The vessel of life
Understanding the ductus arteriosus could avoid a common surgery
It’s the “vessel of life,” according to Jeff Reese, M.D., associate professor of Pediatrics at Vanderbilt University Medical Center.
In the fetus, the ductus arteriosus (DA) is a temporary vascular shunt that routes blood from the pulmonary artery to the aorta, bypassing the uninflated lungs. After the birth of a healthy baby, its work is done. It constricts within 24-36 hours after delivery, and “remodels” into a fibrous ligament during the next several weeks.
For Reese the bottom line is simple: “You have to have it as a fetus. It should close as a newborn.”
But in up to 40 percent of premature babies, the DA doesn’t close properly, resulting in patent ductus arteriosus (PDA), one of the most common congenital heart diseases. The negative effects of PDA are twofold: it conveys excess blood through the open ductus causing lung injury, and it diverts normal blood flow away from the peripheral circulation, causing ischemia, which can damage the body’s organs from lack of oxygen and nutrients.
About 25,000 babies undergo surgery to close the DA every year in the United States, but because of the risks involved it is employed only as a last resort. A drug called indomethacin can also close the shunt, but it also can cause ischemia by constricting other blood vessels.
“We’ve learned over the 30 years that we’ve used indomethacin what the right dose is, not to give it too fast and how many days it needs to be given to get the ductus to constrict but not hurt other vessels, and even with that knowledge, there is still a narrow therapeutic window where children have organ injury because of it,” Reese says.