1,721,129 research outputs found
Demand dynamic biogirdling: ten-year results
No full textDemand dynamic biogirdling: ten-year results. Rigatelli G, Carraro U, Riccardi R, Rigatelli G. J Thorac Cardiovasc Surg. 2009 Jan;137(1):e58-9. No abstract available.
PMID:
19154889
[PubMed - indexed for MEDLINE
A review of the concept of circulatory bioassist focused on the "new" demand dynamic cardiomyoplasty: the renewal of dynamic cardiomyoplasty?
No full textAngiology. 2003 May-Jun;54(3):301-6.
A review of the concept of circulatory bioassist focused on the "new" demand dynamic cardiomyoplasty: the renewal of dynamic cardiomyoplasty?
Rigatelli G, Carraro U, Barbiero M, Riccardi R, Cobelli F, Gemelli M, Rigatelli G.
Source
Cardiomyoplasty Project Unit, Legnago General Hospital, Verona, Italy. [email protected]
Abstract
After the initial enthusiasm, the dynamic cardiomyoplasty lost its reputation owing to the poor long-term results, caused by the muscular degeneration subsequent to chronic continuous electrical stimulation of the latissimus dorsi. An activity-rest stimulation protocol that avoids full transformation of the skeletal muscle, maintaining muscular properties over time, has been successfully tried. This "demand" stimulation protocol showed in humans good results improving NYHA class, ejection fraction value, and survival. The discussion about the capability of this and a unique kind of cardiocirculatory bioassist is due to be reopened. In fact, heart transplant, percutaneous circulatory-supporting device, multisites stimulation therapy, and total artificial heart have some drawbacks, one of which is the economic cost. In developing countries the more economic demand dynamic cardiomyoplasty may still play a role.
PMID:
12785022
[PubMed - indexed for MEDLINE
Cardiocirculatory bio-assist: is it time to reconsider demand dynamic cardiomyoplasty? Review and future perspectives
No full textASAIO J. 2003 Jan-Feb;49(1):24-9.
Cardiocirculatory bio-assist: is it time to reconsider demand dynamic cardiomyoplasty? Review and future perspectives.
Rigatelli G, Barbiero M, Rigatelli G, Cotocni A, Riccardi R, Cobelli F, Carraro U.
Source
Cardiomyopathy Project Unit, Legnago General Hospital, Verona, Italy.
Abstract
In the last 15 years, dynamic cardiomyoplasty has remained an experimental procedure even after the enthusiastic short- and mid-term results, mainly because of the disappointing long-term outcome caused by muscular degeneration secondary to chronic continuous electrical stimulation of the latissimus dorsi. In Italy, a group of muscular pathologists, cardiologists, and cardiac surgeons conducted an experiment of an activity-rest stimulation protocol in humans that should avoid complete transformation of the skeletal muscle, maintaining its properties overtime. This "demand" stimulation protocol gave good results, improving New York Heart Association class, ejection fraction value, and survival. Even though dynamic cardiomyoplasty was excluded from the recent international guidelines for the management of heart failure, the discussion on the ability of this unique kind of cardiocirculatory bio-assistance is due to be reopened, thanks to the results of the new stimulation protocol. Heart transplantation, circulatory supporting devices, multisite stimulation therapy, and the total artificial heart are not always and in all countries the best solutions: the great economic cost, the numerous contraindications, the need for immunosuppression and antithrombotic therapy, and the troublesome follow up constitute important drawbacks. For patients in whom transplant surgery cannot be performed, as well as in developing countries, the nonprohibitively expensive demand dynamic cardiomyoplasty may still play a role.
PMID:
12558303
[PubMed - indexed for MEDLINE
Activity-rest stimulation protocol improves cardiac assistance in dynamic cardiomyoplasty
No full textEur J Cardiothorac Surg. 2002 Mar;21(3):478-82.
Activity-rest stimulation protocol improves cardiac assistance in dynamic cardiomyoplasty.
Rigatelli G, Carraro U, Barbiero M, Zanchetta M, Dimopoulos K, Cobelli F, Riccardi R, Rigatelli G.
Source
Department of Cardiology, Interventional Cardiology Lab and Cardiomyoplasty Project Unit, Legnago General Hospital, Verona, Italy. [email protected]
Abstract
OBJECTIVE:
No data have ever been published regarding cardiac assistance in demand dynamic cardiomyoplasty (DDCMP). We tested the efficacy of the Doppler flow wire in measuring beat-to-beat aortic flow velocity and evaluating cardiac assistance in demand cardiomyoplasty patients.
METHODS:
The technique was tested in seven patients (M/F=6/1; age=57.1+/-6.2 years; atrial fibrillation/sinus rhythm=1/6; NYHA=1.4+/-0.5). Measurements were done using a 0.018inch peripheral Doppler flow wire advanced through a 5F arterial femoral sheath. Three 1-min periods with the stimulator off and three 1-min periods with clinical stimulation were recorded. We measured peak aortic flow velocity in all beats. Latissimus dorsi (LD) mechanogram was simultaneously recorded.
RESULTS:
Comparison between pre-operative and follow-up data showed significantly higher values of tetanic fusion frequency (TFF) and ejection fraction at follow-up, whereas mean NYHA class was significantly lower. Statistical analysis showed an increase in aortic flow velocity not only in assisted versus rest period, but also in assisted versus unassisted beats (8.42+/-6.98% and 7.55+/-3.07%). A linear correlation was found between the increase in flow velocity and LD wrap TFF (r(2)=0.53).
CONCLUSIONS:
In DDCMP, systolic assistance is significant and correlated to LD speed of contraction; demand stimulation protocol maintains muscle properties and increases muscle performance.
PMID:
11888767
[PubMed - indexed for MEDLINE
Maintained benefits and improved survival of dynamic cardiomyoplasty by activity-rest stimulation: 5-year results of the Italian trial on "demand" dynamic cardiomyoplasty
No full textEur J Cardiothorac Surg. 2003 Jan;23(1):81-5.
Maintained benefits and improved survival of dynamic cardiomyoplasty by activity-rest stimulation: 5-year results of the Italian trial on "demand" dynamic cardiomyoplasty.
Rigatelli G, Barbiero M, Rigatelli G, Riccardi R, Cobelli F, Cotogni A, Bandello A, Carraro U.
Source
Cardiomyoplasty Project Unit, Legnago General Hospital, Via T. Speri 18, 37040 Legnago, Verona, Italy. [email protected]
Abstract
OBJECTIVE:
Latissimus dorsi (LD) muscular degeneration caused by continuous electrical stimulation has been the main cause of the poor results of dynamic cardiomyoplasty (DCMP) and its exclusion from the recent international guidelines on heart failure. To avoid full transformation of the LD and to improve results, a new stimulation protocol was developed; fewer impulses per day are delivered, providing the LD wrap with daily periods of rest ("demand" stimulation), based on a heart rate cut-off. The aim of this work is to report the results at 5 years of follow-up of the Italian Trial of Demand Dynamic Cardiomyoplasty and to discuss their impact on the destiny of this type of cardiac assistance.
METHODS:
Twelve patients with dilated myocardiopathy (M/F=11/1, mean age 58.2+/-5.8 years, sinus rhythm/atrial fibrillation=11/1) were submitted during the period 1993-1996 to DCMP and at different intervals to demand protocol. Clinical, echocardiographic, mechanographic and cardiac invasive assessments were scheduled before initiating the demand protocol and during the follow-up at 0, 6 and every 12 months.
RESULTS:
The mean duration of follow-up was 40.2+/-13.8 months (range 18-64). There were no perioperative deaths. The demand stimulation protocol showed a decrease in 5 years in New York Health Association (NYHA) class (3.17+/-0.38-1.67+/-0.77, P=0.0001), an improvement of left ventricular ejection fraction (22.6+/-4.38-32.0+/-7.0, P<0.001), a 5-year actuarial survival of 83.3% (one patient was switched to heart transplantation programme due to clinical worsening and another one died of massive pulmonary embolism).
CONCLUSIONS:
Demand DCMP maintains over time LD muscular properties, enhances clinical benefits and improves survival of DCMP, thus reopening the debate whether this type of treatment should be considered in patients with end-stage heart failure.
PMID:
12493509
[PubMed - indexed for MEDLINE
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Two-stage super-efficiency model for measuring efficiency of education in South-East Asia
Full text linkThis paper aims to measure the efficiency of schools in six South-East Asian countries, taking into account the impacts of information and communication technologies (ICT). The educational institutions of South-East Asia are very dynamic; and to increase their competitiveness at international level, they need to manage their resources in an efficient way. We propose a two-stage super-efficiency model for measuring their efficiency, using 2018 PISA data. In the first stage, the non-parametric data envelopment analysis super-efficiency model is used to rank the schools in this region. Then, a second-stage analysis based on a bootstrapped quantile regression is performed to identify the factors that potentially influence efficiency. We analyze four different scenarios depending on the output considered. In the first stage of the analysis, Singapore has the best performance among the other countries in all scenarios. In the second stage, our results show that ICT is statistically significant as a determinant of efficiency in terms of the ratio of computers connected to the internet. However, the integration of ICT in education is mainly influenced by the socio-economic and educational factors of the analyzed countries. Moreover, concerning the other factors, the lower efficiency schools benefit more from the number of female students than higher efficiency schools. The reverse happens for the proportion of certified teachers
Solving linear multiplicative programs via branch-and-bound: a computational experience
Full text linkIn this paper, linear multiplicative programs are approached with a branch-and-bound scheme and a detailed computational study is provided. Several underestimation functions are analyzed and various partitioning criteria are presented. A particular class of linear multiplicative programs, useful to solve some applicative bilevel problems, is considered from a theoretical point of view to emphasize an efficient solution method. Detailed results of the computational study are provided to point out the performances provided by using various underestimation functions and partitioning criteria, thus improving some of the results of the current literature
How efficient are schools in South-East Asia? An analysis through OECD PISA 2018 data
No full textThis study assesses school efficiency in six South-East Asian countries using OECD PISA 2018 data. The average PISA scores were 425.4 in mathematics, 429.5 in science, and 406.2 in reading, with Singapore scoring the highest and the Philippines lowest. Using stochastic frontier analysis, the study model's efficiency across these domains, finding average efficiency scores of 38.47% in math, 48.83% in science, and 49.82% in reading. The study also examines how ICT affects scores and efficiency, suggesting that internet-connected computers can improve PISA scores, while general computer availability may boost efficiency. This analysis offers a benchmark for schools in the region, providing insights into factors that influence both PISA performance and efficiency
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