OUR PRELIMINARY EXPERIENCE WITH A NEW METHOD OF DIEAp FLAP DISSECTION

INTRODUCTION

With an increase of the life expectancy in post-mastectomy patients¹, the request of breast reconstruction doubled from 13 %to 26% between 1998 and 2007². The autologous reconstruction is worthwhile, especially in those with longer life expectancy, when both costs and quality of life are factored together³.

Utilization of abdominal tissue for autologous breast reconstruction has been long and widely practiced. It is an ideal source, as most patients who develop breast cancer are at the age when they also have excessive abdominal fat and skin. Autologous breast reconstruction has many advantages over implant reconstruction, including reduced risks of infection, capsular contracture, and a more natural and aesthetically pleasing breast.

The muscle-sparing two-transverse rectus abdominis myocutaneous (MS2-TRAM) and the deep inferior epigastric perforator (DIEP) free flap are well-established techniques for autologous breast reconstruction. Debate continues regarding the merits of muscle-preserving techniques to minimize abdominal wall morbidity and to maintain flap reliability⁴. This Big game between reliability and morbidity, MS-TRAM flap and DIEP flap is not over yet.

In this scenario, the reliability of the DIEP flap can be compromised essentially by two factors: the first one is that actually there is no definitive evidence about the relationship between the number and dimension of the perforator vessels and the prediction of flap survival; the second one is that the vascular anatomy of the DIEP flap is extremely variable and we are far to have an evidence-based approach to perforator selection and intramuscular dissection⁵.

In this paper, we propose a new approach for intramuscular dissection of a DIEP flap; this is a new muscle sparing technique enlarging the concepts previously proposed^6,7.

MATERIALS / METHODS

Operative technique

The Operative technique is summarized in Figures 1 and 2.

There are no significant differences in the operative technique between DIEP dissection and our variation. The only different step is the intramuscular dissection; once the deep fascia is incised as much as necessary to gain wide exposure of the perforators, we split the muscle fibres interposed between the vessel and the muscle, showing the perforator course.

After that we proceed cutting a ≈3mm strip of muscle around the vessel.

The cut is conducted parallel to the vessel, which is always kept visible from one side. The cut is “blind” on the other side and if some small branches are accidentally severed during the dissection there is enough space to put a liga-clip or it is possible to coagulate them with a bipolar forceps considering a safe distance of ≈3 mm from the main vessel with no risk of damaging it.

Preservation of function of the remaining muscle is maximized with minimal sacrifice of the motor nerves (Fig. 3).

Because no fascia is resected, a primary tension-free suture of the fascia with a running non-absorbable 1/0 suture is always possible, just like a traditional DIEP flap (Fig. 4).

Patients

This is a retrospective study based on a single surgeon (P.H.) experience in breast reconstruction with the traditional and innovative approach to DIEP flap dissection. The various methods of muscle sparing technique are summarized in Figure 5 and Table 1.

From January 2007 to March 2012, a total of 84 women underwent breast reconstruction after mastectomy. Of these women, 49 patients were treated with traditional DIEP flap of which 21 had unilateral procedures and 28 had bilateral procedures (77 flaps). The new method of dissection was performed in 35 women, with unilateral approach in 14 cases and a bilateral approach in 21 cases (51 flaps). The total number of flaps was 133.

Analysis of outcomes related to flap loss, venous congestion, arterial thrombosis, fat necrosis, abdominal bulge, hematoma and infection was performed. We used the Fisher’s exact test to evaluate statistical differences between the two groups of complications.

The mean operative time for each procedure was also assessed. We used the Mann–Whitney–Wilcoxon (MWW) test to evaluate if there is any statistical difference between the two groups in terms of operative time.

RESULTS

The results are provided in Table 2 and they refer to the total number of flaps.

For all the flaps dissected with the new approach (n=56), outcomes included fat necrosis in one case (1.78%), venous congestion in three cases (5.35%), arterial thrombosis in three cases (5.35%), hematoma in two cases (3.57%), infection in one case (1.78%) and total flap necrosis in one case (1.78 %).

For all traditionally dissected DIEP flaps (n=77), outcomes included fat necrosis in one case (1.29%), venous congestion in one case (1.29%), arterial thrombosis in three cases (3.89%), hematoma in four cases (5.18%), infection in three cases (3.89%) and total flap necrosis in two cases (2.59%).

In both groups there is no onset of abdominal bulges.

The statistical differences are not significant in the two groups of complications (p > 0.1) (see Table 2).

The new approach mean operative time was 3 hours and 10 minutes per flap.

The traditional DIEP mean operative time was 3 hours and 41 minutes per flap.

The operative time for the author’s method is significantly shorter than DIEP flap (p < 0.01) (Figure 6).

DISCUSSION

A recent paper showed that women who underwent autologous breast reconstruction were more satisfied with their breasts than women who underwent implant breast reconstruction⁸. Besides autologous tissue reconstructive techniques, both pedicled and free, are cost-effective options over prosthetic-based reconstruction⁹.

The autologous reconstruction is worthwhile, especially in those with longer life expectancy, when both costs and quality of life are factored together³.

The muscle-sparing two-transverse rectus abdominis myocutaneous (MS2-TRAM) and the deep inferior epigastric perforator (DIEP) free flap are well-established techniques for autologous breast reconstruction. Debate continues regarding the merits of the muscle-preserving techniques to minimize abdominal wall morbidity and to maintain flap reliability⁴.

There are many studies that compare the surgical outcomes of DIEP flap to MS-TRAM flap; many authors report that there are no significant differences in donor-site morbidity, survey-based functional outcome, or patient satisfaction between bilateral TRAM and DIEP flap breast reconstruction^10–12. Despite this, two recent prospective studies comparing the functional impact of DIEP and Muscle-Sparing Free TRAM flaps on the abdominal wall in unilateral and bilateral reconstruction, demonstrate that the muscle-sparing free TRAM flap causes a greater functional decline and the strength is unlikely recovered completely, compared to the DIEP flap^13–14.

Furthermore a recent meta-analysis suggests that the DIEP flap reduces abdominal morbidity but increases flap-related complications compared with the free MS-TRAM flap in breast reconstruction; it is clear from this study that, as a general rule, the DIEP flap is less reliable than the free MS-TRAM flap but that the latter suffers a higher rate of donor-site morbidity¹⁶. The risk for abdominal hernia in those treated with a DIEP flap was approximately one-half that is seen in patients who have undergone a MS-2 TRAM flap procedure^15–16.

There is an on-going debate regarding the choice of a DIEP or a MS-TRAM flap. It is an equilibrium between reliability and morbidity.

The DIEP flap is certainly less reliable than MS2-TRAM flap, especially for two reasons. The first one is the lack of a robust vascularity and of definitive evidence regarding the relationship between the number and dimension of the perforator vessel and the prediction of flap survival.

The second one is the variability of the anatomy of the DIEP and we are far to have an evidence-based approach to perforator selection and intramuscular dissection⁵.

The new approach to dissection proposed by the authors is more reliable than a traditional DIEP flap especially for the easier dissection.

The most important aspect of this method is cuffing of the perforator with about 3 mm strip of the muscle. The vessel is kept clearly visible from one side of the view and leaving a strip of muscle allows us to be sure that:

1. We do not injure the perforator.
2. The perforator is protected during dissection by a small cuff of muscle.
3. The risk of kinking is minor.
4. If a branch is accidentally cut, there is still enough space to put a liga-clip with no risk of damaging the vessel.
5. We do not touch directly the vessel, reducing the risk of a spasm and accidental injury¹⁷.

Based on our preliminary results, in spite of a greater reliability in dissection, the morbidity of this new approach is comparable to that of the DIEP flap. In fact the analysis of the flap-related morbidity in our case series that included fat necrosis, venous congestion, and total flap necrosis, demonstrated no significant difference (p= > 0.1) between the author’s variant and the traditional DIEP flap. Regarding the late surgical complications, the contour abnormalities, such as hernia, found in our cases are comparable in the two groups (MS-3 TRAM / DIEP) (p=> 0.1).

This may be due to the operative technique of the MS-2 TRAM; in fact after the MS-2 free TRAM, there is usually a 2–4 cm segment of anterior rectus sheath that is excised with the rectus abdominis muscle⁶. Contrariwise with the author’s variant the approach is identical to the DIEP flap, completely preserving the anterior rectus sheath (Table 3).

The ease to harvest, using the author’s variant, makes the dissection optimal for the less experienced surgeons that are starting to perform the autologous abdominal based breast reconstruction. Especially in those cases in which the vessel has a long intramuscular course (9–26%)⁵, the “pure” deroofing of the perforator, as described in DIEP dissection refinements¹⁸, is a very fine dissection. The intramuscular dissection of a perforator is a microsurgical procedure and leaving a small cuff of muscle around the vessel allows avoiding direct handling of the perforator with a minor risk of injury.

Another important aspect is the operative time of the author’s method that is definitely shorter than a traditional DIEP flap with a reduction of 14% (p < 0.01).

This value is more important in bilateral breast reconstruction in which the operative time could be too long, especially if a complication occurs.

The cost of a DIEP flap is another important factor that a surgical team must evaluate. In a recent study performed in the UK, the breakdown of costs for microsurgery shows that 83% of the cost originates in the theatre¹⁹.

As a result, the reduction of the dissection time is crucial to decrease the total cost of the operation.

The problem of the vascularity is not exceeded with the author’s variant. This new approach does not increase the perforasome²⁰, because it is based, as well as the DIEP flap, on a single row of perforators^21-22 (see Table 3). As a result, when the perforators encountered during the dissection by the surgeon are particularly small (< 1.5 mm), it is possible to resort to the empirical algorithms proposed^4,23, converting the flap in MS-2 TRAM, this way including both rows of perforators (medial and lateral).

Further investigations will focus on the evaluation of the abdomen strength comparing the dissimilarities between the two groups.

CONCLUSION

The author’s variant to DIEP flap dissection is a new concept in autologous breast reconstruction. This type of dissection is more reliable than the traditional DIEP flap harvest for the ease of the dissection and for the presence of a small protective cuff of muscle around the vessel with a lower risk of perforator injury.

It is a reproducible option of dissection, useful also in less experienced hands and it is a time reducing technique compared with the traditional DIEP flap dissection.

ACKNOWLEDGMENT

The authors thank Annalisa Pappalardo (annalisa.pappalardo@me.com) for the artwork.

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of this article.

Corresponding author:

Lombardo Giuseppe A.G.

Cannizzaro Hospital

Via Messina 829 Catania IT 95129

Italy

E-mail: giuseppelombardouni@gmail.com