MRI Guided Robotic Cardiac Surgery

经皮技术置换主动脉瓣的主要局限性是详细的可视化和耐用的假体。 本研究调查了实时磁共振成像的使用，以提供精确的解剖细节和视觉反馈，以植入经证实的生物瓣膜。 通过实时MRI引导的微创方法，22头猪接受了非体外循环主动脉瓣置换术。 MR成像用于精确识别关键解剖标志。使用额外的术中灌注、流速和功能成像来确认瓣膜的放置充分性和功能。 在实时MR成像下，规定了多个倾斜平面。 通过使用有源（即，MR信号接收无环天线）标记丝增强，该成像允许人工瓣膜的正确放置和定向。通过经心尖入路插入一系列生物假体主动脉瓣（21- 25 mm）。 从放置套管针到展开瓣膜的植入时间小于90秒（77 + 12）。 除了解剖学确认人工瓣膜相对于主动脉瓣环和冠状动脉的适当放置外，还通过MR成像获得了瓣膜和左心室的功能确认。 术中首过灌注扫描记录瓣膜置入后心肌血流充足。 相速度证实人工瓣膜瓣叶充分打开，无瓣膜或瓣周返流。 实时MR成像提供了出色的解剖细节和术中评估，允许在跳动的心脏上放置耐用的人工瓣膜，而不受经皮入路的限制。 我们目前允许动物从这些程序中恢复，并长期跟踪它们，以评估该技术的耐用性。此外，我们已经开始使用MR兼容的机械臂来扩展外科医生的能力。

The principal limitations of percutaneous techniques to replace the aortic valve principal are detailed visualization and durable prostheses. This study investigated the use of real-time magnetic resonance imaging to provide precise anatomic detail and visual feedback to implant a proven bioprosthesis. Via a minimally invasive approach using real-time MRI guidance 22 pigs underwent off-pump aortic valve replacement. MR imaging was used to precisely identify critical anatomic landmarks. Additional intraoperative perfusion, flow velocity and functional imaging were used to confirm adequacy of placement and function of the valve. Under real-time MR imaging, multiple oblique planes were prescribed. Enhanced by the use of an active (i.e. MR signal receiving loopless antennae) marker wire, this imaging allowed correct placement and orientation of the prosthetic valve. Via a transapical approach a series of bioprosthetic aortic valves (21-25mm) were inserted. The time to implantation after the placement of the trocar to deployment of the valve was less than ninety seconds (77 + 12). In addition to anatomic confirmation of adequate placement of the prosthetic valve in relation to the aortic annulus and the coronary arteries, functional confirmation of the valve and left ventricle was also obtained with MR imaging. Intraoperative first pass perfusion scanning documented adequacy of myocardial blood flow after valve placement. Phase velocity confirmed adequate opening of the prosthetic valve leaflets and lack of valvular or paravalvular regurgitation. Real-time MR imaging provides excellent anatomic detail and intraoperative assessment that permits placement of durable valve prostheses on the beating heart without the limitations of percutaneous approaches. We are presently allowing animals to recover from these procedures and following them long term to assess the durability of the technique. Additionally we have started to employ MR compatible robotic arms to extend the surgeons' capability.