Native tricuspid valve dysfunction in patients with congenital heart disease can be a primary lesion, usually associated with Ebstein’s anomaly or atrioventricular (AV) canal defects, resulting in chronic severe tricuspid regurgitation (TR). It can also occur as a secondary lesion due to progressive right ventricular and tricuspid annular dilation found in patients with right ventricular outflow tract dysfunction, as in repaired Tetralogy of Fallot with pulmonic regurgitation (PR) or pulmonic stenosis (PS).

TR is often well tolerated for decades, however, much like PR, eventual clinical sequelae will emerge, including the development of ventricular and supraventricular arrhythmias, elevated central venous pressure with resultant multi-organ congestion (congestive hepatopathy, renal dysfunction, splenomegaly, protein losing enteropathy) and progressive right ventricular dysfunction.

While surgical repair or replacement is often recommended in congenital patients with severe TR with right heart failure symptoms and/or arrhythmias,¹ many patients are at prohibitive surgical risk due to prior sternotomies and comorbidities, such as pulmonary and hepatic disease. Surgical techniques for tricuspid valve repair include the placement of annular bands or rings, as well as more complex operations to relocate or augment the tricuspid valve leaflets (as in Ebstein’s anomaly).²

If surgical valve replacement is warranted, bioprosthetic valves are preferred as there are limited data on the safety and efficacy of mechanical prostheses. Most bioprostheses require replacement within a decade as they often become dysfunctional over time due to leaflet thickening and dysfunction with laminar thrombi often evident on pathologic samples. Progressive regurgitation and/or stenosis may occur with similar clinical sequelae as native tricuspid valve disease.^3,4

There are important anatomic considerations to take into account before intervening percutaneously on the tricuspid valve. It is composed of three leaflets (anterior, posterior and septal), usually anchored by anterior and medial papillary muscles, and is surrounded by three important structures: the AV node, right coronary artery and the ostium of the coronary sinus.

Transcatheter therapies for the tricuspid valve include transcatheter tricuspid valve replacement (TTVR), transcatheter tricuspid valve repair (TTVRe), and, if the predominant pathology is tricuspid stenosis (TS) without moderate or severe TR, transcatheter tricuspid balloon valvuloplasty (TTBV). Balloon valvuloplasty of a bioprosthetic tricuspid valve also has been shown in several case reports to be feasible, with a lasting reduction in the gradient and hemodynamic benefits, in inoperable or high surgical risk patients.⁵

There is a growing body of evidence for the use of both the Melody and Sapien valves in failing tricuspid valve rings or bioprostheses. The procedural success rate is high and immediate hemodynamic benefits are evident.^6-22 The largest experience has been reported by McElhinney and colleagues, with 152 cases (from 53 centers), of which 56 percent had congenital heart disease.²² Acute procedural success was achieved in 150 cases (98.7 percent).

Also, four patients developed late stenosis secondary to thrombus/valve immobility (two on aspirin only, two on warfarin) and three of these patients underwent valve re-intervention. A total of nine patients required late surgical re-intervention for residual or recurrent valve dysfunction, ongoing multiorgan failure from TS or endocarditis. Five patients died within 30 days of implantation, and 22 patients died over the median follow-up of 13.3 months. Causes of death included procedural complications (n = 1), cardiac death unrelated to the procedure (n = 14), and non-cardiovascular causes (n = 7).

In these reports, perivalvular regurgitation is common but is mild in most cases, not requiring occlusion, and those that do require intervention can be managed with a variety of transcatheter occlusion devices, such as Amplatzer Vascular Occluders.²¹

These results are encouraging, however more studies are needed to address the paucity of intermediate and long-term data, especially because transcatheter valves are essentially bioprostheses and at risk of thrombosis,²³ and most clinicians only use aspirin and do not routinely use systemic anticoagulation unless there is another indication such as atrial arrhythmias.

Furthermore, TTVR has been performed in systemic tricuspid valves in patients with L-transposition of the great arteries (L-TGA) or D-transposition of the great arteries (D-TGA) status post Senning or Mustard repair. Eicken and colleagues reported a successful valve-in-valve TTVR in a patient with D-TGA and a failing bioprosthesis via a transjugular and transbaffle approach.²⁴ Our center has performed a valve-in-ring systemic tricuspid valve replacement, also in a patient with D-TGA and severe TR via a transapical approach.

TTVRe is still mostly in the investigational phase with both novel devices as well as off-label use devices being used. In native valves, the MitraClip system, which is designed for percutaneous mitral valve repair, has been used to repair the trileaflet tricuspid valve in functional TR, by grasping and clipping two of the three leaflets, often the septal and anterior leaflets. One of the larger studies (n = 64), by Nickenig and colleagues, showed a 13 percent residual severe TR.^25,26

Other devices used include the Mitralign, which is a device originally designed to remodel the mitral annulus using pledgeted sutures, that has been successfully placed in some patients with severe tricuspid regurgitation.²⁷ Trialign is a system designed by Mitralign specifically for the tricuspid position and works along the same principles of cinching the tricuspid annulus by use of sutures. This system is now in clinical testing and multiple cases have been reported.²⁸ The TriCinch is a percutaneous device designed for annular cinching of the tricuspid annulus with successful implantation performed in humans.²⁹

The Millipede, which involves the transcutaneous placement of a tricuspid annular ring with an attachment system, is still in pre-clinical trials.³⁰ Early feasibility clinical testing is underway of the Forma system, which is a balloon that is anchored across the tricuspid valve via a lead that connects it to the right ventricular apex, similar to a pacing lead. By simply taking up space within the tricuspid valve orifice, the balloon may decrease the degree of tricuspid regurgitation.³¹ Lastly, the Traipta (transatrial intrapericardial tricuspid annuloplasty) device, which is positioned in the AV groove in the pericardial space and serves to decrease the tricuspid annular dimensions, is still in pre-clinical experiments.³²

Caval valve implantation is another potential treatment option for severe tricuspid valve regurgitation, where the valves are implanted in the superior and inferior vena cavae.^{19, 33,34} The HOVER clinical trial and the TRICAVAL clinical trial are currently investigating Sapien XT implantation in the inferior vena cava in patients with severe TR at prohibitive risk for surgical intervention, usually with inferior vena cava pre-stenting to create a landing zone for the Sapien valve. A dedicated bicaval transcatheter valve system, the Tric Valve, which consists of two separate pericardial tissue valves mounted on self-expanding nitinol stents is still in the animal study phase.

Transcatheter valve replacement in patients with congenital heart disease and conduit or bioprosthetic valve dysfunction has become the new standard of care. These minimally invasive and effective techniques have allowed for a reduction in the number of open cardiac surgeries needed over the lifetime of these patients. There is immense potential for advances in technology with increasing application to lesions previously only treated surgically, such as TR. A larger body of evidence with intermediate- and long-term outcomes is needed to assess the longevity of these new techniques when compared with the surgical gold standard.

Joanna Ghobrial, MD, MS, is a graduating Adult Congenital Heart Disease fellow at the Ahmanson/UCLA Medical Center in Los Angeles, CA. Prior to her congenital training she completed an interventional cardiology fellowship.

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Keywords: Cardiology Interventions, ACC Publications, Dilatation, Ebstein Anomaly, Heart Defects, Congenital, Heart Septal Defects, Pulmonary Valve Insufficiency, Pulmonary Valve Stenosis, Tetralogy of Fallot, Tricuspid Valve, Tricuspid Valve Insufficiency