In this report we describe the first transvenous, transatrial septal VIR implantation using the Melody device. Via standard vascular access and transseptal techniques, we successfully deployed the Melody valve into the mitral position from the venous circulation in all animals, without difficulty or complication. The Melody valves were securely seated in all cases. Importantly, although there was a conformational change noted in the Melody valves from “round” to “oval” or “D-shaped” when implanted into the annuloplasty rings, there was no perivalvular leakage noted, and not greater than trivial to mild central MR except in the one animal in which we intentionally oversized the device (). The only significant hemodynamic change noted following VIR was an increase in PA pressure (p=0.008). The exact cause of this difference is unclear, however it was likely due to a trend towards increased cardiac output secondary to sympathetic upregulation (p=0.06) post-VIR. Theoretically, increased PA pressure could also be secondary to pulmonary vein obstruction or to an increase in LA pressure caused by MR and/or MS. However, the pulmonary veins were unobstructed, and the mean LA pressure did not increased following VIR (p=0.55). The success and relative ease of this procedure highlights the potential for this approach in patients with ongoing MV dysfunction despite prior surgical repair.
Irrespective of the cause, surgical repair of systemic atrioventricular (AV) valve regurgitation (mitral, common AV, or tricuspid valves) carries a significant risk for recurrence in both adult and pediatric patients(4
). Despite this risk, in most circumstances, valve repair is still preferred over replacement; due to durability concerns associated with tissue valves and to the reduced need for systemic anticoagulation when compared to mechanical valves(13
). In the last decade, the advent of percutaneous valve replacement has resulted in new minimally invasive therapeutic options for patients with dysfunctional aortic and pulmonary valves(5
). While many promising percutaneous mitral valve (MV) repair technologies have been developed (2
), percutaneous MV replacement with a single device remains elusive. The inherent anatomic features of the MV make fixation and perivalvular seal a troublesome challenge. In particular the mitral annulus lacks a uniform “landing zone” for secure deployment of a percutaneous device. Despite these challenges, promising steps towards one-stage percutaneous MV replacement are being made (15
). In the meantime, minimally invasive surgical MV replacement via valve-in-valve (VIV) and more recently valve-in-ring (VIR) procedures have been described in which the Edwards Sapien device was deployed into previously placed bioprosthetic tissue valves(9
) and/or annuloplasty rings(8
) via a surgical
transapical or transatrial approach. These procedures are intended to extend the functional life of the surgical valve procedure in a manner analogous to Melody and Sapien valve treatment for dysfunctional surgical conduits in the pulmonary position. The VIR and VIV procedures have the potential to change the way that MV patients are managed, especially as percutaneous valve technologies undergo further refinements that optimize their performance in these new settings.
The Melody valves used in this experiment were previously handled and cosmetically flawed, thus not viable for commercial use and not optimal for functionality testing. Furthermore, these devices are engineered for implantation into the pulmonary circulation. They are undersized relative to the normal adult mitral annulus (max functional diameter = 22mm), and not intended for use in the systemic circulation, where the afterload is generally much higher. Despite these limitations, these results were a proof of concept sufficient to demonstrate the feasibility of the transvenous VIR procedure.