Left-sided lesions after anatomic repair of transposition of the great arteries, ventricular septal defect, and coarctation: Surgical factors

AbstractObjectiveThis study was undertaken to identify potential anatomic and surgical factors creating left-sided lesions, namely recoarctation of the aorta and neoaortic regurgitation, after anatomic repair of transposition of the great arteries with ventricular septal defect and aortic coarctation.MethodsFrom 1983 to September 2002, 109 survivors out of 120 patients were studied. Two-stage repair was performed in 42 patients (group A), and single-stage repair was performed in 67 (groups B and C). Before repair, the diameters of the ascending aorta and main pulmonary artery were measured. In the patients with single-stage repair, coarctation was repaired by extended end-to-end anastomosis in 35 patients (group B) and by pulmonary homograft patch augmentation in 32 patients (group C). The ventricular septal defect was closed through the pulmonary artery in 70 patients and through the right ventricle or atrium in 39 patients. The neoaorto-aortic discrepancy was treated by V-shaped resection of the posterior sinus of Valsalva in 7 cases, pulmonary homograft patch in 32 cases, and anterior splitting of the ascending aorta in all cases. Before discharge from the hospital, neoaortic root and ascending aorta diameters and aortic regurgitation grade were recorded. Neoaortic regurgitation progression and reintervention were the end points of follow-up (97.2 ± 61.2 months).ResultsEarly and late survivals were significantly better in group C (P < .001). Risk factors for neoaortic regurgitation at discharge by univariate analysis were single-stage repair (P < .05) and ventricular septal defect closure through the pulmonary artery (P = .0076). On multivariate analysis, the latter was the only risk factor for neoaortic regurgitation at discharge and at last follow-up. Multivariate analysis showed that higher neoaortic root/ascending aorta ratio and ventricular septal defect closure through the pulmonary artery were risk factors for neoaortic regurgitation evolution at last follow-up. There were 29 reinterventions, 19 for recoarctation of the aorta and 10 for neoaortic regurgitation with or without aortic root dilatation. Group B (P < .05), high neoaortic root/ascending aorta ratio (P < .01), and progressive neoaortic regurgitation (P < .05) were risk factors for recoarctation of the aorta. Group A was a risk factor for aortic valve replacement at 10 years (P < .05).ConclusionNeonatal single-stage repair with pulmonary homograft aortic augmentation remains the optimal approach to transposition of the great arteries with ventricular septal defect and aortic coarctation. It provides better early and late survivals and freedoms from left-sided lesions. Avoidance of late recoarctation of the aorta and progressive neoaortic regurgitation requires meticulous closure of the ventricular septal defect and evenly sized reconstruction of the aorta from root to distal arch

Properties of individual contrails: a compilation of observations and some comparisons

Mean properties of individual contrails are characterized for a wide range of jet aircraft as a function of age during their life cycle from seconds to 11.5 h (7.4-18.7 km altitude, -88 to -31 degrees C ambient temperature), based on a compilation of about 230 previous in situ and remote sensing measurements. The airborne, satellite, and ground-based observations encompass exhaust contrails from jet aircraft from 1972 onwards, as well as a few older data for propeller aircraft. The contrails are characterized by mean ice particle sizes and concentrations, extinction, ice water content, optical depth, geometrical depth, and contrail width. Integral contrail properties include the cross-section area and total number of ice particles, total ice water content, and total extinction (area integral of extinction) per contrail length. When known, the contrail-causing aircraft and ambient conditions are characterized. The individual datasets are briefly described, including a few new analyses performed for this study, and compiled together to form a "contrail library" (COLI). The data are compared with results of the Contrail Cirrus Prediction (CoCiP) model. The observations confirm that the number of ice particles in contrails is controlled by the engine exhaust and the formation process in the jet phase, with some particle losses in the wake vortex phase, followed later by weak decreases with time. Contrail cross sections grow more quickly than expected from exhaust dilution. The cross-section-integrated extinction follows an algebraic approximation. The ratio of volume to effective mean radius decreases with time. The ice water content increases with increasing temperature, similar to non-contrail cirrus, while the equivalent relative humidity over ice saturation of the contrail ice mass increases at lower temperatures in the data. Several contrails were observed in warm air above the Schmidt-Appleman threshold temperature. The "emission index" of ice particles, i.e., the number of ice particles formed in the young contrail per burnt fuel mass, is estimated from the measured concentrations for estimated dilution;maximum values exceed 10(15) kg(-1). The dependence of the data on the observation methods is discussed. We find no obvious indication for significant contributions from spurious particles resulting from shattering of ice crystals on the microphysical probes

Orographic cirrus in the global climate model ECHAM5

A comparison of satellite data with simulations from global circulation models shows that there is a lack of cirrus cloud amount in large-scale models above and in the lee of mountains. The formation of orographic cirrus clouds due to gravity waves is usually not parameterized in large-scale models. To improve the simulation of such orographically excited cirrus clouds a coupling of the gravity wave dynamics and the cloud microphysics has been implemented in the climate model European Centre/Hamburg 5 (ECHAM5). As homogeneous freezing of solution droplets strongly depends on the vertical velocity, an increased vertical velocity due to gravity wave activity in the upper troposphere leads to the formation of cirrus clouds with higher ice crystal number densities. A comparison of the new parameterization with measurements shows a better agreement with observations

In-situ measurement methods for atmospheric aerosol particles and cloud elements

A multitude of measurement techniques has been developed in atmospheric science in order to study atmospheric aerosols. In-situ measurements can address many characteristics of aerosol particles such as concentration, size, shape, composition, and optical properties. Measuring aerosol particles as well as cloud droplets and ice crystals throughout the troposphere and lower stratosphere from fast flying research aircraft poses specific challenges with respect to suitable instrumentation

Light scattering on Chebyshev particles of higher order

In this paper we present first results of a light scattering analysis on several Chebyshev particles characterized by higher orders. Chebyshev particles of comparatively lower orders are used in the past to study the effects of nonspherical but concave geometries in remote sensing applications. Here we will show that, based on the developed methodology, accurate results can be also obtained for particles of higher orders exhibiting a more pronounced surface waviness. The achieved results demonstrate that higher order Chebyshev particles can be used to estimate the influence of a weak surface roughness on the light scattering behaviour of the underlying smooth scatterer. The obtained effects correspond with results of other approaches and with the theoretical expectations of a weak surface roughness. In contrast to what is known for regular particles there can be observed an essential difference between the phase functions of the underlying spherical scatterer and the corresponding higher order Chebyshev particle if a higher absorptivity of the scattering medium is considered. This paper demonstrates additionally that Chebyshev polynomials can be simply combined with other smooth geometries than spheres

Microphysical and optical properties of midlatitude cirrus clouds observed in the southern hemisphere during INCA

Airborne microphysical and optical properties of cirrus clouds, jet-stream and wave clouds were measured at temperatures ranging from −25° C to −62° C in the southern hemisphere from Punta Arenas (53° S) in March and April 2000 during the INCA experiment (INterhemispheric differences in Cirrus properties from Anthropogenic emissions). The observations related to cirrus clouds show general decreases of the ice water content (18 mg m−3 to 0.05 mg m−3), extinction coefficient (0.70 km−1 to 0.08 km−1), ice particle concentration (2.2 cm−3 to 0.5 cm−3), and the effective diameter (80 μm to 17 μm) linked to the variation of ambient temperature (−25° C to −60° C). The lowest temperature at which supercooled water droplets were detected was −33° C. The asymmetry parameter shows relatively small variations, with the smallest values (0.758) observed at the lowest temperatures. High-altitude clouds which form with a rapid vertical transport, i.e. jet-stream cirrus and orographic-wave ice-cloud, are characterized by very high values of ice particle concentrations (up to 100 cm−3) compared to mean values as a whole (1.45 cm−3). These two kinds of high clouds are the subjects of detailed case-studies. Although formed at a similar range of temperatures and with similar aerosol properties, the strong differences in cloud properties and humidity fields highlight the key role of the dynamical structure in controlling the formation, evolution and subsequent radiative properties of such high-altitude clouds

The retrieval of cloud microphysical properties using satellite measurements and an in situ database

By combining AVHRR data from the NOAA satellites with information from a database of in situ measurements, large-scale maps can be generated of the microphysical parameters most immediately significant for the modelling of global circulation and climate. From the satellite data, the clouds can be classified into cumuliform, stratiform and cirrus classes and then into further sub-classes by cloud top temperature. At the same time a database of in situ measurements made by research aircraft is classified into the same sub-classes and a statistical analysis is used to derive relationships between the sub-classes and the cloud microphysical properties. These two analyses are then linked to give estimates of the microphysical properties of the satellite observed clouds. Examples are given of the application of this technique to derive maps of the probability of occurrence of precipitating clouds and of precipitating water content derived from a case study within the International Cirrus Experiment (ICE) held in 1989 over the North Sea