Tricuspid Valve Repair: How I Teach It

Abstract

The tricuspid valve has been the “neglected valve” for a long time [1Mascherbauer J. Maurer G. The forgotten valve: lessons to be learned in tricuspid regurgitation.Eur Heart J. 2010; 31: 2841-2843Crossref PubMed Scopus (36) Google Scholar, 2Tornos Mas P. Rodríguez-Palomares J.F. Antunes M.J. Secondary tricuspid valve regurgitation: a forgotten entity.Heart. 2015; 101: 1840-1848Crossref PubMed Scopus (70) Google Scholar]. We believe that all cardiac surgical trainees should have an adequate understanding of the basic anatomy, pathology, and common repair techniques. The tricuspid valve has a complex anatomic structure that includes (1) a saddle-shaped annulus that changes shape in systole and diastole [3Ton-Nu T.T. Levine R.A. Handschumacher M.D. et al.Geometric determinants of functional tricuspid regurgitation: insights from 3-dimensional echocardiography.Circulation. 2006; 114: 143-149Crossref PubMed Scopus (268) Google Scholar]; (2) three leaflets; (3) chordae and papillary muscles; and (4) underlying right ventricular myocardium. Tricuspid competency depends on the interplay of this trifoliate structure with the normal crescent-shaped right ventricle (RV). Acquired tricuspid valve pathology ranges from annular dilation (functional tricuspid regurgitation [TR]), to ruptured chordae to dysplastic leaflets secondary to trauma from endocardial pacing leads. The goal of this review is to provide a summary of the perioperative teaching points that are reviewed with each resident with simple and complex repair techniques that provide successful, reproducible results and satisfactory late outcome. Preoperative evaluation includes transthoracic echocardiography for details about tricuspid anatomy. Transesophageal echocardiography and three-dimensional echocardiography is used for greater valvar anatomic detail or if transthoracic images are insufficient. Magnetic resonance imaging is used for information about right ventricular size and function. Intraoperative transesophageal echocardiography is used routinely for confirmation of preoperative findings and for assessment after repair. Importantly, the conditions of anesthesia in the operating room reduce the degree of TR by at least one grade. Consequently, the decision to proceed with tricuspid repair should be made preoperatively and not in the operating room as the degree of TR is underestimated. Furthermore, that must also be considered with the analysis after repair. Two important anatomic issues that can result in poor outcome are injury to the conduction tissue and injury to the right coronary artery and its major branches. The conduction tissue is located in the triangle of Koch, and in the absence of complex congenital heart disease, its location is consistent and constant. The right coronary artery runs in the atrioventricular groove, and the takeoff of the posterior descending and posterolateral branches is at the crux of the heart just anterior to the coronary sinus where the right ventricular free wall meets the ventricular septum. Most repair techniques require suture placement into the annulus, so knowledge of these two structures is essential to avoid inadvertent injury to either. The subvalvar apparatus anatomy is more variable than the subvalvar apparatus of the mitral valve. Chordal support for the tricuspid valve usually consists of one or two major anterior papillary muscles arising from the anterior free wall, one in the region of the junction between the inferior RV wall and the ventricular septum, and multiple chordae to the septal leaflet. Importantly, TR progresses when the dilated, more rounded shape of the RV pulls the leading edges of the tricuspid leaflets away from each other. That explains, in part, why simple annular reduction maneuvers do not always eliminate central TR when there is severe RV dilation. Our standard approach is aortic and bicaval cannulation with right-angle venous cannulae. In general, we inspect the tricuspid valve with cardioplegic arrest to ensure we understand the anatomic issues and mechanism of TR. We incorporate the pulmonary artery in the cross clamp so filling of the right ventricle at the end facilitates analysis of valve competence. If the repair is going to entail a simple pursestring or banded annuloplasty and the tissue quality is good, then we remove the cross clamp and proceed with annuloplasty with the beating heart. If the repair involves leaflet or subvalvar work, or if tissue quality is fragile, we perform the repair on an arrested heart. That ensures accurate suture placement and the tying and securing of sutures with no motion trauma that can result in the tearing of delicate leaflet or annular tissue. The right atrium is incised parallel to atrioventricular groove starting from the right atrial appendage and heading halfway between inferior vena cava and the atrioventricular groove. It is important to not be too close to the atrioventricular groove because that can result in right coronary compromise during atriotomy closure. Tacking sutures of monofilament 4-0 are placed above the anterior annulus at the 10-o’clock and 2-o’clock postions; a third tacking suture is placed in the crista terminalis to reflect the lower edge of the atriotomy laterally. Valve inspection is essential to identify the pathology and target the repair. The annulus is assessed for dilation, followed by leaflet examination—identification of fenestrations, dysplasia, flail segments, leaflet height, and so forth. The leaflets are retracted up with a blunt hook to visualize the subvalvar apparatus, and the chordae and papillary muscles are assessed. After this anatomic assessment, saline is injected into the right ventricle and valve competency is assessed. The site of the leak is identified and the corresponding cause delineated. If the valve appears anatomically normal and the leak is central, the cause is mostly a dilated annulus. Failure of coaptation may also be due to the relative shorter height of the leaflet (anterior most common). The portion of tricuspid valve annulus that dilates the most corresponds to the inferior leaflet, followed by the anterior leaflet. In contrast to the mitral valve, the septal tricuspid annulus can also dilate (Fig 1). In general, a banded annuloplasty is preferred for annular reduction. Our preference is a C-shaped flexible ring because the geometry of the tricuspid annulus is saddle-shaped and changes throughout the cardiac cycle (Fig 2A). That facilitates the normal interaction between the tricuspid annulus and right ventricle, which may help optimize right ventricular function in the long term. We use a 26-mm ring routinely and a 28-mm ring in patients weighing more than 110 kg. Monofilament, 2-0 nonpledgeted horizontal mattress sutures are used as the monofilament suture slides through the delicate annular tissue easier than the more traumatic braided suture. The first stitch in the annulus is placed at the anteroseptal junction and moves clockwise along the anterior and inferior annulus. The last stitch is pledgeted and anchored in the os of the coronary sinus. Avoiding extending across the septal annulus minimizes the potential injury to the conduction tissue. Anchoring the ring in the coronary sinus ensures that the ring stays intact, as opposed to more superficial bites along the septal annulus that are susceptible to dehiscence. We ensure that the resident is cautious about (1) identifying the triangle of Koch, membranous septum, and the atrioventricular node area (usually a small area of fat with a vein running in the middle of it), and to stay away slightly anterior to it while taking the first annular stitch; (2) not going too deep while taking a stitch along the anterior annulus, to prevent injury to the right coronary artery; and (3) ensuring the last stitch is pledgeted beginning in the coronary sinus and exiting through the junction of the inferior and septal annulus. This final stitch is slightly superficial so it does not penetrate or injure the distal right coronary artery, posterior descending artery, or posterolateral coronary arteries. No stitches are placed beyond this point along the septal leaflet to stay away from the conduction tissue. An additional pledgeted stitch is often placed at the anteroseptal junction. Injury to the tricuspid valve by a lead is becoming an increasingly recognized etiology of TR [4Said S.M. Burkhart H.M. Dearani J.A. Surgical management of congenital (non-Ebstein) tricuspid valve regurgitation.Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2012; 15: 46-60Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar]. Mechanisms of TR include entanglement of the lead with the subvalvar apparatus, leaflet injury or leaflet penetration, or prevention of leaflet excursion by lead presence through the orifice of the valve. Our experience with this entity has demonstrated that valve repair is not always feasible owing to leaflet destruction, and valve replacement may be necessary. This section will focus on reparative techniques (Figs 2B–2D). The first decision is whether to preserve the endocardial system. If the threshold of the ventricular lead is very good, then we make an effort to preserve the endocardial lead. If the threshold is not ideal or if lead removal is necessary to accomplish a successful repair, then the endocardial system is removed and an epicardial pacing system is placed at the end. When the pacing lead is trapped in the subvalvar apparatus, the lead is mobilized as much as possible. A rubber-protected forceps is used to prevent injury to the insulation of the lead during lead manipulation. An incision is made in the involved leaflet from the leading edge to the annulus. The lead is then positioned against the annulus so that leaflet excursion is not compromised. The leaflet is then reapproximated from the leading edge up to the annulus, leaving it slightly loose at the level of the lead and annulus junction. If a part of the leaflet has to be sacrificed owing to marked thickening/dysplasia, it is augmented with a pericardial patch. If there is no penetration of the leaflet or chordal apparatus, the lead is positioned at the most convenient commissure (usually anteroinferior or inferoseptal commissure). A loose commissural stitch is placed to keep the lead from wandering into the orifice of the valve and impinging on leaflet excursion. A ring is applied at the completion of the procedure. The lead can be maintained inside or outside the ring, but should be movable so that future removal by laser extraction, if needed, is not compromised. In the setting of an unsupported leaflet, we use a double-armed, pledgeted Gore-Tex (W.L. Gore & Associates, Flagstaff, AZ) 5-0 as artificial chords (Figs 3, 4). The Gore-Tex chords to the unsupported anterior leaflet are placed as pledgeted sutures into a heavy RV trabeculation toward the apex at its junction with the ventricular septum. Importantly, we do not place the artificial chords into the anterior papillary muscle as one would do with artificial chordal reconstruction for mitral valve repair. The reason for this is twofold. First, positioning the anchoring point of the artificial chords toward the apex facilitates coaptation between the anterior and septal leaflets; in other words, the leading edges are being brought together. Second, it makes the measurement of the chords more reproducible and is not adversely affected by a severely dilated RV that makes proper chordal length more difficult to gauge when attaching to the papillary muscle. Each arm of the pledgeted horizontal mattress suture is placed through the apicoseptal trabeculation (this suture is not tied at this level). Each limb of the suture is then placed through the desired location of the leading edge of the leaflet twice (this allows the leaflet to retain its position without the leaflet slipping in or out too much). Two or three pairs of artificial chords are used.Fig 4Artificial chords to septal leaflet, with pledgets toward the right ventricle apex on septal side. (Left) Coronal section of the heart. (Right) Surgeon's view through right atriotomy. (A = anterior; I = inferior; S = septal.)(Used with permission of Mayo Foundation for Medical Education and Research. All rights reserved.)View Large Image Figure ViewerDownload Hi-res image Download (PPT) The edge of the leaflet is then placed in the plane of the annulus. Annular traction sutures are temporarily loosened, and the valve is examined with saline instillation into the RV. The position of the leaflet is adjusted inward or outward until valve competence is obtained. Sutures are then tied carefully (usually two-handed ties to ensure they are square). Similarly when artificial chords are done for an unsupported septal leaflet, they are also directed toward the apex but more on the septal side. When the leaflet is thin and fragile, pericardial pledgets are used when tying knots against the leaflet edge. The length of the chords automatically adjusts itself with no knot on the apicotrabecular side. A ring is placed as described previously. The height of the anterior leaflet is examined. Ideally, we prefer successful leaflet coaptation with reasonable valve competence before annular reduction maneuvers. When leaflet coaptation is inadequate, we patch augment the anterior leaflet with an ellipse of autologous pericardium to increase its height so that leaflet-to-leaflet coaptation is facilitated before annular reduction (Fig 5). That is accomplished by incising the anterior leaflet off the annulus at the 9 o’clock position and extending clockwise toward the midinferior leaflet (approximately 4 o’clock). An ellipse of fresh autologous pericardium is sutured fixed at four points—at the 9-, 12-, 3-, and 6-o’clock postions—with 4-0 or 5-0 monofilament. The sutures are run toward each other between the points of fixation with occasional locking stitches to prevent a pursestring effect. A ring is then applied. In many ways, tricuspid repair is more challenging and unforgiving than mitral repair. Leaflet tissue tends to be more fragile and the severely dilated right ventricle can make successful leaflet coaptation and competency more difficult. In addition, there are numerous aspects of tricuspid surgery that can result in harm, specifically coronary or conduction tissue injury. When the primary indication for surgery is TR, it is more important to accept an excellent result (less than mild TR). That is in contrast to secondary TR (eg, in the setting of mitral regurgitation) where the degree of TR is expected to improve after correction of the left-sided pathology and accepting a less than perfect result (moderate TR) would be the goal. Although valvuloplasty is generally the goal, there are some situations where replacement may be preferred, such as patients with pulmonary hypertension, massive annular or severe RV dilation, and patients with marked abnormalities of leaflets or subvalvar apparatus. Honoring the same rules of avoidance of conduction and coronary injuries apply in this situation as well. Finally, the choreography of this (and every) operation should be neatly orchestrated into a series of steps that are predictable and reproducible. That orchestration reduces variability, optimizes outcome, and most important, makes it easier to teach [5Dearani J.A. Gold M. Leibovich B.C. et al.The role of imaging, deliberate practice, structure, and improvisation in approaching surgical perfection.J Thorac Cardiovasc Surg. 2017; 154: 1329-1336Abstract Full Text Full Text PDF PubMed Scopus (35) Google Scholar].