Page 467 - Textbook of Pathology, 6th Edition

EFFECTS. Aortic stenosis becomes symptomatic when the cases (Chapter 20). The lesions are characteristically located 451
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valve orifice is reduced to 1 cm from its normal 3 cm . The in the valves and endocardium of the right side of the heart.
symptoms appear many years later when the heart cannot The pathogenesis of the cardiac lesions is not certain. But in
compensate and the stenosis is quite severe. The major effect carcinoid tumour with hepatic metastasis, there is increased
of aortic stenosis is obstruction to the outflow resulting in blood level of serotonin secreted by the tumour. The
concentric hypertrophy of the left ventricle. Later, when increased concentration of serotonin reaches the right side
cardiac failure supervenes, there is dilatation as well as of the heart and causes the lesions but serotonin is inactivated
hypertrophy of the left ventricle (eccentric hypertrophy). on passage of the blood through the lungs and hence the left
The three cardinal symptoms of aortic stenosis are: heart is relatively spared. In addition, high levels of
exertional dyspnoea, angina pectoris and syncope. Exertional bradykinin may play contributory role in carcinoid heart
dyspnoea results from elevation of pulmonary capillary disease. However, chronic infusion of serotonin or bradykinin
pressure. Angina pectoris usually results from elevation of in experimental animals has not succeeded in producing
pulmonary capillary pressure and usually develops due to cardiac lesions; hence the exact pathogenesis of carcinoid
increased demand of hypertrophied myocardial mass. heart disease remains obscure.
Syncope results from accompanying coronary insufficiency.
Sudden death may also occur in an occasional case of aortic MORPHOLOGIC FEATURES. In majority of cases, the
stenosis. lesions are limited to the right side of the heart. Both
pulmonary and tricuspid valves as well as the endo-
AORTIC INSUFFICIENCY cardium of the right chambers show characteristic
cartilage-like fibrous plaques. Similar plaques may occur
About three-fourth of all patients with aortic insufficiency on the intima of the great veins, the coronary sinus and
are males with some having family history of Marfan’s the great arteries. Occasionally, the lesions may be found
syndrome.
on the left side of the heart.
ETIOLOGY. In about 75% of patients, the cause is chronic
RHD. However, isolated aortic insufficiency is less often due EFFECTS. The thickening and contraction of the cusps and
to rheumatic etiology. Other causes include syphilitic leaflets of the valves of the outflow tracts of the right heart CHAPTER 16
valvulitis, infective endocarditis, congenital subaortic result mainly in pulmonary stenosis and tricuspid
stenosis (congenitally bicuspid aortic valve), myxomatous regurgitation, and to a lesser extent, pulmonary regurgitation
degeneration of aortic valve (floppy valve syndrome), and tricuspid stenosis.
traumatic rupture of the valve cusps, dissecting aneurysm,
Marfan’s syndrome and ankylosing spondylitis. MYXOMATOUS DEGENERATION OF MITRAL VALVE
(MITRAL VALVE PROLAPSE)
MORPHOLOGIC FEATURES. The aortic valve cusps are
thickened, deformed and shortened and fail to close. There Myxomatous or mucoid degeneration of the valves of the The Heart
is generally distension and distortion of the ring heart is a peculiar condition occurring in young patients
(Fig. 16.31,C). between the age of 20 and 40 years and is more common in
women. The condition is common and seen in 5% of general
EFFECTS. As a result of regurgitant aortic orifice, there is adult population. The condition is also known by other
increase of the left ventricular end-diastolic volume. This synonyms like ‘floppy valve syndrome’ or ‘mitral valve
leads to hypertrophy and dilatation of the left ventricle prolapse’.
producing massive cardiac enlargement so that the heart may ETIOLOGY. The cause of the condition is not known but in
weigh as much as 1000 gm. Failure of the left ventricle
increases the pressure in the left atrium and eventually some cases it may be genetically determined collagen
pulmonary hypertension and right heart failure occurs. disorder. Association with Marfan’s syndrome has been
The characteristic physical findings in a patient of aortic observed in 90% of patients. Others have noted myxomatous
insufficiency are awareness of the beatings of the heart, degeneration in cases of Ehlers-Danlos syndrome and in
poundings in the head with each heartbeat, low diastolic and myotonic dystrophy. However, the myxomatous valvular
high pulse pressure, rapidly rising and collapsing water changes seen in the aged patients are not related to this entity.
hammer pulse (Corrigan’s pulse), booming ‘pistol shot’
sound over the femoral artery, and systolic and diastolic MORPHOLOGIC FEATURES. Any cardiac valve may be
murmur heard over the femoral artery when it is lightly involved but mitral valve is affected most frequently. The
compressed (Durozier’s sign). Sometimes, angina pectoris disease is usually most severe and most common in the
occurs due to increased myocardial demand or due to posterior leaflet of the mitral valve. The affected leaflet
coronary insufficiency. shows either excessive or redundant leaflet tissue, which
is opaque white, soft and floppy. Cut section of the valve
CARCINOID HEART DISEASE reveals mucoid or myxoid appearance. A significant
feature is the ballooning or aneurysmal protrusion of the
ETIOLOGY. Carcinoid syndrome developing in patients affected leaflet and hence the name ‘mitral valve prolapse’
with extensive hepatic metastases from a carcinoid tumour and ‘floppy valve syndrome’.
is characterised by cardiac manifestations in about half the