Author + information
- Received October 19, 2015
- Revision received December 28, 2015
- Accepted January 7, 2016
- Published online April 19, 2016.
- Josep Rodés-Cabau, MDa,∗ (, )
- Rebecca T. Hahn, MDb,
- Azeem Latib, MDc,
- Michael Laule, MDd,
- Alexander Lauten, MDe,
- Francesco Maisano, MDf,
- Joachim Schofer, MDg,
- Francisco Campelo-Parada, MDa,
- Rishi Puri, MBBS, PhDa and
- Alec Vahanian, MDh
- aQuebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada
- bColumbia University Medical Center/New York-Presbyterian Hospital, New York, New York
- cInterventional Cardiology Unit, Cardiology and Cardiothoracic Surgery Department, San Raffaele University Hospital, Milan, Italy
- dCharité-Universitätsmedizin Berlin, Campus Mitte, Berlin, Germany
- eDepartment of Cardiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
- fDepartment of Cardiovascular Surgery, University Hospital Zurich, Zurich, Switzerland
- gAlbertinen Heart Center and Medicare Center Hamburg, Hamburg, Germany
- hBichat Claude Bernard Hospital-Paris VII University, Paris, France
- ↵∗Reprint requests and correspondence:
Dr. Josep Rodés-Cabau, Quebec Heart & Lung Institute, Laval University, 2725 Chemin Ste-Foy, Quebec City, Quebec G1V 4G5, Canada.
Tricuspid valve (TV) disease has been relatively neglected, despite the known association between severe tricuspid regurgitation (TR) and mortality. Few patients undergo isolated tricuspid surgery, which remains associated with high in-hospital mortality rates, particularly in patients with prior left-sided valve surgery. Patients with severe TR are often managed medically for years before TV repair or replacement. Current guidelines recommend TV repair in the presence of a dilated tricuspid annulus at the time of a left-sided valve surgical intervention, even if regurgitation is mild. This proposed algorithm aims to prevent the inevitable progression to severe TR and the need for a second surgical intervention. Recently, novel transcatheter treatment options were developed for treating patients with severe TR and right heart failure with prohibitive surgical risk. Here we describe currently available transcatheter treatment options for severe TR implanted at different levels: the junction between vena cavae and right atrium; the tricuspid annulus; or between TV leaflets, improving coaptation.
- cardiac catheterization
- pulmonary hypertension
- right ventricular dysfunction
- tricuspid valve
- tricuspid valve insufficiency
Given the possibility of a prolonged clinical latency period, the true prevalence of moderate or severe tricuspid regurgitation (TR) is difficult to gauge, but was estimated by Stuge et al. (1) to affect 1.6 million people in the United States. In a large echocardiographic series of 5,223 veterans, at least moderate TR was found in nearly 16% of subjects (2). However, no prospective evaluations of the incidence of severe TR using strict echocardiographic criteria were undertaken.
The etiology of TR can be divided into primary and secondary causes. Unlike left-sided valve disease, primary tricuspid valve (TV) disease represents only 25% of TR. Primary TR may be due to congenital, rheumatic, neoplastic, traumatic, infective endocarditis, endomyocardial fibrosis, or iatrogenic (following pacemaker lead implantation or right ventricular [RV] biopsy) causes (3) (Table 1).
TR most commonly arises from RV annular dilation following RV pressure or volume overload. Significant functional TR may appear in the context of left-sided heart disease causing pulmonary arterial hypertension (PAH), or in pre-capillary PAH. Functional TR may also arise following RV myocardial infarction and subsequent RV dilation (Table 1). In patients with severe mitral regurgitation and normal left ventricular ejection fraction, the prevalence of at least moderate TR was 24% (4). Following mitral valve surgery, nearly 50% of the population demonstrated an increase in TR severity of more than 2 grades (5).
Right heart catheterization is important for determining the etiology of secondary TR and ruling out the presence of pre-capillary pulmonary hypertension. Evaluating both the degree and origin of PAH (pre-capillary, isolated post-capillary, or combined pre- and post-capillary) (6) is key when deciding whether or not to treat severe TR. Interventions for reducing the degree of TR in the context of pre-capillary PAH or severe PAH may be associated with major negative clinical effects secondary to critical RV failure. Similarly, an early post-operative RV dysfunction after tricuspid surgery has been associated with a negative clinical impact (7).
Significant secondary TR is frequently well tolerated in its early stages, yet progressive dilation of the tricuspid annulus and RV remodeling invariably results in right heart failure. Progressive RV dilation and dysfunction may lead to irreversible RV damage, a common reason for the poor outcomes following late TV surgery.
Several observational studies have reported that moderate-to-severe TR is associated with excess mortality at follow-up, independent of RV function (2,8). In patients with functional TR, it is important to optimize medical therapy of the underlying condition according to guidelines. However, the use of pulmonary vasodilator therapies in post-capillary PAH is controversial. Despite the encouraging results of some single-center studies showing improvements in hemodynamics, symptoms, or exercise capacity, there is not enough evidence of its long-term effectiveness and safety (9). Therefore, the 2015 European guidelines for PAH do not recommend these therapies in patients with PAH secondary to left heart disease (6).
Despite the association of severe TR and poor survival, relatively few patients undergo TV surgery, and patients are mostly managed clinically in the absence of another indication for cardiac surgery. In fact, isolated TV surgery accounts for only 20% of all tricuspid interventions (10). Results from isolated TV surgery series report an in-hospital mortality rate ranging from 2% to 9.8% (10–12), depending on the presence of a prior left-sided valve surgery. Pre-operative hemoglobin, bilirubin, and creatinine levels, as well as measures of RV structure and function, predicted clinical outcome (13). In patients undergoing left-sided valve surgery, the guidelines recommend concomitant TV repair when the tricuspid annulus is dilated, even if TR severity is mild (14,15). This algorithm is designed to prevent evolution to severe TR and eventual RV dysfunction, thus averting the need for TV reoperation at a later date. Because annular dilation is the most common mechanism of functional TR, tricuspid annuloplasty remains the surgical technique for functional TR. Suture annuloplasty and ring annuloplasty are the 2 main surgical techniques used for functional TR, with ring annuloplasty as the currently preferred technique due to increased durability compared with suture techniques (16).
In recent years, novel transcatheter treatment options were developed for treating TR, particularly in patients who were initially managed medically. Patients with severe TR and prior open-heart surgery are often deemed at high or prohibitive operative risk for reoperation, and are thus better candidates for less invasive transcatheter techniques. Patients with functional TR and progressive RV dysfunction with right heart failure, despite optimal medical therapy, may also benefit from a transcatheter-based intervention if an isolated TV repair is not indicated. In this paper, we review the most important aspects of tricuspid anatomy and TR evaluation, and describe various transcatheter techniques that have been implemented to date for treating TR.
TV Anatomy and Imaging
Tricuspid valve anatomy is somewhat more complex compared with left-sided valves. The TV apparatus consists of 3 leaflets (anterior, posterior, and septal), the chordae tendinae, and usually 3 papillary muscles (7). Normal TV anatomy varies considerably, especially in the number, size, and location of the papillary muscles. These morphological differences must be understood in order to differentiate normal from pathological manifestations (17). The most characteristic feature of the normal TV is the presence of direct attachments of chords from the septal leaflet to the ventricular septum (18). The anterior leaflet is the largest and the septal leaflet is the smallest, arising directly from the tricuspid annulus above the interventricular septum (3).
The TV annulus (TA) is a complex nonplanar structure with a more flattened oval shape than the saddle-shaped mitral annulus (19). The posteroseptal TA is more ventricular and the anteroseptal portion is more atrial (Figure 1) (5,20). It is also a dynamic structure, changing its shape and size with loading conditions or during the cardiac cycle. The TV orifice is larger and more triangular than the mitral valve. In patients with functional TR, the TA is more planar and circular than the elliptical annulus seen in healthy subjects (3).
During functional TR, the initial RV dilation leads to TA dilation. The presence of tricuspid papillary attachments arising from the septum and from variable papillary muscles sometimes attached from the free wall very close to the septum ensure that the TV is less affected by free wall dilation than the mitral valve. Annular dilation is the dominant mechanism of functional TR (21,22). Progressive TA dilation occurs in its anteroposterior plane, corresponding to the free wall of the RV, whereas the dilation of the septal segment is limited because of its anatomic relation with the fibrous skeleton of the heart. Significant TR occurs when anterior and posterior leaflets are pulled away from their coaptation point, resulting in TR jets. Leaflet tethering appears at more advanced stages in RV dilation and papillary muscle displacement (7,22).
The anatomic aspects that may represent a challenge for the transcatheter treatment of TR are summarized in Table 2. In patients with secondary TR, the nonplanar structure and lack of calcium compared with other heart valves and the enlarged TA (>40 mm) are, to date, the main difficulties for performing in-human transcatheter TV replacement. The introducer sheath and delivery system should accommodate a bioprosthesis that could be up to twice the size of a transcatheter aortic valve. The angulation between the TA, the inferior and superior vena cava (IVC and SVC, respectively), and the trabeculated RV with the presence of muscular bands could also pose an added challenge. The thin apical wall and the presence of multiple chordae could make a transapical approach difficult (7). The size of a transcatheter device and its placement into the RV should take into account other close structures, such as the AV node and His, coronary sinus, vena cavae, right coronary artery, and right ventricular outflow tract. Some studies suggested that the prevalence of severe TR secondary to pacemaker implantation may be higher than currently perceived (23). The presence of pre-existing pacemaker or defibrillator leads could also limit the feasibility of a transcatheter technique, and to date, this has been a contraindication for transcatheter TV repair techniques.
TV Imaging Assessment
Visualizing the TV should be performed from multiple transthoracic windows (Figures 2A to 2D). Recent American Society of Echocardiography (ASE) guidelines outline the recommended views for performing a comprehensive evaluation of the RV and TV (24). Identifying tricuspid leaflets from standard transthoracic views remains controversial, in part because of the variability of the imaging planes that can be acquired from varying degrees of transducer angulation (25–29). Despite this variability, current European and American Heart Association/American College of Cardiology guidelines suggest using the end-diastolic septolateral dimension from the transthoracic apical 4-chamber view (Figure 2C) as a criterion for intervening, with a diastolic dimension of ≥40 mm (or >21 mm/m2) indicating severe tricuspid annular dilation (14,15).
Grading the severity of TR has been well-described by the ASE and European Association of Echocardiography guidelines (30,31). Table 3 summarizes the parameters most commonly used for this assessment. The majority of parameters are qualitative or semiquantitative in nature. Quantitative assessment of tricuspid regurgitant volume by the proximal isovelocity surface area method has been validated (32,33). Although an effective regurgitant orifice area (EROA) ≥40 mm2 and regurgitant volume of ≥45 ml has been considered an important sign of severe TR, studies using 3-dimensional (3D) imaging of the color Doppler vena contracta suggest that severe tricuspid regurgitation EROA may be >75 mm2 (26,34).
Transesophageal echocardiography (TEE) permits imaging with higher frequencies for improved spatial resolution and a larger number of windows for a more comprehensive examination of the entire TV apparatus. Compared with prior guidelines, the new ASE guidelines for performing a comprehensive TEE examination (35) advocates including additional views of the TV. A TEE examination of the TV should include imaging from several depths and multiplane angles (Figures 2E to 2G). Beginning at the mid-esophageal depth (Figure 2E), advancing the TEE probe results in the low esophageal view (Figure 2F). Because the TV is adjacent to the diaphragm, imaging the region around the gastroesophageal junction (low esophageal and high transgastric views) may permit better imaging of the TV. Transgastric short-axis views of the TV can often be acquired, allowing simultaneous visualization of all valve leaflets (Figure 2G, orthogonal plane). Advancing the TEE probe further into the stomach, along with rightward anterior flexion and returning the multiplane angle to 0° to 20°, produces a deep transgastric view of the TV, which also permits optimal color flow and spectral Doppler evaluation of TR jets.
The approach to 3D imaging of the TV has been addressed in both guidelines (36) and reviews (37). This technique has significantly improved the accuracy of imaging and identification of the tricuspid leaflets and associated anatomic components of the TV complex. Lang et al. (36) suggested a standardized imaging display for the en face view of the TV with the interatrial septum placed inferiorly (at the 6 o’clock position), regardless of the atrial or ventricular orientation (Figure 3A). Standardization of the image display is particularly important when imaging is performed for transcatheter devices, improving communication with the interventionist. Color Doppler imaging with 3D TEE, as noted previously (Figure 3B), can be used to quantify the severity of regurgitation (34).
Intracardiac echocardiography can also be a useful tool during transcatheter tricuspid device implantation. It facilitates echocardiographic guidance during the procedure without the disadvantages of TEE, such as general anesthesia.
Computed tomography and cardiac magnetic resonance imaging
Multidetector computed tomography (MDCT) and cardiac magnetic resonance (CMR) may be useful for imaging the TV, yet both have definite limitations (38–40). MDCT is useful for measuring the TA and can also provide good-quality motion-free images of the RV outlet and trabeculated portions. It also provides information of surrounding structures and their proximity to the device target zone. Imaging the RV inflow region may be particularly challenging with computed tomography (CT), which typically uses antecubital contrast injections; mixing of unenhanced blood from the IVC results in significant streaming artifacts. Temporal resolution during motion-free imaging may not be adequate to show the details of the native RV inlet, although both MDCT and CMR may be superior to echocardiography for imaging the posterior TV leaflet, particularly in congenital disease (41), as well as prosthetic devices (i.e., rings or pacing wires) (38), adjacent anatomy (such as the vena cavae), and chamber volumes (38–41). CMR can be used for quantifying regurgitant volumes when echocardiography is indeterminate (42,43).
Transcatheter therapies for severe TR
The development of transcatheter therapies for treating severe TR is in line with the challenging anatomy of the TV, subvalvular apparatus, and RV. This is probably the reason for the lack of in-human experiences of transcatheter TV replacement. As an alternative, initial experience with valve implantation for treating TR has targeted the venous system in order to limit the negative consequences of reverse vena cava backflow associated with severe TR. Also, 2 percutaneous annuloplasty devices targeting the treatment of TR by decreasing TA dimensions have been developed, and the initial experience with a device designed to reduce TR by occupying the regurgitant orifice area and providing a surface for native leaflet coaptation was recently reported (Central Illustration). Of note, these technologies have been implemented at different centers, with baseline and post-procedural results evaluated in each center, with no central echocardiography core laboratory measurements. Potential variability in the evaluation of the results cannot be excluded.
Bicaval valve implantation with dedicated self-expandable valves
Caval valve implantation (CAVI) has been suggested as a treatment option for patients with severe TR. The procedure addresses the regurgitation of blood into the caval veins, a condition found often in patients with severe, long-standing TR and RV enlargement, but does not address TR per se. As the right atrium serves as a reservoir limiting venous backflow, hemodynamic proof of caval regurgitation is essential prior to CAVI. The main challenges of valve implantation at the level of the vena cava are the large and variable diameter of the IVC and SVC in the presence of chronic severe TR, frequently >45 mm in such cases, and the proximity of the right atrium and hepatic veins.
Valve devices (Tric Valve) specifically designed for SVC and IVC deployment are currently under development for implantation using a transvenous approach (Figures 4A to 4E) (44). The Tric Valve (P&F Products & Features Vertriebs GmbH, Vienna, Austria, in cooperation with Braile Biomedica, São José do Rio Preto, Brazil) consists of 2 self-expandable bioprosthetic valves covering sizes from 28 to 43 mm of both caval veins that are anchored at the cavoatrial inflow. The procedure is guided by fluoroscopy, and echocardiography is used for post-interventional functional control. Self-expandable devices specifically designed for CAVI do not require a pre-stenting of the caval veins. Stent design, sizing, and radial force are therefore crucial to ensure sufficient fixation and paravalvular sealing. The IVC valve is designed with the upper segment protruding into the RA, with the biological valve located above the diaphragm to protect the abdominal vasculature from systolic backflow and avoid occlusion of hepatic veins (44,45). The SVC valve is mounted on a funnel-shaped stent frame to fit the landing zone at the cavoatrial inflow. Both valves are mounted with a trileaflet bovine pericardial valve and a sleeve covering the inside down to the base of the leaflets to prevent paravalvular leakage.
In pre-clinical studies in animals with acute TR, CAVI resulted in a significant reduction of caval backflow and immediate recovery of cardiac output (46,47). Chronic animal studies further confirmed excellent function of caval valves after midterm follow-up (47). Clinical experience started in 2011, when CAVI was first reported for compassionate treatment of patients with severe TR using investigational self-expandable valves (44). Since then, compassionate clinical use has confirmed the technical feasibility of CAVI, as well as the immediate and sustained hemodynamic improvement from the reduction of IVC and SVC backflow (Figures 4F and 4G) (44). However, due to the still limited availability of these devices, only 5 patients have been treated to date, and follow-up data are limited. The chief clinical and procedural features of patients treated with these devices are summarized in Table 4. The device was implanted successfully in 4 cases. Only inoperable patients with significant TR and a deteriorating clinical state were selected on compassionate grounds for treatment with this device. Due to the heterotopic position of the caval implants, the native TV remains severely regurgitant; however, caval regurgitation was abolished in all successfully deployed valves. In 1 patient, the devices could not be deployed as intended, and conversion to surgery was required. After a mean clinical follow-up of 7.4 ± 13.2 months, sustained valve function was observed over time. However, the mortality rate was as high as 80%, mainly due to noncardiac comorbidities. Due to its exclusive compassionate use, clinical experience is currently limited to the most severely ill subgroup of patients, where it results in midterm symptomatic relief and moderately improved physical capacity (44,45).
Major concerns associated with CAVI include the ventricularization of RA pressure, as well as the persistence of atrial and ventricular volume overload, potentially promoting RV failure and atrial fibrillation (45,48,49). In the present limited human experience, no such deleterious effects were observed, even up to 2.5 years of follow-up. RV function remained unchanged, or even improved, and sinus rhythm continued without episodes of atrial fibrillation. Invasive hemodynamic measurements confirm a further reduction of RA and caval vein pressures, with a reduction of symptoms of RV failure. Warfarin anticoagulation was effective and sufficient to prevent thromboembolic complications during follow-up.
A prospective multicenter registry is planned in the near future. The next step involves broadening device availability and evaluating device efficacy in a clinical trial.
Balloon-expandable caval implants
Caval implantations of balloon-expandable valves normally used to treat aortic stenosis (29 mm Edwards Sapien XT or Sapien 3, Edwards Lifesciences, Irvine, California) have also been used off-label for the treating severe TR. The anatomy of the cavoatrial junction (particularly the large diameter and confluence of hepatic veins and their lack of calcification) precludes direct implantation of a balloon-expandable prosthesis, requiring preparation of a landing zone by implanting a self-expandable stent to facilitate safe fixation. This modular assembly also allows handling the variable distances between the hepatic vein confluence and the right atrium. Although this technique has been commonly limited to the IVC, the long segment of the SVC facilitates balloon-expandable valve implantation using the same implant technique, if needed (50).
The procedure is performed using fluoroscopy (pigtail in IVC or JR4 in right hepatic vein) and/or ultrasonic guidance, through the right femoral vein. A stiff wire is placed in the SVC and a 20-F eSheath advanced over it. A self-expandable large stent (i.e., Sinus XL, Optimed Medizinische Instrumente, Ettlingen, Germany), 26 to 30 mm in diameter and 40 to 80 mm in length, tailored to IVC diameters is implanted in the IVC segment downstream of the RA, protruding approximately 5 mm into the RA. The 29-mm balloon-expandable valve mounted on the delivery system is then deployed inside the stent with the lower part just superior to the confluence of the first hepatic vein (Figure 5). For a dual-valve procedure, prior to IVC, the SVC prosthesis is implanted after positioning a self-expanding stent superior to the confluence of the RA (to reduce the risk of vessel wall damage and/or rupture) in the same way.
A total of 10 patients have been treated to date under a compassionate clinical use program. The main clinical data from this initial experience is summarized in Table 4. Because of existing pacemaker/implantable cardioverter-defibrillator leads and the lack of evidence for SVC congestion in most cases, 90% of patients had the valve implanted at the level of the IVC only, with 1 patient undergoing IVC and SVC valve implantation. Successful valve implantation was achieved, and intact valve function without paravalvular leakage and without regurgitation was confirmed by echocardiography in all cases. There were no periprocedural or in-hospital procedure-related complications. Periprocedurally, patients received unfractionated heparin and oral anticoagulation therapy thereafter.
All, but 1 patient in cardiogenic shock due to decompensated PAH at baseline improved by at least 1 New York Heart Association (NYHA) functional class at follow-up. RV function, measured by tricuspid annular plane systolic excursion, improved in 9 patients (51). The 30-day mortality rate was 20%, and no valve malfunction was detected at a follow-up of 4 to 913 days.
Currently, this technology is under evaluation in ongoing studies, a randomized single-center open-label study in Europe (Treatment of Severe Secondary TRIcuspid Regurgitation in Patients With Advance Heart Failure With CAval Vein Implantation of the Edwards Sapien XT VALve [TRICAVAL]; NCT02387697, Charité University, Berlin) and a prospective single-center registry in the United States (Heterotopic Implantation Of the Edwards-Sapien XT Transcatheter Valve in the Inferior VEna Cava for the Treatment of Severe Tricuspid Regurgitation [HOVER]; NCT02339974, Temple University, Philadelphia, Pennsylvania).
The FORMA device
The FORMA Repair System (Edwards Lifesciences) is a novel transcatheter treatment option for patients with severe functional TR. This device acts as a coaptation device, with the objective of reducing the TR grade in patients with significant TR secondary to annular dilation. It is composed of a rail, which is anchored at the apex of the RV, and a spacer, which serves as the coaptation element (i.e., increases the coaptation surface in order to improve leaflet malcoaptation). The spacer consists of a foam-filled polymer balloon, currently available in 2 sizes (12 and 15 mm). The larger spacer requires a 24-F sheath introducer, and its final size is achieved within the vascular system by passive expansion via 8 holes in the spacer shaft (Figure 6).
Access is via the left subclavian or axillary vein, which should be compatible in size to allow the 24-F introducer (vein size is assessed pre-procedurally with CT). Right ventriculography is performed to identify the TA plane and the target anchoring zone at the RV apex. A steerable catheter loaded with the anchoring system is then placed within the RV, and the anchor is deployed at the RV apex, perpendicular to the center of the TA plane, viewed by fluoroscopy. The steerable catheter is retrieved, and the coaptation element is moved forward over the rail within the failing TV. The radiopaque markers assist in placement during fluoroscopy, and its optimal position is verified by intraprocedural 2-dimensional (2D) and 3D TEE. Following achievement of a satisfactory degree of TR reduction, the device is locked within the subclavian region, and extra rail length is placed into a subcutaneous pocket.
To date, 7 patients treated with this device have been reported (52), and their results are summarized in Table 4. The initial first-in-man experience shows that the device was correctly implanted in all patients, without cardiac tamponade, need for conversion to open surgery, or access-site complication. There was no in-hospital mortality and the median hospital stay was 4 days. Seven patients have completed 30-day follow-up without further evidence of device-related complication. TR, as assessed by transthoracic echocardiography (TTE), was moderate in severity in all patients (Figure 6) (52). This reduction in TR was sufficient to promote significant improvements in functional (NYHA) classification, accompanied by marked reductions in peripheral edema in all patients. Diuretic agent doses were reduced from baseline in 2 patients at this early, first follow-up period. Baseline and 30-day follow-up 6-min walking tests were performed in 5 patients, and quality-of-life assessments were performed in 4 patients. Exercise capacity and results of quality-of-life tests improved in 4 patients at 30 days. One walking test was stopped at 5 min due to arthritic pain and failed to improve the baseline result, but improved the walking distance at 5 min compared with baseline.
Device implantation appears safe and feasible, and preliminary efficacy data showed a favorable impact on TR and its hemodynamic consequences. One of the technical challenges for determining procedural efficacy relates to accurately assessing TR post-procedure. The presence of the spacer makes TTE assessment of the proximal isovelocity surface area, vena contracta, and effective regurgitant area measurements difficult.
An early feasibility trial is currently ongoing in the United States (NCT02471807) and larger feasibility studies are planned to start in 2016.
The Mitralign device
Annular dilation (usually >40 mm or >21 mm/m2) is one of the main mechanisms leading to severe functional TR. The Mitralign device (Mitralign, Tewksbury, Massachusetts) is a percutaneous annuloplasty system that reproduces the Kay surgical procedure (53), which converts an incompetent TV into a competent bicuspid valve by plication of both the anterior and posterior tricuspid annulus.
This device features an 8-F articulating wire delivery catheter, a pledget catheter, which is preloaded with 4 mm × 8 mm pledgets, and a plication lock device (Figure 7) (54). Transjugular access with 2 8-F sheaths is obtained, and the deflectable wire delivery catheter is advanced across the TV and positioned into the RV with fluoroscopy and with 2D and 3D TEE guidance. The catheter is articulated under the annulus to either the anteroposterior commissure or the septoposterior commissure, and an insulated radiofrequency wire is advanced and positioned 2 to 5 mm from the base of the leaflet within the annulus. The wire is advanced through the annulus toward the right atrium to avoid right coronary artery perforation (Online Video 1), and is confirmed by TEE. The wire is then externalized and a pledget delivery catheter is advanced across the RV annulus. The wire is removed and half the pledget is delivered and cinched in the subannular region of the ventricle. Upon withdrawal of the pledget delivery catheter, the remaining pledget is extruded and cinched on the atrial surface of the annulus. The steps are repeated on the opposite anatomic site of the posterior commissure. With a dedicated plication lock device, the 2 pledgeted sutures are brought together, plicating the annulus.
The first-in-man procedure was performed in September 2014 (54). An 89-year-old woman with right heart failure due to TA dilation and severe TR underwent this procedure. The procedure was associated with reductions >50% in the TA area and EROA (Figure 7E). A significant decrease in right atrial pressure and increase in left ventricular stroke volume were also observed. The patient tolerated the procedure well, was extubated the same day, and was discharged 5 days post-procedure with significant improvements in effort tolerance.
Meanwhile, more than 20 patients have been treated with this device worldwide, with successful implantation in >90% (Dr. Rebecca T. Hahn, personal communication). Also, an early feasibility study is currently ongoing (the SCOUT study - Early Feasibility of the Mitralign Tricuspid Valve Annuloplasty System (NCT02574650).
The TriCinch device
The TriCinch system (4Tech Cardio, Galway, Ireland) is a percutaneous annuloplasty device designed for functional TR repair (55). This device system consists of a corkscrew anchor, a self-expanding stent, and a Dacron band connecting both. The self-expanding nitinol stent is deployed in the IVC, and 4 stent sizes are currently available (27, 32, 37, and 43 mm) (Figure 8) (55).
Device implantation is performed under fluoroscopy and echocardiographic guidance (intracardiac echocardiography, TEE, or TTE). An 18-F steerable delivery system is advanced through a 24-F femoral vein introducer sheath into the right atrium (Figure 8). The implantation location is identified using baseline cardiac CT and, during the procedure, under fluoroscopic guidance using a coronary wire within the right coronary artery. A stainless steel corkscrew is fixed into the anteroposterior TV annulus. The implantation is checked by selective angiography and an echocardiographic “pull test.” The stent delivery system is advanced and connected to the corkscrew via the Dacron band. The system is tensioned, TEE monitoring is performed, and reduction of septolateral dimension and TR grade is assessed and compared with baseline. Once satisfactory TR reduction is obtained, TV tension is maintained via deploying the stent in the subhepatic region of the IVC with a degree of appropriate oversizing.
The first-in-human implantation of this device was recently reported (55). The device is currently being evaluated in an ongoing feasibility trial, the PREVENT study (Percutaneous Treatment of Tricuspid Valve Regurgitation with the TriCinch System; NCT02098200). The objectives of this trial are to demonstrate acute and post-operative safety and efficacy in TR reduction (≥1 grade) in 24 patients (55). To date, 8 patients have been enrolled, and 3 of them have completed the 6-month follow-up (Table 4). Mean procedural time thus far has been 63 ± 10 min. At the latest follow-up, the device was stable in all 3 patients. Improvements in quality-of-life tests and functional status have also been observed in all patients. Two patients reported an improved NYHA functional class to I, and the other patient improved to class II. The 6-min walking test improved from 293 to 336 m, and the Minnesota Living with Heart Failure questionnaire improved from 44 to 19, on average.
Through this early learning curve, several aspects of the delivery system have been improved, along with the evaluation of tissue quality, perioperative echocardiographic guidance and the pre-operative identification of a safe location of the target position on the TA with respect to the right coronary artery. The next steps for this device will be the release of a 1-step version, to integrate the 2 current delivery systems into 1, which will further simplify the procedure. An early feasibility study is planned to start in the United States in 2016.
Upcoming devices for transcatheter treatment of TR
An initial human experience with the Mitraclip device (Abbott Vascular, Santa Clara, California) for treating severe TR via the transjugular or transfemoral vein approach was recently reported in 4 patients (56,57). The device was successfully implanted and associated with acute TR reduction in all patients. Other successful preclinical experiences with transcatheter tricuspid devices include 2 annuloplasty devices, the transatrial intrapericardial tricuspid annuloplasty (TRAIPTA) device (58), the Cardiac Implants annuloplasty device (59), and the TV occluder device dedicated to improving valve leaflet coaptation (60). There have also been successful pre-clinical experiences with fully transcatheter TV replacement using dedicated transcatheter valve platforms (61). However, to the best of our knowledge, there have not been any attempts of full transcatheter valve replacement in a native TV in humans to date.
Functional TR is a common condition in patients with left heart valve or myocardial disease and has a significant impact on functional status and long-term survival. However, isolated surgical tricuspid replacement/repair remains an infrequent intervention, and is associated with high operative risk, especially in patients with prior left-sided cardiac surgery. The implementation of less invasive therapies in this field is therefore of major clinical interest.
Whereas transcatheter therapy of aortic, mitral and pulmonic valve disease is well established, interventional strategies for TV disease are still in the early stages. The challenges of the TV apparatus are mainly related to the large TA dimensions, lack of valve/annulus calcification, close proximity of the right coronary artery, and fragility of the TA tissue (Central Illustration). This has perhaps precluded the successful development of transcatheter valve systems dedicated to TV replacement. As an alternative to valve replacement, 3 main types of transcatheter therapies for TR have been applied in humans to date (Central Illustration): 1) transcatheter valve implants at the level of the vena cava (either both the SVC and IVC or the IVC only) in order to treat the caval reverse backflow associated with severe TR (Sapien and Tric Valve devices); 2) devices dedicated to decreasing the TA dimensions in order to reduce TR severity (Mitralign and TriCinch devices); and 3) a device dedicated to improving valve leaflet coaptation and reducing TR by occupying the regurgitant orifice area and providing a surface for native leaflet coaptation (FORMA device). More recently, transcatheter edge-to-edge repair of the tricuspid valve has also been applied in patients with TR (Mitraclip device). The initial in-human experiences have been limited to patients considered at very high or prohibitive surgical risk, and have demonstrated feasibility, in addition to some preliminary efficacy data. However, transcatheter treatment of TR remains a major ongoing challenge, which also includes evaluating the effectiveness of these new therapies (e.g., some therapies do not address TR, but its consequences, difficult evaluation of the degree of TR post-device implantation in some cases) and defining the endpoints for future studies. Prospective registries with larger number of patients, centralized echocardiography core laboratory measurements and longer-term follow-up are needed for better evaluating results and efficacy in reducing heart failure and improving patient quality of life. Also, the fact that none of the current transcatheter alternatives mimics the most efficient surgical technique for functional TR (complete ring annuloplasty) should be taken into account for future developments in this field. Ultimately, prospective trials will be required to demonstrate the superiority of these novel therapies over standard medical therapy in this challenging disease subset. Considering the large number of patients with severe untreated TR, providing definitive data on the safety and efficacy of these transcatheter therapies would represent a major paradigm shift in patient management. Meanwhile, such therapies should be limited to those patients with severe comorbidities leading to an extreme or prohibitive surgical risk.
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Dr. Rodés-Cabau has received research grants from Edwards Lifesciences. Dr. Latib is a consultant for Medtronic, Direct Flow Medical, 4-Tech Cardio, and Mitralign. Dr. Laule has received a research grant and proctor fee from Edwards Lifesciences. Dr. Lauten is a consultant for St. Jude Medical, Medtronic, and P&F. Dr. Maisano is a consultant for Abbott Vascular, Medtronic, Valtech, and St. Jude Medical; has received grants from Abbott Vascular; has received royalties from Edwards Lifesciences; and is a co-founder of 4Tech Cardio. Dr. Vahanian is a consultant for Edwards Lifesciences. All other authors have reported that they have no relationships relevant to the contents of this article to disclose. Ted Feldman, MD, served as Guest Editor for this paper.
- Abbreviations and Acronyms
- American Society of Echocardiography
- caval valve implantation
- cardiac magnetic resonance
- computed tomography
- effective regurgitant orifice area
- inferior vena cava
- multidetector computed tomography
- New York Heart Association
- pulmonary arterial hypertension
- right ventricle/ventricular
- superior vena cava
- tricuspid valve annulus
- transesophageal echocardiography
- tricuspid regurgitation
- transthoracic echocardiography
- tricuspid valve
- Received October 19, 2015.
- Revision received December 28, 2015.
- Accepted January 7, 2016.
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