Characterization of intraventricular filling vortices in the clinical setting

描述（由申请人提供）：心脏产生的血流是同步的机电心肌事件和流体动力学过程的结果。血流和心肌之间的相互作用引起心脏的持续重塑，导致最小化能量损失的流动模式。正常左心室中的流动模式由大的舒张期涡流组成，该涡流引导血液朝向流出道的运输。在衰竭的左心室中，进行性不利重构导致异常流动模式，其在引导血液运输方面效率较低，并且可能进一步促进心力衰竭的进展。因此，对正常和病变左心室血流动力学的更深入了解可能会提供对心力衰竭病理生理学的见解，从而导致该综合征的早期诊断和改善治疗策略。近年来，人们对研究左心室内血流模式在血液运输中的作用产生了浓厚的兴趣。尽管取得了重大进展，但我们仍然对流体动力学过程如何与机电事件同步以产生血流知之甚少。我们的初步研究表明，舒张期涡流的位置和性质，因此，他们的能力，通过LV通道血液运输，与心肌事件的周期的时间。本研究的目的是了解舒张期涡流的时间演变对左心室充盈期持续时间的依赖性，并确定这种依赖性如何影响血流输送和整体心室功能。为了开展拟议的研究，我们组建了一个跨学科的研究人员团队，他们具有从心脏病学，超声心动图和磁共振成像到流体动力学，计算力学和图像处理等互补专业知识。我们将验证并应用一种新的超声心动图模式来测量一组在UCSD医疗中心接受心脏栓塞治疗的患者左心室的二维双向时间分辨血流图。我们将使用这些测量来确定这些患者在不同AV和VV延迟下舒张期涡旋的时间演变，并表征这些延迟如何影响左心室内血液的传输。我们假设，更好地了解这种依赖性将增加我们对心脏起搏治疗的好处的理解。它还将通过改善患者选择并使LV收缩能够在最有利的血流动力学条件下发生来改善VV和AV优化的当前方案。

DESCRIPTION (provided by applicant): Blood flow generation by the heart is the result of synchronized electromechanical myocardial events and fluid dynamics processes. Interactions between blood flow and the myocardium elicit the continuous remodeling of the heart, leading to flow patterns that minimize energy losses. The flow pattern in the normal left ventricle consists of a large diastolic vortex that channels the transit of blood towards the outflow tract. In a failing left ventricle, progressive adverse remodeling leads to abnormal flow patterns that are less efficient in channeling blood transit, and which may contribute further to the progression of heart failure. Thus, a deeper understanding of blood flow dynamics in normal and diseased left ventricles may provide insight on the pathophysiology of heart failure, leading to earlier diagnosis and improved treatment strategies of this syndrome. Recent years have witnessed a surge of interest in studying the role of flow patterns in blood transport inside the left ventricle. Despite significant advances, we still understand poorly how the fluid dynamical processes are synchronized with the electromechanical events to generate blood flow. Our preliminary studies suggest that the position and properties of diastolic vortices, and consequently, their ability to channel blood transit through the LV, are related to the timing of the myocardial events of the cycle. The goal of this research is to understand the dependence of the time evolution of the diastolic vortices on the duration of the left-ventricular filling phases, and to determine how this dependence affects blood flow transport and global ventricular function. In order to carry out the proposed research we have assembled an interdisciplinary team of investigators with complementary expertise ranging from cardiology, echocardiography and magnetic resonance imaging, to fluid dynamics, computational mechanics and image processing. We will validate and apply a novel echocardiographic modality to measure two-dimensional bi-directional time-resolved flow maps in the left ventricle in a group of patients undergoing cardiac resynchronization therapy at the UCSD Medical Center. We will use these measurements to determine the time evolution of diastolic vortices in these patients for different AV and VV delays, and characterize how these delays affect the transit of blood inside the left ventricle. We postulate that better knowledge of this dependence will increase our understanding of the benefits of cardiac resynchronization therapy. It will also improve current protocols for VV and AV optimization by improving patient selection and enabling LV contraction to take place under the most favorable hemodynamic conditions.