Dobutamine stress testing for the evaluation of atrial and diastolic ventricular function in Fontan patients

Objective

To assess the atrial and ventricular diastolic function response to dobutamine stress in Fontan patients, and to relate these measurements to exercise capacity and events during the follow-up.

Methods

We performed a secondary analysis of a cross-sectional multicentre study of Fontan patients with intra-atrial lateral tunnel (ILT) or extracardiac conduit (ECC) modification. Subjects underwent cardiac MRI during rest and low-dose dobutamine stress, and cardiopulmonary exercise testing. Atrial and diastolic ventricular function parameters were derived from volume-time curves.

Medical records were abstracted for a composite end-point of death, listing for transplant, arrhythmia and reintervention. Spearman’s r correlation tests and Cox proportional hazards models were used to assess the relation between the dobutamine response for atrial and diastolic ventricular function and outcomes, including exercise capacity.

Results

We included 57 patients (26 ECC; 31 ILT) aged 12.8 (IQR (10.3–15.5)) years. During dobutamine stress atrial cyclic volume change increased (3.0 (0.4–5.9) mL/m², p<0.001), as did early (1.9 (−1.6 to 3.6) mL/m², p=0.001) and late emptying volume (2.2 (0.2–4.4) mL/m², p<0.001).

Ventricular early filling decreased (−1.6 (−5.7 to 0.7) mL/m², p=0.046) and ventricular late filling increased (1.0 (−0.4 to 3.4) mL/m², p<0.001) while stroke volume remained similar.

Only for patients with the ECC modification, atrial early emptying volume increase correlated with peak oxygen uptake (ρ=0.66, p=0.002). No other parameter related to exercise capacity.

During a median 7.1-year follow-up, 22 patients reached the composite endpoint. No parameter predicted events during the follow-up.

Conclusions

Dobutamine stress augmented atrial reservoir and pump function for Fontan patients. Atrial early emptying reserve related to exercise capacity in ECC patients. No other atrial or diastolic ventricular function parameter related to outcomes.

Unawareness and undertreatment of asthma: follow-up in a different geographic area in Denmark

BACKGROUND

Early detection and treatment of asthma is important to minimize morbidity and healthcare costs. The objective of this study was to investigate asthma awareness and management in a western society.

METHODS

In a random sample of 10 400 subjects aged 14-44 years, 686 (6.6%) reported symptoms of asthma in a standardized screening questionnaire. All 686 were evaluated by respiratory specialists and diagnosed by history, symptoms, lung function tests, bronchial challenges and allergy testing. Of these 686 participants, 69 (10%) had asthma alone, 205 (30%) had rhinitis alone and 217 (32%) had both asthma and rhinitis; 195 (28%) had nonasthmatic respiratory reports.

RESULTS

Awareness of asthma was found among 163 (57%) of the 286 asthmatics, and 204 (95%) had doctor-diagnosed rhinitis as well. In a multivariate regression analysis, comorbidity with rhinitis (beta = 0.489, P < 0.001), smoking (beta = -0.116, P < 0.01), doctor-diagnosed bronchitis (beta = 0.086, P < 0.05), and earlier emergency visits at hospital (beta = 0.147, P < 0.001) was significantly associated with awareness. A difference in awareness was found between those who had asthma and rhinitis (62.2%) and those who had asthma alone (40.6%) (P < 0.01). Inhaled corticosteroids (ICS) were used by 27% of those with asthma, including 12% who used both ICS and long-acting beta-agonist.

CONCLUSIONS

More than half of the persons with asthma were aware of their disorder; and the awareness was more likely in those with comorbidity of rhinitis. In general, asthma management was inadequate.

Charge Injection Barriers at a Ribonucleic Acid/Inorganic Material Contact Determined by Photoemission Spectroscopy

Ribonucleic acid (RNA) homopolymer thin films on highly oriented pyrolytic graphite (HOPG) were prepared in ultrahigh vacuum (UHV) directly from aqueous solution by electrospray (ES) injection. The polyadenosine (poly rA) films were prepared in several steps of increasing thickness without breaking the vacuum. Before deposition and between deposition steps, the samples were characterized with photoemission spectroscopy (PES). Both X-ray and ultraviolet photoemission spectroscopy (XPS and UPS) were employed. XPS enabled the detailed measurement of core level peaks, giving insight into the chemical interaction at the interface and the layer morphology. The corresponding UP-spectra sequence allowed us to directly follow the transition from HOPG valence bands to the poly rA highest occupied molecular orbital (HOMO) structure. This enabled the determination of the poly rA ionization energy and work function as well as the charge injection barriers between the Fermi level of the HOPG substrate and the poly rA HOMO. The injection barrier between the lowest unoccupied molecular orbital (LUMO) and the HOPG Fermi level was determined using the HOMO-LUMO gap value determined by optical absorption. The results indicate that significant injection barriers exist between HOPG and the poly rA overlayer, limiting conductivity across this interface.

Nitric oxide flow tagging in unseeded air

A scheme for molecular tagging velocimetry is presented that can be used in air flows without any kind of seeding. The method is based on the local and instantaneous creation of nitric oxide (NO) molecules from N(2) and O(2) in the waist region of a focused ArF excimer laser beam. This NO distribution is advected by the flow and can be visualized any time later by laser-induced fluorescence in the gamma bands. The creation of NO is confirmed by use of an excitation spectrum. Two examples of the application of the new scheme for air-flow velocimetry are given in which single laser pulses are used for creation and visualization of NO.

Methods to correct planar laser-induced fluorescence distributions for local nonuniform laser attenuation

Planar laser-induced fluorescence is often used to obtain two-dimensional density distributions of specific molecules in reactive or nonreactive flows. In opaque environments, such as sooty flames or dusty air flows, the laser intensity decrease over the field of view must be taken into account. We describe two methods to determine the local extinction factor, and, from that, the local laser intensity. Both methods are based on elastic light scattering, one of which employs two elastic light scattering images, recorded simultaneously from the same probe volume, but illuminated from opposite directions. Although exact in principle, this method requires considerable experimental expenditure, and for this reason a more approximate method by use of only a single elastic scattering image is described as well. The results of both methods, applied to combustion diagnostics in an optically accessible Diesel engine, are compared.

Generation of 224-nm radiation by stimulated Raman scattering of ArF excimer laser radiation in a mixture of H2 and D2

Raman shifting of tunable ArF excimer laser radiation in a mixture of H(2) and D(2) produces tunable radiation in the 224-nm region as a result of Stokes shifting the frequency of the fundamental radiation (193 nm) once in both H(2) and D(2). At a total pressure of 25 bars, a 19% H(2) in D(2) mixture is found to provide a maximum conversion efficiency (2.5%) to the 224-nm range. Both fundamental and 224-nm radiation were used to record laser-induced fluorescence excitation spectra of nitric oxide produced in an oxyacetylene flame. From the excitation spectra, we determined the tuning range of the 224-nm radiation to be 270 cm(-1) with a linewidth of 0.9 cm(-1), which is similar to the fundamental laser radiation. We derived the exact Raman shift of the generated radiation by comparing both excitation spectra which was found to be 7142.3(5) cm(-1).

Multiple-Photon Dynamics in Molecules: A New Approach to High Resolution Spectroscopy of Highly Excited Vibrational States

Multi-photon transitions with two simultaneously interacting IR laser fields lead to final excited states with frequencies nnu = n1nu1 + n2nu2, with n the total number of photons absorbed and (n, n1, n2) = (2, 1, 1), (3, 2, 1), (4, 1, 3), etc. The nature of the actual transition is determined by shift measurements, where the lasers are frequency-tuned by deltanui in opposite directions keeping the sum frequency, nnu, resonant with the molecular transition. This technique opens a new spectral range for multi-photon transitions and a unique identification of the observed features. For n1 and n2 both positive the excitation will lead to a "normal" up-up multi-photon transition. Many three- and four-photon transitions in the nu3 vibrational ladder of SF6 could be resolved with a resolution of 1 MHz, as well as four new two-photon transitions. As long as n1 + n2 >/= 0, one of the two ni may be negative resulting in an, e.g., up-down excitation pathway with its particular selection rules. The up-down excitations are demonstrated both for one- and two-photon transitions using the frequency shift technique. The different possible excitation schemes which meet the resonance condition for these transitions lead to interference effects and local couplings to highly excited states. Changes in resonance frequency for a one-photon transition (n = 1), due to these effects, are demonstrated. Evidently, the radiative coupling of participating levels to high-lying or quasi-continuum states may drastically change for different deltanui leading both to ac Stark shift and transition probability variations.

Lymphography in the initial evaluation of endometrial carcinoma

Two hundred eighty-eight patients with endometrial carcinoma underwent a bipedal lymphography. The proportion of positive lymphangiograms is related to the clinical stage, the histologic grade, and the depth of myometrial invasion. Lymphography is not a significant predictor of survival taking into account the other prognostic factors. A histological examination of the lymph nodes was carried out for 138 patients. Lymphography is not very sensitive but is highly specific, detecting only 50% of metastases with a false positive rate that is too high. It therefore is of little diagnostic and prognostic value for operable patients. It is, however, useful for the followup of lymph nodes of patients treated by radiation therapy.