Bridge to recovery in children on ventricular assist devices-protocol, predictors of recovery, and long-term follow-up.

BACKGROUND: The majority of children supported with ventricular assist devices (VADs) are bridged to heart transplantation. Although bridge to recovery has been reported, low recovery patient numbers has precluded systematic analysis. The aim of this study was to delineate recovery rates and predictors of recovery and to report on long-term follow-up after VAD explantation in children. METHODS: Children bridged to recovery at our institution from January 1990 to May 2016 were compared with a non-recovery cohort. Clinical and echocardiographic data before and at pump stoppages and after VAD explantation were analyzed. Kaplan‒Meier estimates of event-free survival, defined as freedom from death or transplantation after VAD removal, were determined. RESULTS: One hundred forty-nine children (median age 5.8 years) were identified. Of these, 65.2% had cardiomyopathy, 9.4% had myocarditis, and 24.8% had congenital heart disease. The overall recovery rate was 14.2%, and was 7.1% in patients with dilated cardiomyopathy. Predictors of recovery were age <2 years (recovery rate 27.8%, odds ratio [OR] 5.64, 95% confidence interval [CI] 2.0 to 16.6) and diagnosis of myocarditis (rate 57.1%; OR 17.56, 95% CI 4.6 to 67.4). After a median follow-up of 10.8 years, 15 patients (83.3%) were in Functional Class I and 3 (16.7%) in were in Class II. Mean left ventricular ejection fraction was 53% (range 28% to 64%). Ten- and 15-year event-free survival rates were both 84.1 ± 8.4%. CONCLUSIONS: Children <2 years of age and those diagnosed with myocarditis have the highest probability of recovery. Long-term survival after weaning from the VAD was better than after heart transplantation, as demonstrated in the excellent long-term stability of ejection fraction and functional class.

Fine- and hyperfine-structure effects in molecular photoionization. II. Resonance-enhanced multiphoton ionization and hyperfine-selective generation of molecular cations.

Resonance-enhanced multiphoton ionization (REMPI) is a widely used technique for studying molecular photoionization and producing molecular cations for spectroscopy and dynamics studies. Here, we present a model for describing hyperfine-structure effects in the REMPI process and for predicting hyperfine populations in molecular ions produced by this method. This model is a generalization of our model for fine- and hyperfine-structure effects in one-photon ionization of molecules presented in Paper I [M. Germann and S. Willitsch, J. Chem. Phys. 145, 044314 (2016)]. This generalization is achieved by covering two main aspects: (1) treatment of the neutral bound-bound transition including the hyperfine structure that makes up the first step of the REMPI process and (2) modification of our ionization model to account for anisotropic populations resulting from this first excitation step. Our findings may be used for analyzing results from experiments with molecular ions produced by REMPI and may serve as a theoretical background for hyperfine-selective ionization experiments.

Fine- and hyperfine-structure effects in molecular photoionization. I. General theory and direct photoionization.

We develop a model for predicting fine- and hyperfine intensities in the direct photoionization of molecules based on the separability of electron and nuclear spin states from vibrational-electronic states. Using spherical tensor algebra, we derive highly symmetrized forms of the squared photoionization dipole matrix elements from which we derive the salient selection and propensity rules for fine- and hyperfine resolved photoionizing transitions. Our theoretical results are validated by the analysis of the fine-structure resolved photoelectron spectrum of O2 reported by Palm and Merkt [Phys. Rev. Lett. 81, 1385 (1998)] and are used for predicting hyperfine populations of molecular ions produced by photoionization.

Forbidden Vibrational Transitions in Cold Molecular Ions: Experimental Observation and Potential Applications.

A range of interesting fundamental scientific questions can be addressed by high-precision molecular spectroscopy. A promising way towards this goal is the measurement of dipole-forbidden vibrational transitions in molecular ions. We have recently reported the first such observation in a molecular ion. Here, we give an overview of our method and our results as well as an outlook on potential future applications.

Nondestructive imaging of individual biomolecules.

Radiation damage is considered to be the major problem that still prevents imaging an individual biological molecule for structural analysis. So far, all known mapping techniques using sufficient short wavelength radiation, be it x rays or high energy electrons, circumvent this problem by averaging over many molecules. Averaging, however, leaves conformational details uncovered. Even the anticipated use of ultrashort but extremely bright x-ray bursts of a free electron laser shall afford averaging over 10{6} molecules to arrive at atomic resolution. Here, we present direct experimental evidence for nondestructive imaging of individual DNA molecules. In fact, we show that DNA withstands coherent low energy electron radiation with deBroglie wavelength in the Angstrom regime despite a vast dose of 10{8} electrons/nm{2} accumulated over more than one hour.