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Table of Contents
ORIGINAL ARTICLE
Year : 2019  |  Volume : 27  |  Issue : 4  |  Page : 151-155

Pedicle lengthening with traction vasculogenesis: Axial and perforator abdominal island flap model in rat


1 Department of Plastic, Reconstructive and Aesthetic Surgery, Necip Fazil City Hospital, Kahramanmaras, Turkey
2 Department of Plastic, Reconstructive and Aesthetic Surgery, Ege University, Izmir, Turkey

Date of Submission12-Aug-2018
Date of Acceptance08-Oct-2018
Date of Web Publication26-Sep-2019

Correspondence Address:
Dr. Cagil Meric Erenoglu
Department of Plastic, Reconstructive and Aesthetic Surgery, Necip Fazil City Hospital, Erkenez Mahallesi, Dulkadiroglu, 46050 Kahramanmaras
Turkey
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/tjps.tjps_56_18

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  Abstract 


Background: Functional vessel elongation is possible with traction vasculogenesis technique. This study questions the effect of traction on pedicle length and flap viability of rat abdominal superficial epigastric and cephalic epigastric perforator flaps. Method: 28 Wistar-Albino rats were divided into 4 groups as superficial epigastric flap control and traction groups and cephalic epigastric perforator flap control and experiment groups. 1 mm daily traction was applied for 10 days to traction subgroups. On the 10th day pedicle length was measured and flaps were raised. 7 days after viable flap areas were measured. Statistical analysis was done. Results: In both superficial epigastric flap and cephalic epigastric perforator flap groups, pedicle length was found to be higher in traction group and flap viability was found to be higher in control groups. No relation was found between pedicle length and flap viability. Discussion: As a novel technique traction vasculogenesis may be applied to flap pedicles for elongation. This elongation process, not surprisingly may reduce the viable flap surface. However, traction vasculogenesis seems promising for functional elongation of axial and perforator flap pedicles under optimal conditions.

Keywords: Axial flap, perforator flap, traction vasculogenesis, vessel elongation


How to cite this article:
Erenoglu CM, Tiftikcioglu YO, Erenoglu BK. Pedicle lengthening with traction vasculogenesis: Axial and perforator abdominal island flap model in rat. Turk J Plast Surg 2019;27:151-5

How to cite this URL:
Erenoglu CM, Tiftikcioglu YO, Erenoglu BK. Pedicle lengthening with traction vasculogenesis: Axial and perforator abdominal island flap model in rat. Turk J Plast Surg [serial online] 2019 [cited 2019 Oct 21];27:151-5. Available from: http://www.turkjplastsurg.org/text.asp?2019/27/4/151/267929




  Introduction Top


Functional isolated vessel elongation with gradual mechanical traction is possible with traction vasculogenesis technique.[1] The gain in vessel length is especially important in flap surgery, where pedicle length is an important parameter for flap selection.[2] Insufficient pedicle length may obligate the surgeon to change the reconstructive plan from regional pedicled flap to free flap. Also, in free flap selection, short pedicle may limit optimal results.

Pedicle elongation may abolish the need for a free flap transfer. If the flap is based on the musculocutaneous perforators, elongation of the perforators between fascia and flap will also render intramuscular dissection unnecessary, reduce donor site morbidity, and simplify the reconstructive plan.

In this study, we applied traction vasculogenesis technique on rat abdominal flap pedicles: cranial epigastric perforator (CEP) and superficial epigastric vessels. At the end of the traction period, the pedicle length and flap viability were assessed in each group.


  Materials and Methods Top


The study was approved by the Animal Care and Use and Ethical Committee of our institution. Twenty-eight adult Wistar albino rats weighing an average of 300 g were used. They were kept in solitary cages and were fed with standard rat chow and tap water. Anesthesia was done by 50 mg/kg ketamine and 15 mg/kg xylazine was given for analgesia and sedation. As the traction device, distractor body of an internal maxillary distraction osteogenesis system (Synthes, Inc.) was used.

Superficial inferior epigastric vessel-based abdominal flap traction subgroup (n = 7)

Under general anesthesia, right-sided hemiabdominal flaps were planned. The whole ventral body of rats was shaved. The upper border was xiphoid process; inferior border was the horizontal line between the two anterior iliac spines, medial border was the vertical line from the xiphoid, and the lateral border was the vertical line from the right anterior iliac spine. The length of the borders and surface area was measured [Figure 1]. Inferior border of the flap was incised, and superficial epigastric artery and vein were found and released from the surrounding loose connective tissue. The length of the pedicle was measured from its origin branching from the femoral artery and vein to entrance to the flap. The pedicle was wrapped by a 5 mm of soft silicone tube for traction. The inguinal fat pad was left in the flap side. Medial border of the flap was incised, and the left hemiabdomen was subcutaneously dissected for traction device inset. The device was placed subcutaneously with an axis perpendicular to the course of the pedicle and secured to underlying rectus muscle at two points to prevent axis deviation. The activation end of the device was left outside the skin for daily turn. Silicone piece was connected to the mobile end of the device with 5/0 Nylon suture. Care was taken to avoid any vascular folding or collapse caused by the silicone. Lateral and superior borders of the flap were not incised, and the flap was not raised not to distort its circulation during the traction period. Medial and inferior incised borders were sutured back. The activation started the next day, and the traction was applied 1 mm/day (0.5 mm twice a day with 12 h period) for 10 days. 10 mm of traction was achieved. On the 11th day rats were reoperated under anaesthesia for flap dissection. The sutured borders were reopened, and the superior and lateral borders were incised. The flap was raised caudally above the rectus fascia. CEPs and branches coming down from the pectoral region were cauterized. The pedicle was found and dissected from the underlying fascia. Major fibrotic tissue surrounding the vessels was cleaned, and the silicone tube and traction device were removed. The pedicle length was measured by mildly pulling the flap cranially. Then, the flap was inset back to its bed and sutured. The new border lengths after inset were measured, and the surface area was recorded with a transparent acetate and millimetric paper. Seven days postoperatively, the vital and necrotic areas of the flap were recorded with transparent paper again, and the flap viability was evaluated. [Figure 2] shows the design for the distraction device for vascular elongation.
Figure 1: Right-sided hemiabdominal flap dimensions and borders

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Figure 2: Design for the distraction device for vascular elongation

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Superficial inferior epigastric vessel-based abdominal flap control subgroup (n = 7)

After the same preparations for the traction group, the right hemiabdominal flap was raised. CEPs and branches coming down from the pectoral region were cauterized. The inguinal fat pad was left in the flap side. Superficial inferior epigastric artery (SIEA) and vein were released from the surrounding loose connective tissue. The flap was mildly pulled cranially and the pedicle length was measured. The flap was inset back to its bed and the new dimensions were recorded as the traction group. Seven days postoperatively, the flap viability was evaluated.

Cranial epigastric perforator-based abdominal flap traction subgroup (n = 7)

Under general anesthesia, right-sided hemiabdominal flaps were planned with the same borders. Incisions were done and SIE vessels and branches coming down from the pectoral region were cauterized. CEPs were visualized and protected. The second perforator from cranial side was isolated and its length was measured from the fascia to the flap. The perforator vessels were wrapped by a 2-mm of soft silicone tube [Figure 3]. The other perforators were protected not to distort flap circulation during traction. On the left side, a subcutaneous pocket was opened for device. It was inset in a position that will pull the midpoint of the vessel on a perpendicular axis and sutured to the underlying rectus muscle on two points to prevent axis deviation. Care was taken to avoid any vascular folding or collapse caused by the silicone. Activation end was left outside the skin. Activation started the next day and traction was applied 1 mm/day (0.5 mm twice a day with 12 h period) for 10 days. 10 mm of traction was achieved. On the 11th day, the rats were reoperated under anesthesia for flap dissection based on the elongated second CEP. Sutured borders were reopened and flap was raised medially above the rectus fascia. Superficial epigastric vessels, other cranial CEPs and branches coming down from the pectoral region were cauterized. Pedicle was found and released from the underlying fascia. Fibrotic tissue surrounding the perforator was mildly cleansed and silicone tube and traction device was removed. The pedicle length was measured by mildly pulling the flap laterally. Then the flap was inset back to its bed and sutured. The new dimensions after inset were measured and surface area was recorded with a transparent acetate and millimetric paper. 7 days postoperatively flap viability was evaluated.
Figure 3: Traction device set for the second cranial epigastric perforator

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Cranial epigastric perforator-based abdominal flap control subgroup (n = 7)

After same preparations for the traction group, right hemiabdominal flap was raised based on the second CEP [Figure 4]. Bleeding vessels were cauterized. Pedicle was released from the surrounding loose connective tissue. The flap was mildly pulled cranially and the pedicle length was measured. The flap was inset back to its bed and new dimensions were recorded as the traction group. Seven days postoperatively, the flap viability was evaluated through transparent acetate and millimetric paper.
Figure 4: Control group of second epigastric perforator-based flap

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Statistical analysis

All data were entered into PASW 18 (SPSS; IBM Corp, Armonk, NY, USA). The Mann–Whitney test and Spearman's rho test were applied.


  Results Top


Group I: Superficial inferior epigastric vessel-based abdominal flap

Pedicle length

The animals were reexplored on the 11th day. The pedicle length of the control and traction groups is shown in [Figure 5]. The mean pedicle length in the control group is 36.71 mm and 51.85 mm in the traction group. Evaluated by the Mann–Whitney test, the pedicle length of the traction group is found significantly higher than that of the control group (P < 0.05). [Figure 6] shows the experimental elongation of the traction group.
Figure 5: Comparison of the length of superficial inferior epigastric vessels between the traction and control groups

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Figure 6: Experimental elongation of the traction group

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Flap viability

The mean corrected flap surface area on the flap dissection day was 1934 mm 2 in the control group and 1976 mm 2 in the traction group [Figure 7]. On the 7th day, the mean viable surface area was 1775 mm 2 (flap viability = 91.83%) in the control group and 1468 mm 2 (flap viability = 74.20%) in the traction group. Evaluated by the Mann–Whitney test, the flap viability is found to be statistically lower in the traction group (P < 0.05). In the traction subgroup, Spearman's rho test revealed no relation between the pedicle length and flap viability (P > 0.05).
Figure 7: Comparison of the flap viability based on the superficial inferior epigastric vessels between the traction and control groups

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Group II: Cranial epigastric perforator-based abdominal flap

Pedicle length

The animals were reexplored on the 11th day. The mean pedicle length in the control group is 11.57 mm and 19.57 mm in the traction group [Figure 8]. Evaluated by the Mann–Whitney test, the pedicle length of the traction group is found significantly higher than that of the control group (P < 0.05).
Figure 8: Comparison of the length of cephalic epigastric perforators between the traction and control groups

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Flap viability

The mean corrected flap surface area on the flap dissection day was 2008 mm 2 in the control group and 2003 mm 2 in the traction group. On the 7th day, the mean viable surface area was 1790 mm 2 (flap viability = 89.22%) in the control group and 112 mm 2 (flap viability = 5.88%) in the traction group [Figure 9]. Evaluated by the Mann–Whitney test, the flap viability is found to be statistically lower in the traction group (P < 0.05). Spearman's rho test revealed that flaps with elongated vessels have less viability rates in the CEP group (P < 0.05).
Figure 9: Comparison of the flap viability based on the cephalic epigastric perforators between the traction and control groups

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  Discussion Top


Abdominal flaps are very convenient options, both transferred as pedicled and free. They can be used to reconstruct defects in a variety of body parts, while their role in breast reconstruction is indispensable. In the evolution period of these flaps, in every step, emphasis was focused on reducing the rectus abdominis muscle damage.[3] Deep inferior epigastric perforator (DIEP) flap, as the final surgical technique that has been reached in breast reconstruction, still has adverse effects on muscle function such as loss of abdominal strength, bulging, and less commonly hernia.[4],[5] SIEA flap has the lowest abdominal wall morbidity, as no fascia or muscle damage is given. However, the availability of suitable vessels is very low compared to DIEP and transverse rectus abdominis myocutaneous flap (TRAM) flaps, and thrombotic complications are seen more often, so SIEA flap constitutes only a small part of options.[6]

Is it possible to achieve a reproducible technique for breast reconstruction with abdominal flap without harming rectus fascia and muscle? And, is it possible to elongate the DIEPs or SIE vessels enough to carry the abdominal skin as a long pedicled island flap without taking the thrombotic risk of anastomosis?

“Traction vasculogenesis” technique, described by Erenoglu et al. in a rat femoral artery and vein model, is based on the elongation of vessels supplied by mechanical traction of a functioning vessel in continuity perpendicular to its course by an internal maxillofacial distractor device.[1] Having achieved a considerable amount of elongation, we applied this novel technique to address its utilization to commonly used abdominal flap models. Rat CEP flap is considered as the homologue of the DIEP flap in human.[7] Our trial of traction vasculogenesis technique on CEP vessels supplied pedicle elongation, but the flap viability was inacceptable (5.88%). SIE flap is similar to, but not considered as a homolog for the human SIE flap. Traction caused considerable elongation with acceptable rates of flap viability (74%). The failure of the flap viability in the CEP elongation group is due to its small caliber and relatively short primary length. Microtrauma caused by the traction process led to thrombosis of these small vessels and caused permanent obliteration. Furthermore, the course of the vessels was not linear and prone to thrombotic events. SIE flap survival in the traction group is the critical result of the study, showing that a fasciocutaneous flap based on the elongated vessels can survive functionally. This means that any pedicle elongated with a suitable device, rate, and technique will supply its flap. The success of the SIE traction subgroup is upon larger caliber, linear course, and longer primary course of the pedicle.

As a pilot model, the study had its limitations, especially for the CEP traction subgroup. Single type and size traction device was used for all vessels and traction rate was same for all groups for standardization. The failure of viability in CEP traction subgroup does not mean that traction vasculogenesis technique is absolutely inapplicable for perforator flaps in human in future. The technique may be refined with further studies, with more applicable size devices, reduced elongation speed, adding antithrombotic and anticoagulant agents, circulation monitoring of traction period, and adding time intervals when traction is released to allow blood flow regulation. When contemplating this yet experimental technique for clinical adaptation, its advantages such as abdominal wall integrity protection and reduced anastomotic thrombosis risk are promising, with the larger caliber abdominal perforators in human.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Erenoglu CM, Tiftikcioglu YO, Uyanikgil Y, Cavusoglu T. Traction vasculogenesis: Experimental vessel elongation by traction in rat model. Turk J Plast Surg 2019;27.  Back to cited text no. 1
    
2.
Wei FC, Mardini S. Flaps and Reconstructive Surgery, 2nd Edition, 2017.  Back to cited text no. 2
    
3.
Granzow JW, Levine JL, Chiu ES, Allen RJ. Breast reconstruction with the deep inferior epigastric perforator flap: History and an update on current technique. J Plast Reconstr Aesthet Surg 2006;59:571-9.  Back to cited text no. 3
    
4.
Selber JC, Nelson J, Fosnot J, Goldstein J, Bergey M, Sonnad SS, et al. A prospective study comparing the functional impact of SIEA, DIEP, and muscle-sparing free TRAM flaps on the abdominal wall: Part I. Unilateral reconstruction. Plast Reconstr Surg 2010;126:1142-53.  Back to cited text no. 4
    
5.
Man LX, Selber JC, Serletti JM. Abdominal wall following free TRAM or DIEP flap reconstruction: A meta-analysis and critical review. Plast Reconstr Surg 2009;124:752-64.  Back to cited text no. 5
    
6.
Selber JC, Samra F, Bristol M, Sonnad SS, Vega S, Wu L, et al. A head-to-head comparison between the muscle-sparing free TRAM and the SIEA flaps: Is the rate of flap loss worth the gain in abdominal wall function? Plast Reconstr Surg 2008;122:348-55.  Back to cited text no. 6
    
7.
Hallock GG, Rice DC. Cranial epigastric perforator flap: A rat model of a true perforator flap. Ann Plast Surg 2003;50:393-7.  Back to cited text no. 7
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]



 

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