Histologic Identification of Prominent Intrapulmonary Anastomotic Vessels in Severe Congenital Diaphragmatic Hernia

Objective To determine whether prominent intrapulmonary anastomotic vessels (IPAVs) or bronchopulmonary "shunt" vessels can be identified in lungs from infants with fatal congenital diaphragmatic hernia (CDH). Study design We performed histology with immunostaining for CD31 (endothelium) and D2-40 (lymphatics), along with high-precision 3-dimensional (3D) reconstruction on lung tissue from 9 patients who died with CDH. Results Each patient with CDH required mechanical ventilation, cardiotonic support, and pulmonary hypertension (PH)-targeted drug therapy. All patients were diagnosed with severe PH by echocardiography, and 5 received extracorporeal membrane oxygenation therapy. Death occurred at a median age of 24 days (range, 10-150 days) from refractory hypoxemia with severe PH, pneumonia, or tension pneumothorax. Histology showed decreased alveolarization with pulmonary vascular disease. In each patient, prominent IPAVs were identified as engorged, thin-walled vessels that connected pulmonary veins with microvessels surrounding pulmonary arteries and airways in lungs ipsilateral and contralateral to the CDH. Prominent anastomoses between pulmonary arteries and bronchial arteries were noted as well. The 3D reconstruction studies demonstrated that IPAVs connect pulmonary vasculature to systemic (bronchial) vessels both at the arterial and venous side. Conclusion Histology and 3D reconstruction identified prominent bronchopulmonary vascular anastamoses in the lungs of infants who died with severe CDH. We speculate that IPAVs connecting pulmonary and bronchial arteries contribute to refractory hypoxemia in severe CDH.