Anti-fibrotic Coatings for Rapidly Exchangeable Bioprosthetic Heart Valve

描述（由申请人提供）：在美国，每年有超过10万名患者需要用人工装置替换患病的心脏瓣膜。尽管用动物组织制成的生物瓣膜被认为是大多数患者的理想选择，但它们在大约15年内就会磨损。因此，它们主要用于预计活不过瓣膜的老年患者。年轻的病人接受更耐用的机械瓣膜，但需要长期服用血液稀释剂。这使得患者无法参加大多数运动，并使患者面临致命出血和中风的风险增加。ValveXchange, Inc. （VXI）是一家医疗设备公司，开发一种由手术植入的基座和可交换的生物假体组织小叶组成的两部分心脏瓣膜。VXI装置是一种不需要抗凝的终身组织瓣膜置换系统。在第一次手术中，首先将对接站缝合到位，并将小叶夹入。这使得外科医生更方便地放置缝合线，而不会有损伤小叶核心的风险。当小叶套开始出现磨损的迹象时，可以使用微创手术或经皮手术迅速更换。快速、微创的小叶置换术大大缩短了手术时间，并消除了对初始人工瓣膜进行技术要求高和潜在危险的再次切除的需要。当小叶组交换时，对接站将永久保留在原位，因此不会破坏主动脉根部的敏感组织；它是心脏传导系统的重要组成部分，也是冠状动脉的起源。

DESCRIPTION (provided by applicant): Each year, over 100,000 patients in the United States need to have their diseased heart valves replaced with artificial devices. Although bioprostheses, valves made from animal tissues, are considered ideal for most patients, they wear out in about 15 years. They are thus used primarily in the elderly patient who is not expected to outlive the valve. Younger patients receive mechanical valves that are more durable, but require chronic administration of blood thinners. This makes participation in most sports impossible and exposes the patient to increased risk for fatal bleeds and strokes. ValveXchange, Inc. ( VXI ) is a medical device company developing a two-part heart valve consisting of a surgically implanted base and an exchangeable bioprosthetic tissue leaflet set. The VXI device is a lifetime tissue valve replacement system that does not require anticoagulation. During the first surgery, the docking station is first sewn in place and the leaflets are snapped in. This allows the surgeon to place sutures more conveniently, without risk of damaging the leaflet core. As the leaflet set begins to show signs of wear it can be exchanged rapidly, using a minimally invasive surgical or percutaneous procedure. Rapid, minimally invasive leaflet exchange dramatically reduces surgical time and eliminates the need the technically demanding and potentially dangerous re-excision of the initial prosthetic valve. As the leaflet set is exchanged, the docking station remains permanently in place so there is no disruption of the sensitive tissue of the aortic root; a vital part of the conduction system of the heart and the origin of the coronary arteries. VXI has successfully completed two Phase I projects. In the first, VXI developed prototype exchangeable valves and demonstrated their technical feasibility in an animal model by exchanging a valve in 23 seconds. In the second, VXI investigated the ability of anti-adhesion coatings to abate fibrotic overgrowth in the hyper-fibrotic sheep model. In this Phase II application we propose to implement our novel anti-adhesion coatings in a chronic sheep model and investigate the long-term host response of the rapidly exchangeable valve. We will fabricate 8 valves each from bare cobalt-chrome, cobalt-chrome treated with a stearate coating, and from pyrolitic carbon. Both stearate and pyrolitic carbon have been shown to repel fibrotic overgrowth in the Phase I study. A control group will make use of the gold standard Edwards pericardial valve. After 3 and 5 months of implantation, the leaflet sets will be exchanged using an open surgical procedure in which the reduced time on cardiac bypass will be documented, and the degree of fibrotic overgrowth measured. Detailed measurements of fibrotic overgrowth and incidence of thromboembolism will be examined at necropsy. This revised resubmission now includes more specific criteria upon which to base a redesign of the valve and the anti-fibrotic coatings. Each year, over 100,000 patients in the United States need to have their diseased heart valves replaced with artificial devices. Although artificial heart valves made from materials of animal origin are considered ideal for most patients, they wear out in about 15 years. They are thus used primarily in the elderly patient who is not expected to outlive the valve. Younger patients receive mechanical valves, made from metals and graphite-like materials. Although these types of valves will last the life of the patient, they require the patient to be on blood thinners. This makes participation in most sports impossible and exposes the patient to increased risk for fatal bleeds and strokes. ValveXchange, Inc. ( VXI ) is a medical device company developing a two-part heart valve consisting of a surgically implanted base and an exchangeable animal tissue-based leaflet set. The VXI device is a lifetime tissue valve replacement system that does not require the patient to be on blood thinners. During the first surgery, the docking station is first sewn in place and the leaflets are snapped in. This allows the surgeon to place his stitches more conveniently, without risk of damaging the leaflet core. As the leaflet set begins to show signs of wear it can be exchanged rapidly, using a minimally invasive surgical or catheter-based procedure. Rapid, minimally invasive leaflet exchange dramatically reduces surgical time and eliminates the need the technically demanding and potentially dangerous re-excision of the initial valve. As the leaflet set is exchanged, the docking station remains permanently in place, so there is no disruption of the sensitive tissue of the aortic root a vital part of the conduction system of the heart and the origin of the coronary arteries. VXI has successfully completed two Phase I projects. In the first, VXI developed prototype exchangeable valves and demonstrated their technical feasibility in an animal model by exchanging a valve in 23 seconds. In the second, VXI investigated the ability of anti-adhesion coatings to abate tissue overgrowth in the sheep, an animal known to generate a prolific healing response. In this Phase II application we propose to implement our novel anti-adhesion coatings in the sheep model and investigate the long-term response of the host to the rapidly exchangeable valve. We will fabricate 24 valves with the mating surfaces between the docking station and the leaflet set made from biocompatible materials, such as steel treated with a number of anti-adhesion coatings shown to repel tissue overgrowth in the Phase I study. A control group consisting of a commercially available valve from a well-established manufacturer will also be used. After 3 and 5 months of implantation, the leaflet sets will be exchanged using an open surgical procedure in which the reduced time on cardiac bypass will be documented, and the degree of tissue overgrowth measured. Detailed measurements of fibrotic overgrowth and incidence of thromboembolism will be examined at necropsy. This revised resubmission adds additional criteria on which redesign of the valve and the anti-adhesion coatings may be necessary.