Cardiac Magnetic Resonance Imaging After Cardiac Resynchronization Therapy

项目摘要 本研究的主要目的是使用心脏磁共振成像（MRI）植入后， 心力衰竭的心脏起搏治疗（CRT），以提供关于以下方面的非常详细和高质量的数据 CRT后左心室（LV）起搏部位特征对LV结构和功能的影响。我们认为 这项工作将为CRT反应和无反应的机制提供深入的了解，以及改善CRT反应和无反应的方法。 CRT实施。心力衰竭的重要性由以下统计数据表征：至少500万 在美国，有250万人患有心力衰竭，250万人需要住院治疗， 被诊断为心力衰竭因此，这项研究与国家科学院的使命高度一致。 心脏、肺和血液研究所，以提高心脏病患者或有心脏病风险者的健康 这样他们就能活得更久更充实CRT涉及植入高级起搏器/除颤器 连接在心脏的三根电线上，旨在使不均匀的心脏收缩更加同步 而且有效。尽管CRT对许多患者非常有益，但无应答率通常为35-50% 当植入物没有通过成像引导时，通常是因为起搏导线的次优定位， 关于疤痕和机械激活。在K23奖项期间，PI展示了MRI表征如何 瘢痕与晚期钆增强和应变与密度（位移编码与刺激 超声心动图）方法以前可用于确定最佳起搏部位，但MRI直接评价起搏效果， 直到最近，新一代的心脏起搏技术才成为可能。 CRT起搏器于2016年2月获批在MRI环境中有条件使用。后CRT 心脏MRI提供的是非常有价值的，因为它可以提供非常详细和可重复的数据， 使用针对应变、体积、壁厚、同步性和 伤疤。在本研究中，将CRT后MRI结果与CRT前MRI结果进行比较，以显示LV 起搏电极导线相对于机械激活和瘢痕的位置改变了CRT后的LV重构， 关于LV电极导线位置和心脏疤痕之间最佳空间关系的其他见解。MRI 结果将与超声心动图结果进行比较，研究结果有望证明这些结果是如何实现的。 为了CRT患者的利益，可以一起使用成像模态。我们将招募40名CRT患者， 进行心脏MRI、超声心动图、心肺运动试验、症状评估和实验室检查 在CRT之前和之后6个月进行测试。预计该项目将对该领域产生重大影响， CRT实施方面的重大改进。这项工作也将促进PI的进展， 通过为MRI引导的CRT临床试验的后续工作提供重要数据， 基于LV起搏电极导线放置，开发CRT后LV重构的计算模型。 1

Project Summary The main objective of this research is to use cardiac magnetic resonance imaging (MRI) after implantation of cardiac resynchronization therapy (CRT) for heart failure to provide very detailed and high-quality data regarding the impact of left ventricular (LV) pacing site characteristics on LV structure and function after CRT. We believe this work will provide insights into mechanisms of CRT response and nonresponse, as well as ways to improve CRT implementation. The importance of heart failure is characterized by the following statistics: at least 5 million people in the United States have heart failure, 2.5 million require hospitalization, and more than 500,000 are diagnosed with heart failure each year. As a result, this research is highly aligned with the mission of the National Heart, Lung, and Blood Institute to enhance the health of individuals with heart disease or at risk for heart disease so they can live longer and more fulfilling lives. CRT involves implantation of an advanced pacemaker/defibrillator attached to three wires in the heart designed to make unevenly pumping hearts contract more synchronously and effectively. Although CRT is very beneficial for many patients, nonresponder rates are typically 35-50% when implants are not guided by imaging, often because of suboptimal positioning of the pacing wires with respect to scar and mechanical activation. During the K23 award, the PI demonstrated how MRI characterization of scar with late gadolinium enhancement and strain with the DENSE (Displacement Encoding with Stimulated Echoes) method before could be used to identify optimal pacing sites, but direct MRI evaluation of the effect of LV pacing sites on LV remodeling after CRT had not been possible until just recently when a new generation of CRT defibrillators was approved for conditional use in the MRI environment in February 2016. A post-CRT cardiac MRI provides is quite valuable because it can provide highly detailed and reproducible data regarding LV structure and function using optimized pulse sequences for strain, volumes, wall thickness, synchrony, and scar. In this study, post-CRT MRI findings will be compared with pre-CRT MRI findings to show how the LV pacing lead location relative to mechanical activation and scar alters LV remodeling after CRT and provide additional insights regarding the optimal spatial relationship between LV lead position and scar in the heart. MRI results will be compared with echocardiography results, and the findings promise to demonstrate how these imaging modalities can be used together for the benefit of CRT patients. We will enroll 40 CRT patients who will have cardiac MRI, echocardiography, cardiopulmonary exercise testing, symptom assessment, and laboratory testing before and 6 months after CRT. The project is expected to have a high impact on the field and lead to important improvements in CRT implementation. This work will also facilitate the PI's progression to independence by providing important data for subsequent work on an MRI-guided clinical trial for CRT and the development of computational models for LV remodeling after CRT based on LV pacing lead placement. 1