Acute and long-term effects of massive balloon dilation on the aortic wall and vasa vasorum.

To investigate the acute and long-term effects on the vasa vasorum after massive overdilation, canine aortic segments were dilated with Gruentzig balloon catheters to more than 100% over normal size. In the acute study, the significant lumen increase was the result of intimal and medial rupture with stretching and thinning of the adventitia. In these areas, the vasa vasorum were stretched and severed, causing adventitial hemorrhage. In the chronic study, areas of previous subtotal wall rupture with adventitial thinning were repaired by scar tissue. This repair included formation of a neomedia, hyperplasia of the adventitia, and proliferation of the vasa vasorum. No progression of luminal dilatation was seen. This study showed that in subtotal aortic wall rupture, even a severely damaged adventitia is capable of preserving the lumen from further dilatation and rupture until healing. Blood flow to the damaged vessel wall was reestablished by revascularization via capillary budding in the aortic wall.