Ultrasound imaging of extracellular matrix remodeling for assessing congestive heart failure

我们开发了一种基于混沌理论的超声射频信号分析系统。利用该系统对人体心肌的超声信号进行了分析，结果表明：(1)心肌病患者的心肌超声信号表现为准周期而非混沌；(2)长期应用醛固酮阻滞剂后，心肌肥厚患者的心肌超声信号由准周期变为混沌。由于醛固酮阻滞剂是众所周知的减少心肌纤维化的药物，我们的数据可能被解读为基于混沌研究的超声射频信号分析提供了一个有用的心肌纤维化指标。为了建立心肌纤维化在高血压心力衰竭患者中的评估价值，我们建立了心肌纤维化导致左心室收缩和舒张期功能障碍的模型。在这个模型中，心肌纤维化与心肌炎性改变和活性氧的增加有关。这些变化被血管紧张素II通过激活促进细胞外基质降解的酶长期阻断而受阻。这在那些有左室重构(扩张)的患者中尤为重要。因此，心肌纤维化似乎是心脏功能和心脏几何形状的重要决定因素，表明心肌纤维化的评估在高血压性心力衰竭中尤为重要。目前，由于感兴趣区域大小的限制，我们的系统不适用于小动物，因此，我们正试图从技术方面改进该系统。

We have developed a system that analyzes ultrasound radiofrequency signals on the basis of chaos theory. This system was used to analyze the ultrasound signals derived from the human myocardium to show (1)that ultrasound signals show quasiperiodic rather than chaotic nature in the myocardium in patients with cardiomyopathy, and that (2)the quasiperiodic nature changes to chaotic nature following long-term administration of aldosterone blocker in patients with cardiac hypertrophy. Because aldosterone blocker is well known to reduce myocardial fibrosis, our data were may be interpreted that the analysis of ultrasound radiofrequency signals on the basis of chaos study provides a useful index of myocardial fibrosis.In order to establish the value of the assessment of myocardial fibrosis in the hypertensive failing hearts, we developed a model in which myocardial fibrosis causes in left ventricular systolic and diastolic dysfunction. In this model, myocardial fibrosis was associated with inflammatory changes in the myocardium and with the increase in reactive oxygen species. These changes were hampered by long-term angiotensin II blockade through the activation of the enzymes that facilitate the degradation of extracellular matrix. This was particularly important in those with left ventricular remodeling (dilatation). Thus, myocardial fibrosis appeared to be an important determinant of cardiac function as well as of cardiac geometry, indicating that assessment of myocardial fibrosis is particularly important in hypertensive heart failure.Currently, our system is not applicable to small animals because of the limitation of the size of region of interest, and therefore, we are attempting to improve the system from the technical aspect.