Objectives To investigate the relation between hypertrophied myocardium and ventricular fibrillation threshold in spontaneously hypertensive rats （SHR）. Methods 20 male SHR were randomly divided into two groups： 10...Objectives To investigate the relation between hypertrophied myocardium and ventricular fibrillation threshold in spontaneously hypertensive rats （SHR）. Methods 20 male SHR were randomly divided into two groups： 10 week group （n= 10） and 18 week group （n=10）. 10 week male Wistar rats were controlled group （n=10）. The systolic blood pressure （SBP）, heart mass index （HMI）, ventricular effective refractory period （VERP） and ventricular fibrillation threshold（VFT） were measured respectively.① The SBP and HMI of SHR were significantly higher than those of Wistar rats（P 〈 0.001）. The VFT of SHR were significantly lower than that of Wistar rats （P 〈 0.001）.②In SHR, the SBP and HMI of 18 week SHR were significantly higher than those of 10 week SHR （P 〈 0.001）. The VFT of 18 week SHR were significantly lower than that of 10 week SHR （P 〈 0.001）. ③There were no significant difference of VERP among 10 week SHR, 18 week SHR and Wistar rats（P 〉 0.05）. ④There was no relationship between HMI and VFT or SBP in Wistar rats. There was significant relationship between HMI and VFT or SBP in different age spontaneously hypertensive rats. ⑤HMI, age and species of animal were the major influent factors of VFT. Conclusions The VFT of hypertrophied myocardium decreased. The higher the degree of hypertrophy of myocardium and the higher the systolic blood pressure were, the lower the ventricular fibrillation threshold was.展开更多
Background Ibutilide has been commonly used for pharmacologic cardioversion of atrial fibrillation and flutter in clinical settings. The objective of this study was to investigate the effects of ibutilide on the defib...Background Ibutilide has been commonly used for pharmacologic cardioversion of atrial fibrillation and flutter in clinical settings. The objective of this study was to investigate the effects of ibutilide on the defibrillation threshold （DFT）, restitution properties, dispersion of refractoriness and activation patterns during ventricular fibrillation （VF）. Methods Ibutilide was administrated intravenously in six open-chest beagles. Before and after the drug administration, 20-second episodes of VF were electrically induced and recorded with a 10×10 unipolar electrode plaque sutured on the lateral epicardium of the left ventricle. DFT and VF activation patterns, including type of epicardial activation maps, VF cycle length （VF-CL）, conduction velocity, wavelength （WL） and reentry incidence, were measured. Restitution properties and dispersion of refractoriness were estimated from activation recovery intervals （ARI） during pacing. Results Compared to baseline, ibutilide markedly decreased the DFT by 31% （（491±14） V vs. （337±59） V, P 〈0.01）. The drug significantly reduced the maximal slope of the restitution curve （1.34±0.08 vs. 0.76±0.06, P 〈0.01） and its epicardial dispersion （0.36±0.09 vs. 0.21±0.06, coefficient of variation, P=0.03）. The dispersion of refractoriness was enhanced at the pacing cycle length of 300 ms to 160 ms by ibutilide. The drug significantly increased the VF-CL （（96±19） ms vs. （112±20） ms, P 〈0.01） and the WL （（41±9） mm vs. （52±14） mm, P=0.02） during VF, and reduced the reentry incidence by 25% （0.08±0.02 vs. 0.06±0.02, P 〈0.01）. In the epicardial activation maps, ibutilide significantly reduced the percentage of more complex activation maps during VF. Conclusions Intravenous ibutilide significantly decreased the DFT. It might be due to reduction of activation pattern complexity during VF.展开更多
目的探讨缬沙坦对自发高血压大鼠左室心肌有效不应期和心室颤动(简称室颤)阈值的影响。方法16只10周龄雄性自发高血压大鼠随机分成缬沙坦组和非缬沙坦组,每组8只;8只10周龄Wistar大鼠做为对照组。喂药8周后分别测定各组大鼠动脉收缩压...目的探讨缬沙坦对自发高血压大鼠左室心肌有效不应期和心室颤动(简称室颤)阈值的影响。方法16只10周龄雄性自发高血压大鼠随机分成缬沙坦组和非缬沙坦组,每组8只;8只10周龄Wistar大鼠做为对照组。喂药8周后分别测定各组大鼠动脉收缩压、左室质量指数、心室有效不应期和室颤阈值。结果①非缬沙坦组和缬沙坦组左室质量指数明显大于对照组(3.7±0.02 mg/g,3.2±0.03 mg/g vs 2.5±0.03 mg/g,P<0.001);非缬沙坦组左室质量指数明显大于缬沙坦组(P<0.001);②非缬沙坦组和缬沙坦组室颤阈值明显低于对照组(15.4±0.4 mA,18.6±0.5 mA vs 26.3±0.5 mA,P<0.001);缬沙坦组室颤阈值明显大于非缬沙坦组(P<0.001)。结论缬沙坦通过逆转自发高血压大鼠左室心肌肥厚提高左室心肌室颤阈值。展开更多
文摘Objectives To investigate the relation between hypertrophied myocardium and ventricular fibrillation threshold in spontaneously hypertensive rats （SHR）. Methods 20 male SHR were randomly divided into two groups： 10 week group （n= 10） and 18 week group （n=10）. 10 week male Wistar rats were controlled group （n=10）. The systolic blood pressure （SBP）, heart mass index （HMI）, ventricular effective refractory period （VERP） and ventricular fibrillation threshold（VFT） were measured respectively.① The SBP and HMI of SHR were significantly higher than those of Wistar rats（P 〈 0.001）. The VFT of SHR were significantly lower than that of Wistar rats （P 〈 0.001）.②In SHR, the SBP and HMI of 18 week SHR were significantly higher than those of 10 week SHR （P 〈 0.001）. The VFT of 18 week SHR were significantly lower than that of 10 week SHR （P 〈 0.001）. ③There were no significant difference of VERP among 10 week SHR, 18 week SHR and Wistar rats（P 〉 0.05）. ④There was no relationship between HMI and VFT or SBP in Wistar rats. There was significant relationship between HMI and VFT or SBP in different age spontaneously hypertensive rats. ⑤HMI, age and species of animal were the major influent factors of VFT. Conclusions The VFT of hypertrophied myocardium decreased. The higher the degree of hypertrophy of myocardium and the higher the systolic blood pressure were, the lower the ventricular fibrillation threshold was.
基金This study was supported by grants from the National Natural Science Foundation of China （No. 81070266 and No. 81000081） Shanghai Science and Technology Committee （No. 10140903100 and No. 11ZR1422800） Program for Innovative Research Team of Shanghai Municipal Education Commission.
文摘Background Ibutilide has been commonly used for pharmacologic cardioversion of atrial fibrillation and flutter in clinical settings. The objective of this study was to investigate the effects of ibutilide on the defibrillation threshold （DFT）, restitution properties, dispersion of refractoriness and activation patterns during ventricular fibrillation （VF）. Methods Ibutilide was administrated intravenously in six open-chest beagles. Before and after the drug administration, 20-second episodes of VF were electrically induced and recorded with a 10×10 unipolar electrode plaque sutured on the lateral epicardium of the left ventricle. DFT and VF activation patterns, including type of epicardial activation maps, VF cycle length （VF-CL）, conduction velocity, wavelength （WL） and reentry incidence, were measured. Restitution properties and dispersion of refractoriness were estimated from activation recovery intervals （ARI） during pacing. Results Compared to baseline, ibutilide markedly decreased the DFT by 31% （（491±14） V vs. （337±59） V, P 〈0.01）. The drug significantly reduced the maximal slope of the restitution curve （1.34±0.08 vs. 0.76±0.06, P 〈0.01） and its epicardial dispersion （0.36±0.09 vs. 0.21±0.06, coefficient of variation, P=0.03）. The dispersion of refractoriness was enhanced at the pacing cycle length of 300 ms to 160 ms by ibutilide. The drug significantly increased the VF-CL （（96±19） ms vs. （112±20） ms, P 〈0.01） and the WL （（41±9） mm vs. （52±14） mm, P=0.02） during VF, and reduced the reentry incidence by 25% （0.08±0.02 vs. 0.06±0.02, P 〈0.01）. In the epicardial activation maps, ibutilide significantly reduced the percentage of more complex activation maps during VF. Conclusions Intravenous ibutilide significantly decreased the DFT. It might be due to reduction of activation pattern complexity during VF.
文摘目的探讨缬沙坦对自发高血压大鼠左室心肌有效不应期和心室颤动(简称室颤)阈值的影响。方法16只10周龄雄性自发高血压大鼠随机分成缬沙坦组和非缬沙坦组,每组8只;8只10周龄Wistar大鼠做为对照组。喂药8周后分别测定各组大鼠动脉收缩压、左室质量指数、心室有效不应期和室颤阈值。结果①非缬沙坦组和缬沙坦组左室质量指数明显大于对照组(3.7±0.02 mg/g,3.2±0.03 mg/g vs 2.5±0.03 mg/g,P<0.001);非缬沙坦组左室质量指数明显大于缬沙坦组(P<0.001);②非缬沙坦组和缬沙坦组室颤阈值明显低于对照组(15.4±0.4 mA,18.6±0.5 mA vs 26.3±0.5 mA,P<0.001);缬沙坦组室颤阈值明显大于非缬沙坦组(P<0.001)。结论缬沙坦通过逆转自发高血压大鼠左室心肌肥厚提高左室心肌室颤阈值。
