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The delay phenomenon: the story unfolds
1Royal Melbourne Hospital, and Department of Surgery, University of Melbourne, Australia.
Plastic and Reconstructive Surgery
|January 10, 2001
Summary
Flap delay causes permanent dilation of choke vessels, not new vessel growth. This active process involves cell changes and vessel enlargement, improving blood flow to flaps.
Area of Science:
- Vascular Surgery
- Tissue Engineering
- Regenerative Medicine
Background:
- Flap delay procedures aim to improve blood supply to flaps.
- Previous research indicated vessel dilation, not angiogenesis, during flap delay.
- Choke vessels, connecting vascular territories, are key to flap perfusion.
Purpose of the Study:
- To investigate the sequential anatomic changes in choke vessels during flap delay.
- To determine if choke vessel dilation is a temporary or permanent phenomenon.
- To elucidate the cellular mechanisms underlying flap delay-induced vascular changes.
Main Methods:
- Flap delay procedures in 200 rabbits and 17 dogs (skin and muscle flaps).
- Postoperative examination at intervals from 1 hour to 1 year.
- Utilized fluorescein dye, angiography, light microscopy, immunohistochemistry, and electron microscopy.
Main Results:
- Initial vasoconstriction followed by progressive choke vessel dilation (peaking at 48-72 hours).
- Temporary fluorescein flow barrier at choke vessels during early delay.
- Microscopy revealed decreased vessel wall thickness, increased lumen diameter, cell hyperplasia/hypertrophy, and endothelial restoration.
- Long-term studies confirmed permanent choke vessel dilation and wall thickening.
- Canine studies corroborated findings, showing persistent dilation even after restoring normal circulation.
Conclusions:
- Flap delay induces a permanent and irreversible dilation of choke vessels.
- This dilation is an active cellular process involving hyperplasia and hypertrophy.
- The findings suggest a universal mechanism for flap delay across species and tissues.