Acoustically Active Catheter for Ultrasound-Guided Intramyocardial Injections

 描述(由申请人提供)：微创干预正在迅速出现。在经心内膜内注射的心肌梗死的细胞治疗中，需要针对心肌内靶点的高度精确的解剖引导，测量左室壁运动，并识别存活的心肌。虽然一些成像方法提供了很好的解剖描述或机电映射，但超声心动图(ECHO)是唯一一种可以将所有上述要求结合到便携式、非电离和经济有效的引导系统中的方法。这样一个全面的解决方案是非常必要的，但目前还不存在。对此，我们提出了一种基于我们的声学活性导管(AAC)原型的创新超声导航解决方案，该原型的尖端安装了压电晶体，晶体以特定频率振动，因此，AAC尖端充当声学“信标”，通过脉冲波(PW)多普勒样本窗口明确识别和空间定位。因此，PW多普勒被用于一种新的应用：它跟踪常规(灰度级)扫描中的AAC尖端，并能够将尖端引导到所需的解剖目标。无需对传统的超声成像仪进行改装。我们的初步工作验证了所提出的导航原理，并证明了其空间定位的准确性。在当前的应用程序中，现有的功能性AAC原型将用作 这是一个平台，用于进一步研究微创手术的声学导航、基于导管的心肌内注射深度控制的进步以及心肌内给药的疗效测定。我们还将利用我们在声学、体外和活体(开胸和闭胸)猪实验、用于参考测量的声学仪器和最先进的超声波技术方面的理论工作。该应用程序是按照以下目标组织的。在目标1中，我们将通过实施AAC尖端的彩色多普勒标记来改进导航功能，允许实时双平面可视化和导管尖端的3D跟踪。在目标2中，我们将通过开发和测试一种测量针插入深度的声学方法来解决心肌内注射的准确性和安全性问题。在目标3中，我们将使用我们以前的局部生化(非破坏性)抑制左心功能的模型，并通过从心脏内引导注射AAC来测试心肌内给药的有效性。我们的团队和两位主要研究人员在心脏干预、ECHO、心血管模型和振动声学方面的互补专业知识有助于实现这些目标。这项研究意义重大，因为特定的局部声源与多普勒跟踪的结合减少了图像引导介入与传统超声检查的复杂伪影。

 DESCRIPTION (provided by applicant): Minimally invasive interventions are rapidly emerging. In cell therapy of infarction by transendocardial injections, highly spatially accurate anatomical guidance towards an intramyocardial target, measurements of left ventricular (LV) wall motion, and identification of viable myocardium are required. While some imaging methods provide excellent anatomical depictions or electromechanical maps, echocardiography (echo) is the only one that could combine all the above requirements into a portable, nonionizing, and cost-effective guidance system. Such a comprehensive solution is highly desired, but currently does not exist. In response, we propose an innovative ultrasound navigation solution based on our acoustically active catheter (AAC) prototype, which has its tip fitted with a piezoelectric crystal The crystal vibrates at a specific frequency, and as a result, the AAC tip then acts as an acoustic "beacon," which is unambiguously identified and spatially localized by a pulsed-wave (PW) Doppler sample window. Thus, PW Doppler is used in a new application: It tracks the AAC tip within conventional (grayscale) scans and enables guidance of the tip to a desired anatomical target. There is no need to modify the conventional ultrasound imager. Our preliminary work has proven the proposed navigation principle and demonstrated its spatial targeting accuracy. In the current application, the existing functional AAC prototype will serve as a platform for further investigations of acoustic navigation of minimally invasive procedures, advancement of depth control of catheter-based intramyocardial injections, and determination of the efficacy of intramyocardial agent administrations. We will also capitalize on our theoretical work in acoustics, in vitro and in vivo (open-chest and closed-chest) pig experiments, sonometric instrumentation for reference measurements, and state of the art ultrasound technologies. The application is organized to the following aims. In aim 1, we will advance the navigation function by implementing a color Doppler marker of the AAC tip, allowing real-time biplane visualization and 3D tracking of the catheter tip. In aim 2, we will address intramyocardial injection accuracy and safety by developing and testing a sonometric approach for needle insertion depth measurement. In aim 3, we will use our previous model of local biochemical (nondestructive) inhibition of LV function and test efficacy of intramyocardial agent delivery by an injection AAC guided from within the heart. Our team and complementary expertise of the two principal investigators in cardiac interventions, echo, cardiovascular models, and vibroacoustics are conducive to accomplishing these aims. The research is significant because the combination of the specific localized acoustic source with Doppler tracking alleviates artifacts complicating image-guided intervention with conventional ultrasonography.