Tricuspid annuloplasty for functional regurgitation
Functional tricuspid regurgitation remains a challenge in term of its precise diagnosis, indications and appropriate surgical treatment. Regression of functional tricuspid regurgitation even after correction of left sided lesions is not certain as it may progress or become stationary [1, 2]. Desirable surgical techniques for tricuspid repair should confer long term stable physiologic and anatomic correction [3, 4, 5]. Cardiac surgeons have to be aware and familiar to all available repair techniques. These include suture annuloplasty, such as semicircular (classical De Vega repair) or simple lateral annuloplasty (Kay), novel techniques such as edge-to-edge or clover technique and suture bicuspidization technique, use of flexible and rigid prosthetic rings or 3D rings, flexible prosthetic bands. Pericardial patch annuloplasty is a promising technique being simple, cost effective and claims long term stable physiologic and anatomic correction .
The tricuspid orifice is the largest of the four cardiac valves, and in normal adults, the valve area is around 7-10 cm2 and the diameter is 36 ± 4.5mm [7, 8]. Anatomic studies had shown that dilatation of the annulus does not affect the three leaflets to the same degree . In congestive heart failure, the tricuspid annulus may be 40 to 45mm in diameter. With right ventricular dilatation, the tricuspid annulus enlarges along the major portion of the attachment of the posterior leaflet (up to 80%), the anterior leaflet (up to 40%), and the lateral third of the septal leaflet (up to 10% only) [8, 9]. Distension also affects the posteroseptal and anteroposterior commissures and to a lesser extent the anteroseptal commissure (fig1) .
3. Clinical presentation
Functional tricuspid regurgitation usually affects middle aged female and it's more common with left sided lesion [10, 11, 12]. Symptoms of left sided valve lesion (if present) dominate early [13, 14] but systemic venous congestive symptoms expressed late according to severity of tricuspid regurgitation [11, 13]. General signs include, cachexia, jaundice, cyanosis, ascites, enlarged tender liver with systolic hepatic pulsation, hepatojugular reflux, congested neck veins in > 50% showing prominent "v" wave up to 75% and lower limb edema [8, 13]. Venous Corrigan's sign occurs if prominent "v" wave followed by prominent "y" wave . Atrial fibrillation has a good relation to tricuspid regurgitation and change the murmur intensity [11, 14]. The systolic pulse of tricuspid incompetence is an early sign, and occurs late in systole "Mancisi's sign" . Local examination shows right ventricular enlargement (left parasternal heave and pulsation), right atrial enlargement (right parasternal pulsation) and rarely thrill . Auscultation reveals tricuspid regurgitation murmur (left parasternal soft holosystolic murmur) . Third heart sound could be heard .
It has no characteristic finding but evidence of right sided enlargement, atrial fibrillation, left sided enlargement, or combination could be present [13, 14].
4.2. Chest Roentgenogram
Marked cardiomegaly secondary to the condition responsible for the dilatation of the right ventricle is usually evident . Right atrial enlargement and right ventricular enlargement is common finding in significant tricuspid regurgitation .
Tricuspid regurgitation was classified by Miyatake into four grades using pulsed Doppler echocardiography. The maximal extent of the regurgitant signal was measured from the coaptation point of the tricuspid valve. It is 1 + if the maximal extent of regurgitant signal was 14 mm, 2 + if it is from 15 to 29 mm, 3 + if it is from 30 to 44 mm and 4+ if it is > 45mm . Doppler echocardiography has shown to correlate well with that demonstrated by contrast echocardiography and right ventriculography .
4.4. Cardiac Catheterization
Ventricularization of right atrial pressure (> 10 mmHg) is the most reliable sign [13, 17]. Functional tricuspid incompetence is seldom seen without significantly increased pulmonary artery pressure  or right ventricular systolic pressure . Duran and coworkers defined tricuspid insufficiency angiographically as the presence of contrast medium in the right atrium in the absence of premature ventricular contractions .
4.5. Magnetic Resonance Imaging
Excellent correlation has been demonstrated between cine magnetic resonance imaging and Doppler Echocardiography or cardiac catheterization . Cine magnetic resonance imaging provides an effective, non-invasive and easily reproducible mean of documenting tricuspid regurgitation and any valvular heart disease. Regurgitant lesion can be seen as areas of relatively decreased signal intensity in the cavity as a result of turbulent blood flow surrounded by relatively high signal from normal laminar blood flow .
5. Operative assessment
Assessment of tricuspid regurgitation is a difficult challenge and could be misleading due to decrease in pulmonary artery pressure after chest opening and preoperative medical treatment [23, 26]. Lellehei and associates recommend direct finger palpation through the right atrium in the beating heart before institution of bypass and by direct inspection if any doubt exists [22, 27].
Arguments about the management of tricuspid insufficiency didn't stop for the last three decades. This was provoked by the concept that functional tricuspid incompetence is reversible once the left-sided lesion is corrected. However, Grondin and colleagues  stated that the distinction between organic and functional tricuspid incompetence is of academic interest and it does not indicate which method of management is most suitable. Attitudes towards correction of tricuspid incompetence have been varied between conservative management and surgical intervention.
6.1. Conservative Management
Controversy occurred between surgeons in efficacy of conservative management of functional tricuspid regurgitation. The widely accepted idea is to be conservative only, if tricuspid incompetence is of trivial or mild degree with normal valve structure and normal ring .If failure of the right side of the heart, in patients with tricuspid regurgitation, is caused by mitral valve disease, early surgical intervention for repair or replacement of the mitral valve, is the best management . Early intervention for left sided valve lesion is the only best prophylactic measure of tricuspid regurgitation .
6.2. Surgical Intervention
Tricuspid valve repair came to light due to progressive natural history of tricuspid regurgitation with higher mortality especially if it's moderate or more and higher incidence of complications following replacement [31, 32]. Carpentier and associates in 1971 published his prosthetic ring as a new reconstructive operation for correction of tricuspid insufficiency. In 1972 De Vega introduced his semicircular technique of annuloplasty in Spain with gratifying results. The three general techniques of tricuspid annuloplasty used to correct functional tricuspid regurgitation are annular plication, annular ring insertion and semicircular annuloplasty .
6.2.1. Annular plication (Kay's Technique or Wooler Annuloplasty):
This is described by Kay in 1965 as mattress or figure of eight sutures placed in the annulus beginning at the commissure between the septal and the posterior leaflets (posteroseptal commissure) and extends medially towards the anteroposterior commissure. These sutures obliterate most, if not all, of the annulus of the posterior leaflet. Usually, three or four sutures of 1-0 silk are required to decrease the size of the annulus to two and half finger breadths. The sutures are pulled taut but not tied until the surgeon is satisfied with the size of the annulus. After tying the sutures, it is difficult to alter the valve configuration. For this reason the repair is maintained by pulling the sutures snug before tying. Basically, a large tri-leaflet valve is converted into a smaller mitral like valve i.e. bicuspidization of the tricuspid valve .
6.2.2. Semicircular suture annuloplasty
220.127.116.11. De Vega Annuloplasty
Since Nerberto G. De Vega, introduced his new technique of semicircular annuloplasty in Madrid 1972, it became extensively used in many centers. Many authors got convinced with the technique as it could be performed rapidly, provides pliable cusps, eliminates insertion of foreign material and is free of the risk of atrioventricular block as there was no need to place sutures in the septal part of the tricuspid annulus . In this method, the right atrium is opened in a longitudinal direction. A double armed needle suture of Ethibond 2-0 is started at the anteroseptal commissure and good bites are taken forward every 5 to 6mm. around the annulus. It is passed around to encircle the base of the anteroseptal commissure, anterior leaflet, anteroposterior commissure, posterior leaflet, posteroseptal commissure and about half of a centimeter of the septal ring. The second needle is passed through a Teflon pledget than courses the same way 2mm parallel to the first to come out through another pledget on the other end. The purse string suture is tied with two fingers inside the orifice to ensure that the proper diameter is produced . De Vega in 1980, reported on 500 patients with this technique over a period of ten years with gratifying results.
The De Vega technique has contributed to a substantial reduction in hospital morbidity and mortality of patients with multiple valve disease, offering good early functional results. However, the usual De-Vega technique is associated with disadvantages such as insufficient reduction of the orifice, insecure annular plication, and recurrence of insufficiency by persistence of annular dilatation . To avoid these drawbacks, possibility of detachment and unpredictability, many modifications have been introduced. To avoid suture detachment, De Vega advised to take deeper stitches . Castro in 1975 passed the purse string suture over a Teflon tape 3 to 4mm wide with the determined length and plicate the annulus over it . Imamura and coworkers suggested that another supporting ligature applied at the root of the knots of annuloplasty suture may provide additional aid in preventing late suture dehiscence . To Ensure Predictability, De Vega advised to tighten the suture around 2 fingers. Meyer and Bircks in 1977 suggested tying the De Vega suture around an individually selected obturator head. The dimensions of the obturator are based upon the size of Carpentier tricuspid ring, selected according to the length of the septal annulus .
Despite these previous modifications, De Vega technique showed substantial worsening in later tricuspid regurgitation. Theoretically, non ring repairs may be affected with persistent pulmonary hypertension allowed the annulus to gradually redilate due to persistent right ventricular systolic hypertension .
18.104.22.168. Segmental Tricuspid Annuloplasty
Jose M. Revuelta in university of Cantabaria, Santander, Spain, and Raul Garcia-Rinaidi in Texas, Houston introduced "Segmental Tricuspid Annuloplasty" technique. To avoid suture tear of the periannular tissues, interrupted stitches are placed over Teflon pledgets . Because this technique does not require installation of prosthetic ring, it is fast, technically simple and prevents a common cause of failure of the De Vega procedure which is tearing of the suture from the myocardium. When excessive stress causes the single, continuous suture to tear, the suture is string across the tricuspid orifice, a condition called "Guitar-string tricuspid" and tricuspid insufficiency recurs .
6.2.3. Ring Annuloplasty (Annular Ring Insertion)
Disappointed with the results of annular plication, and basing their technique on the anatomic studies of Deloche and colleagues in 1973, Carpentier and associates devised the ring annuloplasty. This was first introduced in the fiftieth annual meeting of the American Association of Thoracic Surgery in 1970. Three sizes of rings were first available (26, 28 and 30) . Others have devised similar flexible rings for functional tricuspid incompetence .
6. 2.3.1. Carpentier Ring Annuloplasty
In this technique a prosthetic ring of the proper size is chosen to reconstruct the tricuspid annulus. According to the excellent anatomical studies of Deloche and colleagues, the tricuspid annular dilatation is proved to be asymmetrical affecting maximally the posterior leaflet and the areas of the commissures . The size is chosen according to the measurement of the base of the septal leaflet by the obturator, this is facilitated by applying two traction sutures at the anteroseptal and the posteroseptal commissures. Then a series of twelve to fifteen horizontal mattress interrupted sutures are placed at equidistant points around the annulus. The initial rigid ring was modified to be flexible and C-shaped.
22.214.171.124. Flexible Linear Reducer Annuloplasty
Flexible linear reducer consists of a silicone polymer encasing a braided Dacron core with two notches which allow accommodation of the suture knots and the fold of the annular tissue. It is available in 20cm segments, of which the suitable length is taken. The reducer is fixed by mattress sutures only onto the distended portion of the annulus, namely the anterior and posterior leaflets and the commissural area. The adequate length is twice the length of the septal leaflet and the anterior leaflet insertion should be twice that of the posterior leaflet. Hecart et al, 1980, stated that this technique is easy, quick and reliable and avoid the risk of atrioventricular block and preserves annular flexibility.
6. 2.3.3. The Cosgrove-Edwards annuloplasty band system
A universally flexible annuloplasty band is used in Cosgrove-Edwards annuloplasty system that provides a measured plication of the anterior and posterior annulus. The risk of injury to the conduction system is eliminated as no sutures are placed along the septal annulus . Short-term and midterm results with this surgical technique was described by McCarthy and Cosgrove . The appropriate size was selected according to the length of the septal annulus using the tricuspid sizing obturator. The Cosgrove-Edwards annuloplasty system appears to be a valid option for surgical treatment of secondary tricuspid regurgitation as it is a simple, safe, and easily reproducible .
126.96.36.199. Three dimensional remodeling ring annuloplasty
In 2002, a new generation of prosthetic rings was introduced. The Edwards MC3 ring system has adopted the concept of the remodeling annuloplasty. This ring has a 3-dimensional design and is preconfigured to best accommodate the saddle shape of the annulus. The implantation of this ring was relatively simple and provided excellent early clinical and echocardiographic results. This 3-dimensional configuration may offer a potential advantage with respect to increased stabilization of the annulus. However, the durability of this repair must be assessed with long-term prospective randomized studies. 
6.2.4. Tricuspid annuloplasty using autologous pericardial strip
Beginning in 1998, Chang and associates in Yonsei University College of medicine in Korea developed a new method of tricuspid annuloplasty using glutaraldehyde treated autologous pericardial strip. The pericardium was secured to the tricuspid annulus with interrupted mattress non-absorbable sutures.; they stated that the pericardial annuloplasty for tricuspid regurgitation is considered to maintain annular structures, flexibility of right ventricular pumping function, and to prevent redilatation . This previous conclusion correlates with De la zerda and associates study in David Geffen school of medicine in Los angeles, they concluded that the results of their study indicate that using autologous pericardium for tricuspid annuloplasty is a useful procedure for cases with moderate or severe tricuspid regurgitation, as this technique is a durable and , reproducible . De la zerda and associates were used two rows of continuous horizontal mattress Gore-Tex sutures to secure the the glutaraldehyde-treated pericardium to the tricuspid annulus .While in Chang and associates study they preferred interrupted rather than continuous sutures to minimize annular tear (fig2). We found the technique is quite feasible and effective in producing excellent intra and post operative results. Among its several advantages, it is ready, available without cost, resists infection and flexible allowing growth in the pediatric age group. Our surgical technique is different from Chang in that we perform the repair on a beating heart, which give us better assessment of the tricuspid valve before and after the repair. This also helps in shortening the aortic cross clamp and bypass times which will reflect positively on the morbidity and mortality results of those critical patients. We decide the length of the strip according to the appropriate tricuspid obturator sizer measuring along its rounded margins between the two notches. We prefer to cross the antero septal and the postero septal commissures for better anchoring the repair to the fibrous skeleton of the heart and to minimize recurrence. Testing the tricuspid valve intra operatively we use the coronary sinus suction test in which we apply the pump sucker to the coronary sinus and if the tricuspid valve is competent there should be no blood in the right atrium. Postoperatively, we noticed dramatic decrease in the liver size of those patients in addition to the echocardiography findings as reported by Chang .
6.2.5. Postoperative management
It is relatively common for the cardiac output to be marginal after tricuspid valve surgery. This is usually a reflection of persistent pulmonary hypertension and long-standing right ventricular dysfunction. Nitroglycerin infusion is helpful in reducing pulmonary artery pressure . Intravenous dopamine and dobutamine are used to enhance myocardial contractility. Pulmonary artery balloon counterpulsation has been employed for acute right ventricular failure . Use of a temporary circulatory assist device, such as a centrifugal pump, to bypass the right ventricle may sustain adequate circulation when right ventricular failure is unresponsive to other measures. Digitalis and diuretics are usually employed for several months after tricuspid valve surgery.
6.2.6. Risk factors for recurrent or residual tricuspid regurgitation after tricuspid valve annuloplasty
If significant residual tricuspid regurgitation is left uncorrected, the postoperative morbidity and mortality may be substantially increased [54, 55]. When tricuspid regurgitation is moderate to severe, the risk of operation is significantly increased though long-term improvement in tricuspid regurgitation after mitral valve replacement alone had been documented . Recent study of long-term results after tricuspid valve surgery has identified risk preoperative factors mainly left ventricular function, severe tricuspid valve tethering and high mean pulmonary artery pressure, as important predictors of long-term survival . The results of tricuspid valve surgery must be interpreted with regard to early and late results of mitral and double valve procedures . Indications for tricuspid valve surgery cannot be dissociated from operations of left-sided lesions so results of tricuspid valve operations depend on the appropriate procedure for aortic or mitral valve lesions, the degree and reversibility of left ventricular dysfunction, the degree and reversibility of pulmonary vascular resistance, and the severity of right ventricular dysfunction. Therefore, better results occur if patients present for operation early in the course of congestive heart failure . Duran and Colleagues in 1990, reported that 80% of patients with preoperative tricuspid incompetence did not have postoperative tricuspid regurgitation with low pulmonary vascular resistance, compared with patients with high pulmonary vascular resistance. . Residual tricuspid regurgitation is four times more likely to persist if pulmonary peripheral vascular resistance remains elevated than if it regresses . Approximately 30% of patients have small or moderate postoperative tricuspid systolic gradients after repair and most residual gradients of incompetence are not clinically important if hemodynamic correction of the left-sided heart disease is adequate . Baughman and colleagues at Massachusetts General Hospital reported that male sex, New York heart association functional class IV dyspnea, ascites or pulmonary edema, elevated preoperative bilirubin, mean pulmonary artery pressure greater than 40mmHg and elevated pulmonary vascular resistance, all were associated with increased risk of death after operation. Multivariate risk analysis, identified severity of peripheral edema and level of pulmonary artery pressure as the most predictive combination of those independent variables . The hemodynamic results of tricuspid annuloplasty are assessed by palpation, valvular gradient, and cardiac output determinations, or contrast echocardiography . Table 1 summarizes the risk factors for recurrent tricuspid regurgitation.
TR, Tricuspid regurgitation; TTE, transthoracic echocardiography; BUN, blood urea nitrogen; MR, mitral regurgitation; CE, Carpentier-Edwards rigid ring; LV, left ventricular; COPD, chronic obstructive pulmonary disease; SE, standard error.*[20/BUN], inverse transformation.†Log [MR 1], logarithmic transformation.‡[Hematocrit/30]2 , squared transformation.§Probability for patient receiving Cosgrove ring.llLog [Probability for patient receiving Peri-Guard annuloplasty], logarithmic transformation.¶Log [Probability for patient receiving De Vega procedure], logarithmic transformation.#[Creatinine]2, squared transformation.**Log [Probability for patient receiving Cosgrove ring], logarithmic transformation.††[1/Probability for patient receiving Peri-Guard annuloplasty], inverse transformation.‡‡Log [Probability for patient receiving De Vega procedure], logarithmic transformation.
6.2.7. Results after tricuspid valve annuloplasty
Color Doppler flow mapping provides accurate assessment of the presence and severity of tricuspid regurgitation so this technique aids in the selection of patients appropriate for tricuspid valve repair and is useful in evaluating the adequacy of the repair . While tricuspid valve plastic procedures have been associated with encouraging clinical results, the variety of currently employed procedures suggests a lack of uniform success. Postoperative hemodynamic evaluation has confirmed this lack of complete physiologic correction, with persistent residual diastolic gradients in 40% to 50% of the patients, and residual tricuspid insufficiency in 30% to 40% following tricuspid annuloplasty [23, 59]. Reducing the orifice size without restoring the shape of the tricuspid orifice results in a 15% stenosis to achieve valve competence. This has been confirmed by hemodynamic studies . Tricuspid valvuloplasty is the treatment of choice for acquired (functional) tricuspid insufficiency. Opinions still differ on the best way to render the valve competent without causing stenosis. All competent annuloplasties result in a significant reduction of the valve orifice and in about half of the cases in a transvalvular gradient .These postoperative hemodynamic observations imply that tricuspid annuloplasty by current techniques require careful balancing of persistent residual tricuspid regurgitation against the potential production of tricuspid stenosis by narrowing the annulus. Ring annuloplasty preserves annular geometry more precisely than the De Vega technique. Follow up of patients 64 months after semicircular (De Vega) annuloplasty revealed recurrence of significant tricuspid regurgitation in 1/3 to 1/2 of the patients, while this occurred in 10% of those treated with ring annuloplasty for a similar period  Others have reported a 5% incidence of severe tricuspid regurgitation requiring valve replacement at 85 months following semicircular De Vega annuloplasty . Prosthetic ring tricuspid annuloplasty has been applied to the reconstructive surgery of the tricuspid valve to support the annulus. In 1983, Carpentier reported on 1345 patients with tricuspid valve repair, of them 1210 were achieved by prosthetic ring annuloplasty and 135 by De Vega annuloplasty with incidence of reoperarion of 0.6% and 6% respectively for failure. Carpentier's rigid ring, lays stress on reducing and remodeling the dilated and deformed annulus to prevent recurrence of annular dilatation and valvular regurgitation while Duran's flexible ring, reduces the annulus with preservation of the physiologic motion and shape of the annulus, and reduces the tension on the sutures to decrease the possibility of the detachment. Both rings showed similar good results clinically. Preference for the flexible ring is in the expectancy of preserving the annular motion and shape. McCarthy and associates reported the superiority of rigid ring annuloplasty compared with suture-based tricuspid annuloplasty because of persistent postoperative pulmonary hypertension .
Minato and Itoh, applying the technology of direct imaging by fiberoptic cardioscopy in 1992, found that: a- All prosthetic rings, whether rigid or flexible reduced and remodeled the dilated tricuspid annuli, and improved the valve coaptation. b- The patterns of annular motions with flexible rings were similar to that of normal annulus. The free wall annulus contracted centripetally, and the septal annulus moved toward the free wall side during systole. With the flexible rings, the motions of the anteroseptal and posteroseptal commissures made possible c- The annular planes is forced to horizontal ones in both the flexible and the rigid rings. The repaired annuli appeared rounder than the native annuli; however, because of the elasticity and round-shaped mold of flexible rings, the annular planes were forced to be horizontal ones. However, rigid rings could reduce and remodel the annuli well, but they forced the undulated annular planes to horizontal ones and disturbed the annular motions completely. The annular motion is apparently a natural reserve power to prevent valve regurgitation by bridging the leaflets by 20% to 40% reconstruction of the tricuspid valve besides repairing the valve complex as normally as possible; preserving the annular motion may be a greater advantage of preventing regurgitation more effectively in various hemodynamic conditions in clinical settings. These findings indicate that the flexible rings are superior to rigid rings in the aspect of reinforcing the valve coaptation to prevent further tricuspid regurgitation. The main disadvantage of the flexible rings is that they disturbed the normal undulation of the tricuspid annulus forcing the annular planes to horizontal ones .d- With semicircular tricuspid annuloplasty, the annular motion was reserved. The tricuspid valve annulus dilates during atrial systole to the maximum size that was restricted by the annuloplasty procedure, and narrowed on both the free wall and septal annuli to the minimum size during ventricular systole. Semicircular tricuspid annuloplasty preserves the annular dilatation and contraction during the cardiac cycle. From these findings, we can suggest that semicircular tricuspid valve annuloplasty is the most reasonable method that does preserve the physiologic annular motions, and also the natural undulation, in the opening and closing mechanism of the tricuspid valve . In Chang and coworkers study, they had evaluated tricuspid regurgitation as a function of time after conventional (De Vega) and autologous pericardial strip tricuspid annuloplasty. They found that, in the suture annuloplasty group, mean tricuspid regurgitation, was decreased significantly after the operation and continue unchanged for up to 3 years, but from 3 to 5 years postoperatively it was increased gradually in most patients. Meanwhile, in the autologous pericardial strip annuloplasty group, mean tricuspid regurgitation improved as a function of time (p = 0.05). This result suggests that autologous pericardial strip annuloplasty is superior compared to suture annuloplasty preventing redilatation of the tricuspid annulus .Table 2 shows the prevalence of severe tricuspid regurgitation across time for various annuloplasty techniques .
TR, Tricuspid regurgitation; CL, 68% conﬁdence limits; N/A, not applicable (not enough patients in follow-up at this time).*Model-based time-related estimates (%)
We conclude that using fixed pericardial C-Shaped strip for repairing of tricuspid regurgitation allows an anatomic and functional reconstruction of the tricuspid valve with a good balance between constriction and dilatation according to accurate measurement; also it is cheap and readily available in almost all situations. Further evaluation and long term prospective randomized studies are needed to improve the current techniques to achieve better results.
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