Purkinje Origin of Ischemic Ventricular Tachycardia and Fibrillation

缺血性室性心动过速和颤动的浦肯野起源

• 批准号: 8242630
• 负责人: James B Martins
• 金额: --
• 依托单位: IOWA CITY VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8242630
• 关键词: 3-Dimensional; Ablation; Acute; Acute myocardial infarction; Analysis of Variance; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensins; Animal Genetics; Animal Model; Animals; Anterior Descending Coronary Artery; Anti-Arrhythmia Agents; Antioxidants; Arrhythmia; Biological Assay; Ca(2+)-Calmodulin Dependent Protein Kinase; Calcium; Calcium/calmodulin-dependent protein kinase; Canis familiaris; Cell membrane; Cell physiology; Clinical; Clinical Trials; Clonidine; Coronary Occlusions; Coronary heart disease; Data; Enzymes; Exposure to; Fluorescence; Frequencies; Funding; Genetic Models; Goals; Grant; Hand; Hour; Human; In Vitro; Intervention; Investigation; Ischemia; Laboratories; Link; Lovastatin; Lucigenin; Maps; Measurement; Measures; Membrane Potentials; Methods; Microelectrodes; Mitochondria; Modeling; Myocardial Ischemia; NADH oxidase; NADPH Oxidase; Needles; Oxidants; Oxidoreductase; Oxypurinol; Paper; Pathway interactions; Patients; Pharmaceutical Preparations; Prevention; Production; Protocols documentation; Public Health; Reactive Oxygen Species; Research; Risk; Rotenone; RyR2; SERCA2a; Signal Transduction; Source; Stimulus; Sudden Death; System; Techniques; Testing; Tissues; Translations; Ventricular Fibrillation; Ventricular Tachycardia; Veterans; Work; Xanthine Oxidase; acetovanillone; base; calmodulin-dependent protein kinase II; clinical application; clinically relevant; computerized; dihydroethidium; diphenyleneiodonium; effective therapy; enzyme pathway; heart rhythm; improved; in vivo; inhibitor/antagonist; phospholamban; prevent; public health relevance; receptor; research study; sudden cardiac death

DESCRIPTION (provided by applicant): The aim of this project is to continue mechanistic investigation of a canine model of acute myocardial ischemia. This is a remarkably stable model of inducible ventricular tachycardia (VT) and ventricular fibrillation (VF); focal endocardial or Purkinje VT results in half of the experiments and epicardial reentry in the other. Tissue excised from the endocardial focus is studied in vitro with pacing protocols generating cellular calcium based oscillations termed delayed afterdepolarization (DADs) giving rise to an arrhythmia called triggered activity (TA). Clinical laboratories have confirmed focal VT by recording endocardial signals at the origin of VT and VF in patients with acute myocardial ischemia. Moreover, prevention of focal VT/VF with point source endocardial ablation has been proven. Thus this model is a relevant model for human ischemic VT, which may be either focal or reentry. Experiments from the prior funding period have shown that focal endocardial VT is prevented with agents which also prevent TA, including HMG co-A reductase inhibitors (statins) and PD123319 (angiotensin AT-2 receptor antagonist.) Furthermore the effect of statins may result from inhibition of reactive oxygen species (ROS) since a ROS scavenger called TEMPO blocks both VT and TA in a similar manner while decreasing tissue measurements of ROS. ROS may also result in oxidized calcium calmodulin kinase II (CaMKII), a fundamental contributor to VT/VF including reentry in small and large animal models. The overall aim is to test the hypothesis that ROS linked to oxidized CaMKII are basic mechanisms resulting in focal and reentrant VT/VF in a clinically relevant canine model of VT/VF. Investigation centers on two specific aims. Aim 1: Determine whether the highest levels of the ischemic tissue ROS occur at foci of VT/VF and whether decreasing ROS by the scavenger TEMPOL or by inhibition of various enzyme systems that promote ROS including NADH oxidase, mitochondrial or xanthine oxidase more effectively prevents VT/VF. Aim 2: Determine whether the highest levels of oxidized CaMKII activity occur at the foci of VT/VF and if CaMKII inhibition by KN-93 or KN-92 can prevent ischemic focal VT/VF. In vivo computerized activation mapping of multiple transmural bipolar electrograms incorporating Purkinje signals taken from 16 pole needles placed in the risk zone of the anterior descending coronary artery allow 3-D maps of VT/VF produced by extra-stimuli after coronary occlusion. Drugs to be infused to block VT/VF include TEMPO (30 mg/kg,) apocynin (4 mg/kg,) diphenyleneiodine (7.6 mg/kg,) rotenone (9.5 mg/kg,) oxipurinol (3.7 mg/kg,) KN-93 (0.2 <g/kg,) KN-92 (0.2 <g/kg) administered randomly. After activation mapping, tissue at the mechanistic origin of VTVF will be excised for measurements of ROS, CaMKII, RyR2, phospholamban, SERCA2a, and NCX and in vitro microelectrode testing. All the techniques required for these studies are in hand in the laboratories where this preliminary work was done. These studies will utilize Fishers exact test and analysis of variance for quantitative data. Standard microelectrode technique and tissue assays will fulfill the aims. The ultimate goal will be to develop new, effective therapies to prevent ischemic VT/VF in patients with coronary disease, particularly in Veterans. PUBLIC HEALTH RELEVANCE: Veterans have a high frequency of severe coronary heart disease, making dangerous heart rhythms likely. Anti-arrhythmic drugs do not prevent these rhythms and are harmful. Drugs that inhibit mechanistic pathways leading to elevated intracellular calcium are attractive if they don't interfere with fundamental cell function. Therapies acting on such pathways used together may prevent sudden death. Mechanisms studied herein could be pursued immediately in clinical trials since readily available drugs, statins or angiotensin converting enzyme inhibitors, may be combined for their oxidant and calcium/calmodulin kinase blocking effects to prevent sudden death in patients. Similarly such drugs may be combined with other antioxidants to prevent dangerous heart rhythms.

描述（由申请人提供）： 该项目的目的是继续对急性心肌缺血的犬模型进行机械研究。这是一个非常稳定的诱导性心室心动过速（VT）和心室纤颤（VF）模型。局灶性心内膜或浦肯野VT导致一半的实验和另一个实验。从心内膜焦点中切除的组织在体外研究通过起搏方案，产生基于细胞钙的振荡，称为延迟的造影后（DAD），导致心律失常，称为心律失常，称为触发活性（TA）。临床实验室已通过记录急性心肌缺血患者的VT和VF起源的心内膜信号来证实局灶性VT。此外，已经证明了用点源心内膜消融的焦点VT/VF的预防。因此，该模型是人类缺血性VT的相关模型，该模型可能是焦点或再入。先前资助期的实验表明，还可以防止局灶性心内膜VT，还可以防止TA，包括HMG Co-A还原酶抑制剂（毒素）和PD123319（毒素）和PD123319（血管紧张素AT-2受体拮抗剂。）进一步抑制了毒素的抑制作用（ROSE venter a rose venter a rose venter a rose venter a ros ven a ros ven a ros a ros a ros a ros a ros a ros a ros a ros a ros a ros a ros a ros a ros a ros a ta a的影响均可能导致同时减少ROS的组织测量结果。 ROS还可能导致氧化的钙钙调蛋白激酶II（CAMKII），这是VT/VF的基本贡献者，包括小动物模型中的重新进入。总体目的是检验以下假设：与氧化的CAMKII相关的ROS是在VT/VF的临床相关犬模型中导致局灶性和再进入VT/VF的基本机制。调查以两个具体目标为中心。目标1：确定最高水平的缺血组织ROS是在VT/VF的焦点上发生的最高水平，以及是否通过清道夫tempol降低ROS，还是抑制各种促进ROS的各种酶系统，这些酶系统促进ROS，包括NADH氧化酶，线粒腺软骨或Xanthine氧化酶，更有效地预防了VT/VF。 AIM 2：确定最高水平的氧化CaMKII活性是否发生在VT/VF的灶以及KN-93或KN-92抑制CAMKII是否可以防止缺血性局灶性VT/VF。体内计算机化激活图映射的多个透壁两极电图，这些电图融合了位于前降冠状动脉的风险区域中的16个极头针中取的purkinje信号，允许冠状动脉闭塞后刺激性刺激产生的VT/VF的3-D映射。被注入堵塞VT/VF的药物包括温度（30 mg/kg，）apocynin（4 mg/kg，）二苯基二烯二氨酸（7.6 mg/kg，）rotenone（9.5 mg/kg，kg，kg，kg，）oxipurinol（3.7 mg/kg/kg，kg，kg，0.2 <g/kn）（0.2 <g/kn）。随机。激活映射后，将切除VTVF机械起源的组织，以测量ROS，CAMKII，RYR2，Phospholamban，SERCA2A和NCX以及体外微电极测试。这些研究所需的所有技术都在完成这项初步工作的实验室中。这些研究将利用渔民精确测试和分析定量数据的方差。标准的微电极技术和组织测定将实现目标。最终目标是开发新的有效疗法，以预防冠状动脉疾病患者，特别是在退伍军人中的缺血性VT/VF。 公共卫生相关性： 退伍军人的严重冠心病频率很高，使危险的心律可能。抗心律失常不能阻止这些节奏，并且有害。抑制导致细胞内钙升高的机械途径的药物，如果它们不干扰基本细胞功能，它们就会有吸引力。在使用此类途径上使用的疗法可以防止突然死亡。可以在临床试验中立即采用此处研究的机制，因为可以合并可用的药物，他汀类药物或血管紧张素转化酶抑制剂，以合并其氧化剂和钙/钙调蛋白激酶阻塞的作用，以防止患者突然死亡。同样，此类药物可以与其他抗氧化剂结合使用，以防止危险的心律。