Transcatheter Valve Implantation in Patients With Dysfunctional Left and Right Sided Heart Valves

Many forms of congenital and structural heart disease require surgical placement of prosthetic valves and conduits. These conditions include many common congenital heart abnormalities such as Tetralogy of Fallot, Double Outlet Right Ventricle, Truncus Arteriosus and patients who require the Ross procedure for aortic stenosis. There are a variety of acquired conditions, including calcific aortic valve stenosis that may require surgical or transcatheter valve treatment. Unfortunately, when valved conduits are placed surgically, they ultimately become narrowed or regurgitant and require periodic replacement. Thus, patients with these conditions often undergo multiple open heart surgeries during their lifetime. Although the risk of mortality with this kind of surgery is low, surgical intervention is associated with significantly longer recovery times and more patient discomfort when compared to transcatheter interventions. Over the last decade, techniques have been developed to palliate these forms of congenital and structural heart disease using catheters inserted through blood vessels in the groin. These transcatheter techniques have allowed patients to delay or avoid open heart surgery.

The Medtronic Melody Trancatheter Valve and the Edwards SAPIEN Transcatheter Heart Valve are both bioprosthetic valves mounted within metal stents. Their entire structure is collapsible, allowing it to be inserted through delivery sheaths and threaded into the heart, typically without the need of surgical cardiopulmonary bypass. Some of these procedures may be performed using a hybrid technique of minimal surgical access and transcatheter valve delivery. The valves can then be expanded into place by inflating a balloon (similar to how stents are placed elsewhere in the heart, like the coronary artery). The Melody Valve received a humanitarian device exemption (HDE) from the FDA and the Edwards Sapien Valve has market approval from the FDA.The investigators plan to offer these transcatheter valves as alternatives to eligible patients who require replacement of a stenotic or regurgitant valve in all left and right sided positions.

The intended role of the Melody Transcatheter Pulmonary Valve is to restore pulmonary valve function in patients with a dysfunctional RVOT conduit and a clinical indication for pulmonary valve replacement. Unlike currently available options for pulmonary valve replacement, the TPV is intended to be placed with a transcatheter delivery system, and thus does not require surgical incisions, open heart surgery, cardiopulmonary bypass, or the various morbidities associated with surgical pulmonary valve replacement. The Edwards Sapien Valve is delivered in the same manner, but was intended for use in the aortic position. The ultimate goals and durability of the TPV may differ among patients with different indications. At a minimum, the intention is that the TPV will improve hemodynamic function, mitigate the adverse impact of valve regurgitation and/or obstruction, and effectively extend the longevity of the existing conduit and defer or obviate the need for conduit replacement. These techniques may decrease the number of open heart surgeries required over the course of a patient's lifetime, thereby decreasing the cumulative morbidity and risk associated with such operations.

With regards to valve replacement in any position with an adequate landing zone, the Melody Valve and Edwards Sapien Valve are presently being utilized at multiple United States centers for valve replacement in all positions in patients who are considered high risk candidates for surgical valve replacement. A recent article published by Zahn et al reported an experience in tricuspid valve implantations at three United States centers and one Austrailian center. Procedural success was achieved in all patients. Tricuspid regurgitation was reduced to mild or none in all patients. Noted complications were consistent with known risks of cardiac catheterization and Melody Valve implantation, regardless of indication. Similarly, an article published by Kenny et al demonstrated the successful implantation of the Sapien valve in the tricuspid position. Gillespie et al, recently published a series of Melody implants in the mitral position in sheep that had undergone annuloplasty ring placement. Other investigators have successfully implanted the Melody valve in the aortic and mitral positions in patients with good immediate and short/intermediate term outcomes (Ben-Gal et al, Hasan et al, Gossl et al). The Edwards Sapien Valve has several reports of positive outcomes when implanted within the aortic position (Thomas et al, Moat et al, Webb et al) and two case series that report encouraging results when placed in the mitral position. (Seiffert et al, Cheung et al)