Three-Dimensional Reconstruction Identifies Misaligned Pulmonary Veins as Intrapulmonary Shunt Vessels in Alveolar Capillary Dysplasia

Abstract

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) is a lethal neonatal lung disease. Although death is caused by hypoxia, the role of MPV is unknown. Using three-dimensional-reconstruction of ACD/MPV lung tissue, we report that MPV are intrapulmonary shunt vessels and speculate that MPV contributes to poor prognosis.

Histologic Evidence of Intrapulmonary Bronchopulmonary Anastomotic Pathways in Neonates with Meconium Aspiration Syndrome

“…[3][4][5][6] In these infants, we found prominent anastomotic connections between bronchial arteries and pulmonary arteries as well as markedly dilated bronchial and pulmonary veins. These findings suggest the presence of intrapulmonary shunt vessels that may also contribute to hypoxia.…”

“…8 Past histologic studies in neonates have shown striking intrapulmonary bronchopulmonary anastomoses at autopsy from patients with refractory hypoxemia complicated by ACD/MPV, BPD, and CDH, but intrapulmonary bronchopulmonary anastomoses were not noted in lungs from infants dying without respiratory failure. [3][4][5][6] Along with other causes of hypoxemia in infants with severe pulmonary hypertension, the presence of intrapulmonary bronchopulmonary anastomoses suggests an additional factor contributing to impaired gas exchange in these patients.…”

Pulmonary Hypertension in Preterm Infants with Bronchopulmonary Dysplasia

“…Such vessels were known to exist during fetal development at late gestation and are similar to those described in alveolar capillary dysplasia, a frequently fatal congenital condition. 70,71 However, IAAV are thought to disappear postnatally in healthy newborns. 71 IAAV may contribute to severe hypoxemia in infants with severe BPD.…”

Diffuse Lung Disease

“…The misaligned pulmonary veins in ACD/MPV may actually represent anastomotic bronchial veins associated with intrapulmonary right-to-left shunting. This shunting bypasses the alveolar capillary bed and exacerbates the hypoxemia from right-to-left extrapulmonary shunting associated with persistent pulmonary hypertension of the newborn (PPHN) (Galambos et al 2014). …”