Fig. 21.1
(a) Measurement of the tricuspid annular diameter by transthoracic echocardiography from an apical four chamber view in mid-diastole. This measures the tricuspid annulus from approximately the middle of the septal annulus to the middle of the anterior annulus (green arrow). The corresponding positions on the tricuspid annulus are shown in (b). (b) Measurement of the tricuspid annulus surgically during the operation. This measures the tricuspid annulus from the antero-septal commissure to the antero-posterior commissure with the heart fully stretched out (red arrows)
What Do the Guidelines Recommend?
The American Heart Association/American College of Cardiology 2014 guidelines on valvular heart disease recommend tricuspid valve surgery in the following situations [3]:
- 1.
Patients with severe TR undergoing left sided valve surgery (Class 1 recommendation, Level of Evidence C),
- 2.
Patients with mild, moderate or greater functional TR at the time of left sided valve surgery when either tricuspid annular dilatation or prior evidence of right heart failure is present (Class IIa recommendation, Level of Evidence B),
- 3.
Patients with symptoms due to severe primary TR that are unresponsive to medical therapy (Class IIa recommendation, Level of Evidence C),
- 4.
Patients with moderate functional TR and pulmonary hypertension at the time of left-sided valve surgery (Class IIb recommendation, Level of Evidence C),
- 5.
Asymptomatic or minimally symptomatic patients with severe primary TR and progressive degrees of moderate or greater right ventricular dilatation and/or systolic dysfunction (Class IIb recommendation, Level of Evidence C),
- 6.
Patients with persistent symptoms due to severe TR who have undergone previous left sided valve surgery and who do not have severe pulmonary hypertension or significant right ventricular systolic dysfunction (Class IIb recommendation, Level of Evidence C).
The classes of recommendation are as follows:
-
Class I: Benefits outweigh the risk. Procedure should be performed.
-
Class IIa: Benefits outweigh the risk but additional studies with focused objectives are needed. It is reasonable to perform the procedure.
-
Class IIb: Benefits may outweigh the risk or may be equivalent. Additional studies with broad objective are needed; additional registry data would be helpful. Procedure may be considered.
The levels of evidence are as follows:
-
Level A: Multiple populations evaluated. Data derived from multiple randomized controlled trials or meta analyses.
-
Level B: Limited populations evaluated. Data derived from a single randomized controlled trial or non-randomized studies.
-
Level C: Very limited populations evaluated. Only consensus opinion of experts, case studies, or standards of care available.
Progression of Untreated Tricuspid Regurgitation
The recommendation to intervene on the tricuspid valve when the tricuspid annulus is dilated in the absence of significant tricuspid regurgitation (TR) was first made by Dreyfus, et al., in 2005 [11]. In an observational study on 311 patients undergoing mitral valve repair in whom tricuspid annuloplasty was also performed if the tricuspid annulus was dilated to more than 70 mm measured intra-operatively (from the antero-septal commissure to the antero-posterior commissure), it was observed that NYHA functional class was significantly better at 5 years in those in whom a concomitant tricuspid annuloplasty was performed. In addition, TR progressed in those who did not have a concomitant tricuspid annuloplasty but not in those who did [11]. The observation that mild or moderate FTR progresses in 15–40 % of patients if left untreated has been reported in numerous other studies including a meta-analysis [7, 10, 12–25]. Goldstone, et al., reported that the proportion of patients with moderate or more TR increased from 7.9 % at baseline to 36 % 9 years after isolated mitral valve surgery, and this was associated with right ventricular dysfunction [10]. Of note, the mean tricuspid annular diameter is this study was 40.1 mm, which is the current threshold size at which concomitant tricuspid valve repair is recommended. The study also reported that FTR progressed in those with only mild TR if the baseline indexed tricuspid annular diameter was greater than 21 mm/m2 [10]. Tricuspid annular dilation, TR severity, right ventricular dysfunction, pulmonary hypertension, atrial fibrillation, enlarged left and right atria and rheumatic etiology are amongst the common risk factors for TR progression which have been identified [7, 10, 22, 23, 26, 27]. In a randomized trial of patients with mild tricuspid regurgitation and tricuspid annular dilatation undergoing mitral valve surgery, patients randomized to receive a tricuspid annuloplasty had less TR progression, improved right ventricular reverse remodeling, and better functional outcomes compared to patients who did not receive a tricuspid annuloplasty [15]. Similar observations have been made in a few other studies [18, 28]. Importantly, several studies have reported an association with reduced survival in those with significant late TR or those in whom there is progression of TR [13, 14, 16, 21, 27, 29]. Re-operations on the tricuspid valve in those who subsequently develop symptomatic severe TR also carries a high hospital mortality of between 14 and 35 % [30–32].
Benefits of Tricuspid Annuloplasty
Correction of significant TR has been shown to improve right ventricular geometry and function, and pulmonary artery pressures [28, 33, 34]. Studies have also shown an improvement in functional capacity and survival following tricuspid annuloplasty [11, 13]. Prophylactic tricuspid annuloplasty performed when the tricuspid annulus is dilated but before the onset of severe TR also prevents the progression of TR and right ventricular dilatation, improves the functional capacity and survival of the patient, and avoids the need for future re-operative tricuspid valve surgery which carries a high operative risk [11, 13, 18].
Surgical Technique
Tricuspid annuloplasty can be performed using either a tricuspid annuloplasty ring or band, or by various suture annuloplasty techniques. Several studies have reported a lower recurrence rate of TR when an annuloplasty ring is used as compared to suture annuloplasty, and some have reported improved survival when an annuloplasty ring is used for tricuspid valve repair [35, 36]. Tricuspid ring annuloplasty will be described in this chapter. Tricuspid suture annuloplasty is covered in a separate chapter.
The tricuspid annulus can be sized by measuring its leaflet area by pulling on the anterior papillary muscle which supports both the anterior and posterior leaflets and using an obturator to determine this size (Fig. 21.2a). It can also be sized by measuring the orifice area by matching the corresponding notches of the obturator to the antero-septal and postero-septal commissures i.e., the length of the septal annulus (Fig. 21.2b). If there is a discrepancy in size between the two measurements, then the size obtained by using the orifice area i.e., the septal annulus length, should be used as this is relatively fixed in size and does not dilate. A discrepancy in size with the leaflet area being smaller than the orifice area is also an indication for tricuspid valve repair as this suggests that the leaflets are of insufficient size to achieve valvular competence [9].
Fig. 21.2
(a) Measuring the tricuspid annular size by pulling on the anterior papillary muscle; this usually supports the anterior leaflet and half of the posterior leaflet, although sometimes, it may only support the anterior leaflet. An obturator of the same size is used to determine the size of the annuloplasty ring to use. (b) Measuring the tricuspid annular size by determining the length of the septal annulus. A suture placed in the postero-septal commissure is useful to facilitate this. An obturator is then used to match the corresponding positions on it to the anteroseptal commissure and the posteroseptal commissure to determine the size of the annuloplasty ring to use (From Carpentier et al. [51], with permission from Elsevier)
In the presence of severe FTR, the annuloplasty ring can be undersized to increase leaflet coaptation [37]. For example, if the annulus is sized at 34 mm, a 32 mm ring could be used instead. However, caution must be exercised particularly in elderly patients with weak tissue as the excess tension can cause annular dehiscence particularly at the septal annulus [38]. A series of 2/0 ethibond sutures or equivalent are placed around the tricuspid annulus except at the region of the conduction tissues at the septal annulus (Fig. 21.3). The sutures are then in turn passed through the tricuspid annuloplasty ring. Care is needed around the posterior annulus to avoid the right coronary artery, and in the region of the anterior annulus where too deep a suture may cause injury to the aortic wall and aortic valve leaflets. As a precaution, traction can be exerted on the sutures placed in the posterior leaflet annulus after placement to ensure that there is no visible distortion of the right coronary artery. If any suggestion of distortion or occlusion of the right coronary artery is suggested by this maneuver, the sutures should be removed and placed again carefully.
Fig. 21.3
(a) 2/0 ethibond sutures or equivalent are placed around the tricuspid annulus. The tricuspid annuloplasty ring is designed such that no sutures are placed in the region of the conduction tissues. (b–d) Care is taken to ensure that sutures placed in the annulus are passed through the corresponding positions in the annuloplasty ring; the fixed landmarks to guide this are the commissural sutures which should be placed at the corresponding positions on the annuloplasty ring. This ensures that the tricuspid valve is not distorted as a result of performing the annuloplasty (From Carpentier et al. [51], with permission from Elsevier)
Several commercially available tricuspid annuloplasty rings are available with the newer rings shaped geometrically into a 3-dimensional configuration to match the normal geometry of the tricuspid annulus. Care must be taken during suture placement to ensure that the sutures are passed through the annuloplasty ring at their corresponding positions on the tricuspid annulus so as not to distort the tricuspid valve. Two important landmarks are the anteroposterior commissure and the posteroseptal commissures which should pass through the corresponding positions in the tricuspid annuloplasty ring. The annuloplasty ring is then lowered and the sutures tied. A water test is performed while occluding the pulmonary artery to confirm valve competency. To minimize myocardial ischaemia times, the tricuspid valve annuloplasty can be done after the release of the aortic cross clamp and during the period of rewarming and reperfusion.
Early Results
In less than severe TR, where the indication for intervention on the tricuspid valve is tricuspid annular dilatation, adding tricuspid annuloplasty to left sided heart valve surgery does not increase operative risk and can be performed safely with an operative mortality of less than 1 % [11, 25, 28, 32]. This is despite patients undergoing concomitant tricuspid valve annuloplasty plus mitral valve surgery being older, having worse right and left ventricular function and higher pulmonary artery pressures, and being more likely to be in atrial fibrillation compared to patients having isolated mitral valve surgery [28].
In more severe TR, where the indication for intervention on the tricuspid valve is severe TR, the operative mortality and complication rates are higher but still similar for those undergoing concomitant tricuspid and mitral valve surgery and isolated mitral valve surgery according to the Society of Thoracic Surgeons database [39]. One study did report higher operative mortality in those having concomitant tricuspid and mitral valve surgery compared to isolated mitral valve surgery [40]. However, this was a non-randomized study and it is likely that the higher mortality and complication rates in those undergoing combined mitral and tricuspid valve surgery was due to the fact that these were a sicker and higher risk group of patients compared to those who underwent isolated mitral valve surgery.
Several risk factors for increased operative mortality for tricuspid valve surgery have been identified namely NYHA functional class IV and the presence of liver cirrhosis, and also renal failure, cerebrovascular disease, chronic lung disease, congestive heart failure, non-elective presentation, and reoperation [39, 41]. In one study, the presence of liver disease increased operative mortality from 9.4 to 22.9 % [1]. Yiu, et al., reported that indices of leaflet tethering and right ventricular geometry also had an impact on outcomes with increasing right ventricular size and leaflet tethering being independently associated with adverse outcomes (including heart failure and death) at 1 year, after correcting for age and NYHA functional class III/IV [42].
Complications
Complications relating directly to the tricuspid valve annuloplasty is not common but do occur and include injury to the right coronary artery from too deep placement of the annuloplasty sutures in the region of the posterior annulus, injury to the aortic wall from too deep annuloplasty sutures in the aortic area of the anterior annulus, annular and ring dehiscence in the septal annulus due to friable tissue, and need for a permanent pacemaker, amongst others [38, 43]. Ring dehiscence was reported to be more common following rigid ring annuloplasty compared to flexible band annuloplasty (8.7 % versus 0.9 %) and always occurred in the septal annulus possibly due to the increased shearing forces in this area. [38] Adequate depth and number of sutures should therefore be ensured in this area. The risk of requiring a permanent pacemaker following tricuspid valve repair is between 2.4 and 9.5 % and is similar to that of isolated mitral valve surgery [1, 28, 39].
Injury to the right coronary artery should be suspected if the patient becomes unstable and there are signs of inferior myocardial ischaemia after tricuspid valve annuloplasty. It can occur due to distortion of the right coronary artery due to plication of the annulus by sutures placed at the annulus, away from the right coronary artery itself. It can also be caused by direct injury to the right coronary artery by sutures placed through it or going around it and occluding it. Patients with a very dilated tricuspid annulus are most at risk of this complication due to distortion of the course of the right coronary artery, and also those with very calcified coronary arteries which may make them more susceptible to kinking [44]. Caution should be exercised to avoid too deep sutures in the region of the anteroposterior commissure and avoiding placing sutures in the atrial wall. Options for management in these cases include coronary artery bypass graft surgery, or removal of the annuloplasty ring and sutures if the patient is still in the operating theatre, or if the patient is in the intensive care unit already, coronary angiography to confirm the diagnosis, and percutaneous coronary intervention (PCI). Distortion of the right coronary artery can occur from annular plication away from the right coronary artery itself, in which case, PCI may be successful in restoring coronary flow. However, if the right coronary artery has been occluded or narrowed due to an annuloplasty suture passing around or through it, PCI is unlikely to be successful and coronary artery bypass graft surgery or removal of the annuloplasty ring and sutures would be necessary [43].