Tricuspid Valve Surgery Based on the Mechanisms of Functional Tricuspid Regurgitation

Abstract

The presence of functional tricuspid regurgitation (fTR) in any severity is common in patients with leftsided heart valvular disease. Singh JP et al. reported that the incidence of moderate or severe tricuspid regurgitation (TR) was 0.1%-0.5% in men and 0.5%-5.6% in women in the Framingham offspring data, though 82% of men and 85.7% of women had TR in any grade.1) However, the incidence of fTR accompanying a left-sided lesion is more frequent and varies in published reports because there are differences in the subject, definition of fTR and follow-up period among them. According to several reports, fTR with mitral regurgitation might be more frequent in patients with rheumatic pathology than in those with degenerative. In the study reported by Matsuyama K et al., 55% of patients (n = 175) who underwent mitral valve surgery and suffered from rheumatic etiology, 26% of them had preoperative grade 2 or more fTR. 2)An understanding of the pathology of fTR should be based on the anatomical relationship called "tricuspid complex" consisting of the tricuspid annulus (TA), chordae tendineae, papillary muscles and the right ventricle (RV) as well as "mitral complex." Development of the device and technique of echocardiography has revealed the mechanism of fTR. Although imperfect leaflet closure is the immediate cause of fTR, the three leaflets themselves are commonly normal. Inadequate coaptation of the leaflet is a consequence of geometric change caused by tricuspid annular dilation, right ventricular dilation, distortion of subvalvular apparatus, or a combination of these factors. Most cardiac surgeons have believed that dilation of the TA occurred in anterior and posterior portions because these attach to the free wall of the RV.3)The third potion, septal portion is attached to the right and left fibrous trigons, so that this portion has been considered to be similar to the anterior portion of the mitral annulus and spared from annular dilation, resulting from right-sided chamber dilation.Why do we focus on the tricuspid valve (TV) now? More recently, the TV, often called "forgotten valve" attracts a great deal of attention among cardiac surgeons. The reason is that moderate or greater TR has been reported to be associated with a poor prognosis. Nath et al. reported that increasing TR severity was associated with a worse survival in men, regardless of left ventricular ejection fraction and pulmonary artery pressure. 4) In addition, untreated, moderate or greater fTR at the time of mitral valve surgery has been reported to worsen and to affect both midterm survival and functional status, irrespective of grade of mitral regurgitation after surgery. 5)The period when fTR was believed to disappear after successful left-sided valvular surgery was gone. Methodology of Tricuspid Valve SurgeryTricuspid annuloplasty (TAP) is a gold standard technique for fTR. Because tricuspid annular dilation leading to leaflet coaptation loss is a main cause for fTR, circumferential reduction of the annulus is a key to restore leaflet coapta...