Tricuspid Valve Operations
Tricuspid valve surgery has evolved from an almost ignored valve in the past to an important valve that is critical to address at the time of left valve intervention. The incidence of tricuspid regurgitation associated with left valvular disease is quite significant and most common in conjunction with mitral valve disease; however, association with aortic valve pathology is not uncommon. Most commonly, tricuspid regurgitation is functional or secondary to dilation of the annulus, as a consequence of right ventricle dilation secondary to pulmonary hypertension. However, organic (rheumatic, endocarditis, or degenerative in origin) is not uncommon. The purposes of this chapter are to shed light on the anatomy of the tricuspid valve, and elucidate the etiology and pathogenesis of tricuspid valve disease, mainly tricuspid valve regurgitation, with a special focus on secondary tricuspid valve regurgitation. Indications for surgery as well as different surgical approaches (including different repair techniques and valve replacement) to correct tricuspid valve regurgitation are discussed in detail. A transcatheter approach for tricuspid valve repair or replacement is attractive, desirable, and beneficial to this high-risk population as an alternative to surgery.
Keywords : tricuspid valve, secondary tricuspid regurgitation, tricuspid valve repair, tricuspid valve replacement
· The tricuspid valve is located between the right atrium (RA) and right ventricle and has a valve area of 4 to 6 cm. The tricuspid valve is composed of three leaflets the anterior, posterior, and septal. The leaflets are supported by chordae tendineae and papillary muscles. Compared with the mitral valve, the leaflets and chordae tendineae of the tricuspid valve are thinner and the tricuspid orifice is larger and more triangular.
· The anterior leaflet is the largest of the three leaflets and extends through the anterior portion of the annulus. Its chordae attach to the anterior and septal papillary muscles. The posterior leaflet is the smallest leaflet and extends through the inferior and posterior edges of the annulus; its chordae originate from the posterior and anterior papillary muscles. The septal leaflet is the most medial and is attached directly to the interventricular septum; it is larger than the posterior leaflet, and its chordae attach to the posterior and septal papillary muscles. The septal leaflet is relatively immobile due to its attachment to the fibrous structure of the heart.
· The tricuspid valve is a continuous veil of thin fibrous tissue. Three commissures are delineated by fan-shaped chordae of the three leaflets:
a. Anteroseptal commissure—where the basal attachment of the tricuspid valve reaches its highest level at the membranous interventricular septum and where the anterior and septal walls of the right ventricle join
b. Anteroposterior commissure—forms a deep indentation in the leaflet tissue between the anterior and posterior leaflets
c. Posteroseptal commissure—a deep indentation in the leaflet tissue at the junction of the posterior and septal walls of the right ventricle.
· The tricuspid valve annulus is part of the fibrous skeleton of the heart. It consists of a ring of collagenous tissue that generally extends around the line of attachment of the leaflets of the tricuspid valve. It is very thin and difficult to identify. The tricuspid annulus is a complex three-dimensional (3D) structure; the normal tricuspid valve annulus is saddle-shaped, with the highest points located in an anteroposterior orientation and the lowest points at the area of the septal leaflet. With the development of functional tricuspid regurgitation (TR), changes in the 3D annular shape lead to loss of the saddle shape and more flattening of the annulus; that is, the tricuspid annulus becomes dilated and more planar and circular and hence, restoration of the 3D shape of the annulus may be an important therapeutic goal beyond that of annular reduction alone.
· Normal tricuspid valve annulus diameter in adults is 28 ± 5 mm in the four-chamber view. Significant tricuspid annular dilation is defined by a diastolic diameter of more than 21 mm/m2 (> 35 mm).
· Structures surrounding the tricuspid valve that are of major surgical significance include the coronary sinus, atrioventricular (AV) node, membranous septum, bundle of His, and right coronary artery (Fig. 23.1).
· The conduction system is near the septal leaflet and its anterior septal commissure. The AV node lies in the atrial septum bordering the septal leaflet, superior and anterior to the coronary sinus. Its exact location can be approximated at the apex of the triangle of Koch, a triangle composed of the septal annulus and tendon of Todaro as its sides and the coronary sinus orifice as its base. Extending from the AV node is the bundle of His, which penetrates the right trigone under the interventricular component of the membranous septum (≈ 5 mm inferior to the anterior septal commissure) and runs along the crest of the muscular septum. The membranous septum usually lies beneath the septal leaflet inferior to the anterior septal commissure. The right coronary artery runs anterior to the anterior leaflet annulus and may be injured by deep sutures in the annulus.
Step 2. Preoperative Considerations
1. Causes of Tricuspid Valve Diseases
· This is usually rheumatic in origin. On rare occasions, infective endocarditis, congenital abnormalities, or carcinoid disease may be implicated. Rheumatic tricuspid involvement usually results in both tricuspid stenosis and regurgitation, and it typically coexists with mitral or aortic rheumatic disease. The hallmark features of rheumatic tricuspid stenosis are commissural fusion and leaflet thickening, but calcification is usually absent. Carcinoid syndrome leads to focal or diffuse deposits of fibrous tissue on the endocardium of the valve leaflets and cardiac chambers. The tricuspid valve in carcinoid syndrome is thickened, with retracted leaflets fixed in a semiopen position, resulting in both tricuspid stenosis and regurgitation, and usually not amenable for repair.
· TR can occur with abnormal or normal valve leaflets. Causes of TR associated with abnormalities of the tricuspid leaflets include rheumatic valve disease, endocarditis, carcinoid syndrome, radiation therapy, Marfan syndrome, papillary muscle dysfunction, and congenital disorders such as Ebstein anomaly. Penetrating and nonpenetrating trauma, iatrogenic damages during cardiac surgery, biopsies, catheter placement in right heart chambers, and placement or extraction of pacemakers and defibrillator leads are also rare causes of TR.
· Tricuspid prolapse is generally associated with mitral valve prolapse and is defined as a midsystole posterior leaflet displacement beyond the annular plane. The coaptation line is above the annular plane. Tricuspid prolapse usually involves more than one leaflet, and often the three leaflets are affected. The most common phenotype of tricuspid prolapse is diffuse myxomatous degeneration (Barlow disease). A flail tricuspid leaflet is observed when the free edge of a leaflet is completely reversed in the RA, usually as a consequence of ruptured chordae. It also is common in infective endocarditis in association with vegetations.
· Approximately 80% of cases of significant TR are functional in nature. Regurgitation develops with normal tricuspid valve leaflets as a result of right ventricular (RV) dysfunction and tricuspid annular dilation (functional regurgitation), usually in the context of left-sided valvular disease. Pulmonary hypertension or RV dysfunction leads to elevations of RV systolic and diastolic pressures, RV cavity enlargement, and tricuspid annular dilation. The circumference of the tricuspid annulus lengthens primarily along the attachments of the anterior and posterior leaflets. The septal leaflet portion, on the other hand, is fixed between the right and left trigones and the atrial and ventricular septa, preventing its lengthening. As annular and ventricular dilation progress, the cordal–papillary muscle complex becomes functionally shortened, with tethering of the leaflets, although it remains normal in appearance. This combination of RV enlargement and tricuspid annular dilation prevents leaflet coaptation and leads to valvular incompetence (Fig. 23.2).
· Previously, it was believed that functional TR decreased or even disappeared after surgical correction of left-sided valve disease. This concept influenced cardiac surgery practice for many years. More experience, however, has led to better appreciation of the potential for progression of functional TR and tricuspid annular dilation after left-sided surgery. This effect may occur in spite of the complete correction of the mitral and aortic disease and the resolution of pulmonary hypertension after surgery. Tricuspid annular dilation is the strongest and most consistent risk factor for the development of late TR after left-sided valve surgery.
· Severe TR and its resultant RV dysfunction and venous congestion contribute to an increase in early and late morbidity and mortality after left-sided valve surgery. Moreover, reoperation to correct worsening postoperative TR is associated with a high operative mortality rate and disappointing long-term results. Therefore, a proactive strategy of prophylactic repair of a dilated tricuspid annulus at the time of the initial left-sided valve surgery, regardless of the degree of TR, has been advocated as a strategy to help reduce the incidence of late TR and RV failure and the complexity and higher risk of redo surgery. Concomitant mitral and tricuspid valve repair is associated with significant RV reverse remodeling and improvement in functional class postoperatively.
· Imaging of the tricuspid valve is a challenging process. Functional TR is dynamic in nature, so the degree of severity of TR may change, especially under general anesthesia, and the decision for tricuspid valve intervention should be made before surgery based on preoperative echocardiography and careful clinical assessment of the patient.
· Tricuspid valve analysis can be achieved with two-dimensional (2D)–transthoracic echocardiography (TTE) imaging (the technique of choice). 3D-TTE can be used as an additive approach. Transesophageal echocardiography (TEE) is advised in case of suboptimal TTE images to evaluate the severity of TR. TTE helps determine cause, measures the size of right-sided chambers and the inferior vena cava (IVC), assesses RV systolic function, estimates pulmonary artery systolic pressure, and characterizes any associated left-sided heart disease. TEE describes the morphology and pathophysiology of the tricuspid valve and grades the severity of tricuspid valve regurgitation. It is of note that TEE usually underestimates the measurement of the tricuspid valve annulus. The evaluation of tricuspid valve annulus dilation is a matter of ongoing controversy and is less precise compared with mitral valve annulus assessment.
· Cardiovascular magnetic resonance (CMR) is another imaging modality for the tricuspid valve that allows visualization of the anatomy and function of the tricuspid valve. It also permits quantification of the regurgitant volume and regurgitant fraction.
· The 2014 American College of Cardiology/American Heart Association valve guidelines has indicated the following recommendations:
1. Tricuspid valve repair for patients with severe functional TR who are undergoing concurrent surgery for mitral valve disease (Class I, level of evidence C).
2. Tricuspid valve intervention for severe primary TR in symptomatic patients (Class IIa, level of evidence C). When the tricuspid valve leaflets are too diseased and not amenable to repair, tricuspid valve replacement is believed to be reasonable for patients with severe TR.
3. Tricuspid valve repair may be considered for less than severe TR in patients undergoing mitral valve surgery in the presence of pulmonary hypertension or tricuspid annular dilation (Class IIa, level of evidence B).
4. Tricuspid valve repair may be considered for patients with moderate functional TR and pulmonary artery hypertension at the time of left-sided valve surgery (Class IIa, level of evidence C).
5. Tricuspid valve surgery may be considered for asymptomatic or minimally symptomatic patients with severe primary TR and progressive degree of moderate or greater RV dilation and/or systolic dysfunction (Class IIa, level of evidence C).
6. Reoperation for isolated tricuspid valve repair or replacement may be considered for persistent symptoms due to severe TR in patients who have undergone previous left-sided valve surgery and who do not have severe pulmonary hypertension or significant RV systolic dysfunction (Class IIa, level of evidence C).
◆American College of Cardiology/American Heart Association practice guidelines have recommended against tricuspid surgery for patients with only mild primary TR. Tricuspid surgery is also not indicated for patients with some degree of TR who are asymptomatic, when there is no concurrent left-sided valve disease, or when severe pulmonary hypertension is absent.
◆ Several cardiac surgery centers currently advocate for the routine repair of the dilated tricuspid annulus at the time of left-sided heart surgery, regardless of the degree of TR.13 At our center, we consider valve repair even if there is no associated TR or only a mild degree of TR when the tricuspid annulus diameter is 40 mm or more with the presence of pulmonary hypertension (PH; defined as a mean pulmonary artery pressure ≥25 mm Hg at rest) or 45 mm or more in the absence of PH. Such repair could reduce the risk of RV dysfunction, both in the perioperative period and in the long term, as well as the need for a second operation (Table 23.1).
◆ Functional TR in association with aortic stenosis may persist or even become progressive after aortic valve replacement alone; it is usually associated with left ventricular (LV) diastolic dysfunction. A concomitant tricuspid valve procedure should be considered in select patients with aortic stenosis at the time of aortic valve replacement.
4. Choice of Repair Technique
· Previously, it was believed that the type of tricuspid valve repair performed was of little importance as long as the size of the tricuspid annulus was secured to avoid progressive dilation. For patients with functional TR secondary to left-sided valve disease, the De Vega annuloplasty was thought to be the most appropriate procedure to reduce the size of the tricuspid annulus. However, recent data have demonstrated poor long-term results with the use of the De Vega technique. Although it is a safe and simple procedure, 30% or more of patients may develop recurrent moderate to severe TR after a De Vega repair, with progressive annular dilation and recurrence of symptoms.
· Long-term studies have also illustrated poor long-term durability and high rates of recurrent TR with the use of flexible rings and bands (Duran, Medtronic, Minneapolis, MN; Cosgrove- Edwards, Edwards Lifesciences, Irvine, CA; Peri-Guard, Synovis, MN). Only rigid rings have yielded good long-term results, with the bulk of evidence favoring the semirigid Carpentier- Edwards ring (Edwards Lifesciences) as the most durable after tricuspid valve repair.
· 3D rings that aim to restore the annular geometry, such as contour 3D (Medtronic), GeoForm (Edwards Lifesciences), and 3D MC3 (Edwards Lifesciences) rings are being increasingly used for the treatment of functional tricuspid valve regurgitation with documented good results.
· At our center, we perform tricuspid valve repairs using 3D annuloplasty bands for all patients with a tricuspid annular dilation of greater than 40 mm, regardless of the presence of TR, at the time of concurrent left-sided valve surgery. The De Vega repair is reserved for older patients undergoing left-sided valve surgery who have 2+ TR or less and a tricuspid annular dimension of less than 40 mm. Also, in case of the presence of PH and concerns about postoperative RV dysfunction and the possibility of increasing TR, a quick De Vega repair helps those older patients pass the postoperative phase. In patients with a large annulus (> 50 mm) and severe TR, we perform annuloplasty and edge-to-edge techniques (Fig. 23.3).
◆ Repair of the tricuspid valve is superior to valve replacement because it is associated with lower hospital mortality rates, better long-term survival, better preservation of ventricular function, fewer thromboembolic complications, and reduced risk of endocarditis. However, in the context of organic tricuspid disease with severe leaflet thickening and cordal retraction, tricuspid valve replacement is the preferred surgical intervention.
◆ The choice of prosthesis type in the tricuspid position has been debated in the cardiac surgery community for many years. A meta-analysis has summarized the published literature by comparing outcomes reported for contemporary mechanical and bioprosthetic tricuspid valves. A total of 11 studies, with 646 mechanical and 514 biologic tricuspid prostheses and 6046 follow-up years, were analyzed. Studies that reported prosthetic models from before 1970 were excluded. Overall, the pooled survival and reoperation data did not favor either prosthesis type. Furthermore, the incidence of mechanical valve thrombosis was comparable with the incidence of bioprosthetic valve deterioration.19 Therefore, the type of prosthetic valve is not a risk factor for adverse outcomes after tricuspid valve replacement, and there is no evidence favoring one prosthetic type or the other. In our experience, we almost never used a mechanical valve in the tricuspid position in the current era of the percutaneous valve; a bioprosthetic valve allows safe valve-in-valve implantation.
◆ As in other valve positions, there is no gold standard prosthetic valve available for tricuspid valve replacement. We believe that the choice between a mechanical and bioprosthetic valve in the tricuspid position should be individualized according to the surgeon’s clinical judgment, patient characteristics, anticoagulation considerations, likelihood of pregnancy, socioeconomic status, and lifestyle issues. A patient with drug addiction and a history of endocarditis, who may have difficulty with anticoagulation compliance, should have a bioprosthesis implanted.
· Although not supported by good evidence, it is currently popular to implant undersized rings to improve coaptation during the repair of mitral regurgitation. This strategy may also apply to the repair of functional TR. However, there are no data to support the practice of implanting undersized rings in the tricuspid position. Long-term data from the Cleveland Clinic have demonstrated that the use of a small tricuspid ring for the repair of functional TR does not protect against the development of recurrent late TR. Use of the anterior leaflet for tricuspid valve sizing may be inaccurate to determine tricuspid annular size in functional TR because the tricuspid annulus is dynamic and may change in circumference during systole, with a reduction in annular dimension.
· We generally implant a tricuspid prosthesis (band or valve) identical or close in size to the mitral valve prosthesis used during concurrent mitral repair or replacement.
· When replacing the tricuspid valve, it is almost always possible to place a large bioprosthetic or mechanical valve. Prostheses with an internal diameter greater than 27 mm do not have clinically significant gradients, and thus hemodynamic performance is rarely an issue in tricuspid valve replacement; the patient prosthetic mismatch has not been reported in tricuspid valve replacement as a significant problem.
Step 3. Tricuspid Valve Endocarditis
· In tricuspid valve endocarditis, the tricuspid valve may be infected in isolation or in the context of other infected valves. In contrast to left-sided endocarditis, right-sided native valve endocarditis usually involves previously normal valves. Isolated tricuspid bacterial endocarditis is usually seen in the presence of intravenous drug use, long-standing central venous catheters, cardiac implantable electronic devices, or congenital heart disease. The most common organisms include Pseudomonas aeruginosa, Staphylococcus aureus, gram-negative bacilli and, occasionally, Candida albicans.
· Medical management is the first line of treatment and is generally successful. Surgical intervention is only required for a subset of patients with persistent right-sided heart failure despite medical therapy, recurrent pulmonary septic emboli, septic shock, abscess formation, failure of antimicrobial therapy to control the infection, or presence of a large vegetation risk of pulmonary embolization. If at all possible, tricuspid valve repair with partial valve excision and reconstruction should be considered in tricuspid endocarditis, even with less than optimum results in terms of TR. This is because the main goal of surgery is to eradicate infection, in contrast to the mitral valve, for which eradication of both infection and regurgitation are the main goals. For significant destruction of the valve, however, tricuspid valve excision or replacement may be offered.
· In patients with ongoing intravenous drug addiction, valve excision may prove to be a useful approach that avoids the subsequent risk of prosthetic valve endocarditis. However, the resultant severe TR after valve excision compromises postoperative cardiac function and exposes the patient to a second reoperation for prosthesis implantation. Therefore, primary bioprosthetic valve replacement is usually preferred over total valve excision.
· Different tricuspid valve repair techniques have been described for tricuspid valve endocarditis. Some are simple such as débridement of vegetations, leaflet resection and reconstruction with pericardial patch (autologous or bovine), other repair techniques such as sliding plasty, bicuspidization, edge-to-edge repair, and ring annuloplasty. Resection of more than one leaflet mandates valve replacement.
· Tricuspid valve surgery may be recommended for infective endocarditis secondary to drug abuse. However, redo surgery in these patients constitutes a controversial and ethical issue because the long-term survival depends to a great degree on whether the patient stops the drug abuse.
· Tricuspid valve surgery may be performed through a full sternotomy, right anterior thoracotomy, minimally invasive approach using port access or robotic surgery and, recently, percutaneously. Our standard approach is the median sternotomy approach, which gives full access to the mitral, aortic, and tricuspid valves. In a redo operation in a patient with a dilated RV, femoral cannulation to decompress the heart before the redo sternotomy may be contemplated. Bicaval cannulation with snares is essential to isolate the RA and avoid an air lock in the cardiopulmonary bypass circuit. The IVC cannula is placed in the right atrial appendage and turned inferiorly, whereas the superior vena cava (SVC) cannula is inserted into the body of the RA close to the SVC and turned superiorly. This strategy of crossing the cannulas permits them to be easily retracted from the operative field during mitral and tricuspid surgery (Fig. 23.4). In select cases of redo mitral and tricuspid valve surgery, direct cannulation of the SVC and IVC helps expose both valves, especially if a transseptal approach is used.
· The operation is performed under cardiopulmonary bypass and mild hypothermia, with or without the use of aortic cross-clamping. During isolated tricuspid surgery, we may avoid cross-clamping the aorta. Not cross-clamping prevents cardiac ischemia and enables the evaluation of tricuspid valve motion and the consequences of each suture placement (conduction tissue). A sump sucker is placed in the coronary sinus to improve exposure.
· During multivalve surgery, aortic cross-clamping is essential, and we use antegrade cold blood cardioplegia supplemented with retrograde cardioplegia—direct cannulation of the coronary sinus. We repair the tricuspid valve at the end of the operation, after the left-sided lesions have been addressed, while the patient is being rewarmed. Some centers advocate removing the cross-clamp at this point, but we keep it in place because it improves surgical exposure by working on a bloodless field and motionless heart and puts less stress on the heart while adding just a few minutes to the total aortic cross-clamp time.
· The tricuspid valve is exposed through a conventional oblique right atriotomy, starting from the atrial appendage and passing approximately 2 cm posterior to and parallel with the AV groove toward, but not close to, the IVC. The atriotomy edges are retracted with sutures or a retraction device.
· Meticulous closure of the RA is important to reduce the risk of bleeding, especially in the presence of right-sided dysfunction and pulmonary hypertension. Sometimes, it is essential to support the suture line with pericardium or felt. We always use a double suture line for RA closure. The repair is assessed by careful inspection of the valve by echocardiography and direct visualization by the surgeon.
|Figure 23.4 Cannulation for tricuspid valve surgery|
· De Vega annuloplasty is a simple and inexpensive procedure that does not interfere with the conduction or leaflet tissue while effectively reducing the tricuspid annulus size.28 Because of its simplicity, it requires little additional cross-clamp time and can be performed concomitantly with aortic and mitral surgery.
· The De Vega technique is most applicable to those patients with TR as a result of mild annular dilation (< 50 mm) in whom it is anticipated that good long-term function does not depend on the integrity of the repair. In these situations, the De Vega annuloplasty provides a competent tricuspid valve during the early postoperative course, while the heart remodels after surgical treatment of the left-sided valvular lesions. This may diminish the risk of immediate postoperative RV dysfunction.
· We use the De Vega repair in patients undergoing left-sided valve surgery who have 2+ TR or less and a tricuspid annular dimension less than 50 mm. If there is more than 2+ TR or annular dilation greater than 50 mm, an annuloplasty band should be the norm.
· We use a modification of the De Vega technique that involves the use of two double-armed, pledgeted, 3-0 polytetrafluoroethylene sutures (Fig. 23.5). The first suture is passed as a circular stitch in a counterclockwise direction from the posterior-septal commissure to the middle of the anterior leaflet. Deep bites are taken every 5 to 6 mm into the endocardium and fibrous ring at the junction of the tricuspid annulus and RV free wall. The second limb of the first suture is run parallel to and 1 to 2 mm outside the previous suture in the same counterclockwise direction. At the middle of the anterior leaflet, both sutures are placed through a second pledget. Another double-armed, pledgeted, 3-0 Gore-Tex suture is passed as a circular stitch in the same manner in a clockwise direction, starting from the anterior-septal commissure to the middle of the anterior leaflet. The two sutures are then tightened and tied, producing a purse string effect to reduce the length of the anterior and posterior sections of the annulus and provide adequate leaflet coaptation. The orifice should be able to admit 2.5 to 3 fingerbreadths snugly through the valve, or a 30-mm Hegar sizer may be used.
· Bicuspidization of the tricuspid valve would be considered as a simple technique complementary to annuloplasty in case of a very large annulus or significant tethering or prolapse of the leaflets to repair TR and may achieve good long-term results. Essentially, this procedure converts the tricuspid valve into a bicuspid valve. Interrupted 4-0 polypropylene sutures can be placed between the anterior and posterior leaflets (more often) or between the posterior and septal leaflets to create a bicuspid valve (Fig. 23.6). This process is always combined with an annuloplasty band and occasionally with an edge-to-edge repair similar to the Alfieri technique for mitral valve repair, as described in the following. Concurrently, the posterior annulus may be plicated with a 2-0 or 3-0 polyester suture, with or without pledgets. This usually yields excellent leaflet coaptation while ensuring an adequate orifice for flow
Figure 23.5 De Vega technique.
Figure 23.6 Bicuspidization of tricuspid valve.
· To produce a reduction of the tricuspid annulus with the best long-term durability, an annuloplasty ring or band should be used. The options include the use of a rigid ring (e.g., Carpentier-Edwards), flexible ring (e.g., Duran), or flexible band (e.g., Cosgrove annuloplasty system) or 3D annuloplasty rings (e.g., contour 3D, GeoForm, 3D MC3).16-18 The area of the anterior leaflet or the length of the base of the septal leaflet (intertrigonal distance) may be used to determine the appropriate size. Alternatively, we prefer to implant a tricuspid band identical in size to the mitral band used during the left-sided valve repair. These ring and band devices are designed to restore the valve to its normal configuration and, importantly, to avoid suture placement in the region of the AV node.
· Gentle tension is applied to the tricuspid leaflets during placement of the annulus sutures to identify the exact location of the thin tricuspid annulus. Mattress sutures are placed circumferentially, with wider bites (7 to 8 mm) on the annulus and smaller corresponding bites (4–5 mm) through the fabric of the ring or band (Fig. 23.7). We use finer sutures and needles, typically 4-0 polypropylene, with strong bites passing into the deeper part of the annulus to avoid tearing of the sutures through the fragile annular tissue,
◆ In the setting of complex lesions and severe residual TR, an edge-to-edge tricuspid valve repair may be used as an effective adjuvant procedure to annuloplasty repair. The edge-to-edge technique was originally described by Alfieri for the purpose of mitral valve repair and may be applied to the tricuspid valve in a similar fashion. One technique of edge-to-edge repair involves the use of a stay suture attaching the free edges of each of the three leaflets at the site of the regurgitation. A 4-0 or 5-0 polytetrafluoroethylene suture reinforced with a small pericardial pledget is passed through the middle point of the free edge of each of the leaflets, just at the level where the leaflet turns down to attach to the primary chordae. This effectively creates a triple-orifice tricuspid valve, producing a clover-shaped valve (Fig. 23.8A). A second suture is always used to reinforce the repair.
◆ Alternatively, a double-orifice technique may be used. This is achieved first by bicuspidization of the tricuspid valve with a plication suture along the posterior leaflet annulus. Subsequently, the edge-to-edge repair approximates the septal and anterior leaflets using 4-0 or 5-0 Gore-Tex U stitches at the midpoint of these two leaflets. This achieves a double-orifice edge-to-edge repair in a manner similar to the Alfieri mitral repair. A second suture is used to reinforce the repair, and the two orifices are measured with sizers to ensure that each is at least 14 mm in diameter (see Fig. 23.8B).
◆ In complex tricuspid valve lesions, such as myxomatous degeneration with prolapse or flail leaflets, stitching the ventral areas of the three leaflets produce what is called a clover-shaped valve (Fig. 23.9). This technique should be supported with ring annuloplasty.
Figure 23.7 Annuloplasty band insertion.
Figure 23.8 Edge-to-edge repair of tricuspid valve.
Figure 23.9 Clover leaf repair of tricuspid valve.
· Assessment of tricuspid valve competence after repair is achieved by filling the RV with cold saline and applying pressure on the main pulmonary artery to observe leaflet apposition. Residual leakage or distortion mandates additional repair maneuvers to achieve coaptation. Although open assessment of the tricuspid valve is important, the most accurate evaluation of the adequacy of tricuspid repair is performed using TEE after the patient has been weaned from cardiopulmonary bypass. If the result appears inadequate, further repair should be performed; alternatively, replacement may be necessary.
· As opposed to MV repair, residual mild TR is considered a good and accepted result of tricuspid valve repair. TR function and RV function need to be assessed at the same time, particularly for functional TR repair.
Step 7. Tricuspid Valve Replacement
· When the severity of valvular distortion prevents a satisfactory repair procedure, valve replacement becomes mandatory. Ideally, the subvalvular apparatus should be retained to optimize postoperative RV function, with the leaflet tissues incorporated into the suturing of the prosthesis to the annulus. If the subvalvular apparatus and leaflet tissues are diseased to the point that they will interfere with prosthesis insertion or function, their resection is necessary. However, a 2- to 3-mm fringe of leaflet tissue is left on the annulus, and the septal leaflet is always preserved. The cordal attachments are divided deep in the RV.
· As in mitral valve replacement, the prosthesis size is selected based on the diameter of the AV ring sizing the anterior leaflet. Interrupted pledgeted mattress sutures (2-0 or 3-0 polyester) are passed through the annulus using an intraannular everting technique (Fig. 23.10, 1). Along the area occupied by the septal leaflet, the sutures are placed in the fringe of leaflet tissue to avoid damaging the AV node and bundle of His. The sutures are then passed through the sewing ring of the prosthesis (see Fig. 23.10, 2a), and the prosthesis is parachuted down into the annulus. Subsequently, the sutures are tied and cut (see Fig. 23.10, 3a). Care is taken to avoid injury to the RV endocardium as the prosthesis is passed into the decompressed ventricle. Alternatively, pledgeted mattress sutures may be placed along the septal annulus only, followed by continuous running sutures along the anterior and posterior sections of the annulus (see Fig. 23.10, 2b and 3b).
Step 8. Special Situations
1. Tricuspid Valve Endocarditis Repair
· There is a growing interest in applying Carpentier repair techniques in patients with tricuspid valve endocarditis. Pericardial patching of perforations and ring annuloplasty are standard techniques to produce competent valves and avoid replacement. Moreover, limited resection of a diseased anterior or septal leaflet may be performed. The affected portion is excised in a trapezoidal fashion, and 2-0 polyester sutures are used to plicate that specific annulus segment locally. Subsequently, the resected leaflet edges are reapproximated with interrupted 5-0 or 6-0 polypropylene sutures. A permanent pacemaker may be necessary in those patients who require septal leaflet resection and repair (e.g., patients with complete heart block). If the posterior leaflet is involved, the diseased tissue is removed, and bicuspidization of the tricuspid valve usually results in a competent valve.
2. Tricuspid Valve Endocarditis Resection
· There is an inherent risk involved with valve replacement in patients with ongoing intravenous drug addiction. With active tricuspid valve endocarditis in the setting of drug addiction, the three leaflets and their chordae can simply be excised. A 2- to 3-mm fringe of leaflet tissue is left on the annulus to enable late prosthesis insertion during a reoperation when the addiction is under better control.
· Development and/or progression of tricuspid valve regurgitation after correction of left-sided valve surgery as a result of untreated tricuspid valve regurgitation at the time of left-sided valve surgery or as a result of failed tricuspid valve repair present a challenging situation. One of the challenges for patients with long-standing tricuspid insufficiency is the surgical indications caused by the presence of variable degrees of RV dysfunction, such as pulmonary hypertension and the consequences of severe, chronic, right-sided dysfunction.
· Another challenge is performing surgery in a patient who has a distorted tricuspid valve morphology in the form of severe dilation of the tricuspid annulus, which is usually associated with significant tethering of the tricuspid leaflet and advanced remodeling of the right ventricle. In those cases, tricuspid valve repair alone is often unable to restore durable competence of the tricuspid valve, and most of those patients will need tricuspid valve replacement.
· Finally, there is the challenge of surgical access and exposure in redo settings, with adhesion of the RV to the posterior sternal surface and the possibility of injury to other vital structures during redo sternal reentry. The right anterolateral thoracotomy may offer a safe reentry for isolated tricuspid valve repair; otherwise, secure femoral access and/or initiation of cardiopulmonary bypass peripherally may be required before sternal reentry. In the case of peripheral cardiopulmonary bypass, control of the vena cava may be a challenging task.
· The hospital mortality is usually higher, and the late outcome is often disappointing; inadequate patient selection might be a contributing factor. The predominant causes of death are low cardiac output syndrome and continuing heart failure. The major factors limiting survival are the preoperative condition of the right ventricle, severity of secondary renal and hepatic impairment, and presence of preoperative, severe pulmonary hypertension, for which TR is considered as a safety valve. This highlights the importance of performing surgery early, before the development of significant right-sided dysfunction, and the careful selection of patients for surgery.
Step 9. Postoperative Care
· Weaning from cardiopulmonary bypass and early postoperative care may be particularly challenging in patients with severe preoperative pulmonary hypertension (e.g., mitral stenosis) and RV dysfunction. RV preload should be optimized with volume infusions to improve contractility. However, a right atrial pressure higher than 18 mm Hg may lead to overdilation of the RV. TEE may be helpful in titrating the patient’s volume status. Inotropic support with intravenous milrinone or dobutamine is usually necessary to allow weaning from cardiopulmonary bypass. In severe cases of pulmonary hypertension, however, pulmonary vasodilators (e.g., inhaled nitric oxide, intravenous prostaglandins) may be required to reduce RV afterload in the early postoperative period. Later in the postoperative period, when patients are off inotropic support and recovering on the ward, diuretic agents are aggressively used to treat the characteristic fluid retention in these patients.
· Complete heart block can occur after surgery owing to damage to the conduction system during tricuspid valve procedures (1%–2%). This risk may be increased more than 10% especially in multivalvular procedures, and the presence of preoperative left bundle branch block.
· Ideally, the anchoring sutures for the tricuspid prosthesis should be placed well away from the conduction tissue. After concurrent tricuspid and mitral valve replacement, complete heart block is fairly common. The presence of two rigid prosthetic sewing rings is thought to produce ongoing trauma and eventually lead to AV node dysfunction, either in the immediate postoperative period or months to years after surgery. Approximately 10% of patients receiving double-valve replacement require insertion of a pacemaker in the postoperative period, and the prevalence of this is 25% up to 10 years after surgery. Because of this risk of complete heart block during the initial hospital stay, electrocardiographic monitoring should be continued until discharge. Consideration should also be given to placing permanent epicardial pacemaker leads at the time of surgery.
· Long-term anticoagulation is necessary when mechanical prostheses have been inserted in any of the valve positions. Warfarin administration is started on the evening of postoperative day 1 or 2. Occasionally, intravenous heparin is used until the international normalized ratio is therapeutic, particularly in the context of two or more mechanical prostheses and atrial fibrillation. However, there does not appear to be any evidence to support the practice of intravenous heparin therapy early in the postoperative course in a patient with a single mechanical prosthesis. Long-term anticoagulation is controversial if a bioprosthesis is used in the tricuspid position when bioprostheses have been used for other valve replacements. Regardless, a large number of patients with tricuspid bioprostheses eventually develop other indications (e.g., atrial fibrillation) for long-term anticoagulant treatment.
Step 10. Results of Tricuspid Valve Intervention
· The recurrence rate of significant tricuspid insufficiency after tricuspid annuloplasty is around 8% to 15% as soon as 1 month after surgery and has been attributed to several factors. These include the severity of preoperative TR, pulmonary hypertension, presence of RV dilation, presence of pacemakers, LV dysfunction, increased LV remodeling, severe tethering of the tricuspid leaflets, and use of the De Vega technique rather than ring annuloplasty. Most of the published studies, both randomized and observational, have demonstrated that ring annuloplasty repairs are more durable than suture annuloplasty, particularly in patients with severe tricuspid annular dilation or pulmonary hypertension.
· Long-term survival after tricuspid valve surgery for severe TR is affected by several preoperative factors, including advanced heart failure symptoms, comorbidity, and end-organ dysfunction, more than by the type of surgery or cause of TR. Ring annuloplasty may be associated with better results compared with the De Vega technique. The results of annuloplasty alone are not always consistent. Among other factors, this may be related to the degree of narrowing of the tricuspid orifice; hence, it has been suggested that the size of the tricuspid annulus should be reduced appropriately, considering the patient’s body size, to prevent recurrent TR.
· Tricuspid valve replacement is associated with the adverse impact of prosthesis-related complications, which tend to appear late in the follow-up. There are no technical differences between replacement with bioprostheses and mechanical valves. However, mechanical valves in the tricuspid position in multivalvular procedures are generally associated with a higher mortality rate and also with an increased incidence of thromboembolic complications and valvular dysfunction by pannus, although thrombolysis appears to lead to more favorable results here. On the other hand, bioprostheses appear to degenerate faster in the tricuspid position, especially in younger patients. However, with the advent of percutaneous valve-in-valve implantation, this may be less of a problem in the future.
· A transcatheter approach for tricuspid valve repair or replacement is attractive, desirable, and beneficial to this high-risk population as an alternative to surgery but is still not currently ready to be in routine use. Some of the concepts that have been developed for the percutaneous treatment of mitral regurgitation may be adapted to percutaneous repair of the tricuspid valve percutaneous annuloplasty, edge-to-edge repair, similar to the use of a MitraClip (Abbott, Abbott Park, IL). Different new devices are currently under preclinical development.
· The first percutaneous transcatheter valve-in-valve implantation in a stenosed tricuspid valve bioprosthesis was done in 2011, among other case reports with small patient numbers. To date, two percutaneous devices have been described for transcatheter valve implantation in failing bioprosthetic valves. These are the Edwards SAPIEN valve (Edwards Lifesciences) and its iterations and the Melody valve (Medtronic). However, none of them have been approved or certified to be delivered in the tricuspid position. Therefore, implantation of these devices in tricuspid position is off-label use. The feasibility of percutaneous deployment of stent-mounted valves (e.g., SAPIEN, SAPIEN XT, Melody) into the venous system (IVC and/or SVC) is still being investigated. The focus is not on the TR itself, but rather on its hemodynamic disturbance. These procedures are therefore termed caval valve implantation.
· The transcatheter approach to the tricuspid valve presents challenging technical issues, such as the large dimension of the tricuspid annulus, slow flow of the right heart side, and trabeculated structure of the right ventricle. With regard to access, the angulation of the annulus in relation to the SVC and IVC should be considered. In contrast to the left ventricle, the RV wall is thinner than the LV wall; multiple chordae may prevent the advance of the delivery system and represent a technical challenge to the transapical approach.
Step 11. Pearls and Pitfalls
· Tricuspid valve repair may also be considered for less than severe TR in patients undergoing mitral valve surgery when there is pulmonary hypertension or tricuspid annular dilation. In patients requiring a redo operation for tricuspid valve surgery, the RV is often dilated and adherent to the posterior sternum. Great care should be exercised during the redo sternotomy. If a preoperative computed tomography (CT) scan has shown that there is less than 5 mm of space between the RV and posterior sternal table, peripheral cardiopulmonary bypass initiation is required.
· We use a combination of sharp dissection, oscillating saw, and sternal elevation to perform the redo sternotomy. Blunt digital dissection should be avoided because of the risk of injury to the often friable RV free wall.
· Bicaval cannulation is necessary during tricuspid operations. The SVC cannula may be placed in the body of the RA and steered superiorly, or it may be placed directly in the SVC itself. The sinoatrial (SA) node rests at the anteromedial junction of the RA and SVC. Therefore, the cannulation site should be 2 cm superior or inferior to this region to avoid SA node injury. The atrial incision should be well away from the SA node, and the superior extension of the incision should be limited to 1 to 2 cm from the superior margin of the RA.
· One of the major challenges of tricuspid surgery lies in the placement of sutures. The depths of the suture bites in the annulus must be substantial to avoid tearing through the tissues. However, the sutures should be placed well away from the conduction tissue, coronary sinus, and right coronary artery to avoid iatrogenic injury.
· Long-term surgical follow-up studies have demonstrated that 2+ TR or more and severe tricuspid annular dilation predict the development of late severe TR and the need for tricuspid reoperation. Therefore, ensuring the adequacy of tricuspid repair during the initial operation is critically important.
· Special care should be taken to assess the foramen ovale for patency in all tricuspid operations. These lesions can easily be closed with sutures to reduce the possibility of systemic desaturation from right-to-left shunting, especially in the context of pulmonary hypertension, and to reduce the risk of paradoxic embolization.
· Consideration should be given to placing permanent epicardial ventricular pacing leads in patients undergoing combined mitral and tricuspid valve replacement; up to 25% postoperative complete heart block and transvenous endocardial lead placement might be difficult in tricuspid valve replacement or repair with edge-to-edge repair. RV free wall epicardial pacemaker leads can be placed with ease at the time of surgery, and they can be buried in a pocket anterior to the posterior rectus sheath in the left upper quadrant for later permanent pacemaker implantation, if required.