Site Variability in Cerebral Embolic Protection for Transcatheter Aortic Valve Implantation and Association With Outcomes

Background

The effectiveness of cerebral embolic protection devices (CEPD) in mitigating stroke after transcatheter aortic valve implantation (TAVI) remains uncertain, and therefore CEPD may be utilized differently across US hospitals. This study aims to characterize the hospital-level pattern of CEPD use during TAVI in the US and its association with outcomes.

Methods

Patients treated with nontransapical TAVI in the 2019 Nationwide Readmissions Database were included. Hospitals were categorized as CEPD non-users and CEPD users. The following outcomes were compared: the composite of in-hospital stroke or transient ischemic attack (TIA), in-hospital ischemic stroke, death, and cost of hospitalization. Logistic regression models were used for risk adjustment of clinical outcomes.

Results

Of 41,822 TAVI encounters, CEPD was used in 10.6% (n = 4422). Out of 392 hospitals, 65.8% were CEPD non-user hospitals and 34.2% were CEPD users. No difference was observed between CEPD non-users and CEPD users in the risk of in-hospital stroke or TIA (adjusted odds ratio (OR) = 0.99 [0.86-1.15]), ischemic stroke (adjusted OR = 1.00 [0.85-1.18]), or in-hospital death (adjusted OR = 0.86 [0.71-1.03]). The cost of hospitalization was lower in CEPD non-users.

Conclusions

Two-thirds of hospitals in the US do not use CEPD for TAVI, and no significant difference was observed in neurologic outcomes among patients treated at CEPD non-user and CEPD user hospitals.

Minimally invasive, simplified double-layer left atrial appendage closure

The left atrial appendage (LAA) has been identified as a site of thrombus formation in the heart and as a source of embolism in patients with atrial fibrillation, leading to stroke. Studies suggest that LAA closure may reduce the risk for stroke and the need for anticoagulation; conversely, incomplete closure can increase the stroke risk almost 12-fold. Because open heart surgery is associated with increased risk for subsequent stroke, surgeons generally prefer to close the LAA during heart surgery, as recommended in current atrial fibrillation management guidelines. Building on trends toward minimally invasive approaches in cardiac surgery, we developed a simple, unique, and reproducible method for complete LAA closure during mitral valve surgery that has proven to be safe and efficacious: Our first three patients remained completely free from stroke and minor neurological manifestations 27 months after surgery.

Cannulation Strategies for Minimally Invasive Cardiac Surgery

OBJECTIVE

Operative techniques for minimally invasive cardiac surgery (MICS) have evolved dramatically over the past decade to include a wide demographic of patients. Mastering a variety of cannulation techniques is of paramount importance in performing a safe perfusion strategy and operation. Our aim is to describe cannulation strategies utilized in various MICS procedures.

METHODS

We review numerous cannulation strategies and their application in different minimally invasive procedures.

RESULTS

Cannulation strategies will vary depending on the MICS procedure and other anatomical variations and obstacles. Utilizing the appropriate cannulation strategy will allow for a safe and effective operation.

CONCLUSIONS

Mastering the art of cannulation will provide surgeons with a toolbox to choose from when performing MICS in a wide variety of procedures.

Optical properties of quantum-dot-doped liquid scintillators

Semiconductor nanoparticles (quantum dots) were studied in the context of liquid scintillator development for upcoming neutrino experiments. The unique optical and chemical properties of quantum dots are particularly promising for the use in neutrinoless double-beta decay experiments. Liquid scintillators for large scale neutrino detectors have to meet specific requirements which are reviewed, highlighting the peculiarities of quantum-dot-doping. In this paper, we report results on laboratory-scale measurements of the attenuation length and the fluorescence properties of three commercial quantum dot samples. The results include absorbance and emission stability measurements, improvement in transparency due to filtering of the quantum dot samples, precipitation tests to isolate the quantum dots from solution and energy transfer studies with quantum dots and the fluorophore PPO.

Indication of reactor ν(e) disappearance in the Double Chooz experiment

The Double Chooz experiment presents an indication of reactor electron antineutrino disappearance consistent with neutrino oscillations. An observed-to-predicted ratio of events of 0.944±0.016(stat)±0.040(syst) was obtained in 101 days of running at the Chooz nuclear power plant in France, with two 4.25 GW(th) reactors. The results were obtained from a single 10 m(3) fiducial volume detector located 1050 m from the two reactor cores. The reactor antineutrino flux prediction used the Bugey4 flux measurement after correction for differences in core composition. The deficit can be interpreted as an indication of a nonzero value of the still unmeasured neutrino mixing parameter sin(2)2θ(13). Analyzing both the rate of the prompt positrons and their energy spectrum, we find sin(2)2θ(13)=0.086±0.041(stat)±0.030(syst), or, at 90% C.L., 0.017<sin(2)2θ(13)<0.16.

Coupled molecular switches: a redox-responsive ligand and the redox-switched complexation of metal ions

1,1'-(OC2H4OTos)2-ferrocene was treated with various diaza-[n]-crown-m (n/m = 12/4, 15/5, 18/6) to give three ferrocene cryptands (n/m = 12/4 (FcCrypt), 15/5, 18/6). The complexation of Group 1 and 2 metal ions by FcCrypt leads to large shifts in the redox potentials (up to +500 mV relative to FcCrypt) and consequently to a drastic decrease in the binding strength (up to 10(8)) in the ferrocene cryptands. The redox potential of Fcpda (1,1'-N,N'-bis-(dipicol-2-ylamino)-3.3',4,4'-tetraphenylferrocene) can be modified reversibly by complexation of Zn2 (E(Fcdpa) = -0.13 V, E(Fcdpa-2Zn+) = +0.66 V and E(Fcdpa-Zn2+) = +0.72 V). The X-ray crystal structure of FcCrypt-Ca-(ClO4)2 . H2O was determined; Ca2+ is coordinated by six oxygen (Ca2+-O 238.7, 239.1, 239.5, 242.6, 243.6, 247.7 pm) and two nitrogen donors (Ca2+-N 256.1, 259.2 pm) and displays a short Fe-Ca2+ contact (402.7 pm). The stability constants of FcCrypt-Na+ (IgK=8.32 in CH3CN) and FcCrypt-K+ (IgK = 4.54 in CH3CN) were determined. The precise adjustment of complex stability and redox potentials of Fcdpa, Fcdpa-Zn2+, FcCrypt (+0.12 V), and FcCrypt-Na+ (+0.395 V) allows coupling of the redox-switchable ferrocene cryptand and the redox-responsive aminoferrocene. In a cyclic process starting from a mixture of Fcdpa+PF6- and FcCrypt-Na+ the addition of Zn(CF3SO3)2 raises the redox potential of Fcdpa+ to that of Fcdpa+-Zn2+. This complex oxidizes FcCrypt-Na+, while the oxidized crypt- and displays a drastically reduced affinity towards Na+, so that a mixture containing FcCrypt+, Fcdpa-Zn2+, and uncoordinated Na+ results. The alkali metal ion is recomplexed after cyclam-assisted removal of Zn2+ from the Fcdpa-Zn2+ complex, since Fcdpa is oxidized by FcCrypt+ with reformation of FcCrypt-Na+. Thus two independent chemical processes--the complexation/ decomplexation of Zn2+ and of Na+--are linked indirectly with mediation by electron-transfer reactions.

Ferrocene-cyclam: a redox-active macrocycle for the complexation of transition metal ions and a study on the influence of the relative permittivity on the coulombic interaction between metal cations

The reaction of 1,1'-ferrocene-bis(methylenepyridinium) salt with 1,4,8,11-tetraazacyclotetradecane-5,12-dione, followed by LiAlH4 reduction results in the formation of FcCyclam. Metal complexes of FcCyclam with M2+ = Co2+, Ni2+, Cu2+, and Zn2+ were synthesized from FcCyclam and the respective metal triflates. The complexation of Cu2+ and FcCyclam in CH3CN is preceeded by a rapid electron transfer, followed by a slower complex formation reaction and a reverse electron transfer. The protonation constants of FcCyclam and the stability constants for the Cu2+ complex of FcCyclam (logK = 9.26(4) for the formation of the [Cu(FcCyclam)]2+ complex) were determined in 1,4-dioxane/water 70:30 v/v, 0.1 moldm(-3), KNO3, 25 degrees C. By using FcCyclam one can selectively sense the presence of Cu2+ ions in the presence of Ni2+, Zn2+, Cd2+, Hg2+, and Pb2+ with a very large deltaE approximately 200 mV, depending on pH. The X-ray crystal structures of FcCyclam and of complexes with Co2+, Ni2+, Cu2+, and Zn2+ were determined and Fe-M2+ distances obtained: Fe-Co2+ 395.9, Fe-Ni2+ 385.4, Fe-Cu2+ 377.7, and Fe-Zn2+ 369.0 pm. The redox potential of FcCyclam is influenced in a characteristic manner by the complexation of M2+. A linear correlation of 1/r approximately/= deltaE [r = distance Fe-M2+ from crystal data, deltaE=-E1/2([M(FcCyclam)]2+) - E1/2(FcCyclam)] was found; this is indicative of a mainly Coulomb type interaction between the two metal centers. The nature of the Fe...M2+ interaction was also investigated by determining deltaE in several solvents (mixtures) of different dielectric constants epsilon. The expected relation of deltaE approximately/= 1/epsilon was only found at very high values of epsilon. At epsilon < 40 increased ion-pairing appears to reduce the effective positive charge at M2+ leading to progessively smaller values of deltaE with lowered epsilon. The dependence of deltaE and epsilon can be calculated semiquantitatively by combining the Fuoss ion-pairing theory with the Coulomb model.