Alveolar capillary dysplasia

Alveolar capillary dysplasia (ACD, also congenital alveolar dysplasia) is a very rare congenital malformation involving abnormal development of the capillary vascular system around the alveoli of the lungs. It is a rare cause of persistent pulmonary hypertension in infants. It also may be a rare cause of pulmonary hypoplasia. Until mid-2012, the only possible outcome was neonatal death, with one of the longest surviving infants living 2 months.

Babies with ACD may appear normal at birth but within minutes or hours they develop respiratory distress with persistent pulmonary hypertension. ACD does not respond to standard therapies that resolve simple pulmonary hypertension. The lack of response is an important diagnostic clue.

Cause
ACD is a genetic disorder. This is known because ACD has been reported in multiple families. There is more than one form of ACD. In some families, a form of ACD known as alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) has been linked to the gene FOXF1 on chromosome 16 q24.1-q24.2.

Diagnosis
ACD commonly is diagnosed postmortem, by a pathologist.

Sometimes ACD is diagnosed clinically. This is common when there is a family history of ACD, but rare otherwise. A clinical differential diagnosis of ACD excludes fetal atelectasis.

ACD is not detectable by prenatal imaging. However, some babies with ACD have associated congenital malformations that are detectable by imaging. The identification of genes involved in ACD offers the potential for prenatal testing and genetic counseling.

Treatment
Most babies with ACD have normal Apgar scores at 1 and 5 minutes, but within minutes or hours present with hypoxia and upon investigation are found to have hypoxemia and pulmonary hypertension. Initial treatments address the hypoxia, usually beginning with supplemental oxygen and arrangements for urgent transport to a neonatal intensive care unit.

Therapies that have been tried to extend life include extracorporeal membrane oxygenation and nitric oxide. These are supportive therapies for persistent pulmonary hypertension; they do not treat the ACD. The objective of therapy is to keep the baby alive long enough to obtain a lung transplant. To date no such case has been reported.

Research
Actress NiCole Robinson and her husband Craig Snyder lost a baby to ACD; with his first wife, Craig lost two more babies to ACD. They have founded an organization to support research into ACD.

Advance in experimental treatment
According to the St. Louis Children's Hospital (the Level I pediatric trauma center and pediatric teaching hospital for the Washington University School of Medicine), which is noted worldwide for its record in pediatric pulmonary transplantation, a type of artificial lung device, the Quadrox, was used after ECMO as a bridge to a dual lung transplant in ten-month-old Eleni Scott of the St. Louis suburb of Florissant, Missouri, who after transplantation returned to her home. Doctors have said it is too early to presume it will continue to work here or work in other pediatric patients as an experiment, much less a successful, curative standard therapy, but the infant has survived thus far, meaning that there might be hope for sufferers of this rare condition. For more information, please see the link to the news release.

History
ACD was first described in 1948. A familial association of ACD/MPV was first reported in 1994.