Fontan patient with plastic bronchitis treated successfully using aerosolized tissue plasminogen activator: a case report and review of the literature

Case series of nebulizing r-tPA for COVID-19 induced acute respiratory distress syndrome

Fibrin deposition in the alveolar spaces during pulmonary involvement of COVID-19 impairs the O2/CO2 exchange and leads to respiratory symptoms. In this report, Recombinant Tissue Plasminogen Activator (r-tPA) has been nebulized to 3 critically ill COVID-19 patients in order to resolve the deposited fibrin while avoiding the risk of bleeding. Based on these observations, nebulization of r-tPA may be a potential therapeutic approach and new area of research for future studies.

Pharmacotherapy consideration of thrombolytic medications in COVID-19-associated ARDS

BACKGROUND

In late 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which is responsible for coronavirus disease (COVID-19), was identified as the new pathogen to lead pneumonia in Wuhan, China, which has spread all over the world and developed into a pandemic. Despite the over 1 year of pandemic, due to the lack of an effective treatment plan, the morbidity and mortality of COVID-19 remains high. Efforts are underway to find the optimal management for this viral disease.

MAIN BODY

SARS-CoV-2 could simultaneously affect multiple organs with variable degrees of severity, from mild to critical disease. Overproduction of pro-inflammatory mediators, exacerbated cellular and humoral immune responses, and coagulopathy such as Pulmonary Intravascular Coagulopathy (PIC) contributes to cell injuries. Considering the pathophysiology of the disease and multiple microthrombi developments in COVID-19, thrombolytic medications seem to play a role in the management of the disease. Beyond the anticoagulation, the exact role of thrombolytic medications in the management of patients with COVID-19-associated acute respiratory distress syndrome (ARDS) is not explicit. This review focuses on current progress in underlying mechanisms of COVID-19-associated pulmonary intravascular coagulopathy, the historical use of thrombolytic drugs in the management of ARDS, and pharmacotherapy considerations of thrombolytic therapy, their possible benefits, and pitfalls in COVID-19-associated ARDS.

CONCLUSIONS

Inhaled or intravenous administration of thrombolytics appears to be a salvage therapy for severe ARDS associated with COVID-19 by prompt attenuation of lung injury. Considering the pathogenesis of COVID-19-related ARDS and mechanism of action of thrombolytic agents, thrombolytics appear attractive options in stable patients without contraindications.

Fibrin airway cast obstruction: Experience, classification, and treatment guideline from Denver

BACKGROUND AND OBJECTIVES

Plastic bronchitis (PB) is a condition characterized by the formation of thick airway casts leading to acute and often life-threatening airway obstruction. PB occurs mainly in pediatric patients with congenital heart disease (CHO) who have undergone staged surgical palliation (Glenn, Fontan), but can also occur after chemical inhalation, H1N1, severe COVID-19, sickle cell disease, severe asthma, and other diseases. Mortality risk from PB can be up to 40%-60%, and no treatment guideline exist. The objectives herein are to develop a standardized evaluation, classification, and treatment guideline for PB patients presenting with tracheobronchial casts, based on our experience with PB at the Children's Hospital of Colorado in Denver.

METHODS

We describe 11 patients with CHO-associated PB (post-Fontan [n = 9], pre-Fontan [n = 2]) who presented with their initial episodes. We utilized histopathological analysis of tracheobronchial casts to guide treatment in these patients, utilizing our hospital-wide guideline document and classification system.

RESULTS

We found that 100% of post-Fontan PB patients had fibrinous airway casts, while pre-Fontan PB casts were fibrinous only in one of two patients (50%). Utilizing histopathology as a guide to therapy, PB patients with fibrin airway casts were treated with airway-delivered fibrinolytics and anticoagulants, as well as aggressive airway clearance and other supportive care measures. These therapies resulted in successful cast resolution and improved survival in post-Fontan PB patients.

CONCLUSION

We have shown an improved outcome in PB patients whose treatment plan was based on Denver's PB classification schema and standardized treatment guideline based on tracheobronchial cast histopathology.

Fibrinolytic therapy for refractory COVID-19 acute respiratory distress syndrome: Scientific rationale and review

The coronavirus disease 2019 (COVID-19) pandemic has caused respiratory failure and associated mortality in numbers that have overwhelmed global health systems. Thrombotic coagulopathy is present in nearly three quarters of patients with COVID-19 admitted to the intensive care unit, and both the clinical picture and pathologic findings are consistent with microvascular occlusive phenomena being a major contributor to their unique form of respiratory failure. Numerous studies are ongoing focusing on anticytokine therapies, antibiotics, and antiviral agents, but none to date have focused on treating the underlying thrombotic coagulopathy in an effort to improve respiratory failure in COVID-19. There are animal data and a previous human trial demonstrating a survival advantage with fibrinolytic therapy to treat acute respiratory distress syndrome. Here, we review the extant and emerging literature on the relationship between thrombotic coagulopathy and pulmonary failure in the context of COVID-19 and present the scientific rationale for consideration of targeting the coagulation and fibrinolytic systems to improve pulmonary function in these patients.

The failing Fontan

Nearly 50 years back, Francis Fontan pioneered an operation for tricuspid atresia that bears his name today. The operation has since undergone numerous modifications and continues to be widely applied to an array of single ventricles. Despite restoring normal oxygen levels in the body, the operation creates a neoportal system where adequate cardiac output can be generated only at the expense of increased systemic venous congestion. This results in slow but relentless damage to the end organ systems especially the liver. Continuous surveillance of the patient to monitor this circulation, that will ultimately fail, is of paramount importance. Timely medical and cardiac catheterization and surgical intervention can extend the life span of Fontan patients. Ultimately a change of the hemodynamic circuit in the form of heart transplantation or ventricular assist device will be required to salvage the failing Fontan circuit.

Fungi in Mucoobstructive Airway Diseases

Asthma, chronic rhinosinusitis, and related incurable allergic afflictions of the upper and lower airways are medically important because of their association with the disabling symptom of dyspnea and, at least for asthma, the potential to cause fatal asphyxiation. Extensive research over the past two decades has uncovered both the physiological basis of airway obstruction in asthma and key governing molecular pathways. Exaggerated airway constriction in response to diverse provocative stimuli, termed airway hyperresponsiveness, is mediated through the cytokines interleukin 4 (IL-4) and IL-13 and the transcription factor signal transducer and activator of transcription 6 (STAT6). Overproduction of mucus has long been known to be an essential second component of airway obstruction and is also mediated in part through the IL-4/IL-13/STAT6 pathway. In this review, we discuss a second major signaling pathway which underlies mucus production that is mediated through proteinase-cleaved fibrinogen signaling through Toll-like receptor 4. Unexpectedly, our analysis of human sputum and paranasal sinus fluid indicates that in most cases of severe allergic airway disease, a unique type of airway fungal infection, termed airway mycosis, is pathogenically linked to these conditions. We further discuss how fungal and endogenous proteinases mediate the fibrinogenolysis that is essential to both Toll-like receptor 4 signaling and fibrin deposition that, together with mucus, contribute to airway obstruction.

Strategies to Prevent Cast Formation in Patients with Plastic Bronchitis Undergoing Heart Transplantation

Plastic bronchitis, a rare complication after Fontan palliation, carries a high morbidity and mortality risk. Heart transplantation is an effective treatment option, but casts may occur in the early post-operative period. We present a case series detailing peri-operative management strategies to minimize morbidity and mortality related to plastic bronchitis in patients undergoing heart transplantation. Patient 1 received no treatment pre-, intra-, or post-transplant for prevention of bronchial casts and developed severe respiratory acidosis 18 h following transplant. Emergent bronchoscopy was performed and a large obstructive cast was removed. The patient recovered and received inhaled tissue plasminogen activator (tPA) for 5 days. Patient 2 received inhaled tPA before, during, and for 5 days after transplantation and no bronchial casts developed. Patient 3 underwent intraoperative bronchoscopy just prior to implantation revealing no casts. The patient underwent non-urgent, preemptive bronchoscopy on post-transplant days 1, 3, and 4, removing several partially obstructive bronchial blood clots/casts, with no casts thereafter. Heart transplantation results in eventual resolution of plastic bronchitis. Residual bronchial casts can still be problematic in the peri-operative period. Airway clearance with inhaled tPA or bronchoscopy may prevent the need for prolonged mechanical ventilation and reduce post-operative morbidity in this unique population.

The Long-Term Management of Children and Adults with a Fontan Circulation: A Systematic Review and Survey of Current Practice in Australia and New Zealand

Although long-term survival is now the norm, Fontan patients face significant morbidity and premature mortality. Wide variation exists in long-term Fontan management. With an aim of improving their long-term management, we conducted a systematic review to identify best available evidence and gaps in knowledge for future research focus. We also surveyed cardiologists in Australia and New Zealand managing Fontan patients, to determine the alignment of current local practice with best available evidence. A systematic review was conducted using strict search criteria (PRISMA guidelines), pertaining to long-term Fontan management. All adult congenital and paediatric cardiologists registered with The Australia and New Zealand Fontan Registry were invited to respond to an online survey. Reasonable quality evidence exists for non-inferiority of aspirin over warfarin for thromboprophylaxis in standard-risk Fontan patients. No strong evidence is currently available for the routine use of ACE inhibitors, beta blockers or pulmonary vasodilators. Little evidence exists regarding optimal arrhythmia treatment, exercise restriction/prescription, routine fenestration closure, elective Fontan conversion and screening/management of liver abnormalities. Although pregnancy is generally well tolerated, there are high rates of miscarriage and premature delivery. Thirty-nine out of 78 (50 %) cardiologists responded to the survey. Heterogeneity in response was demonstrated with regard to long-term anti-coagulation, other medication use, fenestration closure and pregnancy and contraception counselling. Substantial gaps in our knowledge remain with regard to the long-term management of Fontan patients. This is reflected in the survey of cardiologists managing these patients. We have identified a number of key areas for future research.

Use of Aerosolized Tissue Plasminogen Activator in the Treatment of Plastic Bronchitis

OBJECTIVE

To present a case of nebulized tissue plasminogen activator (t-PA) treatment for symptomatic plastic bronchitis in a pediatric patient years after a Fontan procedure.

CASE SUMMARY

A 13-year-old boy with a history of corrected congenital heart disease was admitted to the pediatric intensive care unit after 2 weeks of worsening respiratory distress. A chest radiograph and subsequent bronchoscopy revealed extensive mucus plugging due to plastic bronchitis. Casts reaccumulated quickly after manual removal of the mucus and a regimen of aerosolized t-PA was initiated to break down the casts and prevent further cast formation over the 17-day hospital course. The treatment was successful and the patient was discharged home without evidence of bronchial casts.

DISCUSSION

Plastic bronchitis is a potentially devastating condition in which pulmonary infiltrates line the bronchial tree, forming casts and prohibiting effective oxygen exchange. There are few effective treatment options for this condition. The use of aerosolized t-PA for the treatment of plastic bronchitis has been reported to be safe and effective in 4 cases but no consistent regimen, dose, or duration of treatment has been established.

CONCLUSIONS

t-PA can be nebulized and inhaled for successful inhibition of bronchial cast formation. More information to determine the most effective dose and duration of therapy is needed to effectively improve the lives of people with plastic bronchitis.

Inhalational use of antithrombotics in humans: Review of the literature

INTRODUCTION

Off label use of anticoagulants is common. The association between fibrin deposition in the lungs and primary lung disease, injury or prematurity affords a strong theoretical basis for the potential benefit of antithrombotic therapies administered directly to the lung tissue. This review offers a critical appraisal of current evidence related to the inhalational administration of antithrombotic therapy in humans.

MATERIALS AND METHODS

An interrogation of 2 databases across a 13 year period of time was undertaken using key words selected a priori. Identified publications were categorized according to the following themes: 1. Inhaled antithrombotic therapy in healthy subjects 2. Inhaled antithrombotic therapy for vascular thromboprophylaxis 3. Inhaled antithrombotic therapy in smoke inhalation and lung injury 4. Inhaled antithrombotic therapy in asthma or allergy 5. Inhaled antithrombotic therapy for plastic bronchitis post-Fontan surgery 6. Inhaled antithrombotic therapy for other indications.

RESULTS

33 articles were identified consistent with the inclusion criteria developed for this review. Unfractionated heparin, LMWH, activated protein C and thrombolytic agents have been administered via the respiratory track, with asthma and smoke inhalation/lung injury being the most frequently investigated clinical scenarios described. All studies reported had significant methodological limitations.

CONCLUSIONS

The safety and clinical utility of inhaled antithrombotic therapies have not been adequately investigated to support the generation of any firm evidence. This review highlights where inhaled antithrombotic therapies have shown promise and importantly, the further research required to confirm mechanism of action and a definitive risk: benefit profile.

Casting a look at pediatric plastic bronchitis

OBJECTIVES

To review clinical presentations and management strategies for children with plastic bronchitis.

METHODS

Retrospective chart review.

RESULTS

Seven patients required rigid bronchoscopy to remove bronchial casts over a 17-year study period. Mean age at presentation was 60 months. Mean follow-up was 53 months. Co-morbidities included: congenital heart disease (n=3), chronic pulmonary disorders (n=2) and sickle cell disease (n=1). 4 patients required multiple bronchoscopies for recurrent casts. Adjunctive topical therapies were administered in all 7 patients, without complication. Rigid bronchoscopy for cast removal was performed in 2 patients who were on extra-corporal membrane oxygenation (ECMO), using special precautions to safeguard the ECMO catheters.

CONCLUSIONS

Bronchial casts in children may present acutely or sub-acutely. Recurrent casts are unusual; however, in combination with severe cardiac disease may lead to mortality. Adjunctive topical therapies are still under investigation. Special safeguards for ECMO catheters are imperative. This case series complements and adds to the International Plastic Bronchitis Registry.

Airway fibrinogenolysis and the initiation of allergic inflammation

The past 15 years of allergic disease research have produced extraordinary improvements in our understanding of the pathogenesis of airway allergic diseases such as asthma. Whereas it was previously viewed as largely an immunoglobulin E-mediated process, the gradual recognition that T cells, especially Type 2 T helper (Th2) cells and Th17 cells, play a major role in asthma and related afflictions has inspired clinical trials targeting cytokine-based inflammatory pathways that show great promise. What has yet to be clarified about the pathogenesis of allergic inflammatory disorders, however, are the fundamental initiating factors, both exogenous and endogenous, that drive and sustain B- and T-cell responses that underlie the expression of chronic disease. Here we review how proteinases derived from diverse sources drive allergic responses. A central discovery supporting the proteinase hypothesis of allergic disease pathophysiology is the role played by airway fibrinogen, which in part appears to serve as a sensor of unregulated proteinase activity and which, when cleaved, both participates in a novel allergic signaling pathway through Toll-like receptor 4 and forms fibrin clots that contribute to airway obstruction. Unresolved at present is the ultimate source of airway allergenic proteinases. From among many potential candidates, perhaps the most intriguing is the possibility such enzymes derive from airway fungi. Together, these new findings expand both our knowledge of allergic disease pathophysiology and options for therapeutic intervention.

A Role for Low Density Lipoprotein Receptor-Related Protein 1 in the Cellular Uptake of Tissue Plasminogen Activator in the Lungs

PURPOSE

To gain knowledge of lung clearance mechanisms of inhaled tissue plasminogen activator (tPA).

METHODS

Using an in vivo mouse model and ex vivo murine whole organ cell suspensions, we examined the capability of the lungs to utilize LRP1 receptor-mediated endocytosis (RME) for the uptake of exogenous tPA with and without an LRP1 inhibitor, receptor associated protein (RAP), and quantitatively compared it to the liver. We also used a novel imaging technique to assess the amount LRP1 in sections of mouse liver and lung.

RESULTS

Following intratracheal administration, tPA concentrations in the bronchoalveolar lavage fluid (BALF) declined over time following two-compartment pharmacokinetics suggestive of a RME clearance mechanism. Ex vivo studies showed that lung and liver cells are similarly capable of tPA uptake via LRP1 RME which was reduced by ~50% by RAP. The comparable lung and liver uptake of tPA is likely due to equivalent amounts of LRP1 of which there was an abundance in the alveolar epithelium.

CONCLUSIONS

Our findings indicate that LRP1 RME is a candidate clearance mechanism for inhaled tPA which has implications for the development of safe and effective dosing regimens of inhaled tPA for the treatment of plastic bronchitis and other fibrin-inflammatory airway diseases in which inhaled tPA may have utility.

Severe airway obstruction from a bronchial cast after cardiac transplantation

Plastic bronchitis is a rare and difficult to treat disease process in patients with congenital heart disease. Cardiac transplantation has been used increasingly to reverse this process, especially in single ventricle physiology. This case report demonstrates a foreseeable complication after cardiac transplantation in such a patient.

A multifaceted approach to the management of plastic bronchitis after cavopulmonary palliation

BACKGROUND

Plastic bronchitis is a rare, potentially life-threatening complication after Fontan operation. Hemodynamic alterations (elevated central venous pressure and low cardiac output) likely contribute to the formation of tracheobronchial casts composed of inflammatory debris, mucin, and fibrin. Pathologic studies of cast composition support medical treatment with fibrinolytics such as inhaled tissue plasminogen activator (t-PA).

METHODS

This was a retrospective case series of medical, surgical, and catheter-based treatment of patients with plastic bronchitis after cavopulmonary palliation.

RESULTS

Included were 14 patients (86% male, 93% white). Median age at Fontan operation was 2.7 years (range, 1.2 to 4.1 years), with median interval to plastic bronchitis presentation of 1.5 years (range, 9 days to 15.4 years). Cast composition was available for 11 patients (79%) and included fibrin deposits in 7. All patients were treated with pulmonary vasodilators, and 13 (93%) were treated with inhaled t-PA. Hemodynamically significant lesions in the Fontan pathway were addressed by catheter-based (n=9) and surgical (n=3) interventions. Three patients (21%) underwent heart transplantation. Median follow-up was 2.7 years (range, 0.6 to 8.7 years). Symptoms improved, such that 6 of 13 patients (46%) were weaned off t-PA. Rare or episodic casts are successfully managed with outpatient t-PA in most of the other patients. Of the 3 patients who underwent heart transplant, 2 are asymptomatic and 1 has recurrent casts in the setting of elevated filling pressures and rejection.

CONCLUSIONS

A systematic step-wise algorithm that includes optimization of hemodynamics, aggressive pulmonary vasodilation, and inhaled t-PA is an effective treatment strategy for patients with plastic bronchitis after cavopulmonary connection.

Aerosolised heparin in the treatment of Fontan-related plastic bronchitis

Patients with Fontan palliation and single-ventricle physiology encounter multiple comorbidities including plastic bronchitis, a disease characterised by the plugging of small and large airways by rubbery, white casts. To date, no controlled clinical trials have demonstrated effective treatment of plastic bronchitis. We report the application of aerosolised heparin, which has published success in non-cardiac-related pulmonary disease, for this complication in a Fontan patient.

End-organ consequences of the Fontan operation: liver fibrosis, protein-losing enteropathy and plastic bronchitis

The Fontan operation, although part of a life-saving surgical strategy, manifests a variety of end-organ complications and unique morbidities that are being recognised with increasing frequency as patients survive into their second and third decades of life and beyond. Liver fibrosis, protein-losing enteropathy and plastic bronchitis are consequences of a complex physiology involving circulatory insufficiency, inflammation and lymphatic derangement. These conditions are manifest in a chronic, indolent state. Management strategies are emerging, which shed some light on the origins of these complications. A better characterisation of the end-organ consequences of the Fontan circulation is necessary, which can then allow for development of specific methods for treatment. Ideally, the goal is to establish systematic strategies that might reduce or eliminate the development of these potentially life-threatening challenges.

Tissue plasminogen activator prevents mortality from sulfur mustard analog-induced airway obstruction

Sulfur mustard (SM) inhalation causes the rare but life-threatening disorder of plastic bronchitis, characterized by bronchial cast formation, resulting in severe airway obstruction that can lead to respiratory failure and death. Mortality in those requiring intubation is greater than 80%. To date, no antidote exists for SM toxicity. In addition, therapies for plastic bronchitis are solely anecdotal, due to lack of systematic research available to assess drug efficacy in improving mortality and/or morbidity. Adult rats exposed to SM analog were treated with intratracheal tissue plasminogen activator (tPA) (0.15-0.7 mg/kg, 5.5 and 6.5 h), compared with controls (no treatment, isoflurane, and placebo). Respiratory distress and pulse oximetry were assessed (for 12 or 48 h), and arterial blood gases were obtained at study termination (12 h). Microdissection of fixed lungs was done to assess airway obstruction by casts. Optimal intratracheal tPA treatment (0.7 mg/kg) completely eliminated mortality (0% at 48 h), and greatly improved morbidity in this nearly uniformly fatal disease model (90-100% mortality at 48 h). tPA normalized plastic bronchitis-associated hypoxemia, hypercarbia, and lactic acidosis, and improved respiratory distress (i.e., clinical scores) while decreasing airway fibrin casts. Intratracheal tPA diminished airway-obstructive fibrin-containing casts while improving clinical respiratory distress, pulmonary gas exchange, tissue oxygenation, and oxygen utilization in our model of severe chemically induced plastic bronchitis. Most importantly, mortality, which was associated with hypoxemia and clinical respiratory distress, was eliminated.

Pharmacotherapy challenges of Fontan-associated plastic bronchitis: a rare pediatric disease

Pediatric pharmacotherapy is often challenging due to the paucity of available clinical data on the safety and efficacy of drugs that are commonly used in children. This quandary is even more prevalent in children with rare diseases. Although extrapolations for dosing and administration are often made from available adult data with similar disease states, this translation becomes even more problematic in rare pediatric diseases. Understanding of rare disease pathophysiology is typically poor, and few, if any, effective therapies have been studied and identified. One condition that illustrates these issues is plastic bronchitis, a rare, most often pediatric disease that is characterized by the production of obstructive bronchial airway casts. This illness primarily occurs in children with congenital heart disease, often after palliative surgery. Plastic bronchitis is a highly clinically relevant and therapeutically challenging problem with a high mortality rate, and, a generally accepted effective pharmacotherapy regimen has yet to be identified. Furthermore, the disease is ill defined, which makes timely identification and treatment of children with plastic bronchitis difficult. The pharmacotherapies currently used to manage this disease are largely anecdotal and vary between the use of macrolide antibiotics, mucolytics, bronchodilators, and inhaled fibrinolytics in a myriad of combinations. The purpose of this review is 2-fold: first, to highlight the dilemma of treating plastic bronchitis, and second, to bring attention to the continuing need for studies of drug therapies used in children so safe and effective drug regimens can be established, particularly for rare diseases.

Pediatric plastic bronchitis: case report and retrospective comparative analysis of epidemiology and pathology

Plastic bronchitis (PB) is a pathologic condition in which airway casts develop in the tracheobronchial tree causing airway obstruction. There is no standard treatment strategy for this uncommon condition. We report an index patient treated using an emerging multimodal strategy of directly instilled and inhaled tissue plasminogen activator (t-PA) as well as 13 other cases of PB at our institution between 2000 and 2012. The majority of cases (n = 8) occurred in patients with congenital heart disease. Clinical presentations, treatments used, histopathology of the casts, and patient outcomes are reviewed. Further discussion is focused on the epidemiology of plastic bronchitis and a systematic approach to the histologic classification of casts. Comorbid conditions identified in this study included congenital heart disease (8), pneumonia (3), and asthma (2). Our institutional prevalence rate was 6.8 per 100,000 patients, and our case fatality rate was 7%.

Orthotopic heart transplantation in patients with univentricular physiology

Parallel advancements in surgical technique, preoperative and postoperative care, as well as a better understanding of physiology in patients with duct-dependent pulmonary or systemic circulation and a functional single ventricle, have led to superb results in staged palliation of most complex congenital heart disease (CHD) [1]. The Fontan procedure and its technical modifications have resulted in markedly improved outcomes of patients with single ventricle anatomy [2,3,4]. The improved early survival has led to an exponential increase of the proportion of Fontan patients surviving long into adolescence and young adulthood [5]. Improved early and late survival has not yet abolished late mortality secondary to myocardial failure, therefore increasing the referrals for cardiac transplantation [6]. Interstage attrition [7] is moreover expected in staged palliation towards completion of a Fontan-type circulation, while Fontan failure represents a growing indication for heart transplantation [8]. Heart transplantation has therefore become the potential “fourth stage” [9] or a possible alternative to a high-risk Fontan operation [10] in a strategy of staged palliation for single ventricle physiology. Heart transplant barely accounts for 16% of pediatric solid organ transplants [11]. The thirteenth official pediatric heart transplantation report- 2010 [11] indicates that pediatric recipients received only 12.5% of the total reported heart transplants worldwide. Congenital heart disease is not only the most common recipient diagnosis, but also the most powerful predictor of 1-year mortality after OHT. Results of orthotopic heart transplantations (OHT) for failing single ventricle physiology are mixed. Some authors advocate excellent early and mid-term survival after OHT for failing Fontan [9], while others suggest that rescue-OHT after failing Fontan seems unwarranted [10]. Moreover, OHT outcome appears to be different according to the surgical staging towards the Fontan operation and surgical technique of Fontan completion [12].

The focus of this report is a complete review of the recent literature on OHT for failing single ventricles, outlining the clinical issues affecting Fontan failure, OHT listing and OHT outcome. These data are endorsed reporting our experience with OHT for failing single ventricle physiology in recent years.

Management of plastic bronchitis with topical tissue-type plasminogen activator

Plastic bronchitis or cast bronchitis is a rare disease of unclear etiology characterized by formation of airway casts that can lead to life-threatening airway obstruction. There is currently limited data regarding optimal treatment of plastic bronchitis. Several therapies have been suggested, but recurrences are common and mortality remains high. We report the case of a 6-year-old boy with refractory eosinophilic bronchial casts, unresponsive to low-dose systemic corticosteroids, inhaled corticosteroids, azithromycin, and dornase alfa, who was treated successfully and safely with direct instillation of tissue-type plasminogen activator (tPA) to the obstructing casts during flexible bronchoscopy and inhaled tPA. Our case illustrates that the current therapy for plastic bronchitis remains inadequate. To our knowledge, this case is the first to show that direct instillation of tPA can be used safely for treatment of this disease. The use of tPA via direct administration into the airways during bronchoscopy and via a nebulizer appeared to be a safe and effective therapy for plastic bronchitis and should be considered early in the course of the disease to prevent complications of severe airway obstruction.

Barotrauma as aetiological cascade of fatal intrapulmonary plastic bronchitis in a post-Fontan child

The role of barotrauma in the exaggeration of plastic bronchitis after Fontan circulation has yet to be examined. We aim to describe a case of a 4-year old post-Fontan circulation girl where barotrauma suffered during commercial air travel played a role in the aetiological cascade of plastic bronchitis.

Long term respiratory outcomes of congenital diaphragmatic hernia, esophageal atresia, and cardiovascular anomalies

Intrathoracic congenital malformations may be associated with long-term pulmonary morbidity. This certainly is the case for congenital diaphragmatic hernia, esophageal atresia and cardiac and aortic arch abnormalities. These conditions have variable degrees of impaired development of both the airways and lung vasculature, with a postnatal impact on lung function and bronchial reactivity. Pulmonary complications are themselves frequently associated to non-pulmonary morbidities, including gastrointestinal and orthopaedic complications. These are best recognized in a structured multidisciplinary follow-up clinic so that they can be actively managed.

Successful management of plastic bronchitis in a child post Fontan: case report and literature review

PURPOSE

Plastic bronchitis is the occlusion of the major bronchial airways by a firm, gelatinous mucoid cast. It is a rare condition, which while classically described in asthma and sickle cell disease has greater mortality in patients with congenital heart disease. The management of this disease is obscure given the lack of clinical data regarding treatment therapies.

METHODS

We describe a case of an 11-year-old female status after Fontan surgery who presented with respiratory distress secondary to atelectasis of the right lung.

RESULTS

A bronchoscopy was performed demonstrating an obstructing bronchial cast with successful extraction. The plastic bronchitis continued to recur and she was placed on multiple inhaled mucolytics as well as inhaled tissue plasminogen activator with temporary resolution. Further evaluation of the etiology of her casts revealed that she had elevated pulmonary arterial pressures. Repeated bronchoscopic removal of the casts was utilized as well as continuation of the aggressive airway clearance. Ultimately fenestration of her Fontan was performed along with treatment of pulmonary vasodilators sildenafil and bosentan. Although there was improvement of the cast formation, her airway clearance could only be weaned to four times a day therapy with which she was discharged home after a 3-month hospitalization. She continues to remain on this therapy and has not required hospitalization since the initial incident over 1 year ago.

CONCLUSIONS

Plastic bronchitis in a patient with Fontan physiology presents a treatment dilemma that may require comprehensive therapy in severe cases such as described.

Management of plastic bronchitis in a child with mild intermittent asthma

OBJECTIVES

We describe the clinical presentation of a 7 1/2-year-old boy with a history of mild intermittent asthma who presented with left lung collapse and was found to have plastic bronchitis.

METHODS

We reviewed the patient chart and imaging results and performed a literature review of plastic bronchitis and its management.

RESULTS

Bronchoscopy in our patient demonstrated a large white, friable, cast-like material that obstructed the entire left main stem bronchus and could not be easily suctioned. The cast was removed in a piecemeal fashion by means of serial rigid bronchoscopy over a 6-month period with use of both optical forceps and flexible suction catheters. Microscopic examination of the cast-like material showed a predominance of eosinophils along with neutrophils encased in proteinaceous material.

CONCLUSIONS

Plastic bronchitis in children is a rare condition that can mimic foreign body aspiration and can be associated with underlying pulmonary inflammatory disorders or cardiovascular disease. Aggressive bronchoscopic management of the airway obstruction and medical management of the underlying disease process are important for the successful treatment of plastic bronchitis.

Prospective, longitudinal study of plastic bronchitis cast pathology and responsiveness to tissue plasminogen activator

Plastic bronchitis (PB) is a rare disease that often occurs in patients with congenital heart disease (CHD) who have undergone staged single-ventricle palliation. It is characterized by the formation of rubbery "casts" in the airways. PB treatment frequently includes inhaled tissue plasminogen activator (tPA). However, the efficacy of tPA to reduce cast burden is unknown. This is further complicated by our lack of knowledge of cast composition. We obtained spontaneously expectorated PB casts from children (n = 4) with CHD and one adult patient with idiopathic PB. Pathological assessment was made from paraffin-preserved samples. Casts were treated with phosphate-buffered saline (PBS) or tPA. Cast response to tPA was assessed by changes in cast weight and the production of fibrin D-dimer. Independent of dose, tPA reduced cast weight compared with PBS-treatment (P = 0.001) and increased D-dimer levels. Histological staining showed that PB casts from all patients were composed of fibrin and contained notable numbers of lymphocytes. Cast composition did not change over time. Collectively, these data support that in our PB patients, casts are composed of fibrin and are responsive to tPA treatment. This makes inhaled tPA a potentially viable option for symptomatic relief of PB while we work to unravel the complexity of PB pathogenesis.

New concepts: development of a survivorship programme for patients with a functionally univentricular heart

Children with functionally univentricular hearts are now surviving into their third and fourth decades of life. Although survival alone is a remarkable achievement, a lot must still be done to improve the quality and duration of life after the Fontan operation. Challenges that may be faced by these patients include the impact of the Fontan operation on the liver and the density of bone, protein-losing enteropathy, and plastic bronchitis. Paediatric cardiologists are familiar with the haemodynamic issues inherent in Fontan physiology; however, training in cardiology is often not sufficient to give us a complete understanding of the pathophysiology of the complications or of the options for treatment. Collaboration with other subspecialists including gastroenterologists, endocrinologists, and pulmonologists is essential in order to provide the rigorous and nuanced care that our patients need and deserve. A clinic in which a patient can see multiple subspecialists, and in which the subspecialists, as a group, can discuss each patient, can provide a unique and valuable service for patients with a functionally univentricular heart.

Plastic bronchitis: resolution after heart transplantation

Plastic bronchitis (PB) is a rare cause of obstructive airway disease in patients who have undergone partially corrective surgery for congenital heart disease (CHD). The etiology of plastic bronchitis in such patients is ill-defined, and treatment is ineffective. We report resolution of PB and severe obstructive airway disease after heart transplantation in a patient with CHD.

Rare problems associated with the Fontan circulation

The Fontan operation, originally described for the surgical management of tricuspid atresia, is now the final surgery in the strategy of staged palliation for a number of different forms of congenital cardiac disease with a functionally univentricular heart. Despite the improved technical outcomes of the Fontan operation, staged palliation does not recreate a normal physiology. Without a pumping chamber delivering blood to the lungs, the cardiovascular system is less efficient; cardiac output is generally diminished, and the systemic venous pressure is increased. As a result, patients with "Fontan physiology" may face a number of rare but potentially life-threatening complications including hepatic dysfunction, abnormalities of coagulation, protein-losing enteropathy, and plastic bronchitis. Despite the staged palliation resulting in remarkable survival, the possible complications for this group of patients are complex, involve multiple organ systems, and can be life threatening. Identifying the mechanisms associated with each of the rare complications, and developing strategies to treat them, requires the work of many people at many institutions. Continued collaboration between sub-specialists and between institutions will be required to optimise the care for this group of survivors with functionally univentricular hearts.

Four decades of Fontan palliation

The Fontan palliation was introduced in 1968 to treat cardiac malformations unsuitable for biventricular repair. This procedure has transformed the surgical management of congenital heart disease. In this Review, we reflect on the outcomes and clinical problems associated with this unique circulation after more than 40 years of experience. We also summarize the evolution of the Fontan procedure, highlight the long-term clinical issues and their management, and consider future expectations of a circulation driven by a single ventricle with the systemic and pulmonary blood flow in series rather than in parallel.

Safety of prolonged, repeated administration of a pulmonary formulation of tissue plasminogen activator in mice

BACKGROUND

Disruption of fibrinolytic homeostasis participates in the pathogenesis of severe lung diseases like acute respiratory distress syndrome (ARDS), idiopathic pulmonary fibrosis (IPF) and plastic bronchitis. We have developed a pulmonary formulation of tissue plasminogen activator (pf-tPA) that withstands nebulization and reaches the lower airways.

OBJECTIVE

Since treatment of ARDS, IPF and plastic bronchitis will require repeated administration of pf-tPA, the purpose of this study was to determine the safety of prolonged, repeated administration of pf-mouse tPA (pf-mtPA) to the lungs of healthy mice.

METHODS

Male and female B6C3F1 mice received one of two intratracheal (IT) doses of either nebulized pf-mtPA or sterile saline twice daily for 28 days. Weekly blood samples were collected to estimate hematocrit. Following the dosing period, animals were sacrificed for gross necropsy, the acquisition of bronchoalveolar lavage fluid (BALF), and histological assessment of the lungs and other major organs.

RESULTS

The low dose of pf-mtPA was well tolerated by both female and male mice. However, female and male mice that received the high dose experienced a 16% and 8% incidence, respectively, of fatal pulmonary hemorrhage. Although male mice had a lower incidence of bleeding, these events occurred at lower mean (+/-S.E.) doses (1.06+/-0.02mg/kg/d) of pf-mtPA compared with females (1.48+/-0.03mg/kg/d, p<0.001). In addition, male mice had higher BALF mtPA concentrations. Bleeding occurred six and 12 days in male and female mice, respectively, after the initiation of dosing suggesting that mtPA accumulated in the lungs.

CONCLUSION

This study established a safe dose range and demonstrated the feasibility of prolonged, repeated dosing of pf-tPA. High doses (> or =1mg/kg/d) were associated with pulmonary hemorrhage that may be due, in part, to accumulation of drug in the lungs.

Evaluating failing Fontans for heart transplantation: predictors of death

BACKGROUND

Late complications of the Fontan operation represent a significant management challenge. Failing Fontan patients have two modes of presentation: impaired ventricular function (IVF) and those with preserved ventricular function (PVF) but with failing Fontan physiology (protein-losing enteropathy [PLE] and plastic bronchitis [PB]). This study evaluated whether failing Fontan patients referred for heart transplantation had a different outcome based on the mode of presentation.

METHODS

The medical records of all Fontan patients evaluated for heart transplantation at a single institution from 1994 to 2008 were retrospectively reviewed. Demographic, hemodynamic, and laboratory data were collected. Patients were stratified into an IVF or PVF group by echocardiographic criteria. Descriptive statistics and Kaplan-Meier analysis were used for hypothesis testing.

RESULTS

Thirty-four Fontan patients were evaluated for heart transplantation. According to echo description of systolic function, 18 were categorized as IVF and 16 as PVF. The IVF group had a significantly lower cardiac index and venous oxygen saturation, and significantly higher systemic vascular resistance vs the PVF group (p < 0.05). PLE or PB was present in 13 PVF patients and none in the IVF group. Twenty patients underwent transplantation, with similar rates amongst the IVF and PVF groups. Within 1 year from evaluation, 2 IVG patients and 7 PVF patients had died (p = 0.052).

CONCLUSIONS

Failing Fontan patients with PVF have decreased overall survival independent of whether they underwent transplantation. This trend indicates a need to improve the management and timing for transplantation amongst this population.