Development of a Cryo-Anchoring and Radiofrequency Ablation Catheter for Percutaneous Treatment of Mitral Valve Prolapse
Boronyak, Steven Michael
Current treatment for moderate and severe mitral regurgitation (MR), due to degenerative mitral valve (MV) disease, is open-chest surgical repair or replacement, as there are no known pharmacologic therapies that directly affect the disease process. Percutaneous approaches to MV repair have received a great deal of interest. Depending on the lesions present, current MV repairs may include annuloplasty, leaflet resection, or chordal transfer or replacement. While there are several percutaneous annuloplasty and chordal repair devices currently in development, there are currently no percutaneous techniques to perform leaflet resection, which is used in 70-80% of all surgical MV repairs. Thus, there is a need for a percutaneous leaflet resection technique in the expanding MV repair armamentarium. Radiofrequency (RF) ablation is a well-developed technique that has been used to treat cardiac electrophysiology abnormalities and uses electrical energy to form thermal lesions by resistive heating. The primary structural component of MV leaflets is collagen, which denatures and contracts when heated to >65 degrees Celsius. As a result, RF ablation can be used to reduce the size of enlarged myxomatous MV leaflets, providing a percutaneous alternative to open-chest surgical leaflet resection. However, application of RF ablation to MV leaflets in a dynamic hemodynamic environment is difficult without additional catheter stability. To address this, we have developed cryo-anchoring, a technique similar to cryoablation that uses pressurized nitrous oxide to provide cooling of a catheter tip. The sub-freezing temperatures provide adhesion, allowing stable and reversible attachment of a catheter tip to a moving MV leaflet. In this work, we develop and refine a combined RF ablation and cryo-anchoring (RFC) catheter for treatment of degenerative MV disease and characterize treatment efficacy using ex vivo and in vivo animal models. Short-term in vivo results indicate that the RFC catheter is a potential percutaneous alternative to surgical leaflet resection.