Experimentelle und histomorphologische Untersuchungen zu Heilungsvorgängen an Anastomosen der A. carotis am Tiermodell der Wistar-Ratte mit immunhistochemischer Darstellung von Kollagen IV

INTRODUCTION: The main risk in free flap tissue transfer is posed by the microvascular anastomosis. The dangers confronting the anastomosis are thrombosis, aneurysm, and vascular insufficiency. Collagen IV is associated with the basement membrane complex. It plays an essential role in vascular tissue organization and supports mechanical properties of vessels. We used a long-term animal experiment to gain a new understanding of histomorphological apposition of anastomosis and distribution of collagen IV.

METHODS: Seventy Wistar rats, seven groups of ten animals each, were operated. A 4-mm long segment of the common carotid artery was isolated and reinserted. After a varying length of time (between directly after the operation and 6 months later), the common carotid arteries including bifurcation were isolated after cardiovascular perfusion. Carotid arteries were embedded, and cross-sections were stained with hematoxylin and eosin, Verhoeff's tissue elastin stain, and immunohistochemical anti-collagen IV antibody. By using the above-described technique in each section four anastomoses were examined. The histomorphology and intensity of the anti-collagen IV stainings were evaluated.

RESULTS: Compression, shift, and dehiscence as forms of vessel apposition were often seen. We observed an overexpression of collagen IV in the media in cases of compression and shift. The grade of expression of collagen IV in the anastomosis depends on the extent of the injury.

CONCLUSIONS: A well-performed microvascular anastomosis is clinically important not only for the acute phase after the operation, but also for the long-term course. The application of antibodies to identify the collagen IV distribution is valuable for studying vascular healing. Further applications could be used in follow-up studies of vascular prostheses.