Influence of vein valves in the development of @entity4288 in venoarterial grafts in the XXXX .

@entity1 @entity1568 @entity753 @entity4288 @entity1711 @entity95 @entity1710 @entity165
Coronary saphenous vein grafts in @entity1 beings have a more limited long-term patency rate than internal thoracic artery grafts, primarily because of more rapid development of @entity4288 . The factors responsible for this increased susceptibility are not completely understood. To test the hypothesis that vein valves may influence this process, we studied 48 @entity753 @entity95 with jugular vein grafts interposed into the carotid arterial circulation. In 24 animals (group A), the vein segments did not contain a vein valve. In the other 24 animals (group B), a vein valve was present. Both groups were further divided in four subgroups of six to be put to death at 2, 4, 6, and 8 weeks after the operation. All animals were fed a 2% @entity165 diet. At postmortem examination, alternate 2 mm sections were either stained with @entity1710 and @entity1711 for histologic and morphometric studies or frozen in liquid @entity1568 for immunohistochemistry and in situ hybridization studies. Proliferating cell nuclear antigen immunostaining was used to study cell proliferation. Wall thickness of vein grafts increased with time. During the first 2 weeks intimal and medial thickening was primarily due to an increase in numbers of cells. Between 2 and 6 weeks further intimal and medial thickening occurred, but without additional increase in cell numbers. After 6 weeks, foam cells and lipid deposits started to appear. By 8 weeks, changes identical to those seen in arteriosclerotic plaques in @entity1 beings were evident. These changes developed sooner and with more intensity in group B animals (p < 0.01 to 0.001), and they developed faster and with more severity in segments of vein located distal to the valve than in the segments located proximal to the valve (p < 0.001). This is the first controlled experiment demonstrating that the presence of valves in the vein segments is associated with augmented and accelerated intimal changes leading to vein atheromatosis.
