PH Risk and Its Severity Tied to Birth Defect in Blood Vessels of Heart

Pulmonary hypertension (PH) occurs in 60% of children with the heart defect known as patent ductus arteriosus, with girls being more likely to develop PH than boys, a study found.

A child with patent ductus arteriosus has an opening, or duct, between two major blood vessels leading from the heart, the body artery (the aorta) and the pulmonary artery. According to the study, the duct’s size could determine the severity of PH.

The study, “The effects of ductal size on the severity of pulmonary hypertension in children with patent ductus arteriosus (PDA): a multi-center study,” was published in BMC Pulmonary Medicine.

The ductus arteriosus is a blood vessel in the developing fetus that connects the pulmonary artery to the aorta, allowing the blood to bypass the fluid-filled lungs of a fetus.

In an otherwise normal heart, the ductus arteriosus closes within a few days of birth, in response to ventilation of the lungs. But when it fails to close, blood wrongly flows from the aorta to the pulmonary artery — a condition called patent ductus arteriosus. If left uncorrected, patent ductus arteriosus can result in excess blood flow to the lungs, raising pressure within them and ultimately causing PH.

Researchers in Nigeria investigated how many of the children with patent ductus arteriosus in the country actually developed PH, and whether the size of the ductus (opening) influenced their disease.

They analyzed records covering 104 children at three hospitals across that country. Children’s ages were one month to 14 years, with a mean age of 22.72 months or almost 2 years old. Most, 60, were girls and 44 were boys.

PH, defined as a pulmonary artery systolic pressure of 30 mmHg or greater, was found in 60.2% of the children with patent ductus arteriosus analyzed.

While the proportion of girls with PH (51.61%) was similar to that of boys (48.39%), girls were 1.8 times more likely to have PH than boys.

Genetic factors could be behind this difference. “A genetic mutation in the bone morphogenetic protein 2 (BMPR2) gene has been linked to pulmonary arterial hypertension. [Female] children are more likely to express the mutation,” the researchers wrote.

The team also looked at the size of the ductus arteriosus. In this group, the mean ductal size was 3.78 mm, and ranged from a minimum of 1.0 mm to a maximum of 10.0 mm.

“The larger the internal diameter of the [narrowest] portion of the ductus arteriosus … the higher the chance of pulmonary hypertension,” the researchers wrote.

Indeed, ductal size was related to pulmonary artery systolic pressure; that is, when ductal size increased, pulmonary artery systolic pressure appeared to increase as well.

When researchers divided the children according to ductal size, they found that those with a moderate-size duct tended to have moderate PH, while those with a large duct tended to have severe PH.

Based on the results, they suggested that “early closure or ligation [of patent ductus arteriosus] is recommended to avert the development of pulmonary hypertension in children, especially those with [a] large [patent ductus arteriosus].”