Degenerative valve disease

Although there has been a dramatic reduction in rheumatic valve disease in the industrialised countries over the past 30 years, there has not been a similar reduction in valve surgery. This is because the types of patients being referred for surgery have changed. The significant increase in life expectancy in developed countries partly accounts for this change in aetiology, especially in aortic valve disease. In one surgical series over a five year period (from 1981 to 1985), it was found that while the proportion of patients with congenitally bicuspid aortic stenosis remained stable (from 37% to 33%), postinflammatory valve disease decreased from 30% to 18% while degenerative valve disease increased from 30% to 46%.6

Although the incidence of degenerative valve disease increases with age, aging does not seem to be the only factor, as valve disease is not present universally in the elderly (25-45% of octogenarians do not have aortic calcification). Moreover, and most intriguing, the initial lesion of calcific aortic valve disease appears to involve an active process with some similarities to atherosclerosis, including lipid deposition (apo B, apo(a), and apo E), macrophage infiltration, and production of osteopontin and other proteins.7-9 In the Cardiovascular Health Study7 the relation between aortic sclerosis or aortic stenosis and clinical risk factors for atherosclerosis was evaluated in 5201 subjects aged 65 years or more; aortic valve sclerosis was found in 26% and aortic stenosis in 2% of the entire cohort. Independent clinical factors associated with both types of degenerative valve disease included age (twofold increased risk for each 10 year increase in age), male sex (two fold excess risk), and a history of hypertension (20% increase in risk); other significant factors included high lipoprotein Lp (a) and low density lipoprotein (LDL) cholesterol concentrations.

Another study found an association between atherosclerotic risk factors and mitral annulus calcification, and stenotic and non-stenotic aortic valve calcification.8 The analysis was done from a prospective database of 8160 consecutive patients and showed that age (odds ratio (OR) varying from 5.78 to 10.4, depending on age class), hypertension (OR 2.38), diabetes mellitus (OR 2.85), and hypercholes-terolaemia (OR 2.95) were strongly and significantly associated with aortic valve calcification, as were age (OR varying from 8.82 to 67, depending on age class), hypertension (OR 2.72), diabetes mellitus (OR 2.49), and hypercholesterolemia (OR 2.86) with mitral annu

Standing Seam Panels

Figure 15.1. Changes in the incidence of rheumatic fever. Rheumatic fever increased during the period of the industrial revolution, possibly because of overcrowding in urban areas. Later on, it reached a steady state as living standards began to improve. Finally, in the postindustrial period, the decline in incidence was associated with an easier access to medical care, widespread use of antibiotics, and reduced overcrowding. At the present time, when the disease is considered to be nearly eradicated, isolated outbreaks continue to occur.

Figure 15.1. Changes in the incidence of rheumatic fever. Rheumatic fever increased during the period of the industrial revolution, possibly because of overcrowding in urban areas. Later on, it reached a steady state as living standards began to improve. Finally, in the postindustrial period, the decline in incidence was associated with an easier access to medical care, widespread use of antibiotics, and reduced overcrowding. At the present time, when the disease is considered to be nearly eradicated, isolated outbreaks continue to occur.

lar calcification. The most important consequence of this process is aortic calcification and/or aortic stenosis, but the same calcific deposits may be located in the undersurface of the posterior mitral leaflet and, if extensive enough, can cause mitral incompetence and, more rarely, mitral stenosis.

The results of these studies suggest that degenerative valve disease does not have to be regarded as an inevitable consequence of aging, and that these findings might be translated to preventive measures. Taking into consideration that atherosclerotic heart disease, at least coronary heart disease, is to a certain extent a preventable condition, in which efforts have to be made to modify the natural (or unnatural course), the same principles would apply to degenerative valve disease. Accordingly, early forms of aortic stenosis and, probably, of aortic sclerosis and mitral annulus calcification should be considered as indicators to implement measures generally used to treat atherosclerotic vascular disease, including diet modification, tobacco consumption cessation, plasma lipid determinations, and blood pressure control.

The prevalence of degenerative valve disease is not known in underdeveloped countries. Presumably, it is low as life expectancy is much shorter and atherosclerotic heart disease is much less prevalent than in industrialised countries.

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