Combined percutaneous coronary atherectomy and coronary angioplasty: Experience in 19 consecutive patients

AbstractAmong 82 patients undergoing coronary atherectomy, 19 (23%) underwent this procedure in combination with coronary angioplasty. The most frequently involved vessel was the left anterior descending coronary artery. In 11 patients (58%), attempted atherectomy preceded coronary angioplasty. In 6 of the 11, angioplasty was used after the atherectomy catheter could not be positioned across the lesion; 4 patients underwent “rescue” angioplasty after developing vessel occlusion related to atherectomy and 1 patient had an unsatisfactory result of atherectomy. The success rate of the combined intervention was 82% for these 11 patients.In eight patients (42%), atherectomy was performed after initial angioplasty. In four of the eight, atherectomy was a rescue procedure to manage vessel occlusion by thrombus or intimal dissection and was successful in three. In the other four, angioplasty was performed to establish an easier passage for the atherectomy catheter and was successful in three. Thus, the success rate of the combined intervention was 75% for these eight patients.The overall success rate for all 19 patients was 79%; there was one in-hospital death and one non-Q wave infarction, and one patient required immediate coronary artery surgery. Two other patients underwent coronary artery surgery before hospital discharge. Combined intervention with coronary angioplasty and atherectomy seems to be a relatively safe and effective approach in selected patients when either of these procedures alone is unsuccessful or is accompanied by acute coronary complications

Restenosis after directional coronary atherectomy: Differences between primary atheromatoes and restenosls lesions and influence of subintimal tissue resection

AbstractRates of restenosis were evaluated in 70 patients (74 lesions) after successful directional coronary atherectomy. The extent of vascular tissue resection was correlated with restenosis rates for coronary (n = 59) and vein bypass graft (n = 15) lesions.After 6 months, the overall restenosis rate was 50% (37 of 74 lesions); it was 42% (15 of 36 lesions) when intima alone was resected, 50% (7 of 14 lesions) when media was resected and 63% (15 of 24 lesions) when adventitia was resected. Subintimal tissue resection increased the restenosis rate for vein grafts (43% with intimal resection versus 100% with subintimal resection, p = 0.01) but not for coronary arteries (50% versus 48%). There was no overall difference in restenosis rates after atherectomy between primary lesions and restenosis lesions that occurred after balloon angioplasty (46% versus 54%). Among postballoon angioplasty restenosis lesions, a higher rate of restenosis after atherectomy was found with subintimal than with intimal resection (78% versus 32%, p = 0.01).Tissues from patients undergoing a second atherectomy for restenosis after initial atherectomy (n = 8) demonstrated neointimal hyperplasia that appeared histotogically identical to restenotic tissue developing after balloon angioplasty (n = 37).These data suggest that the cellular response to directional coronary atherectomy is characterized by neointimal proliferation similar to that which may develop after balloon angioplasty. The extent of fibrous hyperplasia appears to be related to the depth of tissue resection in vein graft lesions and coronary artery restenosis lesions that occur after balloon angioplasty but not in primary atheromatous coronary artery lesions

Multi-Jet Event Rates in Deep Inelastic Scattering and Determination of the Strong Coupling Constant

Jet event rates in deep inelastic ep scattering at HERA are investigated applying the modified JADE jet algorithm. The analysis uses data taken with the H1 detector in 1994 and 1995. The data are corrected for detector and hadronization effects and then compared with perturbative QCD predictions using next-to-leading order calculations. The strong coupling constant alpha_S(M_Z^2) is determined evaluating the jet event rates. Values of alpha_S(Q^2) are extracted in four different bins of the negative squared momentum transfer~\qq in the range from 40 GeV2 to 4000 GeV2. A combined fit of the renormalization group equation to these several alpha_S(Q^2) values results in alpha_S(M_Z^2) = 0.117+-0.003(stat)+0.009-0.013(syst)+0.006(jet algorithm).Comment: 17 pages, 4 figures, 3 tables, this version to appear in Eur. Phys. J.; it replaces first posted hep-ex/9807019 which had incorrect figure 4

Measurement of Leading Proton and Neutron Production in Deep Inelastic Scattering at HERA

Deep--inelastic scattering events with a leading baryon have been detected by the H1 experiment at HERA using a forward proton spectrometer and a forward neutron calorimeter. Semi--inclusive cross sections have been measured in the kinematic region 2 <= Q^2 <= 50 GeV^2, 6.10^-5 <= x <= 6.10^-3 and baryon p_T <= MeV, for events with a final state proton with energy 580 <= E' <= 740 GeV, or a neutron with energy E' >= 160 GeV. The measurements are used to test production models and factorization hypotheses. A Regge model of leading baryon production which consists of pion, pomeron and secondary reggeon exchanges gives an acceptable description of both semi-inclusive cross sections in the region 0.7 <= E'/E_p <= 0.9, where E_p is the proton beam energy. The leading neutron data are used to estimate for the first time the structure function of the pion at small Bjorken--x.Comment: 30 pages, 9 figures, 2 tables, submitted to Eur. Phys.

Jets and energy flow in photon-proton collisions at HERA

Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to \overline{p}p data and QCD calculations. The comparisons show that the \gamma p events can be consistently described by QCD models including -- in addition to the primary hard scattering process -- interactions between the two beam remnants. The differential jet cross sections d\sigma/dE_T^{jet} and d\sigma/d\eta^{jet} are measured

Continuous measurements of air content: first results from the EDML ice core, Antarctica

The air content in cold glacier ice depends on the pore space volume and on local air pressure and temperature at the time of pore close-off. A new method to measure the air content of glacier ice has been developed and will be presented. The measurement has been integrated into the Continuous Flow Analysis set-up which is used for chemical profiling of the EPICA ice cores. It allows the continuous determination of the air content at high depth resolution (<1cm). The air content has been measured continuously in the deep ice core from Dronning Maud Land, Antarctica from 700 m to 2560 m depth, which corresponds to approx. 10 ka to 200 ka before present. First results indicate that the smoothed profile is not dominated by the 100 ka cycle but instead by the 40 ka insolation cycle. The high resolution record exhibits considerable variability of the air content even on the cm scale.The correlation of the aircontent with insolation shows that local insolation has an influence on the sintering process of snow and firn, as local pressure and temperature are expected to have only a small influence. In particular it can be concluded, that the firn porosity at pore close-off is controlled in the top meters or top centimeters of the snow pack.The high resolution profiles show larger relative variability in the example with higher average air content. This may reflect that the effective pore close-off happens at a shallower depth in this case due to formation of lids in layers with high density, which can trap the air below.These tentative findings suggest that the air content may be controlled by the degree of small-scale density variations, and that these density variations in turn may be connected to local surface insolation