ADAPTIVE AND PARALLEL SIMULATIONS OF CARDIAC FLUID DYNAMICS AND ELECTROPHYSIOLO

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 该项目旨在进行心脏血液-肌肉-瓣膜力学和电生理学的模拟，长期目标是进行力学和电生理学的耦合模拟。虽然描述心脏力学和电生理学的方程是不同的，我们采用一个共同的理论框架，浸没边界（IB）方法，心脏功能的两个方面。IB方法被引入作为解决流体-结构相互作用问题的方法（例如，心脏流体力学），但我们最近将其扩展到描述心脏电生理学。我们最近开发了一个统一的软件实现的IB方法，心脏力学和电生理学。这个模拟框架提供了对分布式内存并行性和空间自适应性的支持，从而使我们能够有效地使用现代超级计算机。McQueen和Peskin开发了心脏结构的三维模型，作为柯朗研究所长期研究工作的一部分，旨在使用心脏血液-肌肉-瓣膜力学的模拟来帮助设计人工心脏瓣膜和其他医疗设备和治疗方法。我们最近将IB方法的新自适应版本应用于第一代McQueen/Peskin心脏模型。在这个项目中，我们将进行额外的心脏力学模拟，但用最近开发的基于CT成像数据的第二代结构模型取代这种早期的理想化心脏结构模型。为了有效地获得真实的压力和流速，我们将利用我们的模拟框架的自适应能力，以局部方式部署非常精细的计算网格，例如，在心脏瓣膜小叶的附近，并且旋涡从这些小叶脱落。使用这种相同的解剖学上真实的CT衍生纤维结构，我们还将对心脏电生理学进行自适应三维模拟。心脏力学和电生理学的这些模型最终将被组合以产生心脏的电-机械-流体模型，其中心脏的电功能的三维模型将被用于以逼真的方式控制肌肉收缩的定时。需要这样的模拟平台来研究心脏疾病的治疗，这些心脏疾病关键地涉及心脏功能的两个方面，例如，具有由束分支传导阻滞引起的不同步机械和电激活的扩张型心肌病，以及通过双心室起搏（心脏起搏治疗）对其进行治疗。耦合我们的心脏力学和电生理学模型的任务将通过我们使用心脏生理学两个方面的统一仿真框架来简化。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project aims to perform simulations of cardiac blood-muscle-valve mechanics and electrophysiology, with a long-range goal of performing coupled simulations of mechanics and electrophysiology. Although the equations that describe cardiac mechanics and electrophysiology are different, we employ a common theoretical framework, the immersed boundary (IB) method, for both aspects of heart function. The IB method was introduced as an approach to problems of fluid-structure interaction (e.g., cardiac fluid mechanics), but we have recently extended it to describe cardiac electrophysiology. We have recently developed a unified software implementation of the IB approach to both cardiac mechanics and electrophysiology. This simulation framework provides support for distributed-memory parallelism and spatial adaptivity, thereby allowing us to use modern supercomputers effectively and efficiently. Three-dimensional models of the structure of the heart have been developed by McQueen and Peskin as part of a longterm research effort at the Courant Institute that aims to use simulations of cardiac blood-muscle-valve mechanics to aid in the design of artificial heart valves and other medical devices and therapies. We have recently applied our new adaptive version of the IB method to the first generation of the McQueen/Peskin model of the heart. During this project, we shall perform additional simulations of cardiac mechanics, but replacing this earlier idealized model of the structure of the heart with a recently-developed second generation structural model that is based on CT imaging data. In order to obtain realistic pressures and flow rates efficiently, we shall utilize the adaptive capabilities of our simulation framework to deploy extremely fine computational grids in a localized manner, e.g., in the vicinity of the heart valve leaflets and the vortices shed from these leaflets. Using this same anatomically realistic CT-derived fiber structure, we shall also perform adaptive three-dimensional simulations of cardiac electrophysiology. These models of cardiac mechanics and electrophysiology will ultimately be combined to yield an electro-mechano-fluidic model of the heart, in which the three-dimensional model of the electrical function of the heart will be used to control the timing of the muscle contractions in a realistic manner. Such a simulation platform is required to study treatments for diseases of the heart which crucially involve both aspects of heart function, e.g., dilated cardiomyopathy with dyssynchronous mechanical and electrical activation resulting from bundle branch block, and its treatment via bi-ventricular pacing (cardiac resynchronization therapy). The task of coupling our models of cardiac mechanics and electrophysiology will be simplified by our use of a unified simulation framework for both aspects of cardiac physiology.