<p><strong>BACKGROUND: </strong>Post-operative chylothorax in patients with congenital heart disease is a challenging problem with substantial morbidity and mortality. Currently, the etiology of chylothorax is poorly understood and treatment options are limited.</p>

<p><strong>OBJECTIVES: </strong>This study aimed to report lymphatic imaging findings, determine the mechanism of chylothorax after cardiac surgery, and analyze the outcomes of lymphatic embolization.</p>

<p><strong>METHODS: </strong>We conducted a retrospective review of 25 patients with congenital heart disease and post-operative chylothorax who presented for lymphatic imaging and intervention between July 2012 and August&nbsp;2016.</p>

<p><strong>RESULTS: </strong>Based on dynamic contrast-enhanced magnetic resonance lymphangiography and intranodal lymphangiography, we identified 3 distinct etiologies of chylothorax: 2 patients (8%) with traumatic leak from a thoracic duct (TD) branch, 14 patients (56%) with pulmonary lymphatic perfusion syndrome (PLPS), and 9 patients (36%) with central lymphatic flow disorder (CLFD), the latter defined as abnormal central lymphatic flow, effusions in more than 1&nbsp;compartment, and dermal backflow. Patients with traumatic leak and PLPS were combined into 1 group of 16 patients without CLFD, of whom 14 (88%) had an intact TD. Sixteen patients underwent lymphatic intervention, including complete TD embolization. All 16 patients had resolution of chylothorax, with a median of 7.5 days from intervention to chest tube removal and 15 days from intervention to discharge. The 9 patients with CLFD were considered a separate group, of whom 3 (33%) had an intact TD. Seven patients underwent lymphatic intervention but none survived.</p>

<p><strong>CONCLUSIONS: </strong>Most patients in this study had nontraumatic chylothorax and dynamic contrast-enhanced magnetic resonance lymphangiography was essential to determine etiology. Lymphatic embolization was successful in patients with traumatic leak and PLPS and, thus, should be considered first-line treatment. Interventions in patients with CLFD&nbsp;were not successful to resolve chylothorax and alternate approaches need to be&nbsp;developed.</p>

<p><strong>BACKGROUND: </strong>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.</p>

<p><strong>METHODS AND RESULTS: </strong>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.</p>

<p><strong>CONCLUSIONS: </strong>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.</p>