磁导航系统指导下心房颤动导管消融学习曲线期间有效性和安全性分析

目的 探讨磁导航系统(magnetic navigation system,MNS)指导下心房颤动(房颤)导管消融学习曲线期间的有效性及安全性.方法 按手术时间顺序,将90例房颤患者分为A、B、C三组,每组30例.穿刺房间隔后采用盐水灌注MNS消融导管行左心房建模和左右肺静脉前庭电隔离,隔离后采用"牛眼图"软件确认.记录并分析三组的手术操作时间、X线暴露时间及暴露量、肺静脉隔离即时成功率和手术相关并发症.术后3至6个月内每月随访一次动态心电图.结果 90例房颤患者均成功实施了MNS指导下的房颤导管消融治疗.三组的手术操作时间相比,差异无统计学意义[(158.4±23.5)min、(150.4±22.5)min和(151.3±23.6)min,P>0.05].B、C组的X线暴露时间及暴露量较A组显著减少,而B、C组相比,差异无统计学意义[(16.8±7.2)min、(8.2±2.6)min和(7.9±3.4)min,A、B组相比P<0.05;(583.7±460.3)mGy、(267.3±191.8)mGy和(225.0±121.0)mGy,A、B组相比P<0.05].A组肺静脉隔离即时成功率96.2%,而B、C组皆达到100%;三组比较,差异无统计学意义(P>0.05).围手术期A组发生2例血胸、1例腹股沟血肿,B组1例新发腔隙性脑梗死,C组未发生并发症;三组之间比较,差异无统计学意义(P>0.05).随访3至6个月,三组手术成功率比较,差异无统计学意义(P>0.05).结论 MNS指导下的房颤导管消融治疗具有较好的安全性和有效性,且学习曲线较短.     

二十二碳六烯酸增加大鼠冠状动脉平滑肌细胞大电导钙离子激活钾离子流的机制

Objective To investigate the mechanism of enhanced large conductance calciumactivated potassium channel currents (BK) in coronary smooth muscle cells (SMCs) by docosahexaenoic acid (DHA). Methods Coronary SMCs were isolated by enzyme digestion. Potassium channels in coronary SMCs were identified by applications of different potassium blockers. Effects of DHA and its metabolite 16,17-epoxydocosapentaenoic acid (16,17-EDP) on BK channels in the absence and presence of cytochrome P450 epoxygenase inhibitor SKF525A were studied by patch clamp in whole-cell configuration. Results BK channels were widely distributed in SMCs, and BK currents in normal SMCs accounted for (64.2±2.7)%of total potassium currents(n =20). DHA could activate BK channels, and its 50% effective concentration (EC50) was (0.23±0.03)μmol/L, however, the effect of DHA on BK channels was abolished after SMCs were incubated with cytochrome P450 epoxygenase inhibitor SKF525A. 16,17-EDP, a metabolite of DHA, could reproduce the effects of DHA on BK channels, and its EC50 was (19.7± 2.8) nmol/L.Conclusion DHA and metabolites can activate BK channels and dilate coronary arteries through activating cytochrome P450 epoxygenase pathway.     

冠状动脉平滑肌细胞大电导钙离子激活钾通道电流的特点

Objective To investigate characteristics of large conductance Ca2+ -activated K+ currents ( BK currents) in normal rat coronary smooth muscle cells. Methods Coronary smooth muscle cells were isolated by enzyme digestion. Potassium channels in coronary smooth muscle cells were identified by applications of different potassium blockers. BK currents were recorded by patch clamp in whole ce11 and single channel configuration,respectively. BK currents amplitude and conductance were calculated. Voltage-sensitive and calciumsensitive characteristics of BK currents and changes with IBTX,a specific blocker,were observed. Results BK currents in normal smooth muscle cells accounted for 65% ± 4% of total potassium currents( n = 12), BK current conductance was (258 ± 42) pS ( n = 6), and current densities were ( 275 ± 40 ) pA/pF at voltage 150 mV ( n = 8). Open probabilities ( NP0 ) of BK channels at calcium 1 μmol/L in external solution and test potentials at 0,20,40,60,80,100,120,140 and 160 mV were 0,0. 0002,0. 0016 ± 0. 0005,0. 0283 ± 0. 0081,0. 05694 ±0. 0102,0. 3533 ± 0. 0514,1. 4922 ± 0. 1578,2. 5975 ± 0. 3632, and 4. 6041 ± 0. 7834, respectively (P＜0.05,n =5). NP0 of BK channels at test potential 60 mV,and calcium in external solution at 0,0. 001,0. 01,0. 1,1,10,50 and 100 μmol/L were 0,0.0001,0.0031 ± 0.0008,0.0042 ± 0.0090,0.0808 ± 0.0105,0.7591 ±0. 1274,2.7242 ±0.4612,and 3.2366 ±0.5728,respectively(P ＜0.05,n =6). Conclusion BK channels are widely distributed in normal coronary smooth muscle cells, have voltage-sensitive and calcium-sensitive characteristics, and play an important role in regulation of coronary vascular tension.     

心室螺旋电极微脱位致膈肌跳动1例

患者女,70岁,因反复胸闷伴头晕1个月收住入院,诊断为三度房室阻滞。行埋藏式心脏起搏器植入术后,心电图提示起搏感知功能正常。术后4h患者主诉心悸,伴剑突下跳动;考虑由膈神经刺激所致。测得电极阻抗、单双极阈值和感知参数均正常。降低心室电极输出,膈肌跳动消失,但出现失夺获。透视观察未发现电极明显移位,考虑螺旋电极微脱位的可能性较大。再次手术重新定位电极后膈肌跳动现象消失,起搏感知功能正常。     

心室起搏管理降低累计心室起搏比例的观察

目的探讨心室起搏管理(MVP)对累计心室起搏比例(CumVP%)的影响。方法在10例植入具有MVP功能的双腔起搏器患者中,先以传统DDDR模式工作1个月,再程控为MVP模式工作1个月,统计两种模式下起搏和感知的时间比例,比较CumVP%变化。结果 DDDR模式下,CumVP%在所有患者中均较高;而MVP模式下,除持续性Ⅲ度房室传导阻滞外,CumVP%均较DDDR模式下显著降低。结论与DDDR模式相比,MVP模式能够显著降低CumVP%。     

长期应用抗精神病药物致极短联律间期室性心动过速

目的:了解抗精神病药的心脏不良反应,以及多形性室性心动过速(室速)的临床特点.方法:回顾分析1例精神分裂症长期应用抗精神病药物后发生多形性室速的临床资料,并复习相关文献.结果:患者有精神分裂症病史10余年,长期服用氯氮平、氯丙嗪.近年反复发作晕厥,发作时心电图呈QT间期正常伴极短联律间期的多形性室速,确诊为药物性心律失常,停用氯氮平、氯丙嗪,应用维拉帕米、美西律后室速终止.结论:抗精神病药存在较严重的心脏不良反应,尤其多药联用时,甚至可发生多形性室速等恶性心律失常.治疗过程中应注意观察心电图变化,发现异常,及时处理,避免严重后果.     

不同起搏频率对心肌应变的影响

目的 探讨心率对心肌应变的影响。方法 选择20例已植入起搏器的病窦综合征患者。利用常规超声心动图和二维斑点追踪显像技术,测心房起搏频率60,70,80,90和100次/分下每搏输出量和纵向、径向和环状方向上左室18节段收缩期应变峰值并计算心输出量和整体纵向、径向和环状应变峰值。结果 随着起搏频率的增加,每搏输出量和左室各节段、各水平及整体在不同方向上的应变峰值递减,心输出量逐渐递增。起搏频率60,70和80次/分时,整体纵向应变峰值分别为-24. 58% ±10. 19%、-23. 13% ±11. 36%和-20. 20% ±9. 48%（P〉0. 05）;而起搏频率90和100次/分时整体纵向应变峰值分别为-15. 56%±8. 89%（P〈0. 05）和-9. 80% ±6. 01% （P〈0. 001）。起搏频率60,70和80次/分时,整体径向应变峰值分别为33.40%±9. 81%、31. 92% ±10. 69%和28. 84% ±10. 58%（P〉0.05）;而起搏频率90和100次/分时整体径向应变峰值分别为23.34%±8.17%（P〈0.05）和15.77%±7.42%（P〈0.001）。起搏频率60,70和80次/分时,整体环状应变峰值分别为-21. 43% ±8. 48%、-20. 23% ±7. 10%和-17. 65% ±7.25%（P〉0.05）;而起搏频率90和100次/分时整体环状应变峰值分别为-13. 65% ±5. 27% （P〈0. 01）和-8. 23% ±3.72%（P〈0.001）。结论 随起搏频率增加,左室各方向应变下降。心率对应变的影响为负性。     

磁导航指导下心房颤动导管消融的临床研究

目的探讨磁导航指导下心房颤动(简称房颤)导管消融的可行性和安全性。方法对22例房颤患者穿刺房间隔后,采用盐水灌注磁消融导管行左房建模和左右肺静脉电位隔离,永久性房颤加房顶线和/或峡部线消融。消融温度前壁和后壁均设定为48℃,前壁消融能量40~45 W,后壁消融能量30~35 W,每点消融时间30~60 s或电位幅度下降80%,盐水灌注流量消融和未消融状态下分别为17 ml/min和2 ml/min。肺静脉电位隔离结束后,采用"牛眼图"确认,同时观察和记录手术操作时间、X线暴露时间、X线暴露量和手术相关并发症。结果 22例房颤患者均成功实现肺静脉电位隔离,手术操作时间(153.4±22.8)min,其中建模及肺静脉电位隔离时间(111.3±15.3)min,消融时间(33.1±5.6)min,X线暴露时间(18.2±7.7)min,X线暴露量(665.4±506.7)mGy,未发生心包压塞和栓塞等严重并发症。结论应用磁导航可成功对房颤患者进行标测和消融,且安全可行,学习曲线短。     

血浆N-末端B型利钠肽原对阵发性心房颤动导管射频消融术后复发的预测价值

54例阵发性心房颤动（房颤）患者首次行导管射频消融术（RFCA）前检测N-末端B型利钠肽原（NT—proBNP）等,并术后随访至少3个月。结果复发组的术前基线NT—proBNP明显高于成功组,基线NT—proBNP升高为预测房颤RFCA后复发的独立危险因素,根据受试者工作特征（ROC）曲线将其预测术后复发的切点值定为193．6ng／L。