Page 466 - Textbook of Pathology, 6th Edition

450 2. Normal-sized or atrophic left ventricle due to reduced as well as pressure since the left ventricle cannot empty
inflow of blood. completely. This results in rise in left atrial pressure and
3. Pulmonary hypertension resulting from passive dilatation. As a consequence of left atrial hypertension,
backward transmission of elevated left artial pressure which pulmonary hypertension occurs resulting in pulmonary
causes: oedema and right heart failure. In symptomatic cases of
i) chronic passive congestion of the lungs; mitral insufficiency, the major symptoms are related to
ii) hypertrophy and dilatation of the right ventricle; and decreased cardiac output (e.g. fatigue and weakness) and
iii) dilatation of the right atrium when right heart failure due to pulmonary congestion (e.g. exertional dyspnoea and
supervenes. orthopnoea) but the features are less well marked than in
mitral stenosis. The effects of mitral insufficiency may be
MITRAL INSUFFICIENCY summarised as under:
1. Dilatation and hypertrophy of the left ventricle.
Mitral insufficiency is caused by RHD in about 50% of 2. Marked dilatation of the left atrium.
patients but in contrast to mitral stenosis, pure mitral 3. Features of pulmonary hypertension such as:
insufficiency occurs more often in men (75%). Subsequently, i) chronic passive congestion of the lungs;
mitral insufficiency is associated with some degree of mitral ii) hypertrophy and dilatation of the right ventricle; and
stenosis.
iii) dilatation of the right atrium when right heart failure
ETIOLOGY. All the causes of mitral stenosis may produce supervenes.
mitral insufficiency, RHD being the most common cause. In
addition, mitral insufficiency may result from non- AORTIC STENOSIS
inflammatory calcification of mitral valve annulus (in the Aortic stenosis comprises about one-fourth of all patients
elderly), myxomatous transformation of mitral valve (floppy with chronic valvular heart disease. About 80% patients of
valve syndrome), rupture of a leaflet or of the chordae symptomatic aortic stenosis are males. It is of 2 main types:
tendineae or of a papillary muscle. A few other conditions non-calcific and calcific type, the latter being more common.
cause mitral insufficiency by dilatation of the mitral ring such
as in myocardial infarction, myocarditis and left ventricular 1. Non-calcific aortic stenosis. The most common cause of
failure in hypertension. non-calcific aortic stenosis is chronic RHD. Other causes are
congenital valvular and subaortic stenosis and congenitally
MORPHOLOGIC FEATURES. The appearance of the bicuspid aortic valve.
SECTION III
mitral valve in insufficiency varies according to the
underlying cause. The rheumatic process produces 2. Calcific aortic stenosis. Calcific aortic stenosis is more
rigidity, deformity and retraction of the valve leaflets and common type. Various causes have been ascribed to it. These
fusion of commissures as well as shortening and fusion include healing by scarring followed by calcification of aortic
of chordae tendineae (Fig. 16.31,C). valve such as in RHD, bacterial endocarditis, Brucella
In myxomatous degeneration of the mitral valve leaflets endocarditis, Monckeberg’s calcific aortic stenosis (page 392),
(floppy valve syndrome) which is described on page 451, healed congenital malformation and familial hypercholes-
there is prolapse of one or both leaflets into the left atrium terolaemic xanthomatosis.
during systole.
In non-inflammatory calcification of mitral annulus seen MORPHOLOGIC FEATURES. The aortic cusps show
in the aged, there is irregular, stony-hard, bead-like characteristic fibrous thickening and calcific nodularity
Systemic Pathology
thickening in the region of mitral annulus without any of the closing edges. Calcified nodules are often found in
associated inflammatory changes. It is thought to reflect the sinuses of Valsalva. In rheumatic aortic stenosis, the
degenerative changes of aging. commissures are fused and calcified, while in non-
rheumatic aortic stenosis there is no commissural fusion
EFFECTS. The regurgitant mitral orifice produces (Fig. 16.32,B).
progressive increase in left ventricular end-diastolic volume

Figure 16.32 Aortic valve diseases. Normal aortic valve (A) contrasted with aortic stenosis (B) and aortic insufficiency (C).