Understanding and managing functional tricuspid regurgitation

Functional tricuspid regurgitation is increasingly recognised as an important clinical condition for which surgical repair is being applied.¹ It primarily arises from left heart failure due to myocardial or valvular dysfunction, leading to right ventricular enlargement and asymmetric tricuspid annular dilation. Untreated tricuspid regurgitation can cause significant clinical symptoms that can lead to “right-sided heart failure” and excess mortality. In this commentary, Sarah T Ward and Steven F Bolling review the current approaches to treating functional tricuspid regurgitation

An important consideration is the development of significant tricuspid regurgitation years after mitral valve surgery, with a growing body of literature supporting the notion that ignoring or “benign neglect” of tricuspid regurgitation at the time of mitral valve surgery may no longer be acceptable. Since reoperations for recurrent tricuspid regurgitation are especially high-risk procedures, more aggressive treatment of tricuspid regurgitation at the time of initial surgery may be important.^2,3 Therefore, it is important to understand the surgical anatomy of the tricuspid valve, the geometric distortions that result in functional tricuspid regurgitation, and the available therapies for treating functional tricuspid regurgitation.

The tricuspid valve complex is analogous to the mitral valve, as coordination of annular, leaflet, chordal, papillary muscle, and right ventricular function are required for effective leaflet coaptation during systole. The tricuspid valve consists of three leaflets: anterior, posterior and septal. The anterior and posterior tricuspid leaflets arise from the annulus along the right ventricular free wall. The septal leaflet arises from the tricuspid annulus directly above the interventricular septum.⁴

The tricuspid annulus has a unique three-dimensional (3D) structure, as shown by Fukuda using 3D transoesophageal echocardiogram (TOE). Healthy participants had a non-planar, elliptical –shaped tricuspid annulus, while patients with functional tricuspid regurgitation had a more planar annulus which was dilated primarily in the septal-lateral direction.⁵

Dilation of the tricuspid annulus is the primary mediator of functional tricuspid regurgitation and, therefore, the main target for surgical correction with annular rings. Tricuspid annular enlargement occurs primarily along the right ventricular free wall, resulting in leaflet malcoaptation.⁶

Conversely, the septal aspect of the tricuspid annulus, analogous to the intertrigonal portion of the mitral annulus, is relatively spared from annular dilation.⁷ As a result, tricuspid annular sizing has been based on the dimension of the base of the septal leaflet.⁸ It has also been shown that the tricuspid annulus diameter is dynamic and can change markedly with loading conditions. During the cardiac cycle, there is a 19% reduction in annular circumference with atrial systole.^5,9 The degree of tricuspid regurgitation can be dynamic and directly affected by right ventricular preload, afterload, and right ventricular systolic function.

Current surgical approaches

The application of a rigid (or semi-rigid) ring for functional tricuspid regurgitation has been shown to offer the most durability over time in multiple series as compared with flexible bands or plication annuloplasty techniques, and may be considered standard of care. McCarthy reported on 790 patients that underwent annuloplasty for functional tricuspid regurgitation during concomitant surgery using four tricuspid annular approaches: Carpentier-Edwards semi-rigid ring, Cosgrove-Edwards flexible band, DeVega procedure, and Peri-Guard annuloplasty. Regurgitation severity increased more rapidly over time with the DeVega and PeriGuard procedures during eight year follow up, whereas regurgitation severity was most stable with the Carpentier-Edwards ring.¹⁰

Similarly, Navia et al reported on 2,277 patients from 1990 to 2008 who underwent tricuspid valve procedures during primarily mitral and aortic operations. By five years, tricuspid regurgitation had increased only slightly to 12% for isolated rigid prosthesis annuloplasty, but was progressively greater for all other annular procedures.¹¹

The approach to tricuspid valve repair sizing is triggered by an annulus diameter of the greater than 40mm and an approach to sizing these cases, may be to “undersize” by at least two ring sizes. Huffman et al examined patients who underwent mitral valve repair with a rigid complete annuloplasty ring, and who simultaneously underwent tricuspid valve repair using the same size tricuspid valve annuloplasty ring. The data suggest that the same size ring can be used for tricuspid valve repair as was used for mitral valve repair, without development of significant tricuspid stenosis or negative effects on right heart function. These findings were confirmed by three large clinical trials by Murkerjhee (USA), Desai (USA) and Bertrand (Europe), which showed that the right ventricular gets better when functional tricuspid regurgitation is repaired.

Current guidelines for the management of functional tricuspid regurgitation

The American College of Cardiology/American Heart Association (ACC/AHA) 2014 practice guidelines for the surgical management of patients with functional tricuspid regurgitation give a Class I indication for tricuspid valve repair in any patient with severe tricuspid regurgitation undergoing mitral valve surgery.¹² In patients with less than severe tricuspid regurgitation, a Class IIb recommendation is given for patients undergoing mitral valve surgery, if there is pulmonary hypertension or any tricuspid annular dilation >40mm. The European Society of Cardiology (ESC) 2012 guidelines take a more aggressive stance, with a Class IIa recommendation for tricuspid valve repair in patients with moderate functional tricuspid regurgitation and a dilated tricuspid annulus (>40 mm) in a patient undergoing left sided surgery.¹³

Despite the ACC/AHA and ESC guidelines, which support surgical repair of tricuspid regurgitation at the time of mitral valve surgery in many patients, tricuspid valve repair currently appears underused. The current surgical volume of tricuspid valve repair with or without concomitant mitral valve surgery (Society of Thoracic Surgeons  National Cardiac Database) averages about 5000 per year. This represents only approximately one-tenth of the greater than 60,000 mitral valve operations performed yearly in the USA.¹⁴

Timing of tricuspid repair

Pre-emptive correction of tricuspid regurgitation should be increasingly applied, as surgical treatment of a left-sided cardiac abnormality will not always result in secondary improvement or amelioration of tricuspid regurgitation.¹ It has been proposed by Dreyfus that at the time of mitral valve repair, the presence of tricuspid annular dilation (≥70mm measured intraoperatively in a flaccid heart, equivalent to a 40mm diameter), even in the absence of significant tricuspid regurgitation, should be an indication for tricuspid valve annuloplasty. This paper also showed that tricuspid regurgitation increased by at least two grades in 45% of the patients who received isolated mitral valve repair without tricuspid valve repair, supporting the notion that tricuspid dilation is an ongoing, progressive process that often warrants pre-emptive surgical treatment.¹⁵ Potentially, any patient with > 2+ tricuspid regurgitation or a tricuspid annular diameter ≥40mm in any echocardiographic view should be considered for repair of tricuspid regurgitation during any left-sided valve surgery

While operative times (cross clamp/bypass) are potentially longer with the addition of tricuspid valve repair, Dreyfus showed no additional increase in 30-day mortality with an added tricuspid valve repair. In fact, Calafiore demonstrated decreased 30-day mortality, with less recurrent tricuspid regurgitation and better five-year survival with the addition of a tricuspid repair in a small retrospective series of 110 patients undergoing mitral surgery.

Conclusion

In conclusion, concomitant surgical repair of tricuspid regurgitation at the time of mitral valve surgery should be considered, as this approach has been shown to result in improved perioperative outcomes, functional class, and potentially survival. In particular, any tricuspid regurgitation with annular dilation cannot simply be ignored when performing corrective surgical procedures for mitral regurgitation, since tricuspid regurgitation does not reliably disappear after successful mitral valve surgery, and reoperations for recurrent tricuspid regurgitation carry high mortality rates. Furthermore, the addition of tricuspid valve repair has been shown not to increase operative mortality, when performing mitral repair. Consequently, aggressive application of tricuspid repair based solely on tricuspid annular dilation is becoming more common. The application of a rigid or semi-rigid ring appears to have improved durability, or at least freedom from recurrence of significant tricuspid regurgtiation. With the dawning of percutaneous options in the area, the use of tricuspid annuloplasty for functional tricuspid regurgitation will be increased.

References

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11. Navia et al. In, American Association for Thoracic Surgery. Boston; 2009
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14. Gammie et al. Circulation 2007; 115: 881–87.
15. Dreyfus et al. The Annals of thoracic surgery 2005; 79: 127–32.

Sarah T Ward and Steven F Bolling are both at Department of Cardiac Surgery, University of Michigan, Ann Arbor,