Adult-Acquired Tricuspid and Pulmonary Valve Disease
Adult-Acquired Tricuspid and Pulmonary Valve Disease
Maureen E. Cheung
Bryan A. Whitson
INTRODUCTION
Right-sided valve disease can occur from a number of primary and secondary causes. These processes are often associated with an asymptomatic period but have a significant independent effect on morbidity and mortality. To appropriately address these pathologies, a thorough understanding of the unique anatomy and function of each of these valves is necessary.
The tricuspid valve consists of three leaflets connected via chordae tendinea to two papillary muscles. It sits within a fibrous annulus and the junction of the right atrial and ventricular myocardium. Unlike the mitral valve, the tricuspid annulus is not saddle shaped but rather elliptical shaped and is dynamic, changing substantially with variations in loading conditions. For example, during the cardiac cycle, there is an approximately 20% reduction in annular circumference during atrial systole compared to diastole.1,2,3,4
The pulmonary valve is a semilunar valve; thus, it does not have an annulus in the traditional sense.1 Instead, it occurs at the intersection of three distinct rings. The first is along the sinotubular ridge of the pulmonary trunk. The second is at the ventriculoarterial junction. And the third is at the basal attachments of the leaflets to the infundibular muscle. The circumferential muscular structure supports the leaflets and the semilunar shape allows for valve competence.
PATHOGENESIS
Tricuspid valve dysfunction can be caused by a number of primary and secondary causes (Table 12.1). Primary tricuspid valve dysfunction occurs in up to 25% of patients with tricuspid regurgitation (TR), with the majority of cases related to a congenital abnormality. In the adult population, primary valve etiology is responsible for 10% of TR presentations.1,5 These are termed acquired primary conditions and include rheumatic disease, carcinoid disease, posttraumatic flail leaflet (chronic presentation), and postendocarditis-related valvular damage.
Secondary causes are responsible for 75% of TR presentations, with the most common overall cause being left-sided valvular pathology, most frequently mitral valve disease.1 This left-sided disease leads to pulmonary hypertension, right ventricular dilation with subsequent tricuspid annular dilation. Other common secondary causes include other pathologies causing right ventricular dysfunction and dilation, myocardial infarction, or infectious processes.1,5,6
In the case of pathologies involving right ventricular dysfunction with dilation, there are two primary sources of tricuspid dysfunction. First, ventricular dilation leads to chordal tethering, causing loss of leaflet apposition and subsequent regurgitation. Second, right ventricular free wall dilation also leads to annular enlargement. This occurs primarily at the anterior and posterior leaflets, with the septal leaflet largely spared because of its origin from the fibrous annulus.1 The annular enlargement leads to leaflet malcoaptation, contributing to functional TR. Myocardial infarction involving the right ventricle can result in either papillary muscle disruption or regional wall motion abnormalities, which can lead to leaflet malfunction and loss of coaptation. On transthoracic echocardiogram, patients with functional TR will have preferential dilation in the septal-lateral direction, resulting in a more circular and flat shape with a more planar annulus, thus losing the elliptical shape found in healthy subjects.2
Another cause of functional TR that is perhaps underrecognized is iatrogenic. These include pacemaker or defibrillator leads and endomyocardial biopsies following orthotopic heart transplants. Pacemaker or defibrillator leads cause tricuspid leaflet dysfunction directly as they pass from the right atrium to the right ventricle. Kim et al. found that of 248 subjects imaged before and after device implantation, 24% had worsened TR by one or more grades.3,6 Another study examined 5-year outcomes of successful tricuspid valve repairs and found a nearly twofold increase in the incidence of severe TR in patients who had pacemakers implanted compared to those without a pacemaker (42% vs 23%, respectively).7
TR following orthotopic heart transplant is exceedingly common with a reported incidence up to 84%, with approximately 34% resulting in decreased quality of life with associated peripheral edema, exertional dyspnea or fatigue, and 6% requiring surgical correction.8 Although the etiology of TR following orthotopic heart transplant is complex and multifactorial, one recognized correlation is with endomyocardial biopsies.8 Endomyocardial biopsies are the current standard of care of graft surveillance; however, the number of biopsies performed is correlated with the development of TR. In one single-center study, they found that the incidence of severe TR in patients with more than 31 biopsies was 60% compared to 0% in patients with less than 18 biopsies performed.8,9 The most common mechanism is direct chordal damage with multiple reports of chordal tissue on pathologic examination. Leaflet tissue has also been reported but is relatively uncommon. In one series, Mielniczuk et al. reported that 47% of patients with new acute-onset TR had evidence of chordae tissue in their biopsy.10
TABLE 12.1 Etiologies and Pathogenesis of Right-Sided Regurgitant Valve Lesions
Etiology
Pathogenesis
Primary Causes (25%)
Infectious endocarditis
Leaflet destruction
Trauma
Blunt or penetrating with disruption of structural components
Carcinoid syndrome
Fibrous tissue deposits on valve cusps
Rheumatic disease
Right and/or left-sided valve thickening
Takayasu arteritis
Involvement of pulmonary arteries with pulmonary hypertension
Congenital causes (ie, Ebstein’s)
Tricuspid valve regurgitation
Iatrogenic:
Pacemaker/defibrillator leads
Endomyocardial biopsies
Direct interference with leaflet coaptation
Structural disruption—chordae or papillary muscle destruction/injury
Secondary Causes (75%)
Left-sided valvular dysfunction
Pulmonary hypertension with progressive right ventricular dilation, tricuspid annular enlargement
Eisenmenger syndrome
Progressive right ventricular dilation, tricuspid annular enlargement
Primary pulmonary hypertension
Progressive right ventricular dilation, tricuspid annular enlargement
Mitral and tricuspid valve prolapse and/or chordae elongation or rupture
Dilated cardiomyopathy
Biventricular failure
Drug induced
Tricuspid valve stenosis is more commonly a primary disease process, usually rheumatic related, and is rarely isolated to the tricuspid valve (See Table 12.2). These patients frequently have mitral valve disease and occasionally aortic valve involvement as well. Additionally, although the patients will have tricuspid valve stenosis, some degree of regurgitation is also present.1
TABLE 12.2 Etiologies and Pathogenesis of Right-Sided Stenotic Valve Lesions
