutions representing conflicting infrastructure pathways. Since many agree that there is no one single template strategy for investing in a hydrogen infrastructure across the globe, emphasis is placed on developing a generic model such that it can be readily applied to different scenarios, geographical regions and case studies. As such, the model supports BP's strategic hydrogen infrastructure planning using high-level optimization programming, and is coined bpIC-H2. The features and capabilities of the model are illustrated through the application to a case study.     

Retrograde nontransseptal balloon mitral valvuloplasty: immediate results and intermediate long-term outcome in 441 cases--a multicenter experience

OBJECTIVES: Our aim was to present the immediate and intermediate long-term results of the application of retrograde nontransseptal balloon mitral valvuloplasty (RNBMV) in four cooperating centers from Greece and India. BACKGROUND: RNBMV is a purely transarterial method of balloon valvuloplasty, developed with the aim to avoid complications associated with transseptal catheterization. Only single-center experience with RNBMV has been previously reported. METHODS: The procedure was attempted in 441 patients with symptomatic mitral stenosis (320 women, 121 men, mean age [+/-SD] 44+/-11 years, mean echocardiographic score [+/-SD] 7.7+/-2.0) from 1988 to 1996. Three hundred eighty-five patients with successful immediate outcome were followed clinically for a mean [+/-SD] of 3.5+/-1.9 (range, 0.5-9.1) years. RESULTS: A technically successful procedure was achieved in 388 (88%) cases. The echocardiographic score (p < 0.001), male gender (p=0.005), preprocedural mitral regurgitation (p=0.007) and previous surgical commissurotomy (p=0.029) were unfavorable predictors of immediate outcome. Complications included death (0.2%), severe mitral regurgitation (3.4%) and injury of the femoral artery (1.1%). Event-free (freedom from cardiac death, mitral valve surgery, repeat valvuloplasty and NYHA class > II symptoms) survival rates (+/-SEM) were 100%, 96.9+/-0.9%, 89.8+/-1.9% and 75.5+/-5.5% at 1, 2, 4 and 9 years, respectively. The echocardiographic score (p < 0.001), NYHA class (p=0.008) and postprocedural mitral valve area (p=0.009) were significant independent predictors of intermediate long-term outcome. CONCLUSIONS: Multicenter experience indicates that RNBMV is a safe and effective technique for the treatment of symptomatic mitral stenosis. As with the transseptal approach, patients with favorable mitral valve anatomy derive the greatest immediate and intermediate long-term benefit from this procedure.     

Transactional support for adaptive indexing

Adaptive indexing initializes and optimizes indexes incrementally, as a side effect of query processing. The goal is to achieve the benefits of indexes while hiding or minimizing the costs of index creation. However, index-optimizing side effects seem to turn read-only queries into update transactions that might, for example, create lock contention. This paper studies concurrency control and recovery in the context of adaptive indexing. We show that the design and implementation of adaptive indexing rigorously separates index structures from index contents; this relaxes constraints and requirements during adaptive indexing compared to those of traditional index updates. Our design adapts to the fact that an adaptive index is refined continuously and exploits any concurrency opportunities in a dynamic way. A detailed experimental analysis demonstrates that (a) adaptive indexing maintains its adaptive properties even when running concurrent queries, (b) adaptive indexing can exploit the opportunity for parallelism due to concurrent queries, (c) the number of concurrency conflicts and any concurrency administration overheads follow an adaptive behavior, decreasing as the workload evolves and adapting to the workload needs.     

ADS: the adaptive data series index

Numerous applications continuously produce big amounts of data series, and in several time critical scenarios analysts need to be able to query these data as soon as they become available. This, however, is not currently possible with the state-of-the-art indexing methods and for very large data series collections. In this paper, we present the first adaptive indexing mechanism, specifically tailored to solve the problem of indexing and querying very large data series collections. We present a detailed design and evaluation of our method using approximate and exact query algorithms with both synthetic and real data sets. Adaptive indexing significantly outperforms previous solutions, gracefully handling large data series collections, reducing the data to query delay: By the time state-of-the-art indexing techniques finish indexing 1 billion data series (and before answering even a single query), our method has already answered \(3*10^5\) queries.     

Aortic function in patients during intra-aortic balloon pumping determined by the pressure-diameter relation

Rats injected with a single, 50-mg dose of bromoethylamine (BEA) developed papillary necrosis accompanied by sever interstitial fibrosis. At 1 mo, the creatinine clearance decreased (control 0.66 versus BEA 0.33 ml/min per 100 g body wt, P = 0.02), and the urine albumin-to-creatinine ratio increased markedly (control 0.19 versus BEA 0.51, P = 0.02). In a group of animals given the angiotensin-converting enzyme inhibitor enalapril (Enal; 100 mg/L) in their drinking water for 4 wk, beginning 1 wk before BEA injection, creatinine clearance improved significantly (BEA 0.33 versus Enal + BEA 0.52 ml/min per 100 g body wt, P = 0.01) and albumin excretion fell to zero. Histologic examination revealed an 88% decrease in the area of papillary necrosis and a decrease in the degree of interstitial fibrosis in the corticomedullary junction. To determine whether this was due to changes in urine flow rate induced by enalapril, a group of animals was injected with BEA, and enalapril at the above dose was begun 1 wk later. After 1 mo, the enalapril-treated animals showed the same improvement in creatinine clearance (BEA 0.33 versus BEA + Enal 0.50 ml/min per 100 g body wt, P = 0.03) and suppression of albumin excretion. The area of papillary necrosis was reduced by 67%. In the BEA animals treated with enalapril, ED-1-positive cells, alpha-smooth muscle actin, and transforming growth factor-beta1 were decreased compared with BEA alone. It is concluded that in this model of papillary necrosis, enalapril protects renal function and decreases interstitial fibrosis mediated at least in part through an angiotensin II/bradykinin-dependent mechanism.