Tricuspid Regurgitation and Stenosis

Definitions and Morphology

Isolated congenital anomalies of the tricuspid valve (TV) are rare structural malformations that involve one or more components of the TV apparatus and result more commonly in tricuspid regurgitation (TR) and less often tricuspid stenosis (TS). The normal components of the TV include the annulus, three leaflets, chordae, and variable papillary muscle anatomy. When viewed from the ventricular aspect, the annulus is shaped like a reversed D and decreases in area by 30% during systole. The septal leaflet lies against the ventricular septum and is apically displaced in relation to the mitral annulus. The posterior leaflet, also known as the inferior leaflet, makes up the largest portion of the annulus and lies against the inferior wall of the right ventricle. The anterior (anterosuperior) leaflet is the largest and most mobile and extends anteriorly from the right ventricular infundibulum to the inferolateral wall. Each of the relatively small papillary muscles has chordal attachments to adjacent leaflets. A distinct feature of the TV, in comparison to the mitral valve, is its chordal attachments to the ventricular septum.

Tricuspid Stenosis

Isolated congenital malformations of the TV apparatus leading to TS are extremely rare. These include an underdeveloped annulus, shortened chordae, hypoplastic leaflets, underdeveloped fused commissures, parachute deformity (all the chordae arise from a single papillary muscle), and a supravalvular ring at the level of the annulus or midportion of the leaflets. In addition, abnormal persistence of the right venous valve can result in a double-chambered right atrium, also known as cor triatriatum dexter, a condition in which the proximal chamber receives all venous return and the distal chamber contains the TV ( Fig. 44.1 ). This perforated partition within the right atrium mimics the clinical presentation of TS.

Tricuspid Regurgitation

Tricuspid regurgitation in adults is most commonly functional in nature, related to right ventricular enlargement and/or dysfunction because of primary right ventricular (RV) myocardial disease, myocardial infarction (usually the right coronary artery), pulmonary hypertension, or left-sided heart diseases rather than as a result of a congenital deformity of the TV apparatus. Functional TR occurs because of the dilation of the tricuspid annulus and asymmetrical alterations of right ventricular geometry that lead to tethering of the TV leaflets and incomplete leaflet coaptation. On the other hand, the Ebstein anomaly (see Chapter 43 ) is the most common cause of congenital TR, followed by TV dysplasia, in which anatomic malformations can include hypoplastic papillary muscles, asymmetrically foreshortened tendinous chordae tethering the leaflets, and underdeveloped, atypical leaflets that prevent the valve from closing completely during systole ( Fig. 44.2A and B ). Partial or complete agenesis of the valvular tissue is often referred to as an unguarded tricuspid orifice. Both malformations have been associated with pulmonary stenosis and atresia (see Chapter 45, Chapter 48 ). Other congenital anomalies leading to TR include (1) right-sided congenital partial absence of the pericardium, (2) papillary muscle rupture in the fetus or neonate, (3) the presence of bileaflet TV or cleft of the anterior leaflet (with or without atrial or ventricular septal defects), and (4) Uhl anomaly (best defined as aplasia or hypoplasia of the right ventricular myocardium, transforming it into a thin, passive, unexcitable conduit). The latter condition resembles arrhythmogenic right ventricular dysplasia/cardiomyopathy, in which the right ventricular myocardium is progressively replaced by adipose and fibrous tissue; this condition is often associated with ventricular arrhythmia and sudden death. Congenital deformities of the TV leading to TR can be mistaken for acquired diseases of the TV, including TV prolapse, endocarditis, TV involvement by rheumatic or carcinoid heart disease, or collagen vascular diseases. TR has also been reported after chest radiation, penetrating or blunt chest trauma, right ventricular endomyocardial biopsy, and endocardial lead placement because of leaflet entrapment, adhesion, or perforation or secondary to atrioventricular discordance with asynchronous ventricular pacing. In an observational study of 248 patients who had echocardiograms before and after placement of permanent pacemaker and implantable cardioverter defibrillator leads, TR worsened by at least 1 grade in 24.2%. Patients with an implantable cardioverter defibrillator had a higher rate of TR worsening compared with patients with a pacemaker (32.4% vs. 20.1%; p <.05). TR has also been seen in patients with chronic, and less often acute, atrial fibrillation resulting from related atrial and TV annulus remodeling. We have observed improved TR following restoration and maintenance of sinus rhythm. TR is also a known sequelae after surgical or device repair of ventricular septal defect resulting from fixation of the septal leaflet to the ventricular septum at the point where it was closed with a patch or device. Drugs such as cabergoline (a dopamine receptor-2 agonist used to treat prolactinomas), fenfluramine-phentermine, and ergotamine, which are serotonin-like or can potentiate the effect of circulating serotonin, can lead to valvular injury. In such injury the septal leaflet of the TV becomes thickened and variably fixed to the septum, whereas the anterior leaflet exhibits reduced mobility, resulting in loss of coaptation and TR, and to a lesser extent TS, and at times simulating carcinoid valvular disease. Drug-induced TV disease is often associated with other valve involvement, and in particular, the mitral valve. Furthermore, the use of gadolinium contrast during magnetic resonance imaging in patients with significant chronic kidney disease has been reported to infiltrate the TV causing TR, likely as part of nephrogenic systemic fibrosis. Irrespective of the cause of TR, severe TR is associated with adverse outcomes.

Genetics and Epidemiology

Little is known about the genetic predisposition to congenital TS and TR. In 1991 Sharland et al. reported that of 450 cases of structural heart disease diagnosed prenatally, 22 (4.9%) were of TV dysplasia and 16 (3.6%) were of Ebstein anomaly.

Review of the surgical pathologic analyses of 363 TVs excised and replaced at the Mayo Clinic between 1963 and 1987 demonstrated that 74% were purely regurgitant, 23% were stenotic and regurgitant, and only 2% were purely stenotic. Rheumatic disease was the most common cause (53%), followed by congenital disease (26%). Female patients accounted for 66% of all TVs excised. Male patients accounted for 61% of the congenital disorders, suggesting a male predominance. This study, however, included isolated TV anomalies and those associated with other congenital defects and excluded patients who had TV repair. A subgroup analysis of 45 patients with isolated TV defects showed that Ebstein anomaly was by far the most common (39 patients), followed by TV dysplasia (4 patients) and congenital TS (1 patient). Interestingly, the relative frequency of rheumatic disease decreased from 79% between 1963 and 1967 to 24% between 1983 and 1987. However, the frequency of all congenital TV anomalies requiring TV replacement increased from 7% to 53% during the same time interval.

Early Presentation and Management

Most isolated congenital TV anomalies, especially those leading to TS, present in infancy and childhood and require early intervention. In comparison, congenital TV anomalies resulting in TR can be tolerated for many years and may remain unrecognized until adulthood. Patients may be asymptomatic, and when symptoms begin, often include exertional fatigue or reduced exercise tolerance. If left untreated, symptoms may progress to severe heart failure with evidence of ascites, edema, and low forward stroke volume state with worsening resultant exertional fatigue, dyspnea, and cold extremities.

Although the initial mortality rates for TV replacement were as high as 30% to 50%, rates have improved to 7% to 17%. Rizzoli et al. reported a postoperative 50% 30-day mortality rate for patients of all age groups with congenital TV diseases. In most cases, death was related to low cardiac output. This high early mortality was due in part to late referral to surgery. The interest in repairing the regurgitant TV has increased more recently. The three basic reconstructive techniques are the Kay plication , in which the posterior (also known as inferior or mural) leaflet is plicated, converting the TV into a functionally bicuspid valve; the de Vega annuloplasty , which uses purse-string sutures to narrow the annulus along the anterior (anterosuperior) and posterior (inferior or mural) leaflets; and the ringed annuloplasty , in which a flexible or rigid ring is placed along the anterior and posterior aspects of the annulus. McElhinney et al. described the possible application of such a repair in children with TV dysplasia. He described two children with this anomaly, primarily with tethering of the septal leaflet because of abnormally short chordae, who underwent the operation at 9 and 11 years of age. The chordae that were tethering the septal leaflet were augmented by interposing appropriate lengths of expanded polytetrafluoroethylene suture and performing commissural annuloplasty. Each patient was reported to be asymptomatic 33 and 42 months after operation respectively. TR resulting from a cleft of the anterior leaflet can be repaired with simple suture and annuloplasty. For patients with Uhl anomaly, various surgical procedures have been performed, including Potts and bidirectional cavopulmonary anastomoses. None was successful in prolonging life. Cardiac transplantation and possibly the RV ventricular assist device appear to be the only options for these patients.