Use of the pectoralis major fasciocutaneous flap in the treatment of post sternotomy dehiscence : a new approach

Conflict of interest: none. ABSTRACT Objective: To describe a new surgical technique for the treatment dehiscence after median thoracotomy transsternal using fasciocutaneous flap composed of the pectoralis major fascia. Methods: Between January 2009 and December 2010, from 1,573 patients submitted to coronary artery bypass graft, 21 developed wound dehiscence after sternotomy and were treated with bilateral pectoralis major muscle fasciocutaneous flap, including partial portion of the rectus abdominis fascia. Patients were followed for a minimum of 90 days postoperatively. Results: All patients had favorable outcome following 90 days, not having any partial or total dehiscence. There were no cases of postoperative infection. Conclusion: The procedure was rapid and effective. Compared with techniques using muscle, myocutaneous or greater omentum flaps, this surgery was less aggressive and maintained the integrity of tissue region. The authors considered that this technique should be used as the first option, leaving the flaps to more complex cases of relapse.


INTRODUCTION
The median transsternal thoracotomy was first described as a surgical approach in cardiac surgery in 1957, and since then it has been widely used.One of its complications is dehiscence of the edges, which usually occurs after infection and is associated to high mortality and morbidity rates (1,2) .
In cases of acute infection, the management comprises early debridement, use of antibiotics and, in some patients, use of a pectoralis or omentum flap to improve vascularization (3)(4)(5) .However, some of these patients progress with dehiscence of sutures and chronic wound.Some dehiscences can be corrected only with debridement and approximation of the edges until the tissues involved are in better conditions.Several methods were described to correct the most complex defects, including muscle, musculocutaneous, simple skin, omentum with skin graft flaps, and more recently, breast tissue flaps (6)(7)(8)(9)(10) .Anger J, Farsky PS, Almeida AF, Arnoni RT, Dantas DC The choice of flap to be employed is related to the type of abnormality observed.The most important indication is amount of tissue loss.The discussion about preference between a muscle, musculocutaneous or skin flap is based on the amount of donor tissue and degree of vascularization, since a well irrigated tissue can favor eradication of infection and increase vitality of the tissues involved, resulting in faster stabilization of the clinical picture, besides enabling preparation of larger flaps (11) .
The use of the pectoralis major fascia has been recently described in plastic surgery procedures (12,13) .This fascia is well vascularized, resistant, and has appropriate thickness.
In our surgical experience, we observed that most dehiscences of sternotomies have no loss of tissues on the edges; thus they required no extra amount of tissue.Actually, it is difficult to place the edges closer due to laceration of the subcutaneous tissue; consequently, we started using the pectoralis major fascia for suture and medial traction of the edges, in cases of short dehiscences with no tissue loss.
Considering the favorable results achieved, we then used flaps containing skin and subcutaneous tissue, including the pectoralis major fascia in larger wounds.In this report, this new technique is presented to repair post-sternotomy wound.

OBJECTIVE
To describe a new surgical technique to repair median transsternal thoracotomy dehiscences using fasciocutaneous flaps from the pectoralis major fascia.

METHODS
From January 1 st , 2009 to December 31 st , 2010, a total of 1573 patients were submitted to myocardial revascularization surgery by transsternal approach at the Instituto Dante Pazzanese de Cardiologia de São Paulo.Twenty-six (0.65%) patients presented dehiscence of suture after surgery and were indicated to have flaps.Infection of the surgical site was the primary cause of dehiscence in 22 patients, and, mediastinitis, in four.Twenty-one patients were treated with bilateral fasciocutaneous flap of pectoralis major; two with breast tissue flap; and three with myocutaneous flap from pectoralis major -in that, two were bilateral and one unilateral.The criterion to choose the breast tissue flaps was effective loss of tissue in the lower third of the sternal wound, in female patients.The muscle or myocutaneous flaps were indicated in cases of effective loss of tissue in male patients, with no possibility of direct approximation.
Of the 21 individuals treated with fascia flap, 8 presented partial or total loss of bone tissue in the sternum, and two patients had additional loss of portions of the costal arches.Twelve were female, and age ranged from 56 to 75 years.The patients were followed up for at least 90 days postoperatively (Table 1).
The study was approved by the Research Ethics Committee of the Instituto Dante Pazzanese of Cardiologia, under number CAAE 0011.0.131.000-09.

Surgical technique
The initial stage was incision on the skin and subcutaneous tissue in normal tissue on the wound edges, up to the margin of the pectoralis major fascia.A vertical incision was made along the fascia, as close as possible to its medial insertion, until reaching the pectoralis major.The fascia was carefully laterally detached from the muscle in its vertical extension.The extension of this dissection depended on the evaluation of the advancement level of the flap.After releasing the fascia on the pectoralis muscle inferior margin, the medial and upper edges of the rectus abdominis fascia were identified.A vertical incision was made, two-millimeter apart from the medial insertion of this fascia, continuing with another, horizontally, also twomillimeter apart from the upper edge of this fascia.
Later the rectus abdominis fascia was detached from the muscle to complement the fasciocutaneous flap of the pectoralis major, maintaining the skin attached.The length depended on evaluation and gain of the flap, as it was released (Figure 1).bringing close to the edge of the fascia (Figure 3).The second layer was composed of non-absorbable mononylon 3-0 suture, crossing the deep dermis in inverted U stitches.The skin was then approximated with separate stitches with non-absorbable mononylon 4-0 suture (Figure 4).Two tubular drains, measuring 4.8-millimeter in diameter, were placed on the bed of the wound.
When the flaps achieved the midline, all the wound area, with its granulation tissue and adjacent fibrosis, were removed and, if necessary, the affected bone tissue was revised, excising the devitalized tissue, and stabilizing the bone with steel wire.
Next, absorbable suture 0 was used to fixate the fascia to the base of the flap, on the bloody surface of the defect.Two to three vertical sutures were made, one-centimeter apart from each other, in order to fill as much as possible the sternal defect and to decrease traction on the final suture of the skin edges (Figure 2).
The skin and subcutaneous tissue were approximated in three plans, the deepest with absorbable suture 2-0,

DISCUSSION
A new surgical technique is described using the pectoralis fascia to correct dehiscences of sternal suture with loss of soft tissue and/or bone.Most dehiscences after median sternotomy can be treated by debridement of the affected tissues and suture of the edges.For the past 40 years, the scientific reports, especially those published after the article by Jurkiewicz (3) , have emphasized the need to use vascularized tissue to fill in the defect in the sternal region and to reduce the possibility of infection.These articles mentioned decreased morbidity when employing muscle or omentum flaps (3,6,7) .
Nevertheless, these techniques lead to large detachments, sequelae in donor areas, reduced or absent activity of muscles and increased morbidity, although the final closure is made on the skin and subcutaneous tissue, over the tissues repaired.
This approach is widely used in the acute phase of infection, even in our department; however, today these principles are no longer useful for us in cases of dehiscence with stable infection and inflammatory reaction of the adjacent tissues.This was demonstrated by Ascherman et al. (14) , who described 114 cases using the pectoralis major as an advancement musculocutaneous flap, with no need to release the pedicles or its medial edge, obtaining a satisfactory result and, even better, if compared to the previous series of patients treated according to Jurkiewicz et al. (3) principles.
In the chronic patients in our department we used advancement musculocutaneous flaps, aiming to fill in the sternal defect and maintain vascularization of the edges in cases of major losses, in particular, skin and subcutaneous tissue losses.In female patients with important losses, a breast tissue flap was employed (10) and, in even larger defects, the musculocutaneous flap of the pectoralis major, based on its medial pedicle, rotated to the medial area; or, yet, the musculocutaneous flap with skin island of the rectus abdominis.
When comparing the result of using skin flaps and musculocutaneous flaps to treat pressure ulcers, Anger et al. (11) demonstrated that the simple skin flaps can have the same efficacy of the muscle flaps and, eventually provide a better cosmetic result, due to less destruction in the donor area.Hence, the muscle flaps would be an option in case of relapses.
The fascia of several regions of the body has been used as simple or compound flap for reconstruction in plastic surgery for many years.The interest in the superficial fascia of the pectoralis major rose from a description of the subfascial insertion of silicon implants for breast augmentation, which led to a more detailed study of its anatomy (13) .The superficial pectoralis fascia

RESULTS
All 21 patients had a good progression, and were discharged, on average after 12 days.The drains were kept for 10 days, on average.No complications, such as dehiscence of sutures or fistulas were observed (Figures 5 and 6).extends from the clavicle to the sternum.In its lateral margin, it unites to the deep fascia of the pectoralis major and both, together, continue with the serratus anterior fascia.In the inferior portion, it contacts the sheath of the rectus abdominis, at the level of the sixth intercostal space.Multiple perforating vessels cross the pectoralis major fascia, especially in the medial region, deriving from the arteries (13) .
The report by Jinde et al. (13) demonstrated that the thickness of fascia varies from 0.20 to 1.14mm, and it is thinner in the upper portion and thicker in the lateral margin.In the medial edge, in contact with the sternum, its average thickness is 0.56mm.Although thin, the fascia is composed of a dense connective tissue and its fibers have a nearly perpendicular orientation regarding the pectoralis major fibers; in other words superomedial to inferolateral.
In the surgeries performed, we observed the fascia in the medial margin is thicker than expected, possibly due to presence of tissue fibrosis resulting from chronic inflammatory reaction of the wound (Figures 7 and 8).
This fascia assumes the characteristic of a tissue that is firm enough to retain the deep approximation stitches.In the use of simple skin flaps, frequent tear of subcutaneous tissue is observed when attempting to approximate the edges, even employing thicker tissues.The fixation of the fascia in the base of the sternal tissue loss, particularly in the fibrotic edges of the resulting wound, reduces dead space and tension in the edge suture.
After the initial success using this technique, we believe the most complex flaps should be reserved for cases with greater losses of contiguous tissues or that require resuturing.Even though, larger samples are required to better evaluate this procedure.

CONCLUSION
The use of the pectoralis major fascia is a less invasive, fast and effective surgery.This initial report had good progression in all patients treated, with no complications.
We consider this technique should be the first option, and the more complex flaps be reserved for relapses.

Figure 1 .Figure 2 .Figure 3 .
Figure 1.Dissection of the rectus abdominis fascia, keeping it attached to the subcutaneous tissue

Figure 4 .Figure 5 .Figure 6 .
Figure 4. Saggital slice of the thorax after completing approximation of the fasciocutaneous flaps.The fascia is represented by a brown line.(Author: Beatriz Souza Nazaré Galezi)

Figure 7 .
Figure 7. Fasciocutaneous flap detached from the pectoralis major.The edge of the fascia is indicated by dark arrows.The white arrow shows the released margin of the pectoralis major

Figure 8 .
Figure 8. Edge of the fascia showing the required thickness to assist approximating the wound margins (indicated by dark arrows)