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犬急性心肌缺血模型进行机制研究。这是诱发室性心动过速 (VT) 和室颤 (VF) 的非常稳定的模型；一半的实验是局灶性心内膜或浦肯野室性心动过速，另一半是心外膜折返。通过起搏方案对从心内膜病灶切除的组织进行体外研究，该起搏方案产生称为延迟后除极（DAD）的细胞钙振荡，从而引起称为触发活动（TA）的心律失常。临床实验室通过记录急性心肌缺血患者 VT 和 VF 起源处的心内膜信号来确认局灶性 VT。此外，点源心内膜消融可预防局灶性 VT/VF。因此，该模型是人类缺血性室性心动过速的相关模型，其可以是局灶性的，也可以是折返性的。先前资助期的实验表明，局灶性心内膜 VT 可以通过同时预防 TA 的药物来预防，包括 HMG co-A 还原酶抑制剂（他汀类药物）和 PD123319（血管紧张素 AT-2 受体拮抗剂）。此外，他汀类药物的作用可能来自于活性氧 (ROS) 的抑制，因为称为 TEMPO 的 ROS 清除剂以类似的方式阻断 VT 和 TA，同时减少 ROS 的组织测量。 ROS 还可能导致氧化钙钙调蛋白激酶 II (CaMKII)，这是导致 VT/VF 的基本因素，包括小型和大型动物模型中的折返。总体目标是检验以下假设：与氧化 CaMKII 相关的 ROS 是导致临床相关犬类 VT/VF 模型中局灶性和折返性 VT/VF 的基本机制。调查集中于两个具体目标。目标 1：确定缺血组织 ROS 的最高水平是否出现在 VT/VF 病灶处，以及通过清除剂 TEMPOL 或通过抑制各种促进 ROS 的酶系统（包括 NADH 氧化酶、线粒体或黄嘌呤氧化酶）来降低 ROS 是否更有效地预防 VT /VF。目标 2：确定最高水平的氧化 CaMKII 活性是否出现在 VT/VF 病灶处，以及 KN-93 或 KN-92 抑制 CaMKII 是否可以预防缺血性病灶 VT/VF。多个透壁双极电描记图的体内计算机化激活映射结合了从放置在冠状动脉前降支危险区域的 16 个极针获取的浦肯野信号，可以绘制冠状动脉闭塞后额外刺激产生的 VT/VF 的 3D 地图。输注阻断 VT/VF 的药物包括 TEMPO (30 mg/kg、) 罗布麻宁 (4 mg/kg、) 二亚苯基碘 (7.6 mg/kg、) 鱼藤酮 (9.5 mg/kg、) 奥昔嘌呤醇 (3.7 mg/kg) KN-93 (0.2 <g/kg)、KN-92 (0.2 <g/kg) 随机给药。激活映射后，将切除 VTVF 机械起源处的组织，用于测量 ROS、CaMKII、RyR2、受磷蛋白、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掌握。这些研究将利用费舍尔精确检验和定量数据方差分析。标准微电极技术和组织分析将实现这一目标。最终目标是开发新的有效疗法来预防冠心病患者（尤其是退伍军人）的缺血性 VT/VF。 公共卫生相关性： 退伍军人患严重冠心病的频率很高，因此很可能出现危险的心律。抗心律失常药物不能阻止这些节律并且是有害的。如果抑制导致细胞内钙升高的机制途径的药物不干扰基本细胞功能，那么它们就很有吸引力。共同作用于这些途径的疗法可以预防猝死。本文研究的机制可以立即在临床试验中进行，因为可以将现成的药物、他汀类药物或血管紧张素转换酶抑制剂组合起来，以发挥其氧化剂和钙/钙调蛋白激酶阻断作用，以防止患者猝死。同样，此类药物可以与其他抗氧化剂结合使用，以防止危险的心律失常。