CARDIOVASCULAR FLOW DYNAMICS--IN VIVO IMAGING STUDIES

该项目强调使用新出现的健壮的非侵入性超声成像技术来量化结构和功能心血管病理的研究。利用流体力学原理，描述了心脏结构异常和病理生理血流事件的时间和空间方面，并验证了它们的量化。在心功能不全的临床治疗中，准确的定量评估对诊断、预后和治疗具有重要意义。此外，非侵入性评估在经济上也是可取的。为此，今年的努力扩展了前几年的研究，包括：1)在体外动物研究中，证实了实际左心室容量与实时三维超声心动图计算的左心室容量之间的强烈相关性。2)在活体条件下，实时三维超声心动图心尖旋转6种平面测量方法与电磁血流探针法和磁共振成像计算左心室容量的参考标准具有较好的相关性。3)实时三维超声心动图在存在左心室不对称性的情况下，即在存在左室室壁瘤的情况下，也可以定量测量左室容量。4)采用实时三维彩色多普勒技术，利用其独特的垂直于血流的c平面，对左心室流出道的横断面血流速度分布进行成像。5)对左心室流出道横断面彩色图像的血流速度数据进行空间积分，得到峰值流速。因此，不需要任何关于流速几何分布的假设，就可以估计峰值流速。6)通过应用时间平均因子校正低估，电磁流量计的参考流量与实时三维彩色多普勒超声心动图有很好的一致性。这些研究已经发表或正在出版中。正在进行的使用三维结构成像和三维多普勒血流成像的研究使用慢性主动脉和二尖瓣反流的动物模型。

This project emphasizes studies using newly emerging robust non invasive ultrasonic imaging technologies for quantifying structural and functional cardiovascular pathology. Using hydrodynamic principles, temporal and spatial aspects of cardiac structural abnormalities and pathophysiologic flow events are described and their quantification validated. In the clinical management of cardiac dysfunction, quantitativelyaccurate assessment is of major importance for diagnosis, prognosis and therapy. Non invasive assessment is, in addition, economically desirable. To these ends, the current year's efforts have extended previous years' studies to include: 1) In ex vivo animal studies, a strong correlation was validated between actual left ventricular volumes and those calculated with real-time, three-dimensional echocardiography. 2) In vivo, apically rotated 6 plane measurement methods with real-time, three-dimensional echocardiography correlated well with reference standards for calculating left ventricular volumes when compared with electromagnetic flow probe methods and magnetic resonance imaging. 3) Real-time, three-dimensional echocardiography was also validated for quantifying left ventricular volumes in the presence of left ventricular asymmetry, i.e. in the presence of left ventricular aneurysms. 4) Using real-time, three-dimensional color Doppler with its unique c-plane, which is perpendicular to flow, the cross-sectional spatial velocity distributions in the left ventricular outflow tract were imaged. 5) Peak flow rates were obtained by spatially integrating the velocity data from the cross-sectional color images of the left ventricular outflow tract. Thus, estimations of peak flow rates were possible without any assumptions about flow velocity geometric distribution. 6) By applying a temporal averaging factor to correct for underestimation, there was an excellent agreement between reference flow rate by electromagnetic flow meter and real-time, three-dimensional color Doppler echocardiography. These studies have been published or are in press. On-going studies using three-dimensional structural imaging and three-dimensional Doppler flow imaging use animal models of chronic aortic and mitral regurgitation.