EXPERIMENTAL DIRECTIONAL ATHERECTOMY INJURY IN ARTERIAL VESSELS - IMPACT OF TRAUMA DEPTH ON CELLULAR-RESPONSE

This study investigates cellular alterations after directional atherec tomy vessel injury (DI) in an experimental model in 50 pigs, Two hundr ed arteries were excised at eight different times (2 hours to 21 days) after DI and were examined by electron microscopy and immunohistochem istry. The extent of injury varied with the number of repetitive passe s of the atherectomy catheter, According to the extent of injury the v essel segments with DI were assigned to three groups: intima injury (g roup 1), media injury (group 2), and adventitia injury (group 3), A my oproliferative response was found in relation to in depth, increasing from group 1 (ratio tissue hyperplasia/media: 0.3 +/- 0.2; p < 0.001) to group 2 (ratio tissue hyperplasia/media: 1 +/- 0.5) and group 3, In tense neutrophil infiltration occurred in groups 2 and 3 (peak 12 hour s after DI) and was followed by the early occurrence of synthetic smoo th-muscle cells (SMC; >50% of all SMC present), Volume fraction of des min and actin was transiently reduced in injured media and myoprolifer ative tissue (7d: 9% vs >90% normal media), SMC proliferation Started in groups 2 and 3 at 48 hours and peaked at 7 days (+500% vs normal me dia, p < 0.001), After DI was done, vascular response started immediat ely and depended on injury depth. A transient myoproliferative respons e resulted, correlating with the extent of vessel trauma.