Ann Thorac Surg 1995;59:1237-1239
© 1995 The Society of Thoracic Surgeons
Case Report
Tricuspid Valve Prolapse Associated With Myxomatous Degeneration
Jacques A. M. van Son, MD, PhD,
Catherine M. Miles, MD,
Albert Starr, MD
Albert Starr Academic Center for Cardiac Surgery and Department of Pathology, St. Vincent Hospital, Portland, Oregon
Accepted for publication October 7, 1994.
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Abstract
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Two surgical patients are presented with tricuspid valve prolapse. One had severe isolated prolapse of the posterior leaflet at its junction with the anterior leaflet accompanied by chordal elongation that was successfully repaired; the other had mild prolapse of all three leaflets with chordal elongation. Myxomatous degeneration of the tricuspid valve was the suspected underlying pathologic disorder in both patients and was histologically proven in the resected leaflet tissue of patient 1.
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Introduction
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Myxomatous degeneration with prolapse is far less common in the tricuspid valve than in the mitral valve. To date, it has been reported primarily in postmortem studies [1–4]. Recently we operated on 2 patients with prolapse of the tricuspid valve in whom myxomatous degeneration may have been the underlying pathologic disorder.
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Patient 1
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A 67-year-old man was seen with increasing exercise limitation, peripheral edema, and hepatic congestion. He denied a history of rheumatic heart disease or infective endocarditis. Two-dimensional echocardiography showed severe isolated tricuspid valve regurgitation with moderate to severe right ventricular dysfunction. Cardiac catheterization confirmed these findings. There was no major coronary artery disease.
At operation, the right atrium and the right ventricle were dilated. When the rather thick-walled right atrium was opened, severe tricuspid annular dilatation was seen. The tricuspid valve insufficiency was characterized by isolated prolapse of the billowed posterior leaflet at its junction with the anterior leaflet as well as localized chordal elongation.
The posterior leaflet was reconstructed by excision of its flail portion (measuring 2 x 1.6 cm) and restoration of leaflet continuity with interrupted 6-0 Dacron sutures. The commissure between the posterior and anterior leaflets was closed with two interrupted sutures. In addition, the tricuspid annulus was remodeled using a 36-mm Carpentier-Edwards ring. In this manner, an excellent repair was obtained with absence of tricuspid valve regurgitation both after filling of the right ventricle with normal saline solution and by transesophageal echocardiography.
Histologic examination of the excised portion of the posterior leaflet showed marked thickening with an excessive amount of myxomatous tissue in the spongiosa layer of the leaflet and invasion of the fibrosa layer (Fig 1
).
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Fig 1. . (Patient 1.) Myxomatous degeneration of posterior leaflet of tricuspid valve: (A) thickening and hyalinization of fibrosa layer (F) and invasion of spongiosa layer (S) into fibrosa layer (arrows); and (B) detail of myxomatous degeneration of spongiosa layer. (Hematoxylin and eosin; A, x125, and B, x500, both before 52% reduction.)
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The postoperative course was uneventful. Early postoperative echocardiography demonstrated only trivial tricuspid regurgitation. Anticoagulation was continued for a 6-week period to allow growth of endothelial tissue over the tricuspid valve ring. Fifteen months postoperatively, the patient is only mildly symptomatic with echocardiographically trivial tricuspid regurgitation.
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Patient 2
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A 79-year-old woman with a known heart murmur of many years noted increasing dyspnea on effort and easy fatigability as well as retrosternal pressure during the year prior to this admission. She denied a history of rheumatic fever or infective endocarditis. The rhythm was sinus. A chest radiograph showed calcification of the aortic valve. At echocardiography, the estimated peak systolic gradient across the aortic valve was 100 mm Hg; additional findings consisted of trivial mitral regurgitation and mild regurgitation and thickening of the tricuspid valve without right atrial enlargement. At cardiac catheterization, the aortic valve could not be passed with the catheter. The pressures in the right atrium, right ventricle, and pulmonary artery were normal. There was no major coronary artery disease.
At operation, we noted mild tricuspid regurgitation that was due to prolapse of all three leaflets, which were thickened, large, and billowed, as well as chordal elongation; these findings were thought to be secondary to myxomatous degeneration of leaflet and chordal tissue. Repair of the tricuspid valve was not performed because there was only a mild degree of regurgitation. The calcified and congenitally bicuspid aortic valve was replaced with a 23-mm Carpentier-Edwards pericardial valve. The mitral valve appeared normal.
The postoperative course was uneventful. The cardiac rhythm was sinus. Eight months postoperatively, the patient is in excellent clinical condition and without cardiac medication.
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Comment
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Myxomatous degeneration of the mitral valve is a widely recognized pathologic entity [5–8] and currently is the most common underlying disorder in patients who are treated surgically for mitral regurgitation [5, 8]. It is characterized by an excessive amount of myxomatous tissue in the spongiosa layer of the leaflets and chordae tendineae. This tissue invades the fibrosa layer with resulting weakness of the leaflets and chordae tendineae, which may stretch and become voluminous and elongated, respectively. The posterior leaflet is more commonly involved than the anterior one [5, 6]. The resulting clinical entity, mitral valve prolapse, has a prevalence in the Framingham Heart Study of 2.5% in men and 7.6% in women as diagnosed by M-mode echocardiography [7].
In contrast to the high prevalence of prolapse secondary to myxomatous degeneration seen in the mitral valve, this clinical and pathologic entity is less common in the tricuspid valve. In large autopsy series [1, 2], the prevalence of tricuspid valve prolapse ranged from 0.3% to 3.2%. In another autopsy study [3], tricuspid valve prolapse was present in 7 (15.6%) of 45 patients with pure tricuspid regurgitation. Tricuspid valve prolapse associated with histologically documented myxomatous degeneration is seldom reported in the surgical literature because in the majority of cases, the tricuspid regurgitation is not severe enough to warrant surgical intervention, and therefore this entity rarely appears in surgical pathologic specimens. In a study [4] of 269 tricuspid valves excised for pure regurgitation, the four common causes were postinflammatory disease (41%), congenital disorder (most commonly Ebstein's malformation) (32%), pulmonary venous hypertension (21%), and infective endocarditis (4%). In only two instances (0.7%) could the underlying etiology not be determined on the basis of clinical history, gross inspection, or histologic examination.
Tricuspid valve prolapse associated with myxomatous degeneration occurs primarily in two groups: patients with mitral valve prolapse who generally have less functional involvement of the tricuspid and pulmonary valves and patients with chronic pulmonary emphysema with or without hypoxic pulmonary hypertension. In the latter group, one might consider a genetic deficiency (such as 
1-antitrypsin deficiency) that leads to weakening of both lung tissue and right-sided heart valves. The 2 patients in this report clearly had prolapse of the tricuspid valve that in all likelihood was not secondary to either of these mechanisms. Inspection of the prolapsed tricuspid valves in these patients revealed a striking similarity to the condition seen in mitral valve prolapse caused by myxomatous degeneration. The leaflets were voluminous, thickened, and billowed. In patient 1, the prolapse was limited to the posterior leaflet of the tricuspid valve, which was partially flail with localized chordal elongation. Tricuspid valve competence was restored by resection of the flail segment, partial closure of the commissure between the posterior and anterior leaflets, and annuloplasty. Histologic examination of the excised portion of the posterior leaflet showed typical findings of myxomatous degeneration with thickening of the leaflet analogous to the findings encountered in myxomatous degeneration of the mitral valve. Patient 2 had mild prolapse of all three leaflets of the tricuspid valve with chordal elongation; because the degree of tricuspid regurgitation was so mild, repair was not performed.
In summary, prolapse of the tricuspid valve resulting from myxomatous degeneration, although uncommon, may be a cause of tricuspid regurgitation. Similar to the situation with mitral valve prolapse, the regurgitant tricuspid valve can be repaired satisfactorily.
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Footnotes
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Address reprint requests to Dr van Son, Division of Cardiothoracic Surgery, UCSF, 505 Parnassus Ave, San Francisco, CA 94143-0118.
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References
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- Pomerance A. Ballooning deformity (mucoid degeneration) of atrioventricular valves. Br Heart J 1969;31:343–51.[Free Full Text]
- Davies MJ, Moore BP, Braimbridge MV. The floppy mitral valve. Study of incidence, pathology, and complications in surgical, necropsy, and forensic material. Br Heart J 1978;40:468–81.[Free Full Text]
- Waller BF, Moriarty AT, Eble JN, Davey DM, Hawley DA, Pless JE. Etiology of pure tricuspid regurgitation based on anular circumference and leaflet area: analysis of 45 necropsy patients with clinical and morphologic evidence of pure tricuspid regurgitation. J Am Coll Cardiol 1986;7:1063–74.[Abstract]
- Hauck AJ, Freeman DP, Ackermann DM, Danielson GK, Edwards WD. Surgical pathology of the tricuspid valve: a study of 363 cases spanning 25 years. Mayo Clin Proc 1988;63:851–63.[Medline]
- Olson LJ, Subramanian R, Ackermann DM, Orszulak TA, Edwards WD. Surgical pathology of the mitral valve: a study of 712 cases spanning 21 years. Mayo Clin Proc 1987;62:22–34.[Medline]
- Hanson TP, Edwards BS, Edwards JE. Pathology of surgically excised mitral valves. One hundred consecutive cases. Arch Pathol Lab Med 1985;109:823–8.[Medline]
- Levy D, Savage D. Prevalence and clinical features of mitral valve prolapse. Am Heart J 1987;113:1281–90.[Medline]
- Waller BF, Morrow AG, Maron BJ, et al. Etiology of clinically isolated, severe, chronic, pure mitral regurgitation: analysis of 97 patients over 30 years of age having mitral valve replacement. Am Heart J 1982;104:276–88.[Medline]
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Abstract
Introduction
