Comparison of adenosine-independent pressure indices to fractional flow reserve in stent-jailed bifurcation side branches.

OBJECTIVES AND BACKGROUND: This study aims to evaluate whether the high correlation and classification agreement of the instantaneous wave-free ratio (iFR) and the resting distal coronary to aortic pressure ratio (Pd /Pa ) with the fractional flow reserve (FFR) can be confirmed in stent-jailed side branches (J-SB). METHODS: Consecutive patients (n = 49) undergoing provisional stenting were prospectively enrolled and a physiological assessment of the J-SB (n = 51) was performed. FFR, iFR, and Pd /Pa were measured and the hemodynamic relevance was determined using cutoff values of ≤0.80, ≤0.89, and ≤0.92, respectively. RESULTS: Both iFR (r = 0.75) and Pd /Pa (r = 0.77) correlated closely with FFR. Classification agreement with FFR was 78% for iFR (81% sensitivity, 77% specificity) and 75% for Pd /Pa (63% sensitivity and 80% specificity). However, angiographic diameter stenosis and pressure indices correlated poorly. For a threshold of ≥70% stenosis, agreement concerning hemodynamic relevance was found in 59% for FFR, 69% for iFR, and 61% for Pd /Pa . CONCLUSION: As reported for other lesion types, FFR and the adenosine-independent pressure indices iFR and Pd /Pa show close correlation and a high classification agreement of approximately 75%-80% in J-SB. Therefore, iFR can be regarded as a recommendable alternative to FFR for the guidance of provisional stenting in bifurcation lesions.

Investigations of the water clusters of the protected amino acid Ac-Phe-OMe by applying IR/UV double resonance spectroscopy: microsolvation of the backbone.

In order to investigate the influence of hydration on the backbone of a peptide or protected amino acid, the successive aggregation of water to Ac-Phe-OMe is analysed by means of IR/UV double resonance spectroscopy. To achieve meaningful results the spectra have been recorded in the region of the amide A and OH stretching vibrations as well as the amide I/II modes. Comparison with ab initio and DFT calculations leads to size-selective structural assignments. Two isomers of the mono- and dihydrated clusters and one isomer of the trihydrated cluster are observed in the molecular beam leading to a formation of the first solvation shell of the backbone. In case of the trihydrated cluster the backbone geometry is remarkably changed compared to the structure of the monomer since a network of water molecules can be formed.

Proton/hydrogen-transfer coordinate of 2,5-dihydroxybenzoic acid investigated in a supersonic beam: combined IR/UV spectroscopy in the S0, S1, and D0 states.

As a model system for intramolecular proton/hydrogen-transfer coordinates, the structure of 2,5-dihydroxybenzoic acid is investigated for the ground, first electronically excited and also the ionic state. Combined IR/UV spectroscopy in molecular-beam experiments is applied and the experimental results are interpreted by the application of DFT and CASPT2 methods. No proton or hydrogen transfer is observed, but evidence is given for a hydrogen dislocation of the intramolecular hydrogen bond in the S(1) state and to lesser extent in the D(0) state. To obtain direct information on the proton/hydrogen-transfer coordinate, IR spectra are recorded both in the region of the OH and especially the CO stretching vibrations by also applying two new variants of combined IR/UV spectroscopy for the S(1) and D(0) states. The CO groups are directly involved in the hydrogen bond and, in contrast to the hydrogen-bonded OH groups, the CO stretching frequencies can be observed in all electronic states.