Page 465 - Textbook of Pathology, 6th Edition

capsulatum, Aspergillus, Mucor, coccidioidomycosis, crypto- The major forms of vegetative endocarditis involving the 449
coccosis, blastomycosis and actinomycosis. Opportunistic valves have already been described. Others along with the
fungal infections like candidiasis and aspergillosis are seen consequences of these valvular diseases in the form of
more commonly in patients receiving long-term antibiotic stenosis and insufficiency of the heart valves are described
therapy, intravenous drug abusers and after prosthetic valve below.
replacement. Fungal endocarditis produces appearance
similar to that in BE but the vegetations are bulkier in fungal MITRAL STENOSIS
endocarditis.
Mitral stenosis occurs in approximately 40% of all patients
4. Viral endocarditis. There is only experimental evidence with RHD. About 70% of the patients are women. The latent
of existence of this entity. period between the rheumatic carditis and development of
5. Rickettsial endocarditis. Another rare cause of symptomatic mitral stenosis is about two decades.
endocarditis is from infection with rickettsiae in Q fever.
ETIOLOGY. Mitral stenosis is generally rheumatic in origin.
Less common causes include bacterial endocarditis, Libman-
VALVULAR DISEASES AND DEFORMITIES
Sacks endocarditis, endocardial fibroelastosis and congenital
Valvular diseases are various forms of congenital and parachute mitral valve.
acquired diseases which cause valvular deformities. Many
of them result in cardiac failure. Rheumatic heart disease is MORPHOLOGIC FEATURES. The appearance of the
the most common form of acquired valvular disease. Valves mitral valve in stenosis varies according to the extent of
of the left side of the heart are involved much more frequently involvement. Generally, the valve leaflets are diffusely
than those of the right side of the heart. The mitral valve is thickened by fibrous tissue and/or calcific deposits,
affected most often, followed in descending frequency, by especially towards the closing margin. There are fibrous
the aortic valve, and combined mitral and aortic valves. The adhesions of mitral commissures and fusion and
valvular deformities may be of 2 types: stenosis and shortening of chordae tendineae. In less extensive
insufficiency: involvement, the bases of the leaflets of mitral valve are
Stenosis is the term used for failure of a valve to open mobile while the free margins have puckered and CHAPTER 16
completely during diastole resulting in obstruction to the thickened tissue with narrowed orifice; this is called as
forward flow of the blood. ‘purse-string puckering’. The more advanced cases have
Insufficiency or incompetence or regurgitation is the failure rigid, fixed and immobile diaphragm-like valve leaflets
of a valve to close completely during systole resulting in back with narrow, slit-like or oval mitral opening, commonly
flow or regurgitation of the blood. referred to as ‘button-hole’ or ‘fish-mouth’ mitral orifice
The congenital valvular diseases have already been (Fig. 16.31,B).
described (page 425). Various acquired valvular diseases that EFFECTS. In normal adults, the mitral orifice is about 5 cm . The Heart
2
may deform the heart valves are listed below: Symptomatic mitral stenosis develops if the valve opening
1. RHD, the commonest cause (page 438) is reduced to 1 cm resulting in significant elevation of left
2
2. Infective endocarditis (page 445) atrial pressure from the normal of 12 mmHg to about 25
3. Non-bacterial thrombotic endocarditis (page 444) mmHg leading to dilatation of the left atrium. The elevated
4. Libman-Sacks endocarditis (page 444) left atrial pressure, in turn, raises pressure in the pulmonary
5. Syphilitic valvulitis (page 401) veins and capillaries, reducing the pulmonary function and
6. Calcific aortic valve stenosis causing exertional dyspnoea which is the chief symptom of
7. Calcification of mitral annulus mitral stenosis. The effects of mitral stenosis can thus be
8. Myxomatous degeneration (floppy valve syndrome) summarised as under:
9. Carcinoid heart disease. 1. Dilatation and hypertrophy of the left atrium.

Figure 16.31 Mitral valve disease. Normal mitral valve (A) contrasted with mitral stenosis (B) and mitral insufficiency (C).