Flap Delay- types, pathophysiology, classification

Flap delay definition, classification, pathophysiology. Types of flap delay, standard delay, pharmacological delay, various delays, angiosomes, flap territories, http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226, flap types, flap delay, Flap delay definition, classification, pathophysiology. Types of flap delay, standard delay, pharmacological delay, various delays, angiosomes, flap territories, http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226, flap types, flap delay, Flap delay definition, classification, pathophysiology. Types of flap delay, standard delay, pharmacological delay, various delays, angiosomes, flap territories, http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226, flap types, flap delay, Flap delay definition, classification, pathophysiology. Types of flap delay, standard delay, pharmacological delay, various delays, angiosomes, flap territories, http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7850104226http://pascal-francis.inist.fr/vibad/index.php?action=getRecord Detail&idt=PASCAL7850104226http://pascal-francis.s

1. Flap Delay Phenomenon Dr. Rajesh B

2. INTRODUCTION Flap delay is a pre-operative technique that involves temporarily restricting the blood supply to the flap for a period of time before the actual transfer. The purpose is to encourage collateral blood flow to the flap, making it more viable when fully transferred to the recipient site. It helps prevent complications like flap necrosis, where the tissue dies due to lack of adequate blood supply.

3. Historical Perspective   The delay procedure has been used for several hundred years However it was not until the early 1900s that the concept was recognized. Blair introduced the term “delayed transfer” in 1921 In the 16th century Tagliacozzi delayed his upper arm flaps by making parallel incisions through the skin and subcutaneous tissue overlying the biceps muscle. In 1965, using the pig model, Milton investigated the effectiveness of four different methods of delaying a flap. He found that in developing a bipedicled flap, the best form of delay was by making two incisions and undermining the skin between the incisions.

4. What is Flap Delay? Technique to enhance the viability of a skin flap by inducing controlled ischemia to improve blood supply before transferring it to a new location. Aims to reduce the risk of flap necrosis and improve tissue survival.

5. The physiologic effect of delay is an enlargement of the existing arteries along the axis of the flap, which has been well documented in experimental animal models. Anastomotic vascular keystones, usually formed by reduced- caliber choke arteries that link adjacent cutaneous perforators, play an integral role in the delay phenomenon When a flap is elevated, these choke vessels, which initially reduce flow from one arterial territory to the next along the flap, enlarge to the caliber of the cutaneous arteries they connect.

6. Goal of flap delay The goal of a flap delay is to • Enhance flap circulation, there by ensuring flap survival after advancement, transposition to a defect • To increase the area of a flap

7. Types of Flap Delay Surgical Standard delay Strategic / vascular Non Surgical

8. Surgical flap delay Surgical flap delay is accomplished in two ways: standard delay, with an incision at the periphery of the cutaneous territory or partial flap elevation; and strategic delay, with division of selected pedicles to the flap to enhance perfusion through the remaining pedicle or pedicles

9. Standard delay Bipedicle delay- A skin flap is mapped out on the donor site and incised on its two longitudinal sides. The flap is undermined to form a bipedicle flap and is sutured back to donor site. Two to three weeks after construction of the bipedicle flap, the third side(distal end) is cut in one or two stages at 2-3 days apart. At the end of this stage, a single pedicle flap is completely raised and the distal portion of the flap is moved to the recipient site for wound coverage without skin necrosis. Surgical delay increased skin flap capillary blood flow between 2 and 7 days of delay. This increase in capillary blood flow was mainly in the distal random portion of delayed skin flaps.

10. Outline Delay (Partial Flap Raising) Description: Outline delay is a variation where the flap is only partially raised initially. The outline of the flap is undermined and lifted, but not completely excised from the donor site, allowing the blood supply to remain intact for a while. After a period of delay, the flap is then fully raised and moved to the recipient site. Mechanism: The partial raising allows for partial restriction of blood supply, stimulating the growth of collateral vessels while maintaining the integrity of the flap’s primary blood flow. Delay Period: Typically, the delay lasts for several days to a week, after which the full flap is separated and transferred. Indications: Often used for smaller flaps or in cases where a more conservative approach is desired to preserve as much tissue as possible.

11. Strategic/vascular delay D ivision of selected pedicles to the flap to enhance perfusion through the remaining pedicle or pedicles is done in strategic delay Examples:- Division of perforators or one or two dominant arteries that supply blood to the rectus abdominis muscle 2–3 weeks before flap surgery significantly augmented viability in TRAM flaps in rats and augmented skin and muscle blood flow and viability in TRAM flaps in pigs. In human patients, ligation of the deep inferior epigastric arteries 2–4 weeks before flap surgery augmented skin blood supply and viability in TRAM flaps

12. Theories of flap delay There are two theories that describe the potential mechanisms by which the delay phenomenon prevents skin necrosis. Ischaemic theory- It suggests that delay acclimatizes the flap to ischemia (tolerance), permitting it to survive with less blood flow than would normally be required. This theory suggests that vascular delay cause adaptive metabolic changes at a cellular level within the tissue. Increased vascularity theory- The second theory is that delay improves vascularity by increasing flow through pre-existing vessels, reorganizing the pattern of blood flow to more ischemic areas.

13. Mechanism of surgical delay in augmentation of pedicle flap viability Surgical delay procedure reduces arteriovenous (AV) shunt flow depletes vasoconstriction and prothrombotic substances in the skin flap induces vascular territory expansion by opening existing choke arteries induces angiogenesis

14. Surgical delay produces reduced arteriovenous (AV) shunt flow In acute skin flap surgery, distal ischemic necrosis is caused by opening of AV shunt flow as a result of sympathetic denervation . F low in the proximal areas is sufficient to supply both the AV shunt and capillary blood flow, but the shunting becomes lethal in the distal areas of the skin flap where the total blood flow was low. In surgical delay, the bipedicle skin flap provides sufficient blood supply to the distal flap during the early period of sympathetic denervation and opening of AV shunts.

15. Surgical delay procedure depletes vasoconstriction and prothrombotic substances in the skin flap Local tissue content of vasoconstricting and prothrombotic substances are known to be elevated by surgical trauma. Surgical delay procedure reduces local production and also allows time to deplete the vasoconstricting and prothrombic substances before converting the bipedicle flap to single-pedicle flaps.

16. Surgical delay procedure induces vascular territory expansion by opening existing choke arteries The capillary blood flow increased significantly within 2 days of delay and a maximum increase in skin flap capillary blood flow occurred between 2 and 3 days of delay, and remained unchanged between 4 and 14 days of delay without an increase in density of arteries ( arteriogenesis ). This increase in capillary blood flow occurred mainly in the distal portion of the skin flap. Flap delay causes vascular territory expansion by recruitment (opening) of existing arteries by opening of existing choke blood vessels.

17. Angiogenesis Flap delay was associated with a significant increase in gene expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF) in the skin paddle of the rat TRAM flaps within 12 hours of flap delay.

18. Other Methods to do Flap Delay Pharmacological Chemical Laser

19. Pharmacologi cal delay The use of drugs have been tried for delays, their role has been quite questionable with variable results The drugs used for medical delay include- Angiogenic agents such as VEGF PDGF and FGF Antispasmodic agents Alpha agonists Beta agonist ( direct vasodilators) Calcium channel blockers Anticoagulants Thrombolytics Antispasmodics Leukocyte aggregation and adhesion inhibitors such as Montelukast

20. Chemical Delay Chemical delay has also been studied as an alternative to surgical delay. In a rat skin flap model, although not as effective as the surgical procedure, the topical combination of nicoboxil and nonivamide proved to be of significant value in order to ameliorate ischemic necrosis in experimental skin flaps.

21. Laser Using flash lamp-pumped pulsed-dye laser at a wavelength of 585nm, it was demonstrated that laser delay is as effective as surgical delay methods Lasering lateral borders leads to dilation and longitudinal rearrangement of the existing vessels rather than angiogenesis Lasering the entire surface results in delay effect by inducing angiogenesis due to activation and degranulation of the mast cells( Ercocen et al. 2003) Some studies found that CO2 and Erbium:YAG lasers are as effective as surgery for delay of skin flaps in the rat model.

22. Indications for Flap Delay Large Flaps: When the flap size is large, it may not have sufficient blood supply to survive without delay. Complex Defects: Used in reconstructing large or challenging defects, such as in the head and neck or breast. Unfavorable Blood Supply: In areas with compromised vascularity, such as the lower legs or certain post-radiation sites.

23. Benefits of Flap Delay Improved Flap Viability: Increased blood flow due to the formation of new blood vessels, improving overall survival. Reduced Risk of Necrosis: Ensures the flap has an adequate blood supply when transferred. Better Aesthetic and Functional Outcomes: More reliable and predictable results in reconstructive surgery

24. Challenges and Risks Timing of Delay: A critical factor is the optimal length of the delay period; too short a time may not allow sufficient vascular growth, while too long may compromise flap survival. Flap Failure: If the delay period is not properly executed, or if the new vascular network doesn’t develop as expected, flap failure can occur. Monitoring and Assessment: Continuous monitoring of the flap and recipient site is necessary during the delay period.

25. Flap delay also has disadvantages: a preliminary operation is required; inadvertent injury to the desired pedicle for flap design is possible; and resultant scar tissue at the site of flap delay may impair subsequent manipulation and inset of the flap at the recipient site.

26. Complications and prevention Complications Preliminary operatio n Injury to the desired pedicle Flap necrosis May impair subsequent manipulation and flap inset Prevention Adequate preoperative planning Proper flap design Proper identification of pedicles Good grasp of the anatomy

27. References Iranpour M, Khodarahmi A, Khodarahmi N, Shafiee M, Malekpourafshar R, Nakhaee N. Montelukast for Medical Delay in Flap Surgery. World J Plast Surg. 2020 Jan;9(1):48-54. doi : 10.29252/wjps.9.1.48. PMID: 32190592; PMCID: PMC7068180. ynn L, Chiu- Collins M.D, Surgical delay: vascular delay. Encyclopedia of Otolaryngology, head and neck surgery.2013 Essentials of plastic surgery, 2nd edition Keynotes in plastic surgery Neligans volume 4: flaps pathophysiology and pharmacology Caitlin S., Thompson-Torgerson, Lacy A. et al. Altered mechanism of thermoregulatory vasoconstriction in aged human skin. Pubmed 2008 Daniel N, Rajan S, David P, et al. salvage of failed free flaps used in head and neck reconstruction. Pubmed 2009

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