To evaluate by intravascular ultrasound (IVUS) the characteristics of the culprit lesion with plaque rupture without significant angiographic stenosis after acute coronary syndromes (ACS).
After ACS, ...IVUS was performed in 68 patients (46.8 years±11.9) without significant angiographic stenosis (31±15%). Plaque rupture was defined as a cavity within the plaque, communicating with the arterial lumen and having an overlying residual fibrous cap fragment. Qualitative analysis defined the type of plaque, and quantitative analysis evaluated plaque plus media area, plaque volume, plaque burden, and arterial remodeling index. Patients were divided into two groups: Group I with plaque rupture (25 patients) and Group II without plaque rupture (43 patients).
All patients with rupture showed soft or mixed plaque but no calcified plaque. In Group I, plaque rupture was associated with a larger plaque burden (49.8±12.3% vs. 39.8±12.1%, P<.0005), a more significant plaque plus media area (7.44±2.9 vs. 5.24±2.4mm2, P<.001), a greater plaque volume (151.9±103.4 vs. 99.2±81.6mm3, P<.007), and a higher ratio of plaque volume over length (8.0±3.8 vs. 5.6±3.7mm3/mm, P<.003). In Group I, positive remodeling was more frequent than intermediate remodeling (P<.03) or negative remodeling (P<.005). In Group II, there was no significant difference between the three types of remodeling.
The plaque ruptures responsible for ACS frequently appear on voluminous plaques with a large plaque burden and positive arterial remodeling.
Étudier par l’échographie endocoronaire les caractéristiques morphologiques de la lésion rompue au décours d’un syndrome coronarien aigu sans lésion angiographique significative.
Une échographie endocoronaire a été réalisée chez 68 patients (46.8±11,9ans) après un SCA (21 IDM et 47 angor instable) sans sténose angiographique significative (31%±15). La rupture était authentifiée par la présence d’une cavité au sein de la plaque, communiquant avec la lumière artérielle et recouverte d’un fragment de chape fibreuse. L’analyse qualitative de la plaque a permis de préciser son type échographique, l’analyse quantitative a évalué la surface plaque+média, le volume de plaque, le comblement athéromateux et l’index de remodelage artériel au niveau de la lésion responsable du SCA. Les patients ont été divisés en deux groupes : Groupe I avec rupture (25 patients), Groupe II sans rupture (43 patients).
Les patients avec rupture présentaient tous une plaque molle ou mixte, non calcifiée. La rupture de plaque était associée à un comblement athéromateux plus important dans le groupe I (49,8±12,3% vs 39,8±12,1%, p<0,0005). Il en était de même pour la surface plaque+media (7,4±2,9mm2 vs 5,2±2,4mm2, p<0,001), pour le volume de plaque (151,9±103,4mm3 vs 99,2±81,6mm3, p<0,007) et pour le rapport volume de plaque sur longueur plus élevé (8,0±4,1mm3/mm vs 5,9±3,7mm3/mm, p<0,003). Dans le groupe I, le remodelage positif était plus fréquemment retrouvé que le remodelage intermédiaire (p<0,03) ou que le remodelage négatif (p<0,005). Dans le groupe II, il n’existait pas de différence significative entre les trois types de remodelage.
Les ruptures, responsables d’un SCA, surviennent essentiellement sur des plaques volumineuses, avec important comblement athéromateux et remodelage artériel positif.
Intracoronary ultrasound (ICUS) is increasingly used in clinical practice to study the natural history of coronary artery disease and to assess the effects of intracoronary, catheter-based ...interventions. However, the risk associated with the procedure is not well documented.
ICUS studies performed in 28 centers were retrospectively included; these centers agreed to contribute to the study among a total of 60 centers initially invited. Among the 2207 ICUS studies, 505 (23%) were performed in heart transplant recipients and 1702 (77%) in nontransplant patients. Indication for ICUS was diagnostic imaging in 915 (41%), drug testing in 244 (11%), and guidance for intracoronary interventions in 1048 patients (47%). There were no complications in 2034 patients (92.2%). In 87 patients (3.9%), complications occurred but were judged to be "not related" to ICUS by the operator. In 63 patients (2.9%), spasm occurred during ICUS imaging. In 9 patients (0.4%), complications other than spasm were judged to have a "certain relation" to ICUS, including acute procedural events in 6 (3 acute occlusion, 1 embolism, 1 dissection, and 1 thrombus) and major events in 3 patients (2 occlusion and 1 dissection; all resulting in myocardial infarction). In 14 patients (0.6%), complications with "uncertain relation" to ICUS were recorded, including acute procedural events in 9 (5 acute occlusion, 3 dissection, and 1 arrhythmia) and major events in 5 patients (2 myocardial infarction and 3 emergency coronary artery bypass surgery). The incidence of acute procedural or major complications judged to be associated with ICUS (uncertain relation or certain relation to ICUS) was compared in different patient groups. The complication rate was higher in patients with unstable angina or acute myocardial infarction (2.1% events) as compared with patients with stable angina pectoris and asymptomatic patients (0.8% and 0.4%, respectively; chi 2 = 10.9, P < .01). These complications were also more frequent in patients undergoing interventions (1.9%) as compared with transplant and nontransplant patients undergoing diagnostic ICUS imaging (0% and 0.6%, respectively; chi 2 = 13.5, P < .001). Adverse events were few, and no association was detected between these events and the size or type of ICUS catheter used.
ICUS is associated with (but not necessarily the direct cause of) a minor acute clinical risk. Vessel spasm is the most frequent event occurring during ICUS. Other complications predominantly occur in patients with acute coronary syndromes and during guidance for intervention.
The L3+C detector, a unique tool-set to study cosmic rays Adriani, O.; van den Akker, M.; Banerjee, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2002, Letnik:
488, Številka:
1
Journal Article
Recenzirano
The L3 detector at the CERN electron–positron collider, LEP, has been employed for the study of cosmic ray muons. The muon spectrometer of L3 consists of a set of high-precision drift chambers ...installed inside a magnet with a volume of about
1000
m
3
and a field of
0.5
T
. Muon momenta are measured with a resolution of a few percent at
50
GeV
. The detector is located under
30
m
of overburden. A scintillator air shower array of
54
m
by
30
m
is installed on the roof of the surface hall above L3 in order to estimate the energy and the core position of the shower associated with a sample of detected muons. Thanks to the unique properties of the L3+C detector, muon research topics relevant to various current problems in cosmic ray and particle astrophysics can be studied.
Bose–Einstein correlations of pairs of identical charged pions produced in hadronic Z decays are analyzed in terms of various parametrizations. A good description is achieved using a Lévy stable ...distribution in conjunction with a model where a particle’s momentum is correlated with its space–time point of production, the
τ
-model. Using this description and the measured rapidity and transverse momentum distributions, the space–time evolution of particle emission in two-jet events is reconstructed. However, the elongation of the particle emission region previously observed is not accommodated in the
τ
-model, and this is investigated using an
ad hoc
modification.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this Report, QCD results obtained from a study of hadronic event structure in high energy
e
+
e
-
interactions with the
L3 detector are presented. The operation of the
LEP collider at many ...different collision energies from 91 to 209
GeV offers a unique opportunity to test QCD by measuring the energy dependence of different observables. The main results concern the measurement of the strong coupling constant,
α
s
, from hadronic event shapes and the study of effects of soft gluon coherence in charged particle multiplicity and momentum distributions.
The lifetime of the tau lepton is measured using data collected in 1994 by the L3 detector at LEP. The precise track position information of the Silicon Microvertex Detector is exploited. The tau ...lepton lifetime is determined from the signed impact parameter distribution for 30 322 tau decays into one charged particle and from the decay length distribution for 3891 tau decays into three charged particles. Combining the two methods we obtain $\tau_{\tau}$ = 290.1 $\pm$ 4.0 fs.
Single- and multi-photon events with missing energy are selected in 619 pb−1 of data collected by the L3 detector at LEP at centre-of-mass energies between 189 and 209 GeV. The cross sections of the ...process e+e−→νν̄γ(γ) are found to be in agreement with the Standard Model expectations, and the number of light neutrino species is determined, including lower energy data, to be Nν=2.98±0.05±0.04. Selection results are given in the form of tables which can be used to test future models involving single- and multi-photon signatures at LEP. These final states are also predicted by models with large extra dimensions and by several supersymmetric models. No evidence for such models is found. Among others, lower limits between 1.5 and 0.65 TeV are set, at 95% confidence level, on the new scale of gravity for the number of extra dimensions between 2 and 6.
Exclusive rho rho production in two-photon collisions involving a single highly virtual photon is studied with data collected at LEP at centre-of-mass energies 89GeV < \sqrt{s} < 209GeV with a total ...integrated luminosity of 854.7pb^-1 The cross section of the process gamma gamma^* -> rho rho is determined as a function of the photon virtuality, Q^2 and the two-photon centre-of-mass energy, Wgg, in the kinematic region: 1.2GeV^2 < Q^2 < 30GeV^2 and 1.1GeV < Wgg < 3GeV.
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