Plastic bronchitis in a post-operative pediatric patient with congenital heart disease.

Priya Kesarwani, MD1, Margo Benoit, MD11 University of Rochester, Department of Otolaryngology Head and Neck Surgery

ABSTRACTObjectives: To discuss a rare case of acute pediatric respiratory distress due to plastic bronchitis and to review the pertinent literature.Study Design: Case report and literature review.Methods: We present the case of a child with congenital heart disease whose post-operative course was complicated by plastic bronchitis. We review a PubMed search generated using keywords “plastic bronchitis” and “congenital heart disease” and “Fontan”, which yielded 24 articles. This was further narrowed to 20 articles by filtering the results for English and pediatric (age 0-18 years) articles.Discussion: Plastic bronchitis can occur in patients with asthma, with bronchopulmonary aspergillosis, with cystic fibrosis and, less commonly, after surgery for congenital heart disease. For cardiac surgical patients, the average time to developing plastic bronchitis is around 1-3 years, and prognosis is poorer with an earlier post-operative diagnosis. Proposed risk factors in pediatric cardiac surgery patients include post-operative chylothorax, chest tube insertion and ascites. Despite medical and surgical treatment strategies, overall disease-specific mortality in cardiac surgery patients is 30-60%. Conclusions: Plastic bronchitis is a rare, potentially-fatal airway condition in post-operative pediatric patients with congenital heart disease, in which extensive endobronchial casts arborize throughout the lung.

METHODSA review of the literature was performed to investigate key questions regarding plastic bronchitis in post-operative patients with congenital heart disease. A PubMed search was generated using keywords “plastic bronchitis” and “congenital heart disease” and “Fontan”, which yielded 24 articles. This was further narrowed to 20 articles by filtering the results for English and pediatric (age 0-18 years) articles.

One suggests that increased systemic venous pressure causes cell membrane dysfunction, disruption of bronchial mucosa integrity and eventual leakage of proteinaceous material into the airways. Another offers that there is retrograde flow of chyle through the lymphatics draining the endobronchial tree, which can occur due to lymphodysplasia and lymphobronchial fistulas often accompanying cardiac anomalies. There are some who propose an underlying genetic predisposition to hypersecretion of mucin when exposed to an inflammatory trigger. Proposed risk factors in pediatric cardiac surgery patients include post-operative chylothorax, chest tube insertion and ascites (4, 5).

Medical therapy for both type I and II casts primarily consists of hemodynamic management, corticosteroids and inhaled lytic agents (heparin, tissue plasminogen activator, acetylcysteine, urokinase and DNAse). The mainstay of management is diagnostic and therapeutic rigid bronchoscopy, which can prove challenging as the casts are often too thick to suction and too soft to grasp with forceps. Thoracic duct ligation has been proposed as a potential treatment for a lipid-rich subclass of type II casts (2). It is thought to decrease intrathoracic lymphatic pressure and flow, and some success has been seen in congenital heart disease patients up to 2 years post-intervention.

Plastic bronchitis after repair of congenital heart disease often recurs and requires repeated bronchoscopic interventions, and the lifetime risk of post-Fontan plastic bronchitis is 1-4% (5). It carries a mortality rate as high as 30-60% (6). In a retrospective case-control study, Schumacher et al found the onsent of symptoms to be a median 2.8 years post-Fontan procedure (5), and generally prognosis is poorer with an earlier post-operative diagnosis (2). The case presented here is unique in the literature, as the patient developed life-threatening respiratory distress due to plastic bronchitis within 16 days of his cardiac surgery.

CASE PRESENTATIONA six year-old male with a history of double-inlet left ventricle, great vessel transposition and an interrupted aortic arch who previously underwent a Norwood procedure, arch reconstruction and bidirectional Glenn in infancy presented for a fenestrated Fontan procedure.  He was admitted to the pediatric cardiac intensive care unit (PCICU) post-operatively. His course was complicated by increased work of breathing on hospital day 16, and chest radiograph revealed complete right lung atelectasis and pleural effusion. Endotracheal intubation became necessary for persistent hypoxia. Bedside bronchoscopy demonstrated tenacious plugging.

Further respiratory decompensation required emergent intervention by Pediatric Otolaryngology in the operating room. The endotracheal tube was removed, and direct laryngoscopy revealed normal anatomy to the level of the subglottis. Advancement of a ventilating bronchoscope to the carina revealed a patent left mainstem bronchus and a completely obstructed right mainstem bronchus (Figure 1). The grasping optical forceps were passed multiple times to remove large soft casts until the endobronchial tree was cleared (Figure 2). His oxygen saturations increasingly improved throughout the case, and right-sided chest rise was eventually observed. He was reintubated and returned to the PCICU for ongoing cardiopulmonary management. He was treated with dornase alpha and alteplase nebulizations, though he required an additional bronchoscopic intervention for cast removal during his hospitalization.

CONCLUSIONSPlastic bronchitis is a rare, potentially fatal airway condition in post-operative pediatric patients with congenital heart disease. Timely management of acutely decompensating patients with obstructing cast requires close post-Fontan monitoring, high index of suspicion, prompt trial of medical therapy and experienced rigid bronchoscopy skills.

REFERENCES1. Ishman S, et al. Plastic bronchitis: An unusual bronchoscopic challenge

associated with congenital heart disease repair. Int J Pediatr Otorhinolaryngol. 2003;67(5):543-8.

2. Angelos PC, MacArthur Pediatric plastic bronchitis: A case reports and literature review. CJ. Int J Pediatr Otorhinolaryngol. 2010;5:66-69.

3. Seear M, et al. Bronchial casts in children: A proposed classifcation based on nie cases and a review of the literature. Am J Respir Crit Care Med. 1997;155(1):664-70.

4. Grutter G, et al. Plastic bronchitis after extracardiac Fontan operation. Ann Thorac Surg. 2012;94:860-4.

5. Schumacher KR, et al. Risk factors and outcome of Fontan-associated plastic bronchitis: A case-control study. J Am Heart Assoc. 2014;3(2):1-6.

6. Madsen P, Shah SA, Rubin BK. Plastic bronchitis: new insights and a classification scheme. Paediatr Respir Rev 2005;6:292–300.

CONTACTPriya Kesarwani, MDpriya_kesarwani@urmc.rochester.edu

INTRODUCTIONPlastic bronchitis is an unusual condition, in which extensive endobronchial casts arborize throughout the lung to cause coughing, wheezing, expectoration of mucoid plugs or casts, hemoptysis, respiratory distress or even death. It differs from ordinary mucus plugging due to its cohesiveness and notoriously difficult removal via bronchoscopy. It can occur in patients with asthma, with bronchopulmonary aspergillosis, with cystic fibrosis and, less commonly, after surgery for congenital heart disease (1-3). Specific to post-operative patients, this process is a complication primarily seen with the Fontan procedure, which is performed for children with congenital single ventricle heart disease in order to divert systemic venous return into the pulmonary circulation.

Figure 1. Endoscopic view through ventilating bronchoscope revealing right mainstem bronchial obstruction.

Figure 2. One of the multiple large casts removed from the right endobronchial tree using optical forceps.

DISCUSSIONGalen (131-200 AD) first hypothesized that bronchial casts were expectorated pulmonary blood vessels. Morgagni thought these structures consisted of inspissated mucus. At the turn of the 20th century, plastic bronchitis was thought to be caused by asthma or infection due to tuberculosis or even adherent pericarditis (1, 2). In 1997, Seear et al categorized bronchial casts based on histology, and this classification system has persisted through the literature (3). The inflammatory type I casts contain fibrin with a dense eosinophilic infiltrate, are associated with bronchopulmonary disorders and are more amenable to medical management. The acellular type II casts consist predominantly of mucin, are associated with post-operative congenital heart disease and are much more likely to require repeated urgent bronchoscopy.

There are several theories on how the casts develop in post-operative congenital heart disease patients (2).