VENTRICULAR FIBRILLATION AND ITS ALTERATION BY PACING

描述(摘自申请者摘要)：心脏骤停 通常由室颤(VF)引起。此应用程序 建议使用心脏标测来回答有关 如何维护VF以及如何改变和控制VF的机制 患者和动物的起搏。有三个具体目标。具体目标1： 量化患者的室颤组织，并确定哪些措施 组织预测自发性室颤终止和除颤 阈值(DFT)。以下有关室颤的假说将在患者身上进行测试 接受心脏手术或心脏复律/除颤器植入术。(1) 心外膜折返性心内膜不常见且持续时间短。(2)传导阻滞较多 经常为激活锋平行而不是垂直于长线 肌纤维轴。(3)需要最小的块长度才能启动 重返大气层。(4)心肌梗死周围的备用组织可能是 对于VF启动，它不会对VF维护做出贡献。(5)数量上 激活前端组织的衡量标准预测VF何时停止 自然而然地。(6)一组略有不同的量化指标 识别DFT低的患者。具体目标2：确定算法以 在猪的室颤期间通过起搏最大限度地捕获心肌。光学和 将进行电测绘以验证以下假设。(1) 逐渐增加起搏速度将增加组织的数量 在某些心脏区域被捕获。(2)逐渐放慢起搏速度将 允许在其他区域捕获更多的组织。(3)交替放缓和 提高起搏速度将最大限度地增加捕获的组织数量。 (4)从两个适当间隔的位置起步会捕捉到比 仅从两侧起搏捕获的组织的总和。(5)自上而下的步伐 到16个站点将同时停止VF。(6)从所在地区的起搏 除颤电势梯度最弱会降低DFT。(7) 心外膜可分为不同的区域，每个区域具有不同的激活率。 (8)从较快的区域起搏比从较慢的区域起搏能捕获更多的组织 域名。具体目标3：确定是否有可能通过 患者在室颤期间的起搏。最成功的起搏技术和大多数 特定目标2的假设将在患者身上进行测试。

DESCRIPTION (Verbatim from Applicant's Abstract): Sudden cardiac arrest frequently is caused by ventricular fibrillation (VF). This application proposes to use cardiac mapping to answer important questions about the mechanisms of how VF is maintained and how VF can be altered and controlled by pacing in patients and animals. There are three specific aims. Specific Aim 1: Quantify VF organization in patients and determine which measures of organization predict spontaneous VF termination and the defibrillation threshold (DFT). The following hypotheses about VF will be tested in patients undergoing cardiac surgery or cardioverter/defibrillator implantation. (1) Epicardial reentry is uncommon and short-lived. (2) Conduction block is more frequent for activation fronts parallel rather than perpendicular to the long axis of myofibers. (3) A minimal length of block is necessary to initiate reentry. (4) While spared tissue around a myocardial infarct may be responsible for VF initiation, it does not contribute to VF maintenance. (5) Quantitative measures of activation front organization predict when VF will stop spontaneously. (6) A slightly different group of quantitative measures identifies patients with a low DFT. Specific Aim 2: Determine algorithms to maximize the capture of myocardium by pacing during VF in pigs. Optical and electrical mapping will be performed to test the following hypotheses. (1) Gradually increasing the pacing rate will increase the amount of tissue captured in some cardiac regions. (2) Gradually slowing the pacing rate will allow the capture of more tissue in other regions. (3) Alternately slowing and increasing the pacing rate will maximize the amount of tissue that is captured. (4) Pacing from two sites spaced appropriately apart will capture more than the sum of the tissue captured by pacing from each side alone. (5) Pacing from up to 16 sites simultaneously will halt VF. (6) Pacing from regions in which the defibrillation shock potential gradient is weakest will lower the DFT. (7) The epicardium can be divided into domains, each with a different activation rate. (8) Pacing from faster domains captures more tissue than pacing from slower domains. Specific Aim 3: Determine if it is possible to capture myocardium by pacing during VF in patients. The most successful pacing techniques and most of the hypotheses of Specific Aim 2 will be tested in patients.