ABSTRACT
BACKGROUND AND AIM: The purpose of this study was to determine the role of dominant frequency (DF) and organised index (OI) in outcomes of pulmonary vein (PV) isolation for paroxysmal atrial fibrillation (AF). METHODS: OI and DF of electrograms in coronary vein (CS) during AF were obtained by frequency spectra analysis in 60 patients with paroxysmal AF who underwent PV isolation. Based on the results of 12 months follow up, 14 patients with recurrent AF were included in group 1 and 46 patients with sinus rhythm were included in group 2. RESULTS: In group 1, no spectral component was reduced by PV isolation. Spectral components were reduced by PV isolation in 23 patients in group 2. The changes of DF after PV isolation was significantly different between groups 1 and 2 (1.2 ± 1.2 vs. 2.4 ± 1.3, p = 0.01); the increment of OI after PV isolation in group 1 was significantly lower than in group 2 (9 ± 13% vs. 22 ± 17%, p = 0.02. CONCLUSIONS: A decrease in DF and an increase in OI after PV isolation may suggest a better clinical outcome.
Subject(s)
Coronary Vessels/physiopathology , Electrophysiologic Techniques, Cardiac , Tachycardia, Ectopic Atrial/diagnosis , Tachycardia, Ectopic Atrial/surgery , Adolescent , Adult , Aged , Atrial Fibrillation/diagnosis , Atrial Fibrillation/surgery , Catheter Ablation , Echocardiography , Echocardiography, Transesophageal , Electrocardiography , Electrocardiography, Ambulatory , Female , Follow-Up Studies , Heart Atria/diagnostic imaging , Humans , Male , Middle Aged , Models, Cardiovascular , Recurrence , Spectrum Analysis , Treatment Outcome , Young AdultABSTRACT
Alternate adsorption of negatively charged Fe(3)O(4) nanoparticles from their pH 8.0 aqueous dispersions and positively charged hemoglobin (Hb) from its pH 5.5 buffers on solid substrates resulted in the assembly of {Fe(3)O(4)/Hb}(n) layer-by-layer films. Quartz crystal microbalance (QCM), UV-vis spectroscopy, and cyclic voltammetry (CV) were used to monitor and confirm the film growth. A pair of well-defined, nearly reversible CV peaks for HbFe(III)/Fe(II) redox couples was observed for {Fe(3)O(4)/Hb}(n) films on pyrolytic graphite (PG) electrodes. Although the multilayered films grew linearly with the number of Fe(3)O(4)/Hb bilayers (n) and the amount of Hb adsorbed in each bilayer was generally the same, the electroactive Hb could only extend to 6 bilayers. This indicates that only those Hb molecules in the first few bilayers closest to the electrode surface are electroactive. The electrochemical parameters such as the apparent heterogeneous electron transfer rate constant (k(s)) were estimated by square wave voltammetry (SWV) and nonlinear regression. The Soret absorption band position of Hb in {Fe(3)O(4)/Hb}(6) films showed that Hb in the films retained its near native structure in the medium pH range. The {Fe(3)O(4)/Hb}(6) film electrodes also showed good biocatalytic activity toward reduction of oxygen, hydrogen peroxide, trichloroacetic acid, and nitrite. The electrochemical reduction overpotentials of these substrates were lowered significantly by {Fe(3)O(4)/Hb}(n) films.
Subject(s)
Ferrosoferric Oxide/chemistry , Graphite/chemistry , Hemoglobins/chemistry , Animals , Buffers , Catalysis , Cattle , Electrochemistry , Electrodes , Hydrogen-Ion Concentration , Nanostructures , Oxidation-Reduction , Protein ConformationABSTRACT
Fe3O4 nanoparticles cast on pyrolytic graphite (PG) electrodes were used to immobilize hemoglobin (Hb), myoglobin (Mb) and horseradish peroxidase (HRP). The Fe3O4 nanoparticles provided a favorable microenvironment for the proteins to directly transfer electrons with electrodes. The protein-Fe3O4 films were used to electrochemically catalyze the reduction of oxygen, trichloroacetic acid, nitrite and hydrogen peroxide, and showed a potential applicability in fabricating biosensors. Transmission electron microscopy (TEM), UV-visible absorption and reflectance absorption infrared (RAIR) spectroscopy, and cyclic and square wave voltammetry, were used to characterize the films.
