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  • 1
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: Junctional rhythm (JR) is commonly observed during radiofrequency (RF) ablation of the slow pathway for atrioventricular (AV) nodal reentrant tachycardia. However, the atrial activation pattern and conduction time from the His-bundle region to the atria recorded during JR in different types of AV nodal reentrant tachycardia have not been fully defined. Methods: Forty-five patients who underwent RF ablation of the slow pathway for AV nodal reentrant tachycardia were included; 27 patients with slow-fast, 11 patients with slow-intermediate, and 7 patients with fast-slow AV nodal reentrant tachycardia. The atrial activation pattern and HA interval (from the His-bundle potential to the atrial recording of the high right atrial catheter) during AV nodal reentrant tachycardia (HASVT) and JR (HAJR) were analyzed. Results: In all patients with slow-fast AV nodal reentrant tachycardia, the atrial activation sequence recorded during JR was similar to that of the retrograde fast pathway, and transient retrograde conduction block during JR was found in 1 (4%) patient. The HAJR was significantly shorter than the HASVT (57 ± 24 vs 68 ± 21 ms, P 〈 0.01). In patients with slow-intermediate AV nodal reentrant tachycardia, the atrial activation sequence of the JR was similar to that of the retrograde fast pathway in 5 (45%), and to that of the retrograde intermediate pathway in 6 (55%) patients. Transient retrograde conduction block during JR was noted in 1 (9%) patient. The HAJR was also significantly shorter than the HASVT (145 ± 27 vs 168 ± 29 ms, P = 0.014). In patients with fast-slow AV nodal reentrant tachycardia, retrograde conduction with block during JR was noted in 7 (100%) patients. The incidence of retrograde conduction block during JR was higher in fast-slow AV nodal reentrant tachycardia than slow-fast (7/7 vs 1/11, P 〈 0.01) and slow-intermediate AV nodal reentrant tachycardia (7/7 vs 1/27, P 〈 0.01). Conclusions: In patients with slow-fast and slow-intermediate AV nodal reentrant tachycardia, the JR during ablation of the slow pathway conducted to the atria through the fast or intermediate pathway. In patients with fast-slow AV nodal reentrant tachycardia, there was no retrograde conduction during JR. These findings suggested there were different characteristics of the JR during slow-pathway ablation of different types of AV nodal reentrant tachycardia.
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  • 2
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: Adenosine can terminate most focal atrial tachycardias (ATs). However, information about the termination mechanism is limited. This study investigated the effects and mechanism of adenosine on terminating focal AT using a three-dimensional noncontact mapping system. Methods and Results: The study consisted of 7 patients (4 men and 3 women; age 44 ± 29 years) with focal AT. Cycle length variation and atrial activation pattern at baseline and just before AT termination by adenosine (3–12mg) were analyzed. Noncontact mapping demonstrated focal AT propagated from the origin (O) with preferential conduction and spread away from the breakout sites to the whole atrium. Compared to baseline AT, termination episodes revealed higher mean beat-to-beat variation of AT cycle length (11.7 ± 11.7 msec vs 4.7 ± 4.5 msec, P 〈 0.001) and standard deviation of normalized AT cycle length (0.033 ± 0.014 vs 0.011 ± 0.005, P 〈 0.001). In termination episodes, adenosine significantly decreased the peak negative voltage of AT-O (–27.2 ± 15.3%, P 〈 0.01), preferential conduction (proximal: –32.1 ± 18.7, mid: –28.4 ± 22.8, distal portion: –29.6 ± 21.4%, P 〈 0.01), and breakout (–31.4 ± 12.5%, P 〈 0.01). However, adenosine did not affect voltage in nontermination episodes. Adenosine shifted the locations of AT-O in 5 of 10 AT episodes with termination. Mean number of shifting AT-O was 2.4 ± 1.5 (range 1–4), with maximum shifting distance of 15.0 ± 3.1 (range 10–19) mm. Focal activation at AT-O simply disappeared in all termination episodes and therefore was not due to conduction block within preferential conduction or breakout site. Catheter ablation lesions covered 50% of total shifting origins, without late recurrence. Conclusion: Adenosine-induced AT termination was associated with significantly decreased electrogram voltage, shifting AT-O locations, and disappearance of focal activation.
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  • 3
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: Voltage mapping has been used to detect diseased myocardium. However, accurate determination of the local atrial voltage at the same site, and simultaneous recordings from multiple mapping sites were limited. The purpose of this study was to investigate the right atrial (RA) substrate properties in patients with supraventricular tachyarrhythmias (SVT). Methods and Results: Forty patients (aged 55 ± 20 years) undergoing noncontact mapping and ablation of SVT constituted the study population. There were eight patients with atrioventricular node reentrant tachycardia (AVNRT), eight patients with focal atrial tachycardia (AT), 14 patients with atrial flutter (AFL), and 10 patients with atrial fibrillation (AF). The mean peak negative voltage (PNV) was analyzed in virtual unipolar electrograms, which were obtained from 256 equally distributed RA endocardial sites during sinus rhythm (SR), atrial pacing, and tachycardia. The mean PNV of global RA during SR (−1.34 ± 0.22 vs. −0.90 ± 0.40 vs. −1.00 ± 0.36 vs. −0.85 ± 0.35 mV, P = 0.04), atrial pacing at cycle lengths of 500 ms (−1.30 ± 0.29 vs. −0.70 ± 0.35 vs. −0.76 ± 0.25 vs. −0.64 ± 0.26 mV, P = 0.02), and 300 ms (−1.54 ± 0.47 vs. −0.94 ± 0.21 vs. −0.75 ± 0.27 vs. −0.57 ± 0.22 mV, P 〈 0.01) were significantly greater in patients with AVNRT compared to AT, AFL, and AF. Furthermore, the mean PNV decreased during atrial pacing with shorter pacing cycle length was demonstrated only in patients with AFL and AF. Conclusion: Negative unipolar voltage analysis of global RA showed different RA substrate characteristics during various SVT. The substrate property of activation and cycle length-dependent voltage reduction may be related to the development of AFL and AF.
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  • 4
    ISSN: 1540-8183
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Rescue percutaneous coronary intervention (PCI) has been used to treat patients after failed thrombolysis in acute myocardial infarction. However, the short- and long-term benefits of rescue PCI have not been known exactly. The goal of this study was to examine the clinical and angiographic outcomes, the success rate of the procedure, and the long-term survival rate after rescue PCI. The clinical and angiographic outcomes of 31 patients (Group I; 59.7 ± 11.4 years, 80.6% male), who underwent rescue PCI were compared with those of 177 patients (Group II; 59.7 ± 9.7 years, 79.7% male), who underwent primary PCI at Chonnam National University Hospital between January 1997 and December 1999. There were no significant differences in the risk factors for coronary artery diseases except for smoking (Group I; 24/31, 77.4% vs. Group II; 76/177, 42.9%, P = 0.011 ). The incidence of cardiogenic shock was higher in Group I than in Group II (Group I; 7/31, 22.6% vs. Group II; 11/177, 6.2%, P = 0.021 ). The coronary angiographic findings were not different between two groups, except for Thrombolysis in Myocardial Infarction (TIMI) flow of Group I was lower than in Group II (Group I; 1.14 ± 0.93 vs. Group II; 1.61 ± 1.14, P = 0.001 ). The primary success rate was 93.6% (29/31) in Group I and 94.9% (168/177) in Group II (P = 0.578) . The baseline ejection fraction was lower in Group I than in Group II (Group I;44.2 ± 8.9%vs. Group II;50.8 ± 11.7, P = 0.023), which improved in both groups (Group I;51.7 ± 7.9%vs. Group II;60.7 ± 13.4%, P = 0.001respectively) at 6 months after the procedures. The survival rates of Group I were 93.5%, 93.5%, and 90.3% and those of Group II were 94.5%, 93.7%, and 91% at 1, 6, and 12 months, respectively. Rescue PCI is associated with the risk factor of smoking. The indication for rescue PCI was more common in patents with cardiogenic shock. The success rate of rescue PCI was comparable to that of primary PCI, and left ventricular function is improved after rescue PCI on long-term clinical follow-up with relatively high survival rate. (J Interven Cardiol 2003;16:209–216)
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  • 5
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Paroxysmal atrial fibrillation (PAF) can be initiated by ectopic activation from the crista terminalis. The crista terminalis conduction gap is also a critical isthmus in atrial reentrant arrhythmias like upper and lower loop reentry. The aim of this study was to investigate the mechanism and results of catheter ablation for complex atrial arrhythmias originating from the crista terminalis using the noncontact mapping system (NCM). The study population consisted of six patients (5 men, 1 woman; 70 ± 9 years) with drug refractory PAF and typical/atypical atrial flutter. NCM identified the earliest ectopic activation originating from the crista terminalis in these six patients. The reentry circuit of atypical atrial flutter propagated around the upper crista terminalis in five patients, and lower crista terminalis in one patient. The reentry circuit of atypical atrial flutter and the initial reentry circuit of AF conducted through the crista terminalis gap in all patients. Radiofrequency applications were delivered on the sites of ectopy, which initiated AF. Substrate modification was also performed over the crista terminalis gap (six patients) and cavotricuspid isthmus (three patients) responsible for the reentry. During a mean follow-up of 9 ± 5 months (range 5–18 months), five patients were free of AF without antiarrhythmic drugs, and one patient did not have AF or atrial flutter using propafenone. NCM demonstrated the mechanism of crista terminalis ectopy-initiating AF and associated typical/atypical atrial flutter. Catheter ablation of crista terminalis ectopy and substrate for the reentry guided by NCM successfully eliminated these atrial arrhythmias.
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  • 6
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: Functional and structural changes of atrial tissue occur during the natural course of atrial fibrillation (AF), and these changes may contribute to further AF. We investigated the changes in AF tissue using cDNA microarray and two-dimensional protein electrophoresis techniques. Methods and Results: We established a porcine model of AF by rapid right atrial appendage pacing at a rate of 600/min. Atrial tissue was obtained after rapid atrial depolarization for 6 weeks. Microarrays containing 6,035 cDNA clones were used to evaluate the alterations of mRNA. Two-dimensional protein electrophoresis was performed to compare protein patterns. In cDNA microarray studies, we identified 387 genes with significant change in the left atrium and 81 genes in the right atrium. Among the genes, the ventricular isoform of the myosin regulatory light chain (MLC-2V) showed the greatest fold of change (9.4 and 7.3 in the left and right atrium, respectively). In protein electrophoresis, the expression levels of three protein spots spanning from 18 to 20 kDa in the acidic region (PI 4.5–5.0) were specifically elevated in the AF group. Interestingly, through tandem mass spectrometric analysis, these three spots were identified as MLC-2V. Thus, MLC-2V expression at the mRNA and protein levels corresponded well, and both indicated a significant increase in AF. Conclusion: Both cDNA microarray and two-dimensional polyacrylamide protein electrophoresis studies revealed characteristic changes in AF tissue. We demonstrated the reprogramming of myosin regulatory light chain isoform composition, with a significant increase of its ventricular isoform (MLC-2V). (J Cardiovasc Electrophysiol, Vol. 15, pp. 214-223, February 2004)
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  • 7
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A uniform BaTiO3 nano layer was coated on spherical Ni particles for multilayer ceramic capacitor applications via a Ti-hydroxide coating using the controlled hydrolysis of a TiCl4 butanol solution containing (C2H5)2NH (diethylamine, DEA) and its subsequent hydrothermal reaction at various [Ba(OH)2], residual [DEA], and hydrothermal temperatures. The hydrothermal conversion was successful at [Ba(OH)2]≥0.065M (Ba/Ti≥1.3) and T≥150°C, and the residual DEA in the Ti-hydroxide coating layer not only affected the formation of the BaTiO3 phase but also resulted in a rough surface morphology. When a minimal amount of DEA was involved in the formation of Ti-hydroxide, a uniform BaTiO3 coating with a clean surface morphology could be attained, which was confirmed by elemental mapping of the coated powder and the observation of hollow spheres after removing the Ni core. The BaTiO3 coating was very effective not only in preventing Ni oxidation but also in shifting the starting point of Ni densification to a higher temperature.
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  • 8
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A facile chemical route to prepare a well-defined Ni powder on a mass-production scale without external heating was suggested. A highly concentrated Ni complex was formed between NiCl2 and N2H4 solution, and subsequent addition of NaOH solution triggered serial reactions from the Ni complex decomposition via Ni(OH)2 formation to the reduction of a Ni(OH)2 gel into well-defined Ni spheres. The high temperature necessary for the reaction was attained not by external heating but by exothermic reactions such as complex formation and reduction. The preparation of monodisperse and spherical Ni powder was attributed to uniform distribution of the reducing agent (N2H4) within the Ni(OH)2 gel.
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  • 9
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: BaTi4O9 thin films were grown on a Pt/Ti/SiO2/Si substrate using rf magnetron sputtering and the structure of the thin films were then investigated. For the films grown at low temperature (≤350°C), an amorphous phase was formed during the deposition, which then changed to the BaTi5O11 phase when the annealing was conducted below 950°C. However, when the annealing temperature was higher than 950°C, a BaTi4O9 phase was formed. On the contrary, for the films grown at high temperature (〉450°C), small BaTi4O9 grains were formed during the deposition, which grew during the annealing. The homogeneous BaTi4O9 thin films were successfully grown on Pt/Ti/SiO2/Si substrate when they were deposited at 550°C and subsequently rapid thermal annealed at 900°C for 3 min.
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  • 10
    ISSN: 1745-4522
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The flesh and skin of Anguilla japonica and Conger myriaster were investigated for their antioxidant activity. Ethyl acetate and diethyl ether extracts (4 mg/mL) after extracting with methanol were tested for 2,2-diphenyl-1-picrylhidrazyl (DPPH) free radical scavenging (FRS) activity for flesh and skin of each eel species. The values were compared with α-tocopherol and butylated hydroxytoluene (BHT). Extracts showing positive results, when tested for DPPH FRS, were examined for dose effect, hydrogen peroxide (H2O2), hydroxyl radical and superoxide scavenging assays and heat stability. All extracts of A. japonica showed a dose-dependent DPPH FRS and significant hydroxyl radical scavenging activities (〉65%). The diethyl ether extract of the flesh of A. japonica showed the highest superoxide scavenging activity. Diethyl ether extracts of A. japonica were heat stable, and ethyl acetate extracts were stable up to 75C. Thus, it can be concluded that A. japonica is rich with heat stable and nonpolar antioxidants.
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