Search

Detailed characterization of exoplanets has begun to yield measurements of their atmospheric properties that constrain the planets' origins and evolution. For example, past observations of the dayside emission spectrum of the hot Jupiter WASP-12b indicated that its atmosphere has a high carbon-to-oxygen ratio (C/O > 1), suggesting it had a different formation pathway than is commonly assumed for giant planets. Here we report a precise near-infrared transmission spectrum for WASP-12b based on six transit observations with the Hubble Space Telescope/Wide Field Camera 3. We bin the data in 13 spectrophotometric light curves from 0.84 to 1.67 μm and measure the transit depths to a median precision of 51 ppm. We retrieve the atmospheric properties using the transmission spectrum and find strong evidence for water absorption (7σ confidence). This detection marks the first high-confidence, spectroscopic identification of a molecule in the atmosphere of WASP-12b. The retrieved 1 σ water volume mixing ratio is between 10-5 and 10-2, which is consistent with C/O > 1 to within 2σ. However, we also introduce a new retrieval parameterization that fits for C/O and metallicity under the assumption of chemical equilibrium. With this approach, we constrain C/O to at 1σ and rule out a carbon-rich atmosphere composition (C/O > 1) at >3σ confidence. Further observations and modeling of the planet's global thermal structure and dynamics would aid in resolving the tension between our inferred C/O and previous constraints. Our findings highlight the importance of obtaining high-precision data with multiple observing techniques in order to obtain robust constraints on the chemistry and physics of exoplanet atmospheres.

We report Hubble Space Telescope optical to near-infrared transmission spectroscopy of the hot-Jupiter WASP-6b, measured with the Space Telescope Imaging Spectrograph and Spitzer's InfraRed Array Camera. The resulting spectrum covers the range 0.29-4.5 μm. We find evidence for modest stellar activity of WASP-6 and take it into account in the transmission spectrum. The overall main characteristic of the spectrum is an increasing radius as a function of decreasing wavelength corresponding to a change of Δ (Rp/R*) = 0.0071 from 0.33 to 4.5 μm. The spectrum suggests an effective extinction cross-section with a power law of index consistent with Rayleigh scattering, with temperatures of 973 ± 144K at the planetary terminator. We compare the transmission spectrum with hot-Jupiter atmospheric models including condensate-free and aerosol-dominated models incorporating Mie theory. While none of the clear-atmosphere models is found to be in good agreement with the data, we find that the complete spectrum can be described by models that include significant opacity from aerosols including Fe-poor Mg2 SiO4, MgSiO3, KCl and Na2S dust condensates.WASP- 6b is the second planet after HD 189733b which has equilibrium temperatures near ~1200K and shows prominent atmospheric scattering in the optical.

We present Hubble Space Telescope optical and near-IR transmission spectra ofthe transiting hot-Jupiter WASP-31b. The spectrum covers 0.3-1.7 $\mu$m at aresolution $R\sim$70, which we combine with Spitzer photometry to cover thefull-optical to IR. The spectrum is dominated by a cloud-deck with a flattransmission spectrum which is apparent at wavelengths $>0.52\mu$m. The clouddeck is present at high altitudes and low pressures, as it covers the majorityof the expected optical Na line and near-IR H$_2$O features. While Na Iabsorption is not clearly identified, the resulting spectrum does show a verystrong potassium feature detected at the 4.2-$\sigma$ confidence level.Broadened alkali wings are not detected, indicating pressures below $\sim$10mbar. The lack of Na and strong K is the first indication of a sub-solar Na/Kabundance ratio in a planetary atmosphere (ln[Na/K]$=-3.3\pm2.8$), which couldpotentially be explained by Na condensation on the planet's night side, orprimordial abundance variations. A strong Rayleigh scattering signature isdetected at short wavelengths, with a 4-$\sigma$ significant slope. Twodistinct aerosol size populations can explain the spectra, with a smallersub-micron size grain population reaching high altitudes producing a blueRayleigh scattering signature on top of a larger, lower-lying populationresponsible for the flat cloud deck at longer wavelengths. We estimate that theatmospheric circulation is sufficiently strong to mix micron size particlesupward to the required 1-10 mbar pressures, necessary to explain the clouddeck. These results further confirm the importance of clouds in hot-Jupiters,which can potentially dominate the overall spectra and may alter the abundancesof key gaseous species.

The water abundance in a planetary atmosphere provides a key constraint on the planet's primordial origins because water ice is expected to play an important role in the core accretion model of planet formation. However, the water content of the solar system giant planets is not well known because water is sequestered in clouds deep in their atmospheres. By contrast, short-period exoplanets have such high temperatures that their atmospheres have water in the gas phase, making it possible to measure the water abundance for these objects. We present a precise determination of the water abundance in the atmosphere of the 2 M Jup short-period exoplanet WASP-43b based on thermal emission and transmission spectroscopy measurements obtained with the Hubble Space Telescope. We find the water content is consistent with the value expected in a solar composition gas at planetary temperatures (0.4-3.5 × solar at 1σ confidence). The metallicity of WASP-43b's atmosphere suggested by this result extends the trend observed in the solar system of lower metal enrichment for higher planet masses.

Abstract Background Normal mammary gland contains an extravascular population of B lymphoblasts, precursors of the immunoglobulin plasma cells that play a key role in the passive protection of neonates by secreting immunoglobulins to colostrum and milk. We investigated the presence of chemoattractants in the milk by analysing the chemoattractant activity of various fractions of this secretion. Milk chemoattractants are potentially involved in the recruitment of lymphocytes from the maternal bloodstream in lactating mammary glands. Results The dilution-related lymphoid cell chemoattraction of whey was associated with a < 10 kDa ultrafiltrate. Active fractions were purified by reverse-phase high performance liquid chromatography. Two peptides of 2.7 kDa (DMREANYKNSDKYFHARGNYDAA) and 1 kDa (RPPGLPDKY) were identified as fragments of the SAA protein family, tentatively identified as SAA2. Only the 2.7 kDa synthetic peptide displayed chemotactic activity, at two different optimal concentrations. At the lower concentration (3.7 nM), it attracted B-cell lymphoblasts, whereas at the higher (3.7 μM), it attracted B lymphocytes. Then, the SAA mRNA expression was analysed and we observed more SAA transcripts during lactation than gestation. Conclusion These data are consistent with the SAA23–45 fragment being involved in preplasma B-cell recruitment to the mammary gland and resultant benefit to the neonate.

There are no planets intermediate in size between Earth and Neptune in our Solar System, yet these objects are found around a substantial fraction of other stars 1 . Population statistics show that close-in planets in this size range bifurcate into two classes on the basis of their radii 2,3 . It is proposed that the group with larger radii (referred to as 'sub-Neptunes') is distinguished by having hydrogen-dominated atmospheres that are a few percent of the total mass of the planets 4 . GJ 1214b is an archetype sub-Neptune that has been observed extensively using transmission spectroscopy to test this hypothesis 5-14 . However, the measured spectra are featureless, and thus inconclusive, due to the presence of high-altitude aerosols in the planet's atmosphere. Here we report a spectroscopic thermal phase curve of GJ 1214b obtained with the James Webb Space Telescope (JWST) in the mid-infrared. The dayside and nightside spectra (average brightness temperatures of 553 ± 9 and 437 ± 19 K, respectively) each show more than 3σ evidence of absorption features, with H 2 O as the most likely cause in both. The measured global thermal emission implies that GJ 1214b's Bond albedo is 0.51 ± 0.06. Comparison between the spectroscopic phase curve data and three-dimensional models of GJ 1214b reveal a planet with a high metallicity atmosphere blanketed by a thick and highly reflective layer of clouds or haze., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Helium is the second-most abundant element in the Universe after hydrogen and is one of the main constituents of gas-giant planets in our Solar System. Early theoretical models predicted helium to be among the most readily detectable species in the atmospheres of exoplanets, especially in extended and escaping atmospheres 1 . Searches for helium, however, have hitherto been unsuccessful 2 . Here we report observations of helium on an exoplanet, at a confidence level of 4.5 standard deviations. We measured the near-infrared transmission spectrum of the warm gas giant 3 WASP-107b and identified the narrow absorption feature of excited metastable helium at 10,833 angstroms. The amplitude of the feature, in transit depth, is 0.049 ± 0.011 per cent in a bandpass of 98 angstroms, which is more than five times greater than what could be caused by nominal stellar chromospheric activity. This large absorption signal suggests that WASP-107b has an extended atmosphere that is eroding at a total rate of 10 10 to 3 × 10 11 grams per second (0.1-4 per cent of its total mass per billion years), and may have a comet-like tail of gas shaped by radiation pressure.

The angle between the spin of a star and the orbital planes of its planets traces the history of the planetary system. Exoplanets orbiting close to cool stars are expected to be on circular, aligned orbits because of strong tidal interactions with the stellar convective envelope. Spin-orbit alignment can be measured when the planet transits its star, but such ground-based spectroscopic measurements are challenging for cool, slowly rotating stars. Here we report the three-dimensional characterization of the trajectory of an exoplanet around an M dwarf star, derived by mapping the spectrum of the stellar photosphere along the chord transited by the planet. We find that the eccentric orbit of the Neptune-mass exoplanet GJ 436b is nearly perpendicular to the stellar equator. Both eccentricity and misalignment, surprising around a cool star, can result from dynamical interactions (via Kozai migration) with a yet-undetected outer companion. This inward migration of GJ 436b could have triggered the atmospheric escape that now sustains its giant exosphere.

Infrared radiation emitted from a planet contains information about the chemical composition and vertical temperature profile of its atmosphere. If upper layers are cooler than lower layers, molecular gases will produce absorption features in the planetary thermal spectrum. Conversely, if there is a stratosphere-where temperature increases with altitude-these molecular features will be observed in emission. It has been suggested that stratospheres could form in highly irradiated exoplanets, but the extent to which this occurs is unresolved both theoretically and observationally. A previous claim for the presence of a stratosphere remains open to question, owing to the challenges posed by the highly variable host star and the low spectral resolution of the measurements. Here we report a near-infrared thermal spectrum for the ultrahot gas giant WASP-121b, which has an equilibrium temperature of approximately 2,500 kelvin. Water is resolved in emission, providing a detection of an exoplanet stratosphere at 5σ confidence. These observations imply that a substantial fraction of incident stellar radiation is retained at high altitudes in the atmosphere, possibly by absorbing chemical species such as gaseous vanadium oxide and titanium oxide.

Thousands of transiting exoplanets have been discovered, but spectral analysis of their atmospheres has so far been dominated by a small number of exoplanets and data spanning relatively narrow wavelength ranges (such as 1.1-1.7 micrometres). Recent studies show that some hot-Jupiter exoplanets have much weaker water absorption features in their near-infrared spectra than predicted. The low amplitude of water signatures could be explained by very low water abundances, which may be a sign that water was depleted in the protoplanetary disk at the planet's formation location, but it is unclear whether this level of depletion can actually occur. Alternatively, these weak signals could be the result of obscuration by clouds or hazes, as found in some optical spectra. Here we report results from a comparative study of ten hot Jupiters covering the wavelength range 0.3-5 micrometres, which allows us to resolve both the optical scattering and infrared molecular absorption spectroscopically. Our results reveal a diverse group of hot Jupiters that exhibit a continuum from clear to cloudy atmospheres. We find that the difference between the planetary radius measured at optical and infrared wavelengths is an effective metric for distinguishing different atmosphere types. The difference correlates with the spectral strength of water, so that strong water absorption lines are seen in clear-atmosphere planets and the weakest features are associated with clouds and hazes. This result strongly suggests that primordial water depletion during formation is unlikely and that clouds and hazes are the cause of weaker spectral signatures.

Hearts in which the arterial trunks arise from the morphologically appropriate ventricles, but in a parallel manner, rather than the usual spiralling arrangement, have long fascinated anatomists. These rare entities, for quite some time, were considered embryological impossibilities, but ongoing experience has shown that they can be found in various segmental combinations. Problems still exist about how best to describe them, as the different variants are often described with esoteric terms, such as anatomically corrected malposition or isolated ventricular inversion. In this review, based on our combined clinical and morphological experience, we demonstrate that the essential feature of all hearts described in this manner is a parallel arrangement of the arterial trunks as they exit from the ventricular mass. We show that the relationship of the arterial roots needs to be described in terms of the underlying ventricular topology, rather than according to the arrangement of the atrial chambers. We then discuss the importance of determining atrial arrangement on the basis of the morphology of the appendages, following the precepts as set out in the so-called "morphological method" and distinguished according to the extent of the pectinate muscles relative to the atrioventricular junctions as opposed to basing diagnosis on the venoatrial connections. We show that, when approached in this manner, the various combinations can be readily diagnosed in the clinical setting and described in straightforward way.

Background: Disagreement currently exists regarding the definition of aortic dextroposition. It is suggested that the term be used interchangeably with aortic overriding, along with suggestions that the aortic valve overrides in the normal heart. The dextroposed aorta, however, does not always override the crest of the muscular ventricular septum. It is incorrect to argue that the normal aortic valve overrides. It is the cavity of the right aortic valvar sinus, rather than the valvar orifice, that sits above the muscular septum when the septum itself is intact. Therefore, to circumvent these difficulties, those using the term "dextroposition" find it necessary to distinguish "true" as opposed to "false" categories. The problems arise because "dextroposition" is remarkably ill-suited as an alternative term for aortic valvar overriding., Methods and Results: In this review, combining developmental, morphologic, and clinical data, we show how aortic overriding is best considered on the basis of biventricular connection of the aortic root in the setting of deficient ventricular septation. When analysed in this manner, it becomes an easy matter to distinguish between one-to-one and double outlet ventriculo-arterial connections. Appreciation of these features emphasises the different spatial alignments of interventricular communications as opposed to the plane of deficient ventricular septation. The concept of overriding is applicable not only to biventricular connection of the aortic root, but also the pulmonary and common arterial roots., Conclusions: The diagnostic techniques now available to the paediatric cardiologist illustrate the features of arterial valvar overriding with exquisite accuracy, informing the discussions now required for optimal decision making.

It is frequent, in the current era, to encounter congenital cardiac malformations described in terms of "cor triatriatum". But can hearts be truly found with three atrial chambers? The morphological method, emphasised by Van Praagh et al, states that structures within the heart should be defined on the basis of their most constant components. In the atrial chambers, it is the appendages that are the most constant components, and to the best of our knowledge, hearts can only possess two appendages, which can be of either right or left morphology. The hearts described on the basis of "cor triatriatum", nonetheless, can also be analysed on the basis of division of either the morphologically right or the morphologically left atriums. In this review, we provide a description of cardiac embryology, showing how each of the atrial chambers possesses part of the embryological body, along with an appendage, a vestibule, a venous component, and a septum that separates them. We then show how it is, indeed, the case that the hearts described in terms of "cor triatriatum" can be readily understood on the basis of division of these atrial components. In the right atrium, it is the venous valves that divide the chamber. In the left atrium, it is harder to provide an explanation for the shelf that produces atrial division. We also contrast the classic examples of the divided atrial chambers with the vestibular shelf that produces supravalvar stenosis in the morphologically left atrium, showing that this form of obstruction needs to be distinguished from the fibrous shelves producing intravalvar obstruction.

Although steps are being taken to produce a universally acceptable coding system for categorisation of the congenitally malformed hearts, obstacles remain in the search for consensus. One of the groups of lesions continuing to produce the greatest problems is those that permit interventricular shunting. The difficulties relate partly to the words used to describe the group itself, as those using Germanic languages describe the holes as ventricular septal defects, whereas those using Romance languages consider them to represent interventricular communications. The two terms, however, are not necessarily synonymous. Further disagreements relate to whether the lesions placed within the group should be sub-categorised on the basis of their geographical location within the ventricular mass, as opposed to the anatomic nature of their borders. In reality, attention to both the features is necessary if we are to recognise the full extent of phenotypic variability. In this review, we first review the evolution and theories of analysis naming the channels that permit interventricular shunting. We then demonstrate that embryologic techniques provide evidence that the changing morphology of the developing murine heart parallels the anatomy of the different lesions encountered in the congenitally malformed human heart. We suggest that, with attention paid to the temporal development of the normal murine heart, combined with a strict definition of the plane of separation between the right and left ventricular cavities, it will be feasible to produce a categorisation that is acceptable to all.

Exoplanets that orbit close to their host stars are much more highly irradiated than their solar system counterparts. Understanding the thermal structures and appearances of these planets requires investigating how their atmospheres respond to such extreme stellar forcing. We present spectroscopic thermal emission measurements as a function of orbital phase ("phase-curve observations") for the highly irradiated exoplanet WASP-43b spanning three full planet rotations using the Hubble Space Telescope. With these data, we construct a map of the planet's atmospheric thermal structure, from which we find large day-night temperature variations at all measured altitudes and a monotonically decreasing temperature with pressure at all longitudes. We also derive a Bond albedo of 0.18(-0.12)(+0.07) and an altitude dependence in the hot-spot offset relative to the substellar point., (Copyright © 2014, American Association for the Advancement of Science.)

We present a robust, fully automatable technology platform that includes computer software for the detailed analysis of low femtomoles of N-linked sugars released from glycoproteins. Features include (i) sample immobilization in 96-well plates, glycan release, and fluorescent labeling; (ii) quantitative HPLC analysis, including monosaccharide sequence, linkage, and arm-specific information for charged and neutral glycans; (iii) automatic structural assignment of peaks from HPLC profiles via web-based software that accesses our database (GlycoBase) of more than 350 N-glycan structures, including 117 present in the human serum glycome; and (iv) software (autoGU) that progressively analyzes data from exoglycosidase digestions to produce a refined list of final structures. The N-glycans from a plate of 96 samples can be released and purified in 2 or 3 days and profiled in 2 days. This strategy can be used for (i) identification and screening of disease biomarkers and (ii) monitoring the production of therapeutic glycoproteins, allowing optimization of production conditions. This technology is also suitable for preparing released glycans for other analytical techniques. Here we demonstrate its application to rheumatoid arthritis using 5 microl of patient serum.

Background: Transmission of echocardiograms via telemedicine links has allowed remote hospitals direct access to pediatric cardiology subspecialty care. This study assessed the accuracy of echocardiogram interpretation across an integrated services digital network (ISDN) telemedicine link., Methods: Telemedicine systems were installed between Cape Fear Valley Medical Center neonatal intensive care unit and University of North Carolina Hospitals. One board-certified pediatric cardiologist interpreted 105 full-length echocardiograms that were videotaped and then transmitted over the system. Six months later, the same cardiologist reinterpreted the 105 original videotape studies from the off-site hospital and results were compared with the interpretations of the transmitted data., Results: Interpretation of transmitted echocardiograms did not differ significantly from the original studies for diagnosis, evaluation of left ventricular function, valve function evaluation, and the presence of a ductus arteriosus. Minor differences in qualitative parameters were seen., Conclusion: Transmission of full-length echocardiograms over the ISDN telemedicine link is comparable to videotape review. There was no loss of significant clinical information, and the minor discrepancies noted did not impact management decisions.

Precise brightness measurements of HD 46375 have been acquired with an automatic telescope to search for transits of its short-period, sub-Saturn extrasolar planet. Transits of the companion do not occur, indicating that the inclination of the orbit i is less than 83 degrees and sini is less than 0.992. This upper limit on sini still preserves the possibility that the mass of the planet is less than Saturn's. Analysis of the photometry for HD 46375 reveals no photometric variability larger than 0.0001+/-0.0002 mag at the orbital period of the planet. This effectively eliminates starspots and stellar pulsations as the cause of the radial velocity variations used to infer the planet's existence.

Doppler measurements from Keck exhibit a sinusoidal periodicity in the velocities of the G0 dwarf HD 209458, having a semiamplitude of 81 m s-1 and a period of 3.5239 days, which is indicative of a "51 Peg-like" planet with a minimum mass (Msini) of 0.62 MJup and a semimajor axis of 0.046 AU. Follow-up photometry reveals a drop of 0.017 mag at the predicted time (within the errors) of transit by the companion based on the velocities. This is the first extrasolar planet observed to transit its star. The radius of the planet derived from the magnitude of the dimming is 1.42 RJup, which is consistent with models of irradiated Jupiter-mass planets. The transit implies that sini>0.993, leading to a true mass of 0.62 MJup for the planet. The resulting mean density of 0.27 g cm-3 implies that the companion is a gas giant.

Background: Knowledge of right ventricular (RV) shape is important to the understanding of RV mechanical function and for the improvement of clinically important RV volume estimation techniques. Refinements to the simplest conceptions of RV shape are presented statistically here, based on a quantitative analysis of three-dimensional magnetic resonance (MR) images of excised lamb hearts., Methods: The passive shape of the heart in six freshly excised lamb hearts was studied with MR imaging with independent passive pressurization of both ventricles. Global features of shape were assessed, including measurement of short-axis, cross-sectional shape parameters associated with the pinched-arc model., Results: The slice-area x apex-base length was found to be highly correlated with the volume of the RV, with little sensitivity to the degree of filling of the ventricle or to the exact slice chosen (r = 0.987; n = 22 from five hearts). The RV was shown to follow a clockwise helical path around the left ventricle of 47 +/- 17 degrees, below the outflow tract, as seen from the apical view, progressing from the apex to the base. Based on the pinched-arc model, the anterior arc is shallower than the posterior arc, with a larger radius of curvature and a smaller angle between the arc and the septal axis. As the RV is passively filled, opposite changes in shape occur between the anterior and posterior regions tending to equalize their shapes., Conclusions: A high degree of regularity of shape does exist in the RV and, thus, can be characterized effectively in terms of a representative cross-sectional shape and in terms of the changes in that shape proceeding from the base to the apex.

Background: There are few congenital anomalies of the heart that have benefited more from thorough anatomic analysis than the complex anomaly known as atrioventricular septal defect in the setting of common atrioventricular junction. Recent advances in understanding the anatomy of this lesion have led to alternative methods of repairing these defects., Methods: The medical records of 21 consecutive patients undergoing repair of complete atrioventricular septal defect have been reviewed. Nine of these patients had a standard one- or two-patch repair, and 12 had direct closure of the ventricular element of the defect., Results: Direct closure resulted in significantly shorter pump and cross-clamp times. Follow-up for an average of 34 months suggests that when direct closure can be performed, the results are comparable with those of the more standard technique., Conclusions: Our initial success with this approach is encouraging; however, longer follow-up is required to establish whether it will be broadly applicable.

A syndrome consisting of unilateral duplication of the great toe in association with anterolateral bowing of the tibia is described. Patients with this syndrome have significant pedal difficulties after surgical management, but the tibial bowing spontaneously resolves without treatment. Tibial shortening is noted relative to the fibula. Associated clinodactyly and dysharmonic maturation of carpals and metacarpals are also seen. Current data are most consistent with a developmental rather than a genetic etiology.

The determinants of right ventricular (RV) performance with damaged RV free wall, such as occurs with RV infarction, are still unclear. Using 20-MHz Doppler ultrasound equipment, we investigated the changes in pulmonary blood flow velocity profiles before and after ligation of the right coronary artery. RV dp/dt, stroke volume, RV stroke work, aortic pressure and cardiac output decreased and central venous pressure rose after the ligation. The RV stroke work-end-diastolic pressure relationship indicated impaired RV function following ligation. We observed shortened acceleration time (65.0 +/- 15.1 vs 54.4 +/- 6.2 ms, P < 0.05) and reduced maximum velocity of forward flow (59.0 +/- 5.9 vs 52.5 +/- 7.6 cm/s, P < 0.05) after the ligation. Acceleration was interrupted earlier after ligation than before ligation. These alterations in flow are thought to be a consequence of the altered movement of the RV free wall and ventricular septum induced by RV infarction.

We studied the detailed profiles of blood flow in the right and left pulmonary arteries using 20 MHz pulsed Doppler ultrasound equipment in a lamb model. Fourteen lambs aged four to six weeks were selected. In six lambs, monocrotaline pyrrole was injected parenterally to create pulmonary hypertension (PH group). Eight other lambs served as unaltered controls (control group). The blood flow velocities were sampled in 1mm increments along the anterior-posterior axis of the branch arteries. The maximum velocity of the forward flow in the left pulmonary artery was higher than that in the right pulmonary artery in the control group (71.7 +/- 15.9 cm/s vs 60.2 +/- 13.5; p < 0.05). The fastest backward flow was located at the posterior position of the vessel in the right pulmonary artery in the control group (71.7 +/- 15.9 cm/s vs 60.2 +/- 13.5; p < 0.05). The fastest backward flow was located at the posterior position of the vessel in the right pulmonary artery in the control group. No significant bias in location was shown in the left pulmonary artery. Using indices of P90, acceleration time, P90*AcT, the velocity waveforms in the PH group were compared with those in the control group. In the left pulmonary artery, every index in the control group showed a significantly greater value that in the PH group. On the other hand, no significant differences were found between either group in the right pulmonary artery.

The effects of pulsatile hemodynamics on right ventricle-pulmonary circulation interactions were studied in control lambs and in two lamb models of altered pulmonary hemodynamics induced at infancy: elevated pulmonary arterial pressure (PAP) was created by the infusion of monocrotaline pyrrole (MCTP), and elevated pulmonary arterial blood flow was obtained by the creation of an arteriovenous fistula (Shunt). High-fidelity PAP, midvessel Doppler blood velocity (PAV), and cardiac output (CO) were measured in open-chest, anesthetized lambs. PAV waveforms were normalized to match the measured CO. Measured pressure and flow signals were separated in the time domain into forward and backward components. Pulmonary input impedance and indexes quantifying the timing of the reflected wave pulse (beginning of reflected pulse, duration of reflected pulse in systole, and duration of reflected wave in diastole) were calculated for each group. Results indicate that in control animals the reflected wave returned late in systole and extended through much of diastole, thereby increasing diastolic pressure like a counterpulsation balloon. No significant differences in the timing indexes were found between Shunt and control animals. In the MCTP group, the reflected wave returned significantly earlier than normal with the peak reflected pulse occurring before valve closure. The resulting augmentation of systolic pressure and, therefore, large pulse pressure is consistent with pressure waveforms observed in clinical pulmonary hypertension. We conclude that early wave reflection exerts a detrimental effect in pulmonary hypertension by unfavorably loading the still-ejecting right ventricle.

Twelve infants born to mothers who received i.v. magnesium sulfate for > 6 weeks for the cessation of preterm labor were evaluated radiographically shortly after birth. All infants were born at > 33 weeks gestational age. All twelve infants demonstrated consistent and unique radiographic abnormalities in the metaphyses of their long bones. The extent of abnormality was at least partially related to the length of magnesium sulfate exposure, and appeared to completely resolve within the first few months of life.

Background: Recently, a successful result with a rapid two-stage arterial switch operation (ASO) was reported for patients with transposition of the great arteries (TGA) with low left ventricular pressure. In this procedure, the interval between pulmonary arterial banding and ASO was approximately 1 week. This successful result indicates the possibility of a nonsurgical ventricular preparation procedure using an obstructing balloon catheter prior to ASO., Methods and Results: A 5F atrioseptostomy catheter was inserted directly into the main pulmonary artery in six lambs aged 20 to 38 days. After the chest was closed, the balloon was inflated twice a day for a period of 2 to 2.5 hours. This procedure was performed for 4 consecutive days. After the final inflation, the ratio of right ventricular weight to total ventricular weight was compared with that in an age-matched control group. After the final inflation, the peak systolic right ventricular pressure and the percentage of peak systolic right ventricular to peak systolic aortic pressure rose to 85.6 +/- 4.7 mm Hg (mean +/- 1 SD) and 79.6 +/- 8.6%, respectively. The percentages of the right ventricular weight to the total ventricular weight were significantly higher after the balloon inflation than those in the control group in terms of wet heart weight (29.5 +/- 1.2% versus 23.0 +/- 1.0%; P < .0001) and dry heart weight (27.0 +/- 2.0% versus 21.0 +/- 1.1%; P < .0001)., Conclusions: The myocardial mass in the right ventricle increased after 4 days of intermittently applied pressure overload. Nonsurgical preparation of the ventricle for ASO in TGA is feasible.

In vitro pulsatile flow visualization studies were conducted to assess the effects of varying radii of curvature of the right ventricular outflow tract (RVOT) and main pulmonary artery (MPA) on the flow fields in the main, right, and left pulmonary arteries of a one month lamb pulmonary artery model. Three glass flow-through models were studied; one with no curvature, one with the correct anatomic curvature, and one with an overaccentuated curvature on the RVOT and MPA. All other geometric parameters were held constant. Pulsatile flow visualization studies were conducted at nine flow conditions; heart rates of 70, 100, and 140 bpm, and cardiac outputs of 1.5, 2.5 and 3.5 l/min with corresponding mean pulmonary pressures of 10, 20, and 30 mmHg. Changes were observed in the pulmonary flow fields as the curvature of the outflow tract, heart rate and mean pulmonary pressure were varied. An increase in vessel curvature led to an increase in the overall radial nature of the flow field as well as flow separation regions which formed faster, originated further downstream, and occupied more of the vessel area. At higher heart rates, the maximum size of the separation regions decreased, while flow separation regions appeared earlier in the cardiac cycle and grew more quickly. Heart rate also affected the initiation of flow reversal; flow reversal occurred later in the cardiac cycle at lower heart rates. Both heart rate and mean pulmonary pressure influenced the stability of the pulmonary flow field and the appearance of coherent structures. In addition, an increase in mean pulmonary pressure increased the magnitude of reverse flow.(ABSTRACT TRUNCATED AT 250 WORDS)

For a better understanding of the characteristics of blood flow in the pulmonary artery, we constructed three-dimensional images of velocity profiles of blood flow in the pulmonary artery from pulsed Doppler ultrasound recordings in 14 lambs aged 28-40 days. In 8 lambs, pulmonary hypertension was created by the central venous injection of monocrotaline pyrrole. Six lambs served as unaltered controls. The velocity data were sampled in 2 mm increments along both an anterior-posterior axis and a right-left orthogonal axis in the main pulmonary artery. Using a computer-generated cross-sectional velocity matrix consisting of 0.25 mm square grids, the velocity of blood flow was estimated at each intersection. The cross-sectional velocity matrices were generated at 5 msec intervals during the entire cardiac cycle. In all animals, significant velocity reversal was detected near the posterior wall. In 7 of 14 animals, the peak forward velocity was located near the posterior wall. Three of 8 hypertensive models showed reacceleration during the mid-systolic phase at the center of the velocity waveform, but one reacceleration disappeared at a point only 2 mm away from the center of the vessel toward the posterior wall. Acceleration time correlated well with the mean pulmonary arterial pressure (PAP) (r = -0.85) and the log10 PAP (r = -0.86). Corrected acceleration time (acceleration time divided by the square root of the cardiac cycle length) also correlated with PAP (r = -0.78) and the log10 PAP (r = -0.81).

The velocity pattern of the blood flow in the pulmonary artery was investigated in an animal model of acute pulmonary hypertension. Nine anesthetized, open-chest dogs were embolized with polystyrene microspheres, and the velocity pattern of the blood flow in the pulmonary artery was studied with use of an invasive pulsed Doppler technique. Phasic intraluminal velocity was recorded with use of a miniature piezoelectric crystal activated by 20-MHz Doppler pulses and mounted on the tip of a needle probe introduced into the pulmonary artery. The recorded Doppler quadrature signals were processed by spectral analysis. Significant increases occurred in mean, systolic, and diastolic pulmonary arterial pressures (p less than 0.0002), in pulmonary vascular resistance (p less than 0.005), and in negative velocity time (duration in milliseconds that the mean velocity was directed toward the pulmonic valve) (p less than 0.002). Significant decreases occurred in right ventricular ejection time (p less than 0.006) and in positive velocity time (duration in milliseconds that the mean velocity was directed away from the pulmonic valve) (p less than 0.005). A significant shortening in the time to peak velocity (acceleration time) was found (p less than 0.005). Second-order regression analyses demonstrated an inverse correlation between the ratio of positive velocity time to negative velocity time and the mean pulmonary artery pressure in all animals (r = 0.71). These findings should be compared with the velocity patterns of the blood flow in the pulmonary artery obtained under pulmonary hypertensive conditions due to various causes to facilitate interpretation and understanding of clinical investigations.

SummaryComplete transposition is a morphologic entity which exists by virtue of a concordant atrioventricular connection co-existing with a discordant connection at the ventriculoarterial level. If diagnosed in this manner, all variants can be described simply and unambiguously in terms of associated malformations along with variations in relationships and infundibular morphology.

The coronary sinus is an important landmark for the position of the atrial component of the atrioventricular conduction axis and, thus, assumes special relevance to the surgeon in the operating room. We describe here 2 patients with atrioventricular septal defect characterized by an unusual termination of the coronary sinus within the left atrium. We discuss the potential importance of this finding to the disposition and surgical avoidance of the conduction tissues.