Author + information
- aSwedish Heart and Vascular, Seattle, Washington
- bCardioVascular Center Frankfurt, Frankfurt, Germany
- cHenry Ford Health System, Detroit, Michigan
- ↵∗Address for correspondence:
Dr. Sameer Gafoor, Swedish Heart and Vascular 550 17th Avenue Suite 680, Seattle, Washington 98122.
If something is easy to repair, it is easy to construct.
—Leo Fender (1)
If something is easy to repair, it isn’t always easy to replace.
What are the indications for surgical replacement versus repair of tricuspid regurgitation (TR)? Clinically, patients with advanced endocarditis, orthotopic heart transplantation, significant trauma-induced injury, carcinoid, or other types of primary TR may be treated with tricuspid valve replacement rather than repair (2). From an anatomic perspective, those patients with tethering, significant distortion of the valve, left ventricular and right ventricular (RV) dysfunction, or severe pulmonary hypertension may benefit from tricuspid valve replacement (3). However, surgical replacement of the tricuspid valve is not a straightforward procedure. In a small study of 228 patients, Fu et al. (4) discussed how patients with replacement compared with patients who underwent repair had a higher average aortic cross-clamping time, cardiopulmonary bypass time, ventilation time, longer intensive care unit stay, as well as an earlier complication rate (27.3% vs. 15.8%) and fatality (16.8% vs.6.3%). Some predictors of untoward outcomes from the Society of Thoracic Surgeons database are age, sex, stroke, hemodialysis, ejection fraction, lung disease, New York Heart Association functional class, re-operation, and urgent and/or emergency status (5); the National Inpatient Sample (NIS) added stroke, peripheral vascular disease, and liver disease to this list (6). From 2005 to 2014, the NIS noted that the total volume of isolated tricuspid valve replacement increased, but the mortality trend stayed relatively stable (6).
Percutaneous tricuspid valve intervention is a growing field, with patients undergoing leaflet-to-leaflet repair, incomplete and complete ring annuloplasty, receiving coaptation devices, and undergoing vena caval implantations. Overall, the procedures are safe (7). However, the results may vary; the ability to reduce TR from severe to mild and the durability of such a result are still in question. Surgical literature has taught us that residual TR is a marker for poor outcomes (8). The need for a percutaneous tricuspid valve replacement is this: how do we decrease the peri-procedural mortality in patients with severe symptomatic TR who are not surgical candidates for tricuspid valve replacement or percutaneous tricuspid valve repair?
In a case series of percutaneous tricuspid valve replacement, Hahn et al. (9) described implantation of the novel GATE (NaviGate Cardiac Structures, Inc., Irvine, California) valve in the tricuspid position through a surgical transatrial approach. The device allowed replacement of annular diameters of 40 to 52 mm; the trileaflet valve had 12 right ventricular tines and 12 right atrial winglets, and was introduced through a 42-F introducer sheath. One patient died on day 28; the other 4 patients had RV remodeling, an increase in forward cardiac output, and improvement in symptoms.
Imaging requirements before transcatheter tricuspid replacement are crucial to procedural success. The investigators described the tricuspid valve, and RV size and function measurements in detail, including views seen on transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), and computed tomography (CT).
Therefore, tricuspid sizing is a 4-dimensional (4D) entity, with the fourth axis being time. Sizing is critical for tricuspid valve replacement because the NaviGATE anchoring mechanism is dependent on intact leaflet function. Unlike aortic—or at times—even mitral valves, oversizing is 2% to 5% above the area-derived average diameter, which allows little room for error. No valvular repair emphasizes the importance of integration of multimodality imaging more than tricuspid interventions; these interventions require understanding of pathophysiology, anatomical barriers, and 4D dynamic changes that occur with volume status. Although TTE and TEE are limited in ability to provide a holographic roadmap of the delivery of tricuspid valves, CT may aid in planning. Although CT is limited in dynamic intraprocedural guidance, TEE and TTE can integrate peri-procedural CT and fluoroscopic findings. Discrepancy between TEE and CT is important to adjudicate correctly, as the investigators noted in Patient #3. In addition, sizing is dependent on fluid status. The investigators emphasized that patients were admitted 3 to 5 days before the procedure and were diuresed for optimal weight reduction. This might have directly affected RV volume and the RV cavity, as well as tricuspid annulus sizing depending on baseline etiology of TR. What must be emphasized is optimal timing for planning in this patient population; a patient who might be a good fit during pre-procedural assessment might not be a good candidate at the time of the procedure and vice versa. The heart team must be dynamic to adjust for these issues and plan accordingly.
What is not known is the long-term durability of the device, and the RV function and response to tricuspid valve replacement in patients with severely enlarged RVs. Just as in patients with mitral regurgitation and dilated left ventricles, similar analogies could be made in reference to severe dilated RVs: will there be benefit with a tricuspid valve replacement in these patients and long-term improvement in RV function and output? In addition, how will this work in patients with a normal conical-shaped RV and torrential TR or a tubular-dilated RV? Pre-procedural measurements for the procedure included a combination of annulus, ventricle, and access measurements. At this time, valve access can be either through the internal jugular or by the thoracotomy and the transatrial approach, and the team will have to learn the meaning of the phrase “most co-axial deployment axis perpendicular to the centroid point of the spline interpolated tricuspid annulus” well to have this be reproducible and reliable between imagers and implanters. It would be interesting to note how many patients were turned away from the procedure or because of the anatomic “screen fail” rate. For aortic valves, this is few; for transcatheter mitral valves, the rates can be quite significant (which is often the case for technologies in their infancy). Clinical parameters of RV success, such as RV change in pressure divided by change in time, are likely to predict in which patients tricuspid valve replacement may be futile or challenging, adding to the clinical screen fail rate. During the procedure, multimodality imaging integration is required by the structural heart team for procedural success. Access entry and fine tuning were done here by TEE. Canting of the valve (see Figure 7A ) is immensely important to catch and adjust for, because in this early technology development period, re-capturability and re-positionability is often not feasible. Interaction with the coronary artery, coronary sinus, atrioventricular node, chordae, or other adjacent structures is important to evaluate and report early in the procedure. Immediately after valve deployment, peri-procedural valve gradient, paravalvular leak, and stability of the valve are important for initial evaluation, as well as RV function and response to the sudden loss of a “pop-off” mechanism. From a complication standpoint, effusion and chest wall bleeding are important to catch early by imaging, especially in patients undergoing the transjugular approach.
From a post-procedural standpoint, multiple late complications may occur. Aside from lack of thrombus on the device (all patients seem to require anticoagulation; thrombus can form even in the immediate post-procedural period), device success includes minimal leaks, low gradients, and stable devices without migration. Over time, valve complications may include erosion, pericardial effusion, and coronary artery and/or sinus interaction. Late atrioventricular node interference that requires a pacemaker may be important as well. Patients can likely be followed by TTE; however, RV reverse remodeling may be seen earlier with cardiac CT or cardiac magnetic resonance imaging, which are more accurate and reproducible than TTE for RV volumes and ejection fraction. RV support may be needed in the early post-procedural period until the patient stabilizes; therefore, centers must be facile with this technology.
Although many studies describe the “forgotten nature” of the tricuspid heart valve, with approximately 19,000 references found in PubMed, we can move past this term. The investigators should be commended on this movement forward into percutaneous tricuspid valve replacement. Through this study, we learn more about real-time sizing, the ability of the RV to tolerate loss of the pop-off mechanism, and the importance of complication recognition and management. Imaging—and dynamic real-time imaging at that—is sine qua non for these valves, in which small fluid shifts can lead to large implantation consequences. Which patients do best with percutaneous tricuspid valve replacement? These patients may be younger and/or have an earlier course with good RV function, a higher need for complete resolution of TR, and an ability to tolerate anticoagulation. The need is definitely present; the high mortality for these patients demands a safer solution.
↵∗ Editorials published in JACC: Cardiovascular Imaging reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Dr. Gafoor has been a consultant for Abbott Lifesciences; and is a consultant/proctor for Medtronic. Dr. Wang has been a consultant for Edwards Lifesciences, Boston Scientific, and Materialise.
- ↵AZ Quotes. Leo Fender quotes. Available at: https://www.azquotes.com/author/4731-Leo_Fender. Accessed November 22, 2018.
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