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Secondary tricuspid regurgitation or dilatation: Which should be the criteria for surgical repair?Dreyfus GD, Corbi PJ, Chan KMJ, Bahrami T. Ann Thorac Surg 79:127-132, 2005.Reviewer: Mark A. Chaney, MD
Abstract: Secondary tricuspid dilatation may or may not be accompanied by tricuspid regurgitation (TR). Tricuspid dilatation can be objectively measured whereas TR can vary according to preload, afterload, and right ventricular function. This investigation attempted to determine whether surgical repair of the tricuspid valve based on tricuspid dilatation rather than TR could lead to potential benefits. In 311 patients undergoing mitral valve repair, the tricuspid valve was examined. Tricuspid annuloplasty was performed only if the tricuspid annular diameter was greater than twice the normal size (≥70 mm) regardless of the grade of regurgitation. 163 patients (52%) received mitral valve repair alone and 148 patients (48%) received mitral valve repair plus tricuspid annuloplasty. There was no difference between the two groups with regard to hospital mortality and actuarial survival rate (up to 10 years follow-up). However, the New York Heart Association functional class was significantly improved in patients receiving tricuspid annuloplasty. Furthermore, TR increased by more than two grades in 48% of patients not receiving tricuspid annuloplasty and in only 2% of patients receiving tricuspid annuloplasty (p<0.001). These investigators conclude that remodeling annuloplasty of the tricuspid valve based on tricuspid dilatation improves functional status irrespective of the grade of regurgitation. Considerable tricuspid dilatation can be present even in the absence of substantial TR, and is an ongoing disease process that will, with time, lead to severe TR. Comments: "Secondary" TR associated with mitral valve disease is thought by many to decrease or even disappear following surgical correction of mitral valve disease. This concept has been widely accepted and influences current surgical practice regarding management of TR (most attack the primary lesson - the mitral valve - and leave the tricuspid valve alone). This clinical investigation reveals that this may not be the correct path to take. Knowledge of the pathophysiologic processes that lead to TR is important. The tricuspid annulus is a component of both the tricuspid valve and the right ventricle. For TR to occur, the tricuspid annulus, and hence the right ventricle, has to be dilated (excluding overt leaflet dysfunction). If the tricuspid annulus and right ventricle are not dilated, there is very low probability that TR can occur. Furthermore, dilatation of the tricuspid annulus is only possible in its anterior and posterior aspects (corresponds to the free wall of the right ventricle). In addition to tricuspid dilatation, three important factors determine whether TR occurs: preload, afterload, and right ventricular function. Thus, significant TR may not be detected echocardiographically despite considerable pathology of the tricuspid valve. Thus, the absence of TR or the presence of only mild TR does not mean that the tricuspid orifice is free of any abnormality such as tricuspid annular dilatation. Considerable tricuspid dilatation may not always re-sult in pronounced TR at a given time. Such undetected and untreated TR may influence functional capacity of patients and lead to subsequent progression of TR. Current practice regarding management of secondary TR (focuses on assessment of TR severity, advocates treatment of primary lesion alone) may be incorrect. For example, treatment of the mitral lesion alone does not correct tricuspid dilatation nor does it affect preload or right ventricular function. As tricuspid annular dilatation seems to be the underlying mechanism regarding nonorganic TR, it may be a more reliable indicator of tricuspid valve pathology compared with TR. Successful treatment of secondary tricuspid valve pathology may necessitate the correction of tricuspid annular dilatation in addition to mitral valve surgery. This has been these investigators' practice during the last twelve years. In 311 patients undergoing mitral valve surgery, the tricuspid valve was surgically evaluated irrespective of the grading of the preoperative TR. The tricuspid annular diameter was directly measured from the anteroseptal commissure to the anteroposterior commissure using a supple ruler. Patients with a tricuspid annular dimension greater than or equal to 70 mm (twice the normal size) underwent a remodeling tricuspid annuloplasty. They prospectively recorded all patient data to determine if tricuspid valve repair for secondary tricuspid valve dilatation (irrespective of TR severity) improves outcome. This clinical study involving more than 300 patients, some of whom were followed up for more than ten years, indicates that tricuspid annuloplasty performed at the time of mitral valve surgery improves functional capacity and may prevent progression of TR severity. However, the authors acknowledge that the "threshold" size to correct tricuspid dilatation requires further study and perhaps lesser degrees of tricuspid dilatation should also be corrected. What we, as cardiac anesthesiologists, should take away from these findings is that there is little or no correlation between tricuspid dilatation and TR and that tricuspid dilatation is more reliable than TR when assessing secondary tricuspid valve disease. Interestingly, in this study, significant TR was not detected for the majority of patients receiving remodeling tricuspid annuloplasty during the preoperative assessment despite an annular diameter of greater than twice normal. 88% of these patients demonstrated grade 0 or 1 TR at preoperative echocardiographic assessment. Thus, there was no correlation between TR and tricuspid dilatation. Furthermore, the aim of treating tricuspid annular dilatation at the same time that mitral valve surgery is performed is to prevent future progression to symptomatic TR. Table of Contents:
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