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This Article Full Text Full Text (PDF) All Versions of this Article: 288/3/H1224    most recent 00640.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Harder, Y. Articles by Menger, M. D. Search for Related Content PubMed PubMed Citation Articles by Harder, Y. Articles by Menger, M. D.

Evolution of a "falx lunatica" in demarcation of critically ischemic myocutaneous tissue

¹Institute for Clinical and Experimental Surgery, University of Saarland, Homburg/Saar, Germany; and ²Department of Plastic, Reconstructive and Aesthetic Surgery, Inselspital, University of Berne, Berne, Switzerland

Submitted 28 June 2004 ; accepted in final form 20 October 2004

Using intravital microscopy in a chronic in vivo mouse model, we studied the demarcation of myocutaneous flaps and evaluated microvascular determinants for tissue survival and necrosis. Chronic ischemia resulted in a transition zone, characterized by a red fringe and a distally adjacent white falx, which defined the demarcation by dividing the proximally normal from the distally necrotic tissue. Tissue survival in the red zone was determined by hyperemia, as indicated by recovery of the transiently reduced functional capillary density, and capillary remodeling, including dilation, hyperperfusion, and increased tortuosity. Angiogenesis and neovascularization were not observed over the 10-day observation period. The white rim distal to the red zone, appearing as "falx lunatica," showed a progressive decrease of functional capillary density similar to that of the necrotic distal area but without desiccation, and thus transparency, of the tissue. Development of the distinct zones of the critically ischemic tissue could be predicted by partial tissue oxygen tension (Pt) analysis by the time of flap elevation. The falx lunatica evolved at a Pt between 6.2 ± 1.3 and 3.8 ± 0.7 mmHg, whereas tissue necrosis developed at <3.8 ± 0.7 mmHg. Histological analysis within the falx lunatica revealed interstitial edema formation and muscle fiber nuclear rarefaction but an absence of necrosis. We have thus demonstrated that ischemia-induced necrosis does not demarcate sharply from normal tissue but develops beside a fringe of tissue with capillary remodeling an adjacent falx lunatica that survives despite nutritive capillary perfusion failure, probably by direct oxygen diffusion.

ischemia; myocutaneous flap; necrosis; microcirculation; angiogenesis; partial tissue oxygen tension; capillary remodeling; capillary dilation; capillary tortuosity