Clinical impact of sex differences and procedural setting in transcatheter aortic valve implantation.

Background: Transcatheter aortic valve implantation (TAVI) is a well-established treatment for symptomatic patients with aortic stenosis. Yet, the impact of sex differences and public vs. private procedural setting on TAVI outcomes remain uncertain.

Learning Curve for In-Hospital Mortality of Transcatheter Aortic Valve Replacement: Insights from the Brazilian National Registry.

Background: Robust data on the learning curve (LC) of transcatheter aortic valve replacement (TAVR) are lacking in developing countries.

Objective: To assess TAVR's LC in Brazil over time.

Methods: We analyzed data from the Brazilian TAVR registry from 2008 to 2023.

Recent Developments and Current Status of Transcatheter Aortic Valve Replacement Practice in Latin America - the WRITTEN LATAM Study.

Background: Transcatheter aortic valve replacement (TAVR) is a worldwide adopted procedure with rapidly evolving practices. Regional and temporal variations are expected to be found.

Objective: To compare TAVR practice in Latin America with that around the world and to assess its changes in Latin America from 2015 to 2020.

Incidence, Predictor, and Clinical Outcomes of Multiple Resheathing With Self-Expanding Valves During Transcatheter Aortic Valve Replacement.

Background No study has evaluated the impact of the additional manipulation demanded by multiple resheathing (MR) in patients undergoing transcatheter aortic valve replacement with repositionable self-expanding valves. Methods and Results This study included a real-world, multicenter registry involving 16 centers from Canada, Germany, Latin America, and Spain. All consecutive patients who underwent transcatheter aortic valve replacement with the Evolut R, Evolut PRO, and Portico valves were included.

Aortic Valve Replacement in Low-Risk Patients With Severe Aortic Stenosis Outside Randomized Trials.

Background: Recent randomized trials including low-risk patients showed positive results for transcatheter aortic valve replacement (TAVR) compared to surgical aortic valve replacement (SAVR), but patients with non-tricuspid aortic valve (NTAV), severe coronary artery disease (SevCAD), and those requiring concomitant mitral/tricuspid valve (CMTV) or concomitant ascending aorta replacement (CAAR) interventions were excluded.

Objectives: This study sought to evaluate the presence and impact of the main clinical variables not evaluated in TAVR versus SAVR trials (NTAV, SevCAD, and CMTV or CAAR intervention) in a large series of consecutive low-risk patients with severe aortic stenosis (SAS) undergoing SAVR.

Methods: Single-center study including consecutive patients with SAS and low surgical risk (Society of Thoracic Surgeons score of <4%) undergoing SAVR.

Valve-in-Valve Challenges: How to Avoid Coronary Obstruction.

Coronary obstruction is a rare but life-threatening complication in patients undergoing transcatheter aortic valve replacement (TAVR). Aortic valve-in-valve (VIV) procedures to treat failed surgical bioprosthesis is associated with ~6-fold higher risk for coronary obstruction in certain situations. The primary mechanism consists in the occlusion of the coronary ostium by the dislodged leaflet from the bioprosthesis after deployment of the transcatheter heart valve (THV), which most commonly occurs during the index procedure, but in up to 1/3 of cases a delayed presentation ensues.

Potential of transcatheter aortic valve replacement to improve post-procedure renal function.

Background: Baseline comorbidities including renal dysfunction are frequently found in patients treated with transcatheter aortic valve replacement (TAVR) and may increase the risks of acute kidney injury (AKI), although some of them may actually improve renal function. We aimed to evaluate the potential of TAVR to acutely improve post-procedure renal function.

Methods: This is a prospective single-center registry of consecutive patients with severe symptomatic aortic stenosis treated by transfemoral TAVR.

Direct Transcatheter Heart Valve Implantation Versus Implantation With Balloon Predilatation: Insights From the Brazilian Transcatheter Aortic Valve Replacement Registry.

Background: Direct transcatheter aortic valve replacement (TAVR) is regarded as having potential advantages over TAVR with balloon aortic valve predilatation (BAVP) in reducing procedural complications, but there are few data to support this approach.

Methods And Results: Patients included in the Brazilian TAVR registry with CoreValve and Sapien-XT prosthesis were compared according to the implantation technique, with or without BAVP. Clinical and echocardiographic data were analyzed in overall population and after propensity score matching.

Does Ad Hoc Coronary Intervention Reduce Radiation Exposure? - Analysis of 568 Patients.

Background: Advantages and disadvantages of ad hoc percutaneous coronary intervention have been described. However little is known about the radiation exposure of that procedure as compared with the staged intervention.

Objective: To compare the radiation dose of the ad hoc percutaneous coronary intervention with that of the staged procedureMethods:The dose-area product and total Kerma were measured, and the doses of the diagnostic and therapeutic procedures were added.

Surgical cutdown versus percutaneous access in transfemoral transcatheter aortic valve implantation: Insights from the Brazilian TAVI registry.

Objective: To compare the 1-year outcomes of complete percutaneous approach versus surgical vascular approach for transfemoral transcatheter aortic valve implantation (TAVI), among "real-world" patients from the multi-center Brazilian TAVI registry.

Background: Vascular access still remains a major challenge for TAVI via transfemoral approach. Vascular access through complete percutaneous approaches or through open surgical vascular techniques seems to be acutely similar.

Structure, spectroscopy, and spectral tuning of the gas-phase retinal chromophore: the beta-ionone "handle" and alkyl group effect.

The low-lying singlet states (i.e. S0, S1, and S2) of the chromophore of rhodopsin, the protonated Schiff base of 11-cis-retinal (PSB11), and of its all-trans photoproduct have been studied in isolated conditions by using ab initio multiconfigurational second-order perturbation theory.

The retinal chromophore/chloride ion pair: structure of the photoisomerization path and interplay of charge transfer and covalent states.

Ab initio multi-reference second-order perturbation theory computations are used to explore the photochemical behavior of two ion pairs constituted by a chloride counterion interacting with either a rhodopsin or bacteriorhodopsin chromophore model (i.e., the 4-cis-gamma-methylnona-2,4,6,8-tetraeniminium and all-trans-nona-2,4,6,8-tetraeniminium cations, respectively).

Solvent effects on the vibrational activity and photodynamics of the green fluorescent protein chromophore: a quantum-chemical study.

Vibrational activities in the Raman and resonance Raman spectra of the cationic, neutral, and anionic forms of 4'-hydroxybenzylidene-2,3-dimethyl-imidazolinone, a model compound for the green fluorescent protein chromophore, have been obtained from quantum-chemical calculations in vacuo and with the inclusion of solvent effects through the polarizable continuum model. It is found that inclusion of solvent effects improves slightly the agreement with experimental data for the cationic and neutral forms, whose spectra are qualitatively well-described already by calculations in vacuo. In contrast, inclusion of solvent effects is crucial to reproduce correctly the activities of the anionic form.

Photoisomerization mechanism of 11-cis-locked artificial retinal chromophores: acceleration and primary photoproduct assignment.

CASPT2//CASSCF/6-31G photochemical reaction path computations for two 4-cis-nona-2,4,6,8-tetraeniminium cation derivatives, with the 4-cis double bond embedded in a seven- and eight-member ring, are carried out to model the reactivity of the corresponding ring-locked retinal chromophores. The comparison of the excited state branches of the two reaction paths with that of the native chromophore, is used to unveil the factors responsible for the remarkably short (60 fs) excited state (S(1)) lifetime observed when an artificial rhodopsin containing an eight member ring-locked retinal is photoexcited. Indeed, it is shown that the strain imposed by the eight-member ring on the chromophore backbone leads to a dramatic change in the shape of the S(1) energy surface.

Counterion controlled photoisomerization of retinal chromophore models: a computational investigation.

CASPT2//CASSCF photoisomerization path computations have been used to unveil the effects of an acetate counterion on the photochemistry of two retinal protonated Schiff base (PSB) models: the 2-cis-penta-2,4-dieniminium and the all-trans-epta-2,4,6-trieniminium cations. Different positions/orientations of the counterion have been investigated and related to (i) the spectral tuning and relative stability of the S0, S1, and S2 singlet states; (ii) the selection of the photochemically relevant excited state; (iii) the control of the radiationless decay and photoisomerization rates; and, finally, (iv) the control of the photoisomerization stereospecificity. A rationale for the results is given on the basis of a simple (electrostatic) qualitative model.

On the mechanism of the cis-trans isomerization in the lowest electronic states of azobenzene: S0, S1, and T1.

In this paper, we identify the most efficient decay and isomerization route of the S(1), T(1), and S(0) states of azobenzene. By use of quantum chemical methods, we have searched for the transition states (TS) on the S(1) potential energy surface and for the S(0)/S(1) conical intersections (CIs) that are closer to the minimum energy path on the S(1). We found only one TS, at 60 degrees of CNNC torsion from the E isomer, which requires an activation energy of only 2 kcal/mol.

Excited-state singlet manifold and oscillatory features of a nonatetraeniminium retinal chromophore model.

In this paper we use ab initio multireference Møller-Plesset second-order perturbation theory computations to map the first five singlet states (S(0), S(1), S(2), S(3), and S(4)) along the initial part of the photoisomerization coordinate for the isolated rhodopsin chromophore model 4-cis-gamma-methylnona-2,4,6,8-tetraeniminium cation. We show that this information not only provides an explanation for the spectral features associated to the chromophore in solution but also, subject to a tentative hypothesis on the effect of the protein cavity, may be employed to explain/assign the ultrafast near-IR excited-state absorption, stimulated emission, and transient excited-state absorption bands observed in rhodopsin proteins (e.g.

A simple approach for improving the hybrid MMVB force field: application to the photoisomerization of s-cis butadiene.

MMVB is a QM/MM hybrid method, consisting of a molecular mechanics force field coupled to a valence bond Heisenberg Hamiltonian parametrized from ab initio CASSCF calculations on several prototype molecules. The Heisenberg Hamiltonian matrix elements Q(ij) and K(ij), whose expressions are partitioned here into a primary contribution and second-order correction terms, are calculated analytically in MMVB. When the original MMVB force field fails to produce potential energy surfaces accurate enough for dynamics calculations, we show that significant improvements can be made by refitting the second-order correction terms for the particular molecule(s) being studied.

Cyclooctatetraene computational photo- and thermal chemistry: a reactivity model for conjugated hydrocarbons.

We use ab initio CASSCF and CASPT2 computations to construct the composite multistate relaxation path relevant to cycloocta-1,3,5,7-tetraene singlet photochemistry. The results show that an efficient population of the dark excited state (S(1)) takes place after ultrafast decay from the spectroscopic excited state (S(2)). A planar D(8)(h)-symmetric minimum represents the collecting point on S(1).

Pseudopeptide foldamers: the homo-oligomers of pyroglutamic acid.

As a part of a program evaluating substituted gamma-lactams as conformationally constrained building blocks of pseudopeptide foldamers, we synthesized the homo-oligomers of L-pyroglutamic acid up to the tetramer level by solution methods. The preferred conformation of this pseudopeptide series in structure-supporting solvents was assessed by FT-IR absorption, 1H NMR and CD techniques. In addition, the crystal structure of the N alpha-protected dimer was established by X-ray diffraction.

Reaction path analysis of the "tunable" photoisomerization selectivity of free and locked retinal chromophores.

Multiconfigurational second-order perturbation theory computations and reaction path mapping for the retinal protonated Schiff base models all-trans-nona-2,4,6,8-tetraeniminium and 2-cis-nona-2,4,6,8-tetraeniminium cation demonstrate that, in isolated conditions, retinal chromophores exhibit at least three competing excited-state double bond isomerization paths. These paths are associated with the photoisomerization of the double bonds in positions 9, 11, and 13, respectively, and are controlled by barriers that favor the position 11. The computations provide a basis for the understanding of the observed excited-state lifetime in both naturally occurring and synthetic chromophores in solution and, tentatively, in the protein environment.

Rates and Equilibria of the Michael-Type Addition of Benzenethiol to 2-Cyclopenten-1-ones.

The triethylamine-catalyzed addition reactions of benzenethiol to 2-cyclopenten-1-one and its 2- and 3-methyl derivatives have been found to be appreciably reversible in chloroform solution. Rates and equilibria have been carefully measured at 25 degrees C in order to assess the negative influence on addition exerted by methyl groups substituted on the carbon-carbon double bond. 2-Methyl-2-cyclopenten-1-one has been found to react with benzenethiol under kinetic control to give the cis adduct as the sole detectable product in a highly stereoselective anti addition process.