Cardiac Cryoablation Catheter

描述(申请人提供)：房颤(房颤)是临床上最常见的心律失常，也是需要住院治疗的最常见的心律失常。美国有近300万人患有房颤。40岁以上的美国人一生中有四分之一的风险会患上房颤。目前只有一种实用的治疗方法，即射频消融导管肺静脉隔离术(PVI)。在300万患有心房颤动的患者中，每年只有大约3000人(0.1%)通过这一复杂而危险的程序得到治疗和治愈。射频消融会造成高温损伤，并不可避免地涉及一定程度的组织破坏，从而增加穿孔和中风的风险。相比之下，冷冻对组织的破坏导致最小的组织破坏，并保留了基本的组织结构。冷冻消融治疗因其固有的安全性而颇具吸引力，但由于技术上的缺陷，通过插管进行冷冻消融的前景尚未完全实现。目前使用的心脏冷冻消融导管存在冷却功率不足的问题。瓶颈是通过狭窄的导管可以排出的蒸汽量(就像通过吸管呼吸一样)。结果，冷冻消融的成功率降低了，尽管射频消融有缺点，但不可避免地，射频消融仍是首选治疗方法。我们提出了一种方法，通过消除排出蒸汽的需要，显著增加心脏冷冻消融导管的冷却功率。取而代之的是，蒸汽将在闭路循环微型低温制冷系统中重新循环。我们的目标是压缩、冷凝和重复使用导管内的蒸汽。先进制冷技术公司(ART)计划通过两项创新技术实现这些目标：1)ART的激光驱动压缩机技术和2)ART的微通道热交换器技术。由此产生的液化器(压缩机+冷凝器)将消除将蒸汽全部排出的需要。在第一阶段将解决以下三个具体目标：1.我们的激光驱动压缩机技术将蒸汽加压到液化压力的可行性。2.我们的换热器技术有效冷却、冷凝和液化蒸汽的可行性。3.活体心脏组织冷冻消融演示。在随后的工作中，该装置将被植入心脏冷冻消融球囊导管。更强的低温将通过为主流心电图学家提供安全的工具来治疗普通公众，从而影响公众健康。与公共健康相关：美国有300万人患有房颤。40岁以上的美国人一生中有四分之一的风险会发展为房颤。目前，每年只有3000人(0.1%)接受复杂、有风险且不广泛使用的程序治疗。该项目将帮助开发一种设备，为医生提供一种更安全、更简单、成本更低的程序，为更多患有这种虚弱疾病的人服务。

DESCRIPTION (provided by applicant): Atrial fibrillation (AF) is the most frequent arrhythmia encountered in clinical practice and is the most common arrhythmia necessitating hospital admission. Nearly three million people in the U.S. have Atrial Fibrillation. Americans over 40 have a one in four lifetime risk of developing Atrial Fibrillation. Currently there is only one practical treatment, pulmonary vein isolation (PVI) with a radiofrequency (RF) ablation catheter. Of the 3 million people suffering from Atrial Fibrillation, only about 3,000 (0.1%) annually are treated and cured with this complex and risky procedure. RF ablation creates hyperthermia lesions and inevitably involves some degree of tissue disruption that increases the risk for perforation and stroke. In contrast, the destruction of tissue by freezing results in minimal tissue disruption and preserves basic underlying tissue architecture. Treatment using cryoablation is attractive because of its inherent safety, however the promise of cryoablation via catheterization has not yet been fully realized because of technical shortcomings. Currently used cardiac cryoablation catheters suffer from lack of cooling power. The bottleneck is in the amount of vapor that can be exhausted through the narrow catheter (like breathing through a straw). As a result, the success of cryoablation is reduced and, by necessity, radio frequency ablation has remained the treatment of choice despite its shortcomings. We propose a method to dramatically increase the cooling power of cardiac cryoablation catheters by eliminating the need to exhaust the vapor. Instead, the vapor will be re-circulated in a closed cycle miniature cryo refrigeration system. Our goal is to compress, condense and re-use the vapor inside the catheter. Advanced Refrigeration Technologies (ART) proposes to achieve these aims with two innovative technologies: 1) ART's laser-powered compressor technology and 2) ART's microchannel heat exchanger technology. The resulting liquefier (compressor+condenser) will eliminate the need to exhaust the vapor all together. During Phase I the following three specific aims will be addressed: 1. Feasibility of our laser-powered compressor technology to pressurize vapor to liquefaction pressure. 2. Feasibility of our heat exchanger technology to effectively cool, condensate and liquefy the vapor. 3. Demonstration of cryoablation on live heart tissue. In subsequent work, the device will be implanted in a cardiac cryoablation balloon catheter. Stronger cryo will impact public health by providing to the mainstream electrocardiologists a safe tool to treat the general public. PUBLIC HEALTH RELEVANCE: Three million people in the U.S. suffer from Atrial Fibrillation. Americans over 40 years old have a one in four risk of developing Atrial Fibrillation in their lifetime. Currently, only 3,000 (0.1%) annually are treated with a procedure that is complex, risky and not widely available. This project will help develop a device that will provide doctors a safer, simpler and lower cost procedure that will serve larger numbers of people suffering from this debilitating condition.