Pulmonary vasodilation therapy with sildenafil citrate in a patient with plastic bronchitis after the Fontan procedure for hypoplastic left heart syndrome

Pulmonary Complications in Patients With Fontan Circulation: JACC Review Topic of the Week

The Fontan operation has resulted in significant improvement in survival of patients with single ventricle physiology. As a result, there is a growing population of individuals with Fontan physiology reaching adolescence and adulthood. Despite the improved survival, there are long-term morbidities associated with the Fontan operation. Pulmonary complications are common and may contribute to both circulatory and pulmonary insufficiency, leading ultimately to Fontan failure. These complications include restrictive lung disease, sleep abnormalities, plastic bronchitis, and cyanosis. Cyanosis post-Fontan procedure can be attributed to multiple causes including systemic to pulmonary venous collateral channels and pulmonary arteriovenous malformations. This review presents the unique cardiopulmonary interactions in the Fontan circulation. Understanding the cardiopulmonary interactions along with improved recognition and treatment of pulmonary abnormalities may improve the long-term outcomes in this growing patient population. Interventions focused on improving pulmonary function including inspiratory muscle training and endurance training have shown a promising effect post-Fontan procedure.

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.

Management of circulatory failure after Fontan surgery

With improvement in survival after Fontan surgery resulting in an increasing number of older survivors, there are more patients with a Fontan circulation experiencing circulatory failure each year. Fontan circulatory failure may have a number of underlying etiologies. Once Fontan failure manifests, prognosis is poor, with patient freedom from death or transplant at 10 years of only about 40%. Medical treatments used include traditional heart failure medications such as renin-angiotensin-aldosterone system blockers and beta-blockers, diuretics for symptomatic management, antiarrhythmics for rhythm control, and phosphodiesterase-5 inhibitors to decrease PVR and improve preload. These oral medical therapies are typically not very effective and have little data demonstrating benefit; if there are no surgical or catheter-based interventions to improve the Fontan circulation, patients with severe symptoms often require inotropic medications or mechanical circulatory support. Mechanical circulatory support benefits patients with ventricular dysfunction but may not be as useful in patients with other forms of Fontan failure. Transplant remains the definitive treatment for circulatory failure after Fontan, but patients with a Fontan circulation face many challenges both before and after transplant. There remains significant room and urgent need for improvement in the management and outcomes of patients with circulatory failure after Fontan surgery.

Current Treatment Options for the Failing Fontan Circulation

The Fontan operation was introduced in 1968. For congenital malformations, where biventricular repair is unsuitable, the Fontan procedure has provided a long-term palliation strategy with improved outcomes compared to the initially developed procedures. Despite these improvements, several complications merely due to a failing Fontan circulation, including myocardial dysfunction, arrhythmias, increased pulmonary vascular resistance, protein-losing enteropathy, hepatic dysfunction, plastic bronchitis, and thrombo-embolism, may occur, thereby limiting the life-expectancy in this patient cohort. This review provides an overview of the most common complications of Fontan circulation and the currently available treatment options.

Congenital Heart Disease-Associated Pulmonary Hypertension

Presently, with increasing survival of patients with congenital heart disease (CHD), pulmonary arterial hypertension (PAH) associated with CHD is commonly encountered in children and adults. This increased prevalence is seen despite significant advances in early diagnosis and surgical correction of patients with structural CHD. PAH is the cause of significant morbidity and mortality in these patients and comes in many forms. With the increased availability of targeted therapies for PAH, there is hope for improved hemodynamics, exercise capacity, quality of life, and possibly survival for these patients. There may also be opportunities for combined medical and interventional/surgical approaches for some.

Fontan failure and the role of pulmonary vasodilator therapy

Background

The Fontan circulation is a palliative procedure for patients born with a single ventricle physiology. The Fontan circulation is associated with significant late morbidity commonly including atrial arrhythmias.

Case presentation

We report a case of an adult Fontan patient who developed protein losing enteropathy (PLE) following persistent atrial arrhythmias. Treatment with a pulmonary vasodilator, sildenafil, resolved the PLE.

Conclusions

The importance of a low pulmonary vascular resistance to maintain wellbeing in the Fontan patient is discussed, as is the role of pulmonary vasodilators.

Focused Update on Pulmonary Hypertension in Children-Selected Topics of Interest for the Adult Cardiologist

Pulmonary hypertensive vascular disease (PHVD), and pulmonary hypertension (PH), which is a broader term, are severe conditions associated with high morbidity and mortality at all ages. Treatment guidelines in childhood are widely adopted from adult data and experience, though big differences may exist regarding aetiology, concomitant conditions and presentation. Over the past few years, paediatric aspects have been incorporated into the common guidelines, which currently address both children and adults with pulmonary hypertension (PH). There are multiple facets of PH in the context of cardiac conditions in childhood. Apart from Eisenmenger syndrome (ES), the broad spectrum of congenital heart disease (CHD) comprises PH in failing Fontan physiology, as well as segmental PH. In this review we provide current data and novel aspects on the pathophysiological background and individual management concepts of these conditions. Moreover, we focus on paediatric left heart failure with PH and its challenging issues, including end stage treatment options, such as mechanical support and paediatric transplantation. PH in the context of rare congenital disorders, such as Scimitar Syndrome and sickle cell disease is discussed. Based on current data, we provide an overview on multiple underlying mechanisms of PH involved in these conditions, and different management strategies in children and adulthood. In addition, we summarize the paediatric aspects and the pros and cons of the recently updated definitions of PH. This review provides deeper insights into some challenging conditions of paediatric PH in order to improve current knowledge and care for children and young adults.

Cost-Effectiveness of Percutaneous Lymphatic Embolization for Management of Plastic Bronchitis

BACKGROUND

Plastic bronchitis is a dreaded complication of single ventricle physiology occurring following palliation via Fontan procedure. Medical management of plastic bronchitis often fails, requiring heart transplantation. Percutaneous lymphatic embolization is an emerging treatment for plastic bronchitis.

METHODS

To determine the cost-effectiveness of competing management strategies, a modified Markov model was constructed with patients transiting through treatments-medical management, lymphatic embolization, or heart transplantation from a hospital system perspective. Health state transitions were modeled using an institutional review board-approved retrospective review of the Children's Hospital of Pennsylvania's plastic bronchitis cohort. Medication pricing data were obtained from the National Inpatient Sample. Differences in costs and quality-adjusted life years (QALYs) over a five-year horizon for each group were determined. The incremental cost-effectiveness ratio was then calculated.

RESULTS

The mean cost of lymphatic embolization from procedure performance was US$340,941, US$385,841 for heart transplantation, and US$594,520 for medical management. The mean quality-adjusted survival of lymphatic embolization yielded an additional 0.66 QALYs (P < .03) relative to heart transplantation and 1.3 (P < .0001) relative to medical management. Orthotopic heart transplantation yielded an additional 0.66 QALYs (P = .06) when comparing heart transplantation to medical management. Compared to medical management, lymphatic embolization generated an incremental cost-effectiveness ratio of US$192,105. Similarly, compared to heart transplantation, lymphatic embolization yielded an incremental cost-effectiveness ratio of US$68,030.

CONCLUSIONS

Of the available plastic bronchitis treatments, with a willingness to pay of US$150,000, lymphatic embolization produces an incremental cost-effectiveness ratio within the bounds considered to be cost-effective, potentially causing financial benefits to the health system.

Bronchoscopic and histologic findings during lymphatic intervention for plastic bronchitis

BACKGROUND

Percutaneous lymphatic intervention (PCL) is a promising new therapy for plastic bronchitis (PB). We characterized bronchoalveolar lavage (BAL) and cast morphology in surgically repaired congenital heart disease (CHD) patients with PB during PCL. We quantified respiratory and bronchoscopic characteristics and correlated them with post-intervention respiratory outcomes.

METHODS

We retrospectively reviewed patients with PB and surgically repaired CHD undergoing PCL and bronchoscopy at our institution. Pre-intervention characteristics, bronchoscopy notes, BAL cell counts, virology, and cultures were collected. A pathologist blinded to clinical data reviewed cast specimens. Respiratory outcomes were evaluated through standardized telephone questionnaire.

RESULTS

Sixty-two patients were included with a median follow-up of 20 months. No patients experienced airway bleeding, obstruction, or prolonged intubation related to bronchoscopy. Of BAL infectious studies, the positive results were 4 (8%) fungal, 6 (11%) bacterial, and 6 (14%) viral. Median BAL count per 100 cells for neutrophils, lymphocytes, and eosinophils were 13, 10, and 0, respectively. Of 23 bronchial casts analyzed, all contained lymphocytes, and 19 (83%) were proteinaceous, with 14 containing neutrophils and/or eosinophils. Median BAL neutrophil count was greater in patients with proteinaceous neutrophilic or eosinophilic casts compared to casts without neutrophils or lymphocytes (P = 0.030). Post-intervention, there was a significant reduction in respiratory medications and support and casting frequency.

CONCLUSIONS

The predominance of neutrophilic proteinaceous casts and high percentage of positive BAL infectious studies support short-term fibrinolytic and anti-infective therapies in PB in select patients. Flexible bronchoscopy enables safe assessment of cast burden. PCL effectively treats PB and reduces respiratory therapies.

Lymphatic dysfunction in critical illness

PURPOSE OF REVIEW

The essential role of the lymphatic system in fluid homeostasis, nutrient transport, and immune trafficking is well recognized; however, there is limited understanding of the mechanisms that regulate lymphatic function, particularly in the setting of critical illness. The lymphatics likely affect disease severity and progression in every condition, from severe systemic inflammatory states to respiratory failure. Here, we review structural and functional disorders of the lymphatic system, both congenital and acquired, as they relate to care of the pediatric patient in the intensive care setting, including novel areas of research into medical and procedural therapeutic interventions.

RECENT FINDINGS

The mainstay of current therapies for congenital and acquired lymphatic abnormalities has involved nonspecific medical management or surgical procedures to obstruct or divert lymphatic flow. With the development of dynamic contrast-enhanced magnetic resonance lymphangiography, image-directed percutaneous intervention may largely replace surgery. Because of new insights into the mechanisms that regulate lymphatic biology, pharmacologic inhibitors of mTOR and leukotriene B4 signaling are each in Phase II clinical trials to treat abnormal lymphatic structure and function, respectively.

SUMMARY

As our understanding of normal lymphatic biology continues to advance, we will be able to develop novel strategies to support and augment lymphatic function during critical illness and through convalescence.

Diagnosis, Evaluation and Treatment of Pulmonary Arterial Hypertension in Children

Pulmonary Hypertension (PH), the syndrome of elevated pressure in the pulmonary arteries, is associated with significant morbidity and mortality for affected children. PH is associated with a wide variety of potential underlying causes, including cardiac, pulmonary, hematologic and rheumatologic abnormalities. Regardless of the cause, for many patients the natural history of PH involves progressive elevation in pulmonary arterial resistance and pressure, right ventricular dysfunction, and eventually heart failure. In recent years, a number of pulmonary arterial hypertension (PAH)-targeted therapies have become available to reduce pulmonary artery pressure and improve outcome. A growing body of evidence in both the adult and pediatric literature demonstrates enhanced quality of life, functional status, and survival among treated patients. This review provides a description of select etiologies of PH seen in pediatrics and an update on the most recent data pertaining to evaluation and management of children with PH/PAH. The available evidence for specific classes of PAH-targeted therapies in pediatrics is additionally discussed.

Managing adult Fontan patients: where do we stand?

The Fontan operation is performed as a palliative procedure to improve survival in infants born with a functionally univentricular circulation. The success of the operation is demonstrated by a growing adult Fontan population that exists with this unique physiology. Late follow-up has demonstrated expected and unexpected sequelae, and has shown multisystem effects of this circulation. This review discusses the challenges of managing the late complications in terms of understanding this unique physiology and the innovative therapeutic interventions that are being investigated. The challenge remains to maintain quality of life for adult survivors, as well as extending life expectancy.

Innovative solutions are required to meet the challenges of the Fontan circulation faced in adult lifehttp://ow.ly/XTSm305oH8b

Pulmonary Hypertension in Children

The prevalence of PH is increasing in the pediatric population, because of improved recognition and increased survival of patients, and remains a significant cause of morbidity and mortality. Recent studies have improved the understanding of pediatric PH, but management remains challenging because of a lack of evidence-based clinical trials. The growing contribution of developmental lung disease requires dedicated research to explore the use of existing therapies as well as the creation of novel therapies. Adequate study of pediatric PH will require multicenter collaboration due to the small numbers of patients, multifactorial disease causes, and practice variability.

Percutaneous Lymphatic Embolization of Abnormal Pulmonary Lymphatic Flow as Treatment of Plastic Bronchitis in Patients With Congenital Heart Disease

BACKGROUND

Plastic bronchitis is a potentially fatal disorder occurring in children with single-ventricle physiology, and other diseases, as well, such as asthma. In this study, we report findings of abnormal pulmonary lymphatic flow, demonstrated by MRI lymphatic imaging, in patients with plastic bronchitis and percutaneous lymphatic intervention as a treatment for these patients.

METHODS AND RESULTS

This is a retrospective case series of 18 patients with surgically corrected congenital heart disease and plastic bronchitis who presented for lymphatic imaging and intervention. Lymphatic imaging included heavy T2-weighted MRI and dynamic contrast-enhanced magnetic resonance lymphangiogram. All patients underwent bilateral intranodal lymphangiogram, and most patients underwent percutaneous lymphatic intervention. In 16 of 18 patients, MRI or lymphangiogram or both demonstrated retrograde lymphatic flow from the thoracic duct toward lung parenchyma. Intranodal lymphangiogram and thoracic duct catheterization was successful in all patients. Seventeen of 18 patients underwent either lymphatic embolization procedures or thoracic duct stenting with covered stents to exclude retrograde flow into the lungs. One of the 2 patients who did not have retrograde lymphatic flow did not undergo a lymphatic interventional procedure. A total of 15 of 17(88%) patients who underwent an intervention had significant symptomatic improvement at a median follow-up of 315 days (range, 45-770 days). The most common complication observed was nonspecific transient abdominal pain and transient hypotension.

CONCLUSIONS

In this study, we demonstrated abnormal pulmonary lymphatic perfusion in most patients with plastic bronchitis. Interruption of the lymphatic flow resulted in significant improvement of symptoms in these patients and, in some cases, at least temporary resolution of cast formation.

Effect of Sildenafil on Pressure-Volume Loop Measures of Ventricular Function in Fontan Patients

Sildenafil has been reported to improve exercise capacity in Fontan patients, but the physiologic mechanisms behind these findings are not completely understood. The objective of this study was to study the acute effect of sildenafil on pressure-volume loop (PVL) measures of ventricular function in Fontan patients. Patients after Fontan operation who were presenting for a clinically indicated catheterization were enrolled. Patients were randomized in a double-blinded fashion to receive placebo (n = 9) or sildenafil (n = 10) 30-90 min prior to catheterization. PVLs were recorded using microconductance catheters at baseline and after infusion of dobutamine (10 mcg/kg/min). The primary outcome was change in ventriculoarterial (VA) coupling. For the entire cohort, VA coupling trended toward improvement with dobutamine (1.4 ± 0.4 to 1.8 ± 0.9, p = 0.07). End-systolic elastance showed improvement (2.6 ± 0.9 to 3.8 ± 1.4 mmHg m(2)/ml, p < 0.01) with dobutamine infusion. The cohorts had similar VA coupling at baseline (p = 0.32), but the sildenafil cohort trended toward having less of an improvement in VA coupling with dobutamine stress (p = 0.06). There were no differences between PVL measures of systolic or diastolic function between treatment groups, both at baseline and after dobutamine infusion. Patients with Fontan circulation had improved contractility and trended toward improvement in VA coupling with dobutamine stress. Acute sildenafil administration was not associated with improved PVL measurements of ventricular function in this population. These results suggest that clinical improvements seen with administration of sildenafil in Fontan patients are not associated with an acute improvement in ventricular function.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov ; Clinicaltrials.gov Identifier: NCT01815502.

Pulmonary vasodilator therapy in the failing Fontan circulation: rationale and efficacy

The Fontan operation is the final step of palliation for patients with a functionally single ventricle. Since its introduction in the 1970s, the Fontan surgery has become part of a successful surgical strategy that has improved single ventricle mortality. In recent years, we have become more aware of the limitations and long-term consequences of the Fontan physiology. Pulmonary vascular resistance plays an important role in total cavopulmonary circulation, and has been identified as a potential therapeutic target to mitigate Fontan sequelae. In this review, we will discuss the results of different pulmonary vasodilator trials and the use of pulmonary vasodilators as a treatment strategy for Fontan patients.

Pediatric Pulmonary Hypertension: Guidelines From the American Heart Association and American Thoracic Society

Pulmonary hypertension is associated with diverse cardiac, pulmonary, and systemic diseases in neonates, infants, and older children and contributes to significant morbidity and mortality. However, current approaches to caring for pediatric patients with pulmonary hypertension have been limited by the lack of consensus guidelines from experts in the field. In a joint effort from the American Heart Association and American Thoracic Society, a panel of experienced clinicians and clinician-scientists was assembled to review the current literature and to make recommendations on the diagnosis, evaluation, and treatment of pediatric pulmonary hypertension. This publication presents the results of extensive literature reviews, discussions, and formal scoring of recommendations for the care of children with pulmonary hypertension.

Pulmonary vasodilator therapy and early postoperative outcome after modified Fontan operation

Although mortality is low after the modified Fontan procedure, there is a significant percentage of patients with prolonged postoperative recovery. The objective of this study is to evaluate the usefulness of postoperative administration of oral sildenafil and inhaled nitric oxide on early postoperative outcome. A prospective interventional and comparison study with a historical cohort was conducted. Between January, 2010 and March, 2013, 16 patients received oral sildenafil during immediate modified Fontan postoperative period. Inhaled nitric oxide was also administered if the patient was kept intubated 12 hours after surgery. Early postoperative outcome was compared with a historical cohort of 32 patients on whom the modified Fontan procedure was performed between March, 2000 and December, 2009. Postoperative administration of sildenafil and nitric oxide had no influence on early postoperative outcome after the modified Fontan procedure in terms of duration of pleural effusions, mechanical ventilation time, length of stay in the ICU, and length of hospital stay.

Plastic bronchitis associated with influenza virus infection in children: a report on 14 cases

BACKGROUND

Plastic bronchitis (PB) is a rare disease characterized by formation of bronchial casts. It is usually associated with congenital heart disease, sickle cell disease, lymphoma, and lung diseases such as asthma and pneumonia.

OBJECTIVES

To report 14 cases of PB with influenza A or influenza B infection.

METHODS

We analyzed the clinical manifestations, bronchoscopic and histologic findings, clinical courses, and outcomes.

RESULTS

These cases indicate that PB is a life-threatening complication of severe influenza. Plastic bronchitis should be considered in the diagnosis of children with acute respiratory distress such as lung atelectasis accompanied by influenza.

CONCLUSIONS

Diagnosis should be made by bronchial endoscopy and histopathology, and bronchial casts removed as early as possible.

Add-on treatment with nebulized hypertonic saline in a child with plastic bronchitis after the Glenn procedure

Plastic bronchitis (PB), although a rare cause of airway obstruction, has mortality rates up to 50% in children after Fontan-type cardiac surgery. We present the case of an 18-month-old female patient with PB following pneumonia. At 6 months of age, the patient underwent the Glenn procedure due to functionally univentricular heart. Fiberoptic bronchoscopy revealed complete blockage of the left bronchus by mucoid casts. Pharmacotherapy consisted of glucocorticosteroids, azithromycin, and enalapril maleate. The child also received nebulized 3% NaCl solution, which proved to be beneficial. In children submitted to Fontan-type procedures, physicians must be alert for PB, which can be triggered by respiratory tract infection.

Predictors of sildenafil effects on exercise capacity in adolescents and adults with Fontan circulation

OBJECTIVE

A single dose of sildenafil improves exercise capacity in Fontan patients. However, a recent study failed to show a long-term effect of sildenafil. This study evaluated whether there are factors that might predict sildenafil effects.

METHODS

We studied 36 patients (16-42 years, 14 female) with univentricular heart after various modifications of the Fontan surgery (13 APC, 16 AVC, 7 TCPC). They performed two cardiopulmonary exercise tests, with at least 120 min rest and a single dose of 50 mg sildenafil in between.

RESULTS

After sildenafil administration, patients improved their peak oxygen uptake from 64.5 to 67.3 % predicted (p = 0.0003) without change in ventilatory efficiency ([Formula: see text] slope), oxygen saturation (SpO2) at rest or at peak exercise, respiratory exchange ratio. In addition, resting systolic blood pressure was slightly reduced after sildenafil administration. There was a moderate negative correlation of this improvement to baseline peak oxygen uptake (r = -0.395; p = 0.017). The change in peak oxygen uptake could not be correlated to time of surgery, type of surgery, NT-pro-BNP, or to other clinical data. Nevertheless, all four patients with NT-pro-BNP levels higher than 1,000 pg/ml had the most prominent improvements in exercise capacity.

CONCLUSIONS

Fontan patients have an improved exercise capacity after a single dose of sildenafil. Patients with worse baseline peak oxygen uptake profit more.

Comparison of fenestrated and nonfenestrated patients undergoing extracardiac Fontan

BACKGROUND

The purpose of this study is to compare morbidity and mortality between fenestrated (F, 61 patients) and nonfenestrated (NF, 54 patients) extracardiac Fontan patients during two eras from July 1995 to December 2010: era 1(1995 to 2004) and era 2 (2005 to 2010).

METHODS

Variables evaluated included morphology, hemodynamics, chest tube volume and duration, intensive care and hospital stay, oxygen saturation, neurologic events, rhythm, and readmissions for chylous effusions. Follow-up in 114 hospital survivors was longer in the nonfenestrated cohort (F, 5.0 ± 3.3 years; NF, 7.1 ± 4.6 years; p < 0.005).

RESULTS

Cohorts were similar in body size, morphology, and hemodynamics. Fenestration in hypoplastic left heart syndrome was appreciatively higher in era 2. Bypass time (F, 69 ± 27 minutes; NF, 57 ± 21 minutes) and conduit size (F, 18.8 mm; NF, 19.1 mm) were similar. There was 1 early nonfenestrated Fontan death (1 of 54; 2%) and 4 late deaths (F, 2 of 61, 5%; NF, 2 of 53, 4%; p = 0.86). Room air saturation was higher in NF patients (F, 89%; NF, 94%; p < 0.05). Total chest tube volume was similar, but fenestration was associated with greater chest tube drainage among hypoplastic left heart patients (HLHS, 5,582 ± 3,286 mL; non-HLHS, 3,405 ± 2,533 mL; p = 0.06; odds ratio; 2.0). Readmission to treat chylous effusions, loss of sinus rhythm, actuarial freedom from death, all neurologic events, pacemaker insertion, and Fontan takedown were similar in both cohorts.

CONCLUSIONS

Fenestration was associated with lower discharge oxygen saturations, but late outcomes in fenestrated and nonfenestrated patients are equivalent.

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.

Current challenges in pediatric pulmonary hypertension

Pulmonary arterial hypertension (PAH) in the pediatric population is associated with a variety of underlying diseases and causes, significantly morbidity and mortality. In the majority of patients, PAH in children is idiopathic or associated with congenital heart disease (CHD), with pulmonary hypertension (PH) associated with connective tissue disease, a rare cause in children. Classification of pediatric PH has generally followed the WHO classification, but recognition of the importance of fetal origins of PH and developmental abnormalities have led to the formation of a new pediatric-specific classification. Incidence data from the Netherlands has revealed an annual incidence and point prevalence of 0.7 and 4.4 for idiopathic PAH and 2.2 and 15.6 for associated pulmonary arterial hypertension-CHD cases per million children. Although the treatment with new selective pulmonary vasodilators offers hemodynamic and functional improvement in pediatric populations, the treatments in children largely depend on results from evidence-based adult studies and experience of clinicians treating children. A recent randomized clinical trial of sildenafil and its long-term extension has led to disparate recommendations in the United States and Europe.

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.

Sildenafil and ventriculo-arterial coupling in Fontan-palliated patients: a noninvasive echocardiographic assessment

The fundamental role of pulmonary vascular resistance in the Fontan circulation is obvious. Medications decreasing this resistance may have an impact on the fate of this population. Hence, we assessed noninvasively the effect of oral sildenafil on the ventriculo-arterial coupling in patients with Fontan circulation. In a single-center, prospective case series study, 23 patients with fenestrated extracardiac total cavopulmonary connection age 12-31 years were enrolled in this study. Clinical characteristics and echocardiographic examination were performed before and after a 1 week course of sildenafil at 0.5 mg/kg every 8 h. Sildenafil had no effect on heart rate and blood pressure. However, oxygen saturation was significantly increased with sildenafil (87.6 ± 4.3 vs. 90.1 ± 3.6; P < 0.0001). The calculated noninvasive ventricular end-systolic elastance (Ees) was greater after sildenafil compared with the pre-sildenafil values (1.59 ± 0.17 vs. 1.72 ± 0.27 mm Hg/ml; P = 0.001). Moreover, significant decreases in arterial elastance (Ea) (1.62 ± 0.53 vs. 1.36 ± 0.43 mm Hg/ml; P < 0.0001), ventricular end-diastolic elastance (Eed) (0.05 ± 0.021 vs. 0.04 ± 0.013; P = 0.002), and, finally, ventriculo-arterial coupling index (0.99 ± 0.26 vs. 0.76 ± 0.15; P < 0.0001) were found after sildenafil administration. The intolerable side effects that led to stopping the sildenafil occurred only in one (4 %) patient. Sildenafil has increased ventricular systolic elastance and improved ventriculo-arterial coupling in patients palliated with Fontan circulation. Short-term sildenafil was well tolerated in most of the patients with only minor side effects.

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.

Modulation of pulmonary vascular resistance as a target for therapeutic interventions in Fontan patients: focus on phosphodiesterase inhibitors

Despite advancements in surgical techniques over the past 20 years, Fontan patients have decreased exercise capacity as a consequence of an inherent inability to adequately increase cardiac output during exercise. They are also affected by several complications that are associated with considerable morbidity and mortality. As the systemic and pulmonary circulations are placed in series without a subpulmonary ventricle propelling blood through the pulmonary vasculature, the systemic venous pressure and the respiratory mechanics are the only forces driving pulmonary blood flow. In Fontan circulation, pulmonary vascular resistance is the single most important factor involved in the limitation of cardiac output and treatments able to decrease pulmonary vascular resistance might conversely improve cardiac output and exercise capacity. In this article we discuss the initial experience with the use of sildenafil in Fontan patients and we discuss the possible mechanisms through which sildenafil might positively act in Fontan circulation.

Lost unilateral capillary perfusion during nonpulsatile pulmonary circulation: successful recovery by oral sildenafil

Good status of pulmonary perfusion is essential for a successful outcome after the Fontan procedure. Increased pulmonary pressure and vascular resistance, small size of the pulmonary arteries, and significant branch stenoses reflect some of the main problems causing failing Fontan circulation. Here we report a child who underwent a staged Fontan procedure with subsequent subtotal loss of the left-sided pulmonary perfusion, although branch stenosis was successfully treated by stent implantation. Oral sildenafil caused restoration of the capillary vascular bed, improved left-sided lung perfusion, and resulted in significant clinical benefit.

Hypoplastic left heart syndrome: current considerations and expectations

In the recent era, no congenital heart defect has undergone a more dramatic change in diagnostic approach, management, and outcomes than hypoplastic left heart syndrome (HLHS). During this time, survival to the age of 5 years (including Fontan) has ranged from 50% to 69%, but current expectations are that 70% of newborns born today with HLHS may reach adulthood. Although the 3-stage treatment approach to HLHS is now well founded, there is significant variation among centers. In this white paper, we present the current state of the art in our understanding and treatment of HLHS during the stages of care: 1) pre-Stage I: fetal and neonatal assessment and management; 2) Stage I: perioperative care, interstage monitoring, and management strategies; 3) Stage II: surgeries; 4) Stage III: Fontan surgery; and 5) long-term follow-up. Issues surrounding the genetics of HLHS, developmental outcomes, and quality of life are addressed in addition to the many other considerations for caring for this group of complex patients.

The Fontan pathway: What's down the road?

The Fontan circulation results from routing of the systemic venous blood to the pulmonary circulation without a hydraulic source of a ventricle. Although a hypertrophied right atrium was thought to be essential for this circulation, the current form of the operation has neither the right atrium nor any valves in the venous circulation that is connected to the pulmonary arteries directly. Modifications in the operative model was one of the early steps in improving outcome. Use of fenestration, staging of Fontan completion and better perioperative management have led to a significant drop in mortality rates in the current era. Despite this, there is late attrition of patients with complications such as arrhythmias, ventricular dysfunction, and unusual clinical syndromes of protein-losing enteropathy (PLE) and plastic bronchitis. Management of failing Fontan includes a detailed hemodynamic and imaging assessment to treat any correctable lesions such as obstruction within the Fontan circuit, early control of arrhythmia and maintenance of sinus rhythm, symptomatic treatment for PLE and plastic bronchitis, manipulation of systemic and pulmonary vascular resistance, and Fontan conversion of less favorable atriopulmonary connection to extra-cardiac total cavopulmonary connection with arrythmia surgery. Cardiac transplantation remains the only successful definitive palliation in the failing Fontan patients.

Impact of oral sildenafil on exercise performance in children and young adults after the fontan operation: a randomized, double-blind, placebo-controlled, crossover trial

BACKGROUND

Children and young adults with single-ventricle physiology have abnormal exercise capacity after the Fontan operation. A medication capable of decreasing pulmonary vascular resistance should allow improved cardiac filling and improved exercise capacity.

METHODS AND RESULTS

This study was a double-blind, placebo-controlled, crossover trial conducted in children and young adults after Fontan. Subjects were randomized to receive placebo or sildenafil (20 mg three times daily) for 6 weeks. After a 6-week washout, subjects crossed over for an additional 6 weeks. Each subject underwent an exercise stress test at the start and finish of each phase. After taking sildenafil, subjects had a significantly decreased respiratory rate and decreased minute ventilation at peak exercise. At the anaerobic threshold, subjects had significantly decreased ventilatory equivalents of carbon dioxide. There was no change in oxygen consumption during peak exercise, although there was a suggestion of improved oxygen consumption at the anaerobic threshold. Improvement at the anaerobic threshold was limited to the subgroup with single left or mixed ventricular morphology and to the subgroup with baseline serum brain natriuretic peptide levels ≥100 pg/mL.

CONCLUSIONS

In this cohort, sildenafil significantly improved ventilatory efficiency during peak and submaximal exercise. There was also a suggestion of improved oxygen consumption at the anaerobic threshold in 2 subgroups. These findings suggest that sildenafil may be an important agent for improving exercise performance in children and young adults with single-ventricle physiology after the Fontan operation. Clinical Trial Registration- URL: http://clinicaltrials.gov. Unique identifier: NCT00507819.

Pulmonary hypertension in congenital shunts

Pulmonary arterial hypertension frequently arises in patients with congenital heart disease. The vast majority present with congenital cardiac shunts. Initially these may manifest as left-to-right (i.e. systemic-to-pulmonary) shunts. The natural history of disease progression involves vascular remodeling and dysfunction that lead to increased pulmonary vascular resistance and, finally, to the development of Eisenmenger's syndrome, which is the most advanced form. The anatomical, pathological and structural abnormalities occurring in the pulmonary circulation of these patients are, to some extent, similar to those observed in other forms of pulmonary arterial hypertension. This understanding has recently led to significant changes in the management of Eisenmenger's syndrome, with the introduction of treatment specifically targeting pulmonary vascular disease. Early closure of the cardiac shunt remains the best way of preventing pulmonary vascular lesions. However, it is still not clear which preoperative parameters predict safe and successful repair, though hemodynamic evaluation is still routinely used for assessment. Postoperative pulmonary hypertension, both in the immediate period after surgical repair and during long-term follow-up, remains a real therapeutic challenge. The clinical situation of a single ventricle with Fontan circulation also presents difficulties when pulmonary vascular lesions are present. This article reviews pulmonary hypertension associated with congenital shunts and discusses a number of the specific problems encountered.

Sildenafil in the management of the failing Fontan circulation

BACKGROUND

Sildenafil is increasingly being used in the management of pulmonary arterial hypertension in the newborn. Its role in patients with congenital cardiac disease is less well defined and as yet has only been reported sporadically.

AIM

Present our experience with sildenafil treatment in patients with a failing Fontan circulation.

PATIENTS AND METHODS

Retrospective review of 13 symptomatic patients after Fontan palliation who received treatment with sildenafil between January, 2006 and July, 2008.

RESULTS

Three patients suffered from protein-losing enteropathy, four patients presented with bronchial casts, two had severe cyanosis after fenestrated Fontan procedure, two had prolonged chylous effusions, one had a previous failure of Fontan and take-down, and one patient had arrhythmias and end-stage cardiac failure requiring conversion to an extra-cardiac Fontan. Sildenafil was used in the dosage of 1-2 milligrams per kilogram 3-4 times per day. Protein-losing enteropathy and alpha-1-antitrypsin levels improved in all three patients on sildenafil treatment. One of these patients had a concomitant catheter creation of a fenestration, as did two patients presenting with bronchial casts and both patients with persistent chylous effusions. All four patients with bronchial casts and two patients with cyanosis improved significantly on sildenafil treatment. Chylous effusions decreased after sildenafil and stent enlargement of a fenestration. There were no significant side effects requiring sildenafil withdrawal over a treatment period ranging from 2 months to 2 years.

CONCLUSIONS

Sildenafil can be used safely and effectively in the treatment of patients with a failing Fontan circulation.

Plastic bronchitis requiring bronchoscopy

OBJECTIVE

We report two cases of plastic bronchitis presenting with acute respiratory failure and mimicking foreign body inhalation.

METHOD

The clinical findings, differential diagnoses and radiological investigation are discussed.

RESULTS

Plastic bronchitis is an uncommon condition, particularly in children. The condition may present to otolaryngologists with symptoms mimicking foreign body inhalation. It is important to consider plastic bronchitis as a differential diagnosis, based on its clinical and radiological signs. Early intervention, in the form of bronchoscopy, can be both diagnostic and therapeutic.

CONCLUSION

Plastic bronchitis is uncommon and its clinical and radiological features are non-specific. The recommended management is early bronchoscopy to establish the diagnosis and enable therapeutic intervention.

Postoperative use of oral sildenafil in pediatric patients with congenital heart disease

We sought to determine the efficacy of postoperative oral sildenafil therapy (OST) in pediatric patients with congenital heart disease (CHD). A retrospective review of 45 postoperative patients with CHD who received OST was performed. Patients were categorized into three groups according to clinical indications: (1) to stabilize pulmonary vascular reactivity after biventricular repair (group 1 [n = 15]), (2) to lower pulmonary vascular resistance after bidirectional cavopulmonary shunt (group 2 [n = 12]), and (3) to improve post-Fontan hemodynamics (group 3 [n = 18]). Thirty-four patients (34 of 45 [75.6%]) had received inhaled nitric oxide (iNO) while on OST. Mean pulmonary arterial pressure (mPAP), mean systemic blood pressure (mSBP), and peripheral oxygen saturation (SpO(2)) were recorded during the first 24 hours after the initiation of OST. In group 1, the baseline mPAP/mSBP ratio (0.60 +/- 0.17) decreased significantly after the second (0.46 +/- 0.14, p = 0.004) and fourth (0.50 +/- 0.18, p = 0.025) doses of OST. In group 2, baseline SpO(2) (71.0 +/- 12.3%) increased after the fourth dose (75.1 +/- 12.3%, p = 0.04) of OST, without significant changes in mPAP. In group 3, baseline mPAP (14.8 +/- 3.3 mmHg) decreased significantly after the first (13.9 +/- 2.8 mmHg, p = 0.025) and second (13.3 +/- 1.9 mmHg, p = 0.016) doses of OST, without changes in SpO(2). In thirty-one (31 of 34 [92%]) subjects, iNO was discontinued within a median of 2 days after the initiation of OST, without rebound phenomena. There were no OST-related complications. Sildenafil citrate can be used safely in postoperative pediatric patients with CHD. Benefits from OST may be manifested differently in various clinical settings.