Safety of neonatal sternal wound reconstruction after open heart surgery

Abstract

An open sternal wound is a dreaded complication after open heart surgery for neonatal congenital cardiac anomalies. Vascularised muscle flap reconstruction of sternal wound defects, to prevent life-threatening mediastinal infections, is the standard of care in adults and children. However, there is paucity of published literature regarding the safety of this technique in neonates. We describe a successful operative technique for complex reconstruction of an open heart sternal defect on a neonatal male patient. On 6 months postoperative follow-up, we identified an issue with sternal instability. Patient underwent a subsequent operation for reinforcement of the sternal wound repair with Vicryl mesh. The authors report safety of using three separate vascularised muscle flaps in a single neonatal operation. Long-term follow-up of the sternal wound reconstruction is warranted to determine need for secondary procedures.

Background

Complications after complex congenital heart surgery is a challenging problem in the infant and paediatric population and include risks of bleeding, sternal wound infection and mediastinitis, a life-threatening complication.^{1 2} Many reports have discussed the diagnosis and management of wound complications in adults and children, but there are few reports in infants. Pectoralis major muscle flap (PMF) transfer is well described and has become the standard of care with good results in the management of open sternal wounds in adults and children.^{3 4} Although the same technique has been successfully reported in the paediatric population, it is not well described in neonates.^4–11 In this report, we describe our experience using bilateral PMFs in two different configurations and an abdominal based flap for neonatal sternal wound reconstruction. This technique has been previously described by Taub et al.⁹ However, they used delay phenomenon which warranted the need for additional procedure. We describe our technique without using delay phenomenon which helped facilitate single stage closure. On longitudinal follow-up, we found an issue concerning sternal instability that was corrected with a secondary procedure.

Case presentation

A 4-weeks-old male infant was born at term with a total anomalous pulmonary venous return to the coronary sinuses. He underwent surgical repair of the anomaly and required institution of extracorporeal membrane oxygenation (ECMO) postoperatively due to pulmonary hypertension and left ventricular diastolic dysfunction. In the immediate postoperative period, a large haematoma and cardiac arrest developed, requiring chest compressions, which further resulted in a small amount of blood leaking through the mediastinal dressing with temporary improvement. On emergent surgical re-exploration, no major sources of bleeding were identified aside from minor sites in the chest wall that were treated appropriately with electrocautery. A large amount of blood had accumulated in the right pleural space, and additional pleural drains were placed. The wound was left open with the apex of the left ventricle protruding well above the plane of the sternal edges due to dilation of the heart and hyperinflated lungs. Immediate sternal wound closure was not attempted as it would have caused significant haemodynamic and respiratory compromise. Vacuum-assisted closure (VAC) therapy (Acelity L.P., 3 M KCI) was applied to the mediastinal wound at negative pressure of 75 mm Hg continuous, after covering the exposed heart with xeroform gauze.¹² As the patient was on ECMO, serial wound dressing changes were performed bedside under anaesthesia with negative pressure wound therapy (NPWT) on postoperative day 4 and day 7. All blood cultures and wound cultures were negative for infection. Consideration was given for a surgical delay procedure, at the time of the last VAC change, for use of the left rectus abdominis skin muscle flap for definitive sternal wound reconstruction.⁹ This option would have required delaying the definitive sternal wound closure by a week to 2 weeks. Hence, we planned to use the left rectus abdominis muscle flap without a skin paddle for vascularised coverage of the left ventricle.

Treatment

On postoperative day 10, the patient was taken back to the operating room for sternal wound reconstruction and complex delayed primary closure. The entire sternal wound was dehisced with the sternal defect approximately 11 cm wide, with the heart and great vessels exposed and no evidence of infection. The lungs were hyper inflated with the apex of the left ventricle protruding well above the plane of the sternal edges. A left subcostal incision was extended as a left paramedian abdominal incision. This was extended to the left groin crease. A turnover left vertical rectus abdominis pedicle muscle flap based on the left superior epigastric vessels provided vascularised coverage of the heart. A turnover right PMF to cover the inferior half of the sternal wound based on perforators of the right internal mammary artery and vascularised mediastinal coverage was completed with a rotation advancement flap of the left pectoralis major muscle based on the thoracoacromial vessels for the upper half of the sternal wound. An incision was made on the right deltopectoral groove to assist in dividing the humeral insertion of the right pectoralis major muscle. Blake drains were used to obliterate dead space at the donor sites and for the mediastinum. A full-thickness skin graft was harvested from the left groin at the beginning of the procedure. The skin graft was applied directly over the rectus muscle flap for coverage of the lower end of the sternal defect. This was performed to prevent constriction of the left superior epigastric pedicle with attempted skin closure. We were able to approximate the skin in the midline for the upper portion of the sternal wound. The abdomen donor site was reinforced with STRATTICE Reconstructive Tissue Matrix mesh (LifeCell Corp. Allergan) to mitigate risk of postoperative abdomen wall bulge or hernia.

Immediate postoperative picture is shown in figure 1.

Figure 1.

Immediate postoperative picture at the completion of 3-muscle flap reconstruction.

Patient was on total parenteral nutrition (TPN) in the perioperative period. He was started on nasogastric enteral feeding postoperative day 2. He successfully took formula by mouth 4 weeks after surgery and was weaned off TPN and enteral feeding. The patient had an uneventful recovery and was discharged 6 weeks after definitive sternal wound closure.

Six months following the muscle flap transfer, he was found to have significant mobility of the sternal edges. The paediatric cardiothoracic surgeons were concerned that this was contributing to mild impairment of his respiratory function. The patient was taken back to the operating room for reinforcement of the sternal closure, where a median sternotomy was performed. The myocutaneous flaps were both raised, the sternal edges were identified and dissected from the deep mediastinal tissues, and the heart and lungs were identified. Vicryl mesh was used to approximate and bring the sternum together, resulting in optimal stability of the chest wall. The patient did well postoperatively.

Outcome and follow-up

The patient was serially followed by both the cardiothoracic and plastic surgery teams. At 1-year follow-up, all the incisions had healed as shown in figure 2. The patient was followed up closely by our paediatric heart centre demonstrating normal growth and development and no requirement for additional chest wall surgeries. Minimal contour deformity noted at the lower end of the sternum at site of the full-thickness skin graft is becoming less prominent as the child is growing. Patient did have a minor paediatric urological procedure 15 month later.

Figure 2.

Healed flap donor site on the chest, at 1 year.

Discussion

Paediatric sternal wounds after repair of congenital heart disease are infrequent, especially in neonates.^{1 2} Reconstruction of sternal wounds has been well described in adults but is only sporadically reported in neonates.^{4–11 13} The successful use of the pectoralis advancement flap was first described by Stahl and Kopf.⁵ They reported on three neonates who underwent bilateral PMF with preservation of the humeral attachments. In 1994, Backer et al reported on three neonates who underwent chest wall reconstruction using three different reconstruction approaches: unilateral PMF, bilateral PMF and a rectus abdominis muscle flap.⁶ Grant et al reported four patients between 1991 to 1996 who required muscle flap reconstruction for treatment of deeply infected sternotomy wounds.⁷ Two patients were closed with bilateral PMF, and the other two patients were closed with vertical rectus abdominis muscle flaps (one using an attached skin paddle). In 1998, Sung et al reported a case of a 2-month-old infant who underwent closure of an infected sternal wound following open cardiac surgery with bilateral PMF and a unilateral rectus abdominis muscle flap.⁸ In 2005, at the same institution, Taub et al reported their refined technique in a 2-week-old neonate who was evaluated for postoperative sternal wound dehiscence and instability following open cardiac surgery.⁹ However, they used a surgical delay procedure by ligation of the left inferior epigastric pedicle at the time of the last VAC change, followed by transposition of the left rectus muscle a week later with application of a full-thickness skin graft to the sternal defect. Erez et al reported six pectoralis muscle flaps in neonates between 1995 and 1998.¹⁰ Five neonates underwent unilateral turnover pectoralis muscle flaps, while one underwent bilateral rotational pectoralis muscle flap. In 2003, Kollar et al reported their experience of using a modified chest closure technique employing bilateral pectoral myocutaneous advancement flaps after sternal reapproximation for postoperative mediastinitis in three cyanotic neonates.¹¹ Finally, Zabel et al reviewed their experience with sternal reconstruction using unilateral and bilateral pectoralis muscle flap advancement in infants for sternal wound infections in post-sternotomies.⁴ However, the youngest patient was 4 months of age at the time of flap transfer.

Delayed sternal closure is a technique that offers critical haemodynamic and pulmonary stability.¹³ Since described by Jones et al in 1980, flap reconstruction is considered the standard therapy for deep sternal wound infections and sternal reconstruction.¹⁴ Data from the adult population suggests that sternal wound infections and reconstruction managed by plastic and reconstructive surgeons with early closure has a clear benefit over the conservative approach used by cardiothoracic surgeons. Pedicled muscle flaps have been shown to promote early wound closure and reduce mortality.¹⁵ Turnover PMF based on the internal mammary artery perforators, the unipedicled pectoralis major muscle rotational advancement flap based on the thoracoacromial artery, and the myocutaneous PMF have all been used for sternal reconstruction with excellent results.¹⁶

Complication rates of sternal reconstruction for deep sternal wound infections have been shown to be 18.8% in the current literature.¹⁴ These include recurrent wound infections (6.5%), haematoma (6.1%), wound dehiscence (6.1%), re-exploration for wound necrosis (5.9%), partial flap loss (3.8%), and abdominal hernia formation after rectus abdominus harvest (2.2%).¹⁴ Although NPWT is commonly used for the treatment of neonatal poststernotomy wound dehiscence, the use of extracellular dermal matrix has also recently been shown to be successful.^{12 17} This strategy, however, may be successful in cases where the heart and great vessels are not exposed. In our patient case, the heart was protruding through the wound and hence, warranted the need for early closure with three separate vascularised muscle flaps, as shown in figure 3.

Figure 3.

Illustration demonstrating three separate muscle flaps in different configurations from both chest and abdomen used for closure, pedicles are shown in red. Illustration drawn by corresponding author, Barkat Ali, MD.

We achieved chest wall stability, protection of the mediastinal structures, and a satisfactory maintenance of an aesthetic appearance without developing infection. To our knowledge, this is the first report of this complex reconstructive strategy using three vascularised muscle flaps and early closure in a neonate, without employing a surgical delay technique. The patient in our case subsequently developed significant sternal instability that was not interfering with mechanical ventilation at 3-month follow-up. Furthermore, his sternal instability started to mildly impair respiratory action, and he required a return to the operating room for closure. This highlights the importance of following these patients longitudinally as need for secondary procedures may arise.

Learning points.

• Sternal wound reconstruction is infrequently performed in neonates.

• Immediate reconstruction of open sternal wounds with early closure is safe and effective in neonates.

• Patients undergoing sternal wound reconstruction require longitudinal follow-up as secondary procedures may be needed for sternal instability.