MECHANICS OF LV SUCTION AND DIASTOLIC FILLING

到目前为止，脑室抽吸的机制尚不清楚，其 在维持生理舒张期功能方面的作用尚未得到证实。 心室抽吸被认为在几乎所有的 心脏早期快速充盈相的爆发性特征 循环(发生大量的心室流入时)；极大地促进 心脏有效运转所需的舒张期充盈 快速的心率和锻炼；并增加总体 通过应用部分机械能来提高心脏的效率 收缩到动力舒张期。脑室抽吸失败 与心力衰竭时左心房压力过高有关 心。此应用程序中描述的工作的长期目标是 确定脑室抽吸的力学和结构基础 并阐明了舒张期吸力对左心室的重要性。 生理和病理生理条件下的灌浆。这 由于我们的实验室最近取得了三项进展，现在可以实现这一目标： 首先，通过自动化的计算机化分析获得 成百上千个植入的不透射线标记的立体视频放射照片 在整个左侧同时出现三维应变 第二，左、右室心肌的新实验技术 房压钳制和左室容量钳制 (伺服控制)，在揭示的初步测试中显示出希望， 首次建立了左心室的力学相关关系 吸力；第三，一种新的计算机图形方法来可视化 大量同时发生的瞬时区域应变和剪切 允许识别模式，包括空间和时间模式，而不是 在其他方面可以在来自研究的无数数据中辨认出来，例如 这些。拟议的研究涉及以下问题：(1)什么是 可以在存在的情况下形成的吸力压力范围 一个正常的二尖瓣装置？(2)什么是重要的 吸力对左心室充盈的贡献？(3)是弹性的 心肌扭转变形中储存的能量，跨壁 压缩、面内应变或这些剪切机和 应变？(4)弹性反冲和应变的区域分布是什么？ 舒张期局部能量释放的顺序及其如何 影响左心室内的压力梯度？(5)占总压力的多少？ 二尖瓣充盈可以通过二尖瓣充血来解释。 向左心房后退？(6)对左心房的影响 伴随(A)容量超负荷的病理生理情况 局部舒张期肥厚和(B)压力超负荷性肥厚 力学，收缩过程中弹性能量的储存和释放 在舒张期，左心室形成吸力的能力？和(7) 能量储存和释放的顺序和比例是多少？ 从结缔组织基质和肌细胞中提取以帮助填充？这个 对这些问题的回答应该提供重要的新信息 关于舒张期功能的这些基本方面。

To date, the mechanism underlying ventricular suction is unknown, and its role in maintaining physiological diastolic function is unproven. Ventricular suction is thought to play an important role in the almost explosive character of the early, rapid filling phase of the cardiac cycle (when much of ventricular inflow occurs); to contribute greatly to the diastolic filling necessary for efficient operation of the heart at rapid heart rates and with exercise; and to increase the overall efficiency of the heart by applying part of the mechanical energy of systole to power diastole. A failure of ventricular suction has been implicated in the excessively high left atrial pressures in the failing heart. The long range goal of the work described in this application is to determine the mechanical and structural basis for ventricular suction and elucidate the importance of diastolic suction to left ventricular filling under both physiological and pathophysiological conditions. This goal is now attainable due to three recent advances in our laboratories: First, the ability to acquire, by automated computerized analysis of stereo videoradiograms of implanted radiopaque markers, hundreds of simultaneous three-dimensional strains throughout the entire left ventricular myocardium; Second, a new experimental technique for left atrial pressure clamping and left ventricular volume clamping (servo-controlled) which shows promise in preliminary tests of revealing, for the first time, the mechanical correlates of left ventricular suction; and Third, a new computer graphics approach to visualization of large numbers of simultaneous instantaneous regional strains and shears allowing recognition of patterns, both spatial and temporal, not otherwise recognizable in the myriad of data arising from studies such as these. The proposed studies address the following questions: (1) What is the range of suction pressures which can be developed in the presence of a normal mitral valvular apparatus? (2) What is the importance of the contribution of suction to left ventricular filling? (3) Is elastic energy stored in myocardial torsional deformation, transmural compression, in-plane strains, or combinations of these shears and strains? (4) What are the regional distributions of elastic recoil and the sequence of regional energy release during diastole and how do these influence gradients of pressure within the LV? (5) What fraction of total LV filling can be accounted for by the mitral valve engulfing blood as it recoils toward the left atrium? (6) What are the effects of the pathophysiological conditions accompanying (a) volume overload hypertrophy and (b) pressure overload hypertrophy on regional diastolic mechanics, the storage of elastic energy during systole and its release during diastole, and the capability of the LV to develop suction? and (7) In what sequence and what proportion is energy stored in and released from the connective tissue matrix and the myocytes to aid filling? The answers to these questions should provide important new information regarding these fundamental aspects of diastolic function.