Concerns Regarding the Expanded Use of the One-Step Technique for Simultaneous Landing Zone Stenting and Placement of the Melody Transcatheter Pulmonary Valve

In the December 2021 issue of the Journal of Invasive Cardiology, Guyon et al¹ expand on the innovated “one-step” technique reported by Boudjemline,² broadening the method beyond the use of Max LD stents (Medtronic), demonstrating that various combinations of stents can be utilized for the same technique.

We fully agree that no effort should be spared to reduce radiation exposure while maintaining safety and efficacy. As stated in the report, prestenting prior to percutaneous pulmonary valve implantation (PPVI) is necessary to prevent Melody valve stent fracture. Often, the areas requiring prestenting need aggressive angioplasty with high-pressure balloons. During simultaneous stenting, the degree of dilation is limited by the burst pressure of the balloons used in the given system. As mentioned by the authors, in several of their cases, the recoil of the conduit was the concern and served to determine the number of stents needed. Multiple stents necessitate higher inflation pressure to achieve optimal stent dilation because the combined strut strength increases with the number of stents deployed simultaneously.

Furthermore, the balloon-in-balloon catheter has a rated burst pressure of 3 atm.² It would largely fail to relieve the outflow tract obstruction and dilation to the desired dimension. Depending on the obstruction, achieving optimal expansion may not always be possible with multiple simultaneous stents. Those who benefit from prestenting may require a high-pressure stent angioplasty, as indicated in this study, where two-thirds of the group were prestented. Data on the percentage of total Melody valves that required presenting during the study period would be helpful to provide, as the criteria for which patients would benefit from prestenting and how many stents are required are still elusive.

Additionally, there is a concern with the size of the delivery system that is necessary to accommodate multiple simultaneous stents. This introduces complexity, requiring appropriate access as well as a potential risk for stent migration when multiple stents are implanted. If there are any stent complications, including stent migration, the primary objective of reducing radiation exposure is failed. Postdilation of the Melody valve, as described with the additional stents in place, can damage and affect the integrity of the valve, which would be undesirable. The authors described preimplantation testing, including balloon sizing for coronary compression testing and/or preprocedural 3-dimensional imaging, to demonstrate the coronaries are remote from the implantation area. We believe this evaluation is an important step because should the coronaries become occluded with multiple simultaneous stenting, they may become impossible to recover. Although this may be a possible technique for PPVI, this should not be used as a primary approach due to the risks described above.

References

1. Guyon PW, Nijres BM, Justino H, et al. Expanded use of the one-step technique for simultaneous landing zone stenting and placement of the Melody transcatheter pulmonary valve. J Invasive Cardiol 2021 Dec;33(12):E954-E959. Epub 2021 Nov 18.

2. Boudjemline Y. A new one-step procedure for pulmonary valve implantation of the melody valve: simultaneous prestenting and valve implantation. Catheter Cardiovasc Interv. 2018;91:64-70. Epub 2017 Sep 25. doi: 10.1002/ccd.27332

3. NuMED for Children. BIB® stent placement balloon catheter. Accessed February 15, 2022. https://www.numedforchildren.com/product/bibr-stent-placement-balloon-catheter

We are thankful for the letter to the editor as the questions and concerns proposed will further clarify our approach with the following points:

(1) The concern raised of not always achieving an adequate landing zone with the simultaneous stenting technique is valid. We acknowledge that placing the stents separately prior to placing the Melody valve allows for gauging how many stents are needed before recoil is eliminated. For that reason, in calcified conduits, we placed at least 2 Palmaz stents as well as a covered stent on top of the valve, with the Palmaz stents providing strength and the covered stent providing protection from conduit tear.

(2) The concern about coronary testing is also valid and should not be adopted by all without thorough understanding of the 3-dimensional (3D) relationship of the conduit to the coronary arteries. We have adopted a different technique than the traditional approach that we published in 2017.¹ In the traditional approach, the landing zone is prepared using high-pressure balloons to achieve a predetermined size in which the valve can land (usually 22 mm if a Melody valve is being used in older patients). During this aggressive ballooning, conduit tears can occur, especially in small, heavily calcified conduits, with high morbidity and on occasion mortality. This is felt to be needed for coronary compression testing. That being said, if a tear occurs during this high-pressure balloon dilation where coronary compression was observed, placing a covered stent to stop the bleeding and contain the tear at that diameter will result in compression of that coronary artery. At that point, one would be between a rock and a hard place with a catastrophic outcome. Our approach is different, and relies on extensive 3D preparation ahead of the case, where either a separate computed tomography scan with 3D segmentation (and sometimes 3D printing) before the catheterization procedure or 3D rotational imaging at the time of the catheterization is done to accurately assess the distance between the coronary arteries and the conduit before valve placement. The goal is to place the valve size that is suitable for the specific patient rather than to place a 22 mm valve every time. If during this evaluation the coronaries are deemed too close to the conduit or will not allow placement of an appropriately sized valve, the procedure is aborted without the predilation with the high-pressure balloons that can result in catastrophic rupture of the conduit and tears. That being said, it is possible that our approach is too conservative and we may miss the opportunity to place a percutaneous valve and send more patients to surgery.

(3) Regarding the concern that a larger-size sheath/delivery system is needed and that there is concern for stent migration, we have not had to upsize the sheath size, as we use the Ensemble delivery system that comes with the Melody valve to place the stents and the valve simultaneously. We have not experienced stent migration in either direction with placement of the simultaneous stent/valve system.

(4) Regarding the concern that placing multiple stents over the valve prevents adequate dilation of the conduit, we agree that using the low-pressure Bib balloon (NuMed) does not achieve adequate dilation; for that reason, a high-pressure balloon is used if needed after the stents and valve are in place. In our experience, having the stents on top of the valve and performing dilation afterward has not resulted in inadequate dilation and has not damaged the valve.

Sincerely,

Howaida El-Said, MD, PhD

Professor of Pediatric Cardiology

University of California San Diego

Director of Cardiac Cath Lab

Rady Children’s Hospital

Adult Congenital Heart Disease Certified

Chair of CHD Council SCAI

Reference

1. Pockett CR, Moore JM, El-Said HG. Three dimensional rotational angiography for assessment of coronary arteries during bloody valve implantation: introduction of a technique that may improve outcomes. Neth Heart J. 2017;25(2):82-90. doi: 10.1007/s12471-016-0931-6

• Expanded Use of the One-Step Technique for Simultaneous Landing Zone Stenting and Placement of the Melody Transcatheter Pulmonary Valve
• Use of the STEMI Team for Treatment of Patients with Pulmonary Embolism: A Pilot Study
• Use of Ultrasound-Accelerated, Catheter Directed Local Thrombolysis for Venous and Arterial Occlusions in a Pediatric Hospital