Transcatheter Tricuspid Valve Replacement: Principles and Design

REVIEW published: 19 September 2018 doi: 10.3389/fcvm.2018.00129 Transcatheter Tricuspid Valve Replacement: Principles and Design Ozan M. Demir 1,2† , Damiano Regazzoli 1† , Antonio Mangieri 1 , Marco B. Ancona 1 , Satoru Mitomo 1 , Giora Weisz 3 , Antonio Colombo 1 and Azeem Latib 1,4* 1 Interventional Cardiology Unit, Cardio-Thoracic-Vascular Department, San Raffaele Scientific Institute, Milan, Italy, Department of Cardiology, Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom, 3 Department of Cardiology, Montefiore Medical Center, New York, NY, United States, 4 Division of Cardiology, Department of Medicine, University of Cape Town, Cape Town, South Africa 2 Edited by: Maurizio Taramasso, UniversitätsSpital Zürich, Switzerland Reviewed by: David Chistian Reineke, Inselspital, Switzerland Paolo Denti, San Raffaele Hospital (IRCCS), Italy *Correspondence: Azeem Latib † These authors have contributed equally to this work as first authors Specialty section: This article was submitted to Structural Interventional Cardiology, a section of the journal Frontiers in Cardiovascular Medicine Received: 11 June 2018 Accepted: 29 August 2018 Published: 19 September 2018 Citation: Demir OM, Regazzoli D, Mangieri A, Ancona MB, Mitomo S, Weisz G, Colombo A and Latib A (2018) Transcatheter Tricuspid Valve Replacement: Principles and Design. Front. Cardiovasc. Med. 5:129. doi: 10.3389/fcvm.2018.00129 Tricuspid regurgitation (TR) may affect as much as 65–85% of the population with the prevalence of moderate-to-severe TR in the United States reported at greater than 1.6 million. However, only 8,000 tricuspid valve operations are performed annually in the United States. As severe TR is associated with poor outcomes, there is an unmet clinical need for surgical or percutaneous transcatheter based treatment of TR. Over the last two decades there have been significant developments in percutaneous transcatheter based therapies for valvular disease. However, this progress has not been mirrored for the tricuspid valve until recently; we are now at a cross-roads of new transcatheter devices becoming available for treatment of TR. In this review, we discuss the principles of performing transcatheter tricuspid valve replacement, analyze the devices that can be utilized and outline the challenges related to this procedure. Keywords: tricuspid regurgitation, valve replacement, cardiac imaging, tricuspid valve, structural heart disease INTRODUCTION Tricuspid regurgitation (TR) is a commonly encountered manifestation of valvular heart disease, it may affect as much as 65–85% of the population (1, 2). The majority of these are no more than mild TR which is deemed non-pathological and a normal variant, however, moderate-tosevere TR is usually pathological and associated with poor prognosis (3). The etiology of TR can be divided into primary (organic) and secondary (functional), in relation to the presence of structural abnormalities of the tricuspid valve (TV) apparatus. Approximately 80% of significant TR is functional (FTR), occurring due to annular dilation and subsequent leaflet tethering causing malcoaptation (4, 5). Organic TR can be either congenital or acquired. Congenital primary TR may arise due to Ebstein’s anomaly, atrioventricular defects and myxomatous prolapse. Acquired primary TR can occur due to endocarditis, rheumatic disease, carcinoid, flail leaflets caused by trauma, or from pacemaker lead implantation (6). Patients with TR often experience clinical symptoms of right-sided heart failure, including dyspnea, restriction of functional capacity, frequent hospitalization, liver, and kidney failure. The prevalence of moderate-to-severe TR in the United States has been reported at greater than 1. 6 million. Despite this only 8,000 TV operations are performed annually in the United States (7). Furthermore, with increasing severity of TR, 1-year mortality increases, reaching greater than 36% in those with severe TR (3). Hence, there is an unmet clinical need for surgical or percutaneous treatment of TR. Over the last two decades, there has been significant developments in transcatheter based therapies for valvular disease. However, this progress has not been mirrored for the TV Frontiers in Cardiovascular Medicine | www.frontiersin.org 1 September 2018 | Volume 5 | Article 129 Demir et al. Principles of TTVR need a great capability of adaptation to the aforementioned anatomical characteristics: self-expanding devices may be more effective and with lower risk of annular stretching and damage. On the other hand, the TV prosthesis is associated with a lower risk of outflow tract obstruction as compared with mitral valve and active grasping of the native tricuspid leaflets may be not needed (10). However, at present valve anchoring is still a major unanswered issue. • Interaction with conduction system and with pacing devices: The atrioventricular (AV) node lies in the muscular portion of the atrio-ventricular septum, near the ostium of the coronary sinus (at the apex of the triangle of Koch). The bundle of His is a direct continuation of the AV node and it passes through the right trigone of the central fibrous body to reach the ventricular septum. This area is near to the commissure between septal and anterior tricuspid leaflets (11). This close relationship between the tricuspid structure and the conduction system may be an issue when planning TTVR. In fact, surgical annuloplasty with dedicated tricuspid rings is often incomplete in order to avoid placing stitches in the septal area to reduce the incidence of complete AV block and subsequent pacemaker implantation. Percutaneously implanted bioprosthesis will likely not be able to avoid stretching that area. The incidence of rhythm disturbances is therefore expected to be higher than with repair, eventually leading to a second major issue: how to manage pacemaker devices during valve implantation. Indeed, prosthesis deployment may lead to a dislodgment of a preexisting ventricular lead and, on the other hand, the prosthesis itself may hamper PM implantation. • Antithrombotic regimen: No evidence is available on the selection of antithrombotic regimen specifically following TTVR (12). However, considering the low flow on the rightside of the heart and the size of the TTVR prosthesis, we would recommend life-long anticoagulant therapy in all patients with many patients already having an indication for anticoagulation, e.g., atrial fibrillation. • Durability: Concerns regarding structural valve degeneration remains an important drawback of surgical and transcatheter bioprostheses (13). There is scarcity of evidence regarding the durability of bioprostheses in the tricuspid position however data from early experience are reassuring whilst we await long-term outcomes. In comparison, currently there is no data on TTVR durability. Hence, this will be a major issue when percutaneous treatment of the T (...truncated)