Sternotomy healing by secondary intention in a complex single ventricle patient after stage 1 palliation

Abstract

Delayed sternal closure is an important and commonly utilized strategy in neonates following cardiac surgery to optimize postoperative cardiac output. We present the case of an infant with hypoplastic left heart syndrome (HLHS) who underwent stage 1 Norwood/Sano palliation and did not tolerate sternal closure in the immediate post-op period, even when attempted after delay, due to persistent hemodynamic instability. Our approach involved closure of the skin and subcutaneous tissue to allow for sternotomy healing by secondary intention. This technique may be considered in rare instances when delayed sternal closure is not possible.

Introduction

Following complex neonatal operations for congenital heart disease, it is not uncommon to leave the sternum open at the time of the primary operation to prevent cardiac compression and consequent systolic and diastolic dysfunction when myocardial edema is present. In such cases, the standard practice is to perform delayed primary sternal closure within 24 to72 hours. We present an unusual case in which the sternum was unable to be safely reapproximated in a neonate and was left to heal by secondary intention, with no short-term adverse consequences observed with this approach.

Case report

A 39-week gestational age baby, prenatally diagnosed with HLHS (MA/AS) and a restrictive atrial septum, was born following an uncomplicated delivery. The initial echocardiogram demonstrated a mean gradient of 4 mmHg across the atrial septum. At the time, the patient was stable with adequate systemic oxygen saturations and minimal pulmonary congestion on chest x-ray. However, over the next several days, pulmonary congestion worsened, and the atrial septal gradient increased to 8 mmHg. On DOL 6, interventional palliation was completed with a balloon atrial septostomy and percutaneous placement of bilateral pulmonary flow restrictors. She remained on prostaglandin until 1 month of age. At a weight of 3.3 kg, she underwent a Norwood procedure with a 6 mm Sano shunt. Her CPB time was 256 min, aortic x-clamp time was 123 min, and regional cerebral perfusion time was 107 min. The heart was very edematous at the end of this operation and any sternal apposition resulted in hemodynamic instability. A sternal retractor was left in situ to optimize cardiac output.

Bedside mediastinal exploration with removal of the sternal retractor and patch placement on the skin was performed on POD 3. On POD 4, an attempt at sternal closure resulted in hemodynamic instability. On POD 6, chest re-exploration continued to reveal significant myocardial edema and manual re-approximation of the sternum resulted in a 4 mmHg rise in the central venous pressure. At this point, the patch was removed, and the skin was reapproximated. On POD 9 and 11, mediastinal explorations were necessitated by the accumulation of pericardial fluid, which was felt to be compromising cardiac output. However, on both occasions, it was still felt that sternal closure would not be tolerated. The decision was made to forgo primary sternal reapproximation and allow the sternum to heal by secondary intention. Over the course of the next week, serial examination revealed close apposition of the sternal edges. The child was mechanically ventilated via synchronized intermittent mandatory ventilation (SIMV), pressure regulated volume control (PRVC), with pressure support (PS). She initially required relatively high tidal volumes (12 mL/kg), but this was weaned as diuresis improved in the first post-operative week. For diuresis, she received a continuous infusion of intravenous bumetanide (max 40 mcg/kg/hr) from POD 0-POD 9 and was then transitioned to intermittent furosemide. She was weaned off all inotropic support and successfully extubated on POD 45 to non-invasive ventilation. She was weaned to room air 1 week following extubation. The midline incision continued to heal well with excellent skin integrity and no induration or discoloration, as shown in Fig. 1. The child underwent a 2nd stage bidirectional Glenn procedure at 6 months of age. Notably, after dissection through the subcutaneous tissue, her Sano shunt was immediately encountered in the midline as the sternal edges were not completely opposed (see Fig. 2). This came with no surprise, as the Sano shunt was seen closely related to the sternum on her pre-Glenn cardiac catheterization (see Fig. 3). The remainder of the dissection was uneventful and the Glenn shunt was completed without the use of cardiopulmonary bypass. On completion of her operation, extensive mobilization of the sternum was then completed allowing standard wire closure.

Fig. 1.

Image of patient’s chest 2 months post-op showing healed midline incision

Fig. 2.

Image showing incomplete approximation of the sternal edges, with Sano shunt visible in the midline

Fig. 3.

Image showing RV-PA conduit (Sano shunt) relationship to sternum, as seen during pre-Glenn cardiac catheterization

Discussion

The hemodynamic effects of sternal closure immediately after open-heart surgery in infants have long been recognized, necessitating adjunct surgical approaches [1]. Premature sternal reapproximation in infants, especially neonates, can reduce cardiac output by decreasing diastolic filling, secondary to increased thoracic pressure compressing the heart [2]. Delayed sternal closure refers to leaving the sternum open for a period of time, generally 24 to 72 h, before closing. This technique is most commonly employed in complex neonates, especially following stage 1 surgical palliation [3].

When delayed sternal closure is not feasible, alternative techniques can be employed. Barlas et al. described a case of pectoralis major muscle flap transfer in two configurations and an abdominal base flap to treat sternal wound dehiscence in a neonate [4].Vacuum-assisted closure [5] and medical grade zipper closure [6], have also been reported in adult patients. However, sternal healing by secondary intention has not been previously reported following stage 1 palliation. Healing by secondary intention refers to leaving the wound open to heal from the deep layers to the more superficial layers. In an effort to mitigate the risk of infection and minimize the hemodynamic implications, our approach involved approximating the most superficial layers, namely the skin and subcutaneous tissue.

While the long-term effects of our approach are not known, our short-term assessment has been favorable. Sternal abnormalities in infants, including a congenitally absent sternum and sternal dehiscence, can destabilize the chest wall and result in flail chest type physiology. Flail chest impairs alveolar gas exchange due to paradoxical chest wall movement and lung injury. The flail segment moves inward during inspiration and outward during expiration, reducing tidal volume and lung expansion. This leads to decreased airflow, alveolar collapse (atelectasis), and reduced lung volume, ultimately resulting in ventilation-perfusion mismatch. As a result, oxygen uptake decreases and carbon dioxide builds up, leading to hypoxemia and hypercapnia. These changes severely compromise respiratory function and can become life-threatening. Additionally, it predisposes patients to recurrent chest infections [7]. However, our patient did not suffer from adverse respiratory consequences and showed no evidence of sternal wound infection. Moreover, she was able to tolerate immediate sternal closure after her stage 2 palliation.

Conclusions

In congenital heart surgery, complex problems often require innovative approaches. Though delayed sternal closure is a common management technique, in rare instances precipitated by hemodynamic instability or with unalterable anatomic limitations, closing the superficial layers of the midline incision and allowing the sternum to heal by secondary intention may be considered.

Abbreviations

AA

Aortic atresia

DKS

Damus Kaye-Stansel

DOL

Day of life

HLHS

Hypoplastic left heart syndrome

ICU

Intensive care unit

MA

Mitral atresia

NIRS

Near-infrared spectroscopy

RV

Right ventricle

POD

Post-operative day

Author contributions

K.G.S., S.G., R.B., and R.H. designed the study, collected and analyzed the data, and wrote the manuscript. All authors contributed equally.

Funding

No funding to disclose.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Disclosures

The authors have nothing to disclose.

Competing interests

The authors declare no competing interests.