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发心脏的持续重塑，导致能量损失最小化的流动模式。正常左心室的血流模式由一个巨大的舒张期涡流组成，该涡流将血液输送到流出道。在衰竭的左心室中，进行性的不利重塑导致异常的血流模式，从而降低了血液输送的效率，并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深入了解可能有助于深入了解心力衰竭的病理生理学机制，从而导致对这种综合征的早期诊断和改进治疗策略。近年来，人们对血流模式在左心室内血液传输中的作用的研究兴趣激增。尽管取得了重大进展，但我们对流体动力学过程如何与机电事件同步以产生血流仍知之甚少。我们的初步研究表明，舒张期涡旋的位置和性质，以及它们引导血液通过左心室的能力，与该周期中心肌事件的发生时间有关。本研究的目的是了解舒张期旋涡的时间演变与左心室充盈相持续时间的依赖关系，并确定这种依赖关系如何影响血流输送和整体心功能。为了开展拟议的研究，我们组建了一个跨学科的研究团队，他们拥有互补的专业知识，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。我们将验证并应用一种新的超声心动图方法来测量UCSD医学中心接受心脏再同步治疗的一组患者的左心室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的房室和室速延迟时舒张期涡旋的时间演变，并表征这些延迟如何影响血液在左心室内的运输。我们假设，对这种依赖性的更好了解将增加我们对心脏再同步治疗好处的理解。它还将通过改进患者选择并使LV收缩能够在最有利的血流动力学条件下进行，从而改进当前的VV和AV优化方案。

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.