In this report we describe the first transvenous, Valve-In-Ring implantation procedure, using the Melody® Valve in combination with 4 distinct classes of annuloplasty ring (AR): 1) Rigid complete ring; 2) Partial ring; 3) Flexible ring; and 4) Saddle-shaped ring. The Melody valves were securely implanted in all cases except for one (90%), with no perivalvular leakage noted, and not greater than trivial to mild central MR excluding the one animal in which we intentionally oversized the device. Importantly, there was no LV outflow tract obstruction, nor aortic valve insufficiency noted following VIR insertion. The success and relative ease of this procedure irrespective of AR type, highlights the potential for this approach in patients with ongoing MV dysfunction despite prior surgical repair.
Many promising percutaneous mitral valve (MV) repair technologies have been developed [5
]. However, one-stage percutaneous MV replacement remains elusive [23
]. Minimally invasive surgical (transapical or transatrial) MV replacement via valve-in-valve (VIV) and more recently valve-in-ring (VIR) procedures have been published [17
], which underscore the potential of repurposing “failing” surgical hardware (bioprosthetic valves and annuloplasty rings) as “landing zones” for subsequent minimally invasive valve replacement. Our experience supports and further refines this concept and demonstrates that a purely percutaneous approach to VIR implantation is feasible, in all types of annuloplasty devices, including, complete, partial, rigid, flexible, and saddle-shaped rings.
In patients with ischemic mitral regurgitation (IMR) the VIR procedure has the potential to be truly transformative. The optimal treatment for IMR remains controversial. The recent documentation of high recurrence rates of IMR after ring annuloplasty[5
] has resulted in equipoise between the relative merits of repair versus replacement in this expanding cohort of patients. In fact there is an ongoing NIH funded clinical trial conducted within the Cardiothoracic Surgical Trials Network that has been developed to assess whether repair or replacement are best suited for patients with severe IMR. The availability of a fully percutaneous VIR procedure that is safe, fast, and effectively reframes the debate between repair and replacement in IMR. Annuloplasty could be performed in nearly all patients, maximizing the number who would experience the potential benefits of repair, while at the same time setting the stage for a quick, minimally-invasive remedial procedure–VIR - should symptomatic MR recur after surgery.
This was a proof of principle study designed to test the feasibility of percutaneous VIR into four different mitral AR types. The Melody® valves used in this experiment will in all likelihood not be the optimal design for treating the majority of patients with failed mitral valve repair procedures since the majority of patients having such surgeries receive annuloplasty devices with nominal sizes of 28 mm or greater. We believe that the VIR procedure will be an important addition to the treatment of recurrent MR and believe that a product with a wide variety of sizes needs to be designed specifically for this indication.
Additionally, the devices were previously handled and thus not optimal for functionality testing. Furthermore, they are undersized relative to the normal adult mitral annulus (max functional diameter = 22mm), and are not intended for use in the systemic circulation, where the after load is generally much higher than in the pulmonary circulation. Despite this, the Melody valves were sufficient to demonstrate the feasibility of the transvenous VIR procedure in all types of annuloplasty rings, and the functioned well in the short term. This was an acute study, therefore we cannot comment on the durability of Melody devices in the Mitral position in the longer term.
This report demonstrates a purely percutaneous, transvenous approach to mitral VIR replacement using the Melody valve in 4 different types of annuloplasty ring. The relative ease of access to the mitral space from the venous side with standard catheter sizes and techniques is encouraging in terms of the feasibility of this approach in patients. All reports to date describing the VIR and VIV procedures, including this one, have employed valves that were developed for use in either the aortic or pulmonary positions; it is likely that devices designed specifically for mitral VIR and VIV procedures will further increase the ease of valve deliverability, durability and functionality in the mitral position, potentially resulting in widespread acceptance of this new treatment strategy.