2,167 research outputs found
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
Exploring a black box: cross-national study of visit effects on visitors to large physics research centers in Europe
No full textResults from a cross-national quantitative study of 3,301 visitors to four large physics research centers in Europe focus on short-term learning and motivational effects. The authors collected data from these visitors before and after visiting the centers as part of a research project funded by the European Union. Overall, visitors' knowledge of the research centers increased. However, effects on learning of scientific concepts are not so clear. The visits mostly seem to reaffirm visitors' prior attitudes and images related to the centers. The findings imply that these visits offer some learning potential and, for school students, increased motivation to enter a scientific profession, but in terms of altering visitors' images they seem rather ineffective. Nevertheless, because of their uniqueness in allowing different publics an authentic glimpse of the production of scientific knowledge, visits to research centers remain an important public communication activity
Cardiovascular and ventilatory control during exercise in chronic heart failure: role of muscle reflexes
No full textDuring exercise nervous signals are generated by stimulation of mechanically (muscle mechanoreflex) and chemically (muscle metaboreflex) sensitive skeletal muscle receptors. These receptors and their associated afferent fibres are sensitive to muscle work and reflexively adjust the haemodynamic, ventilatory and circulatory responses during physical effort. Thus the muscle reflex is essential in achieving normal responses to exercise in healthy subjects. In chronic heart failure, characterised by exercise intolerance with early occurrence of dyspnea or fatigue, peripheral muscle abnormalities (i.e. muscle atrophy, decreased peripheral blood flow, fibre-type transformation, and reduced oxidative capacity) trigger an exaggerated muscle reflex. This abnormality has recently been implicated in the genesis of the disabling symptoms. We review the role of the muscle reflex in regulating the cardiovascular and the ventilatory systems during exercise in both healthy and diseased condition
New advances in dynamic cardiomyoplasty: Doppler flow wire shows improved cardiac assistance in demand protocol
No full textASAIO J. 2002 Jan-Feb;48(1):119-23.
New advances in dynamic cardiomyoplasty: Doppler flow wire shows improved cardiac assistance in demand protocol.
Rigatelli G, Carraro U, Barbiero M, Zanchetta M, Pedon L, Dimopoulos K, Rigatelli G, Maiolino P, Cobelli F, Riccardi R, Volta SD.
Source
Department of Cardiology, Legnago General Hospital, Verona, Italy.
Abstract
No data have been published on real cardiac assistance with demand dynamic cardiomyoplasty. We tested the utility of a Doppler flow wire in measuring beat by beat aortic flow velocity and evaluating cardiac assistance in demand cardiomyoplasty patients. The technique was tested in seven patients (M/W = 6/1; age, 57.1+/-6.2 years; atrial fibrillation/ sinus rhythm = 1/6; New York Heart Association [NYHA] classification = 1.4+/-0.5). Measurements were done using a 0.018 inch peripheral Doppler flow wire advanced through a 5 French arterial femoral sheath. Three 1 minute periods with the stimulator off, and three 1 minute periods with clinical stimulation were recorded. We measured peak aortic flow velocity in all beats. Latissimus dorsi mechanogram was simultaneously recorded. Comparison between preoperative and follow-up data showed significantly higher values of tetanic fusion frequency 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 the 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 increase in flow velocity and latissimus dorsi wrap tetanic fusion frequency (r2 = 0.53). In demand dynamic cardiomyoplasty, systolic assistance is significant and correlated to the latissimus dorsi speed of contraction; a demand stimulation protocol maintains muscle properties and increases muscle performance.
PMID:
11814090
[PubMed - indexed for MEDLINE
Elderly versus non-elderly patients with intra-abdominal candidiasis in the ICU
No full textIntra-abdominal candidiasis (IAC) has a considerable cost in terms of mortality and morbidity. We sought to study the epidemiology, characteristics and outcome of elderly (>75 years old) versus non-elderly patients with IAC and risk factors for mortality in elderly patients
K-meson vector and tensor decay constants and B(K)-parameter from N(f) = 2 tmQCD
No full textWe present work in progress on the computation of the K-meson vector and tensor decay constants, as well as the B-parameter in Kaon oscillations. Our simulations are performed in a partially quenched setup, with two dynamical (sea) Wilson quark flavours, having a maximally twisted mass term. Valence quarks are either of the standard or the Osterwalder-Seiler maximally twisted variety. These two regularizations can be suitably combined in order to obtain a BK parameter which is both multiplicatively renormalizable and O(a) improved
Biogeographical determinants for total and endemic species richness in a continental archipelago
No full textWe examined the relationship between plant species richness and biogeographical variables (island area, island maximum elevation, distance from nearest inhabited island, distance from nearest mainland) using a data set comprising 201 islands of the Aegean archipelago. We found that endemic species richness was strongly correlated to total species richness. Single-island endemic species richness was most strongly correlated to island maximum elevation, and then to island area, with an apparent small island effect for islands smaller than 47 km(2). Total species richness was most strongly correlated to island area (with no apparent small island effect), and less strongly correlated to island maximum elevation. Distance from the mainland or other inhabited islands displayed limited predictive value in our data set. The slope of the relationship between species richness and geographical factors (island area, elevation, distance from island/mainland) was steeper for endemic species richness than for total richness. Finally, the different scales of endemicity (single-island endemics, island group endemics and Aegean regional endemics) displayed similar qualitative trends and only differed quantitatively. Thus, we conclude that different biogeographical factors act as drivers for total species richness than for endemic species richness
Top quark phenomenology of the ADD model and the minimal length scenario
No full textWe study top-(anti)quark pair production at the Tevatron and Large Hadron Collider in the context of the minimal length scenario of the Arkani-Hamed, Dimopoulos and Dvali model of extra dimensions. We show that sizable effects onto both the integrated and differential cross section due to graviton mediation are expected for a string scale, MS, of Ô(1–10 TeV) and several extra dimensions, δ, all compatible with current experimental constraints. Potential limits on MS are extracted. We also highlight clear phenomenological differences between a simple Arkani-Hamed, Dimopoulos and Dvali scenario and its modification based on using the minimal length scenario as a natural regulator for divergent amplitudes of virtual KK graviton exchange
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