The XXXX . Study on pathogenesis.

@entity1 @entity339 @entity384 @entity4091 @entity3454 @entity730 @entity397 @entity340 @entity884
The pathogenesis of the @entity3454 is not fully solved. An almost invariable histological finding is the great accumulation of mucinous material in the valve leaflets and constitutes the basis of the @entity340 . The presence of a mucinous layer in normal valves-- the @entity4091 --is not well recognised. To establish the normal range of the extent of this zone, 50 excised mitral valves from @entity1 aged 2 to 89 years and who died as a result of road traffic accidents or non-cardiac causes have been analysed by measuring the thickness of the zone in relation to the valve thickness. A range of 0 to 60 per cent was found and this was not influenced by age. The findings were compared with 50 @entity1 clinically diagnosed as suffering from the @entity3454 . A value of over 60 per cent (range 62 to 94%) was found in 43 @entity1 . The increase in the extent of the mucinous material was considered to be a secondary change in the thickened fibrosa which normally accompanies the @entity3454 . Measurements of @entity4091 falling within the normal range were found in seven @entity1 . The clinical features, complications, and accompanying conditions have also been analysed. @entity397 had occurred in 20 @entity1 , @entity884 in three, and @entity730 was found in four valves. In four @entity1 the aortic valve was also involved and accompanying @entity384 in an additional @entity1 . It is suggested that these @entity1 should not be included in the group of Marfan's forme fruste, nor in the typical floppy @entity339 . Apart from the valvular theory, the myocardial theory in the pathogenesis of the syndrome has been discussed and the components ensuring normal mitral valve function have been reviewed. It is concluded that an inherent, prominent @entity4091 predisposes to the @entity3454 , particularly if any one of the components of normal valve function is abnormal.
