|Calcific Aortic Stenosis|
3 different etiologies:
Congenital aortic stenosis.
Congenital bicuspid aortic valve.
Unknown: Degenerative calcific aortic stenosis.
Rheumatic calcific aortic stenosis: Fusion of the valve commissures in the healing phase of valvulitis initiates stenosis. Deformity with obstruction to blood flow results in hemodynamic fibrosis and calcification, which progresses as obstructions increase.
Congenital bicuspid valve: Not functionally stenotic at birth or in early adult life, but susceptible to acquired fibrosis and calcification causing stenosis in 6th and 7th decades. This susceptibility may be due to hemodynamic cummulative injuries due to the deformity.
Degenerative calcific stenosis: This is acquired on a previously normal valve. Pathogenesis unknown, but often attributed to "wear and tear" effects implying hemodynamic injury. A weak explanation. Original deformity not obstructive,
Rheumatic: Less than 10% of cases in U.S.. Usually associated with healed rheumatic mitral valvulitis.
Congenital bicuspid valve: Deformity alone does not cause stenosis, in contrast to congenital aortic stenosis present from birth. (see pathogenesis).
Degenerative calcific stenosis: An acquired disease of old age manifested usually in the eighth decade
|General Gross Description|
The left ventricle is hypertrophied in all these cases, regardless of pathogenesis.
The rheumatic cases show fusion of the cusp commissures with variable degrees of superimposed fibrosis and calcifications.
The bicuspid cases show thickening of the cusps with variable degrees of calcifications. One of the cusps will show a thickened fold dividing it into two smaller cusps, as if it resulted from a congenital fusion of one commissure. The calcifications can be deforming and bulky.
The so-called "degenerative cases" of unknown cause show 3 distinct separate cusps, thickened by calcifying fibrosis, and distorted by bulky irregular or nodular protruding calcific excresences.
|General Microscopic Description|
Fibrosis with hyalinization and calcification is the predominant microscopic change common to all forms.
The deforming calcific masses which dominate the gross changes are amorphous calcified matter separated by a hyalin matrix. This is different from usual dystrophic calcification which is restricted to calcification of existing structures or scarring. These "degenerative" changes are not characteristic of arteriosclerosis.
Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 544-5.
Harrison's Principles of Internal Medicine, 13th Ed: Isselbach et. al. (eds). New York, McGraw-Hill, 1994, pp.1059-61.
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|Calcific Aortic Stenosis
||Synopsis by: J. Hasson, MD (T39000M55400)