MECHANICS OF DIASTOLIC SUCTION

描述（改编自申请人的摘要）：本研究的目标 研究的目的是了解左心室收缩的意义和机制， (LV)恢复力（RF）和二尖瓣抽吸流入。 存在RF 当收缩末期容积（ESV）小于平衡时， 音量. 研究者将在开胸手术中使用呼吸机系统， 将左心房压力（SBP）快速夹持在所需值的狗。 当收缩压低于左心室舒张压时，充盈受阻，左心室 在ESV完全放松。 负的完全松弛压力（FRP）表明 存在RF。 当mmHg = 0 mmHg（准零源压）时，填充 只通过吸力产生。 该系统允许调查人员 通过操纵负载将ESV与RF（负FRP）和抽吸流量关联起来 条件 申请人表示，研究人员此前已 描绘了在充盈的“生理”范围内存在的RF幅度 以及急性冠脉闭塞对FRP的影响。 初步数据 表明1）全身和冠状动脉内（左前降支 多巴酚丁胺增加RF和抽吸流量; 2）前壁 透壁变形模式是特别重要的机制， RF;和3）RF在起搏心动过速心力衰竭中明显受损。 研究人员现在建议更全面地描述这种关系 与LV扭转（“扭转”）和RF相关的前壁变形之间的关系， 抽吸 此外，研究人员将检验以下假设： 胸内负压、心包约束和心内 流体静压梯度对RF或吸力没有重大影响。 最后， 调查人员将开始确定变化的作用和机制 在RF和抽吸中，作为舒张压的病理生理学组成部分， 在几种过载状态下填充异常。

DESCRIPTION (adapted from the applicant's abstract): The goal of this research is to understand the significance and mechanism of left ventricular (LV) restoring forces (RFs) and mitral inflow by suction. A RF is present and suction occurs when end-systolic volume (ESV) is less than equilibrium volume. The investigators will employ a servomotor system in open chest dogs which rapidly clamps left atrial pressure (LAP) at a desired value. With LAP less than LV diastolic pressure, filling is prevented and the LV fully relaxes at ESV. A negative fully relaxed pressure (FRP) indicates presence of a RF. With LAP = 0 mmHg (quasi-zero source pressure), filling occurs exclusively by suction. The system allows the investigators to relate ESV to RFs (neg FRP) an suction flow by manipulating loading conditions. The applicant indicates that the investigators have previously delineated the magnitude of RF present over "physiologic" range of filling and the effect of acute coronary occlusion on FRP. Preliminary data indicate that 1) both systemic and intra-coronary (left anterior descending artery) dobutamine increase RFs and suction flow; 2) anterior wall transmural deformation patterns are especially important as a mechanism of RFs; and 3) RFs are markedly impaired in pacing tachycardia heart failure. The investigators now propose to more completely delineate the relationship between anterior wall deformation linked to LV torsion ("twist") and RFs and suction. In addition, the investigators will test the hypothesis that negative intra-thoracic pressure, pericardial restraint and intra-cardiac hydrostatic gradients do not have a major effect on RFs or suction. Last, the investigators will begin to determine the role and mechanism of changes in RFs and suction as a component of the pathophysiology of diastolic filling abnormalities in several overload states.