| 1. |
- Yuan, S, et al.
(författare)
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Effect of dofetilide on cardiac repolarization in patients with ventricular tachycardia. A study using simultaneous monophasic action potential recordings from two sites in the right ventricle
- 1994
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Ingår i: European Heart Journal. - 0195-668X. ; 15:4, s. 22-514
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Tidskriftsartikel (refereegranskat)abstract
- Monophasic action potentials (MAP) were simultaneously recorded from the right ventricular (RV) apex (RVA) and the outflow tract (RVOT) before and after an infusion of dofetilide in 10 patients with documented ventricular tachycardia. After the drug infusion, the MAP duration (MAPd), repolarization time, and corrected QT interval were significantly prolonged during sinus rhythm, RV pacing, and RV extra stimulation. The prolongation of MAPd at 90% repolarization during RV pacing at a cycle length of 500 ms was 31 +/- 6 ms (13%) and 26 +/- 7 ms (11%) at RVA and RVOT, respectively. The ventricular effective refractory period was significantly prolonged by 33 +/- 9 ms (13%) and 22 +/- 7 ms (9%) at driving cycle lengths 600 and 500 ms, respectively. The MAPd shortening with decreasing diastolic time intervals was significantly diminished by dofetilide in early extra beats during RV extra stimulation, suggesting a relatively more pronounced effect of this drug at the early diastolic phase. The dispersion of repolarization, defined as the difference in MAPd between RVA and RVOT, and the activation time were not significantly changed. In conclusion, acute administration of dofetilide in patients with ventricular tachycardia significantly prolonged the time intervals of ventricular repolarization and refractoriness in a parallel fashion, without affecting intraventricular conduction. The effect of dofetilide on MAPd prolongation appeared not to be reverse use-dependent in this study in humans. These results verify the selective class III antiarrhythmic property of dofetilide and warrant further studies in patients.
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| 2. |
- Yuan, S, et al.
(författare)
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Localization of cardiac arrhythmias : conventional noninvasive methods
- 1991
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Ingår i: International Journal of Cardiac Imaging. - 0167-9899. ; 7:3-4, s. 193-205
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Tidskriftsartikel (refereegranskat)abstract
- Noninvasive localization of the accessory pathway (AP) in patients with the Wolff-Parkinson-White syndrome and of the site of origin of ventricular tachycardia (VT) is reviewed. 12-lead electrocardiography (ECG) is the most readily available method for localization of both the AP and the site of VT origin. Many published ECG criteria are introduced. The application of body surface potential mapping, vectorcardiography, nuclear phase imaging, echocardiography, computed tomography, nuclear magnetic resonance, and signal-averaged ECG in the localization of these arrhythmogenic substrates is also described. We believe that ECG is the most sensitive noninvasive method for AP localization as well as being convenient and simple; it may be used as the only noninvasive method for the initial evaluation. The left lateral AP, which occurs with an incidence of more than 40%, could be localized preoperatively by noninvasive methods only. For localization of the site of VT origin, none of the noninvasive methods is accurate enough for guiding the surgical and catheter-mediated ablative therapies so far.
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| 3. |
- Olsson, Bertil, et al.
(författare)
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Effect of pentisomide (CM 7857) on myocardial excitation, conduction, repolarization, and refractoriness. An electrophysiological study in humans
- 1991
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Ingår i: Journal of Cardiovascular Pharmacology. - 0160-2446. ; 18:6, s. 54-849
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Tidskriftsartikel (refereegranskat)abstract
- The electrophysiological effects of pentisomide upon the intact human heart were evaluated using programmed stimulation and recording of intracardiac monophasic action potentials (MAP) in 17 patients with various ventricular arrhythmias. After i.v. administration of pentisomide, 85-135 mg, the atrial-His interval increased by 8 +/- 12 ms (p less than 0.05) during sinus rhythm and by 13 +/- 21 ms (p less than 0.05) at atrial pacing of 600 ms cycle length (600 ms pacing). The His-ventricular interval also increased by 6 +/- 10 ms during sinus rhythm (p less than 0.05) and by 5 +/- 9 ms at 600 ms pacing (NS). The QRS duration prolonged by 9 +/- 10 ms (p less than 0.01) and 6 +/- 8 ms (p less than 0.01) during 600 and 500 ms ventricular pacing, respectively. The right ventricular MAP duration to 90% repolarization was significantly shortened, by 20 +/- 21 ms (p less than 0.01) during sinus rhythm, by 16 +/- 17 ms (p less than 0.01) at 600 ms ventricular pacing, and by 11 +/- 16 ms (p less than 0.01) at 500 ms ventricular pacing. The corrected QT interval was shortened by 21 +/- 28 ms (p less than 0.01). The present study supports that pentisomide is a class-I antiarrhythmic agent with a marked effect on depolarization (action of class Ia and Ic) and on repolarization (action of class Ib). This unique combination of cellular electrophysiological properties indicates that the clinical antiarrhythmic efficacy of pentisomide may differ from that of hitherto available antiarrhythmic drugs.
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| 4. |
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| 5. |
- Yuan, S, et al.
(författare)
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Monophasic action potentials : concepts to practical applications
- 1994
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Ingår i: Cardiovascular Electrophysiology. - : Wiley. - 1045-3873 .- 1540-8167. ; 5:3, s. 287-308
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Tidskriftsartikel (refereegranskat)abstract
- Monophasic Action Potentials. Monophaisc action potential (MAP) recordings reproduce the repolarization time course of intrucellular action potentials with high accuracy and provide precise information on the local activation time. With the advantage of in vivo application and the development of the safer and simpler contact catheter technique, MAP recording has become the method of choice for evaluating myocardial repolarization changes. This review aims to provide information on practical application of MAP recording in the clinical setting. MAPs can easily be recorded from the endocardium with the contact catheter technique in the electrophysiology laboratory and from the epicardium with electrode probes during open heart surgery. The technical aspects are described in detail. The rate dependence of myocardial excitability and repolarization and the effect of antiarrhythmic drugs on MAP duration and effective refractory period are thoroughly reviewed. The use of MAPs in detecting myocardial ischemia, in studying early afterdepolarization and triggered arrhythmias, in measuring dispersion of repolarization, in identifying intracardiac conduction and the development of the T wave, and in verifying the arrhythmogenic effect of mechanoelectric feedback are presented. Computerized automatic analysis of MAPs and the limitations of the MAP technique are also discussed.
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| 6. |
- Zhang, Yong-Yuan, et al.
(författare)
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Antibodies to hepatitis C virus and hepatitis C virus RNA in Chinese blood donors determined by ELISA, recombinant immunoblot assay and polymerase chain reaction
- 1993
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Ingår i: Chinese Medical Journal. - 0366-6999. ; 106:3, s. 171-174
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Tidskriftsartikel (refereegranskat)abstract
- Antibodies to hepatitis C virus (anti-HCV) were determined in Chinese blood donors from the city of Wuhan by ELISA screening tests and confirmatory recombinant immunoblot assay (RIBA). 281 and 222 sera were sampled under similar conditions in 1989 and 1990, respectively. The first collection of sera was sent to Sweden in lyophilized form, the second directly as fresh, unfrozen sera. A high proportion (22%) of the lyophilized sera were positive in the screening assay but only 6 (2.10%) were positive by RIBA with antibodies against both the C100-3 and 5-1-1 peptides. HCV RNA could be detected by polymerase chain reaction (PCR) analysis in 3 of the 6 sera and in one reacting with C100-3 only. In the second material of fresh sera only 3 were positive in the screening anti-HCV ELISA, but none was RIBA or PCR positive. Thus, the overall prevalence of anti-HCV among the 503 Chinese blood donors as identified by RIBA was 1.2%, and that of HCV RNA by PCR was 0.8%. The confirmed antibody prevalence is higher than that reported in the western literature.
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