A rare constellation of eventration of right diaphragm, severe right lung hypoplasia, and LPA sling

Abstract

Left pulmonary artery sling (LPAS) is a rare congenital cardiac anomaly and is commonly associated with complete tracheal rings and various degrees of tracheobronchial compression. We present a very rare association of LPAS and congenital eventration of right hemidiaphragm in this case report.

Introduction

Left pulmonary artery sling (LPAS) is a rare vascular malformation with reports claiming a hospital-based prevalence of 0.14% among patients with congenital heart defects [1]. It has varied presentations from an incidental finding in adults to severe stridor and respiratory distress in infants. Congenital eventration of diaphragm (CED) is another rare condition caused by a developmental defect of the muscular portion of the diaphragm [2]. We present a very rare association of LPAS and CED in an infant.

Case report

A 2-month-old girl presented to us with stridor and difficulty in breathing since birth and was diagnosed to have LPAS and CED of the right hemi-diaphragm. Echocardiography and computed tomographic (CT) angiography was performed to know further details. The left pulmonary artery (LPA) was arising from the proximal right pulmonary artery (RPA), looping around the trachea and proximal right main bronchus and crossing the midline to enter into the left hilum. There was an associated small atrial septal defect (ASD) with left to right shunt, mild pulmonary arterial hypertension, with preserved right ventricular function (Fig. 1a–c). The liver was found occupying most of the right hemithorax and the right lung was severely hypoplastic. The right main bronchus and RPA were hypoplastic at hilum with a Z score of − 3 (Fig. 2a–c). There was no evidence of complete tracheal rings or other tracheal anomalies. As the child had stridor due to tracheal compression by the LPA along with respiratory distress due to CED, we planned for a single-stage repair using cardiopulmonary bypass. We started with the sternotomy approach. The LPA was mobilized off its origin from the proximal RPA, disconnected and re-implanted on the main pulmonary artery on its postero-lateral surface (Fig. 3a, b). ASD was repaired. The patient was weaned off cardiopulmonary bypass. The right pleura was widely opened. As the exposure for diaphragmatic repair was sub-optimal, the chest was closed in the standard manner. The patient’s position was changed to left lateral decubitus position, and right pleural cavity was entered via the 5th intercostal space. The muscular part of the diaphragm was found replaced by a membrane. The right hemidiaphragm was plicated using multiple radial and circumferential plication sutures (Fig. 3c, d). Postoperatively, the right lung did not expand much as expected. Multiple postoperative echocardiographic evaluations were done to confirm the absence of residual lesions or severe pulmonary arterial hypertension. We had difficulty in weaning the child off the ventilator as the single functioning left lung was affected by pneumonia. As we did not have bronchoscopy at that time, retrospective CT evaluation of the tracheal tree was done, and it ruled out anomalies of the trachea and the major bronchi. The situation was complicated by bloodstream sepsis and multi-organ dysfunction syndrome. The child died due to sepsis 3 weeks after surgery.

Fig. 1.

Pre-operative Computed tomography scan images (A) (cross-sectional image) showing Left Pulmonary Artery Sling, MPA - Main pulmonary artery (B) (Sagittal section) showing Left Pulmonary Artery Sling, Liver occupying the entire right thoracic cavity and hypoplastic right lung (C) (3D reconstructed image) Liver occupying the entire right thoracic cavity, hypoplastic right lung

Fig. 2.

Pre-operative Computed tomography scan images (A) (Sagittal section) showing hypoplastic Right pulmonary artery and right lung. (B) (Sagittal section) showing hypoplastic right mainstem bronchus and well-developed trachea and left bronchus. (C) Cartoon depicting Left pulmonary artery sling and eventration of right hemidiaphragm with hypoplastic right lung

Fig. 3.

Intra-operative images (A) Disconnected Left Pulmonary Artery anastomosed to Main pulmonary Artery (B) Re-implanted Left Pulmonary Artery on Main pulmonary Artery (C) Plication of Right HemiDiaphragm (D) Cartoon depicting Re-implanted left pulmonary artery on to the main pulmonary artery and plicated Right hemidiaphragm

Discussion

Contro coined the term Vascular sling to differentiate them from vascular rings [3]. LPAS is an uncommon congenital vascular malformation causing airway compression. It is associated with intrinsic anomalies of the tracheobronchial tree and other congenital heart defects like ASD, ventricular septal defect (VSD), and patent ductus arteriosus (PDA)[4]. Embryology of LPAS is still not clear, and the proposed hypothesis includes failure of LPA development and caudal capillary connection of the left post branchial plexus with the right pulmonary artery [5, 6]. Classification of LPAS was proposed by Wells et al. as early as 1988 [7] according to the level of tracheobronchial pattern. Type I has tracheal bifurcation at T 4–5 vertebral level and type II has bifurcation at T 6–7 vertebral level. Associated tracheal and pulmonary anomalies determine the prognosis and type I A has the best prognosis. Congenital eventration of the diaphragm (CED) is another rare condition (incidence < 0.05%) characterized by cephalad displacement of all or part of an intact diaphragm with poor development of the muscular part. Left hemidiaphragm is more commonly involved than the right. Left pulmonary artery sling associated with congenital diaphragmatic hernia is a known association [1]. Left pulmonary artery sling associated with diaphragmatic eventration is not reported to date, and our patient had an even rare occurrence of eventration of right instead of the more common left hemidiaphragm. Our patient had no trachea-bronchial lesions and hence we have assigned it as LPAS type I. There are two management strategies for this type of association. First, is two-staged management addressing the lesion causing maximum symptoms in the first stage and dealing with the other one later. This runs the risk of inter-stage progression of the second pathology and postoperative morbidity. The second strategy is single-stage correction of both lesions as we did. Our patient had serious symptoms due to both pathologies and hence, a single-stage repair. LPA reimplantation can be done as off pump technique or using cardiopulmonary bypass. One must bevel the LPA and relocate it on the proximal main pulmonary artery in its posterior surface to prevent angulation and stenosis in the long-term [8]. Leaving an inter-atrial communication will help in the postoperative period when there is a high suspicion of pulmonary hypertensive crisis. A radical approach of pneumonectomy and LPA reposition was also an option. We had kept it as a salvage option in case of respiratory failure, but pneumonia and sepsis complicated the clinical course in our patient. The development of lung and tracheobronchial tree decides the prognosis of patients with such associations. Ours was a late referral with severe hypoplasia of the right lung. Ante-natal diagnosis and multi-modality treatment will help in better management of such complex and rare associations.

Funding information

This work was supported by U. N. Mehta Institute of Cardiology and Research Centre itself and received no specific grant from any funding agency, commercial or not-for-profit sectors.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

This case report was approved by our institutional ethics committee.

Informed consent

Obtained

Research involving human participants and/or animals

This article does not contain any studies with human participants or animals performed by any of the authors.