MECHANICS OF LV SUCTION AND DIASTOLIC FILLING

迄今为止，心室抽吸的机制尚不清楚，其 维持生理舒张功能的作用尚未得到证实。 脑室抽吸被认为在几乎所有的 心脏早期快速充盈期的爆发性特征 循环（当大量心室流入发生时）;对 心脏有效运转所必需的舒张期充盈， 快速心率和运动;并增加整体 心脏的效率，通过应用部分机械能， 收缩期到动力期 脑室抽吸失败 与左心房压力过高有关， 心 本申请中描述的工作的长期目标是 以确定心室抽吸的机械和结构基础 并阐明舒张期抽吸对左室舒张功能的重要性 在生理和病理生理条件下的填充。 这 由于我们实验室的三项最新进展，现在可以实现这一目标： 首先，通过自动计算机化分析， 植入的不透射线标记物的立体视频放射图，数百个 同时三维应变整个左 第二，一种新的实验技术， 心房压力和左心室容量阻断 （伺服控制），这表明在初步测试显示， 左心室的机械相关性 第三，一种新的计算机图形学方法， 大量同时发生的瞬时区域应变和剪切 允许识别模式，空间和时间， 在研究中产生的无数数据中， 这些. 建议的研究解决以下问题：（1）什么是 在存在以下因素的情况下可以形成的吸入压力范围 二尖瓣结构正常吗(2)的重要性是什么 吸引对左心室充盈的贡献？(3)是弹性 跨壁心肌扭转变形中储存的能量 压缩、面内应变或这些剪切和 应变？(4)弹性后坐力的区域分布和 区域能量释放顺序以及这些能量是如何释放的 影响LV内的压力梯度？(5)占总数的多少 左心室充盈可以由二尖瓣吞噬血液来解释，因为它 向左心房反弹(6)什么是影响的 伴随（a）容量超负荷的病理生理状况 心肌肥厚和（B）压力超负荷性心肌肥厚对局部舒张功能的影响 力学，收缩期间弹性能量的储存及其释放 以及左心室产生吸力的能力？（七） 能量以什么顺序和比例储存和释放 从结缔组织基质和肌细胞中提取来帮助填充的 这些问题的答案应该提供重要的新信息 关于舒张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.