Melody Valve Implantation Into the Branch Pulmonary Arteries for Treatment of Pulmonary Insufficiency in an Ovine Model of Right Ventricular Outflow Tract Dysfunction Following Tetralogy of Fallot Repair

Abstract

Background Transannular patch (TAP) repair of tetralogy of Fallot often results in significant right ventricular outflow tract (RVOT) dilation and distortion. We hypothesized that insertion of Melody valves into the proximal right and left branch pulmonary arteries (PAs) would reduce pulmonary regurgitation fraction (PRF) in an ovine model of pulmonary insufficiency and dilated RVOT. Methods and Results Ten sheep underwent baseline cardiac catheterization, surgical pulmonary valvectomy, and TAP placement. A subset (n=5) had Melody valves (2 devices per animal) inserted into the proximal right and left PAs during the surgical procedure. Melody valves were placed distal to the right-upper-lobe (RUL) artery branch, leaving the RUL “unprotected.” Preoperative MRIs (n=5) were used to determine baseline RV ejection fraction (RVEF) and left ventricular (LV) EF. All surviving animals (n=9) underwent MRI and catheterization 6 weeks postsurgery. Mean PRF was lower in the Melody valve group (15±6% versus 37±3%; P=0.014). The unprotected RUL was responsible for 64% of the PRF measured in the Melody valve group. In the non-Melody group, the RVEF was lower than baseline (P=0.003) and than in the Melody group (P=0.05). The LVEF was also lower in the non-Melody group versus baseline (P=0.004) and versus Melody (P=0.01). Conclusions Bilateral branch PA Melody valve implantation significantly reduced PRF and altered RV and LV function favorably in a model of TAP for tetralogy of Fallot. This novel intervention may offer potential benefit in treating patients with anatomically heterogeneous disease of the RVOT.

Bilateral Branch Pulmonary Artery Melody Valve Implantation for Treatment of Complex Right Ventricular Outflow Tract Dysfunction in a High-Risk Patient

“…Our recent preclinical experiments have demonstrated the feasibility and potential benefits of bilateral branch PA Melody valves, 3 and this report describes our first successful attempt in a human patient. The patient's hemodynamic measures were significantly improved acutely by our intervention, and we are hopeful that this will translate into clinical improvement over time.…”

“…Our group has a longstanding interest in these complex patients, and we have recently published preclinical studies describing the feasibility and short-term effects of implanting 2 Melody valves-1 into each proximal branch PA-in an ovine model of postoperative pulmonary insufficiency and dilated RVOT. 3 This report describes bilateral branch PA Melody valve implantation to treat complex RVOT dysfunction in a high-risk patient.…”

The future of transcatheter pulmonary valvulation

“…Other reports described advanced techniques to make these patients suitable for the transcatheter technique (i.e. the use of two Melody valves implanted in respective pulmonary arteries in a single patient; jailing and/or Russian doll techniques) [9,[15][16][17]. Cheatham et al showed that PPVI using a 24 mm balloon catheter for the deployment of the Melody valve was feasible, without impairment of valvular function (RVOT diameter of 26 mm) [18].…”

Recent Progress in the Understanding and Management of Postoperative Right Ventricular Outflow Tract Dysfunction in Patients With Congenital Heart Disease

“…For example, experimental studies and case reports have demonstrated the feasibility and physiological efficacy of implanting a TPV in each proximal branch pulmonary artery when complex anatomy precludes seating a device within the RVOT per se. 45,46 Extending this concept, TPV implantation into only a single branch pulmonary artery might be beneficial in certain circumstances, given the finding that PR often arises with considerable asymmetry from the left and right pulmonary arteries. 47 The clinical incentive to extend TPV therapy beyond the approved indications is further evidenced by other creative, off-label approaches to TPV replacement in patients with a large RVOT such as seating the Melody valve in a scaffold of bare metal stents that are anchored in the branch pulmonary arteries and extend proximally into the outflow tract.…”