Echocardiographic Assessment of Myocardial Perfusion

描述（申请人的逐字描述）：对比度增强 超声波已经成为一种有价值的实验和临床工具， 器官灌注它使用充气微泡作为灌注示踪剂， 在它们通过任何血管隔室的过程中散射超声。 因为微泡的血管内流变学与红细胞类似， 血细胞，超声造影可用于测量微泡 (or红细胞）在组织中的速度。此外，由于微泡 完全保留在血管内空间，对比增强超声 也可用于测量血容量分数（MBV）。在此之前， 在赠款周期中，我们使用MCE来揭示MBV的许多重要方面， 在了解心肌血流量的局部控制方面具有重要意义 血流量（MBF）以及冠状动脉病变后发生的适应性变化 动脉疾病特别是，我们已经深入了解了 毛细血管调节MBF。我们已经证明毛细血管负责 用于限制在正常冠状动脉中看到的最大充血反应 并且毛细血管血容量在狭窄远端减少 在充血期间。我们还表明，核示踪剂上的灌注缺陷 成像与狭窄远端MBV的可逆性降低相关， 而不是由于迄今为止所假设的“流动失配”。 该提案的目的是进一步定义MBV的适应性变化， 在生理条件下发生的毛细血管阻力， 动脉粥样硬化性心脏病这项建议的具体目标是 评估：1.在正常冠状动脉循环中毛细血管如何调节MBF 自动调节功能已耗尽。2.毛细血管远端发生了什么 充血时狭窄。3. MBV的阶段性变化是否可用于 检测静息时冠状动脉狭窄的存在和程度。4.是否 血液粘度的变化影响冠状动脉血流储备。 研究将在开胸犬模型中进行，使用对比增强 超声和大鼠骨骼肌使用活体显微镜。的 最终的目的是进一步了解毛细血管在 医疗保险基金的地方法规。

DESCRIPTION (the applicant's description verbatim): Contrast-enhanced ultrasound has become a valuable experimental and clinical tool for assessing organ perfusion. It used gas-filled microbubbles as perfusion tracers, which scatter ultrasound during their transit through any vascular compartment. Because microbubbles have an intravascular rheology similar to that of red blood cells, contrast-enhanced ultrasound can be used to measure microbubble (or red blood cell) velocity in tissue. Additionally, because the microbubbles remain entirely within the intravascular space, contrast-enhanced ultrasound can also be used to measure the blood volume fraction (MBV). Over this previous grant cycle, we have used MCE to unravel many important aspects of MBV, which have major relevance in understanding the local control of myocardial blood flow (MBF) as well as the adaptive changes that occur consequent to coronary artery disease. In particular, we have gained insights into the role capillaries in regulating MBF. We have shown that capillaries are responsible for limiting the maximal hyperemic response seen in the normal coronary circulation and that capillary blood volume decreases distal to a stenosis during hyperemia. We have also shown that perfusion defects on nuclear tracer imaging is related to reversible decreases in MBV distal to a stenosis rather than due to 'flow mismatch' as has heretofore been assumed. The aim of this proposal is to further define adaptive changes in MBV and capillary resistance that occur under physiological conditions and in atherosclerotic heart disease. The specific aims of this proposal are to assess: 1. How capillaries regulate MBF in the normal coronary circulation when autoregulation is exhausted. 2. What happens to capillaries distal to a stenosis during hyperemia. 3. Whether phasic changes in MBV can be used to detect the presence and magnitude of coronary stenosis at rest. 4. Whether changes in blood viscosity affect coronary blood flow reserve. Studies will be performed in open chest canine models using contrast-enhanced ultrasound and in the rat skeletal muscle using intravital micrscopy. The ultimate aim is the further understanding of the role of capillaries in the local regulation of MBF.