When fetuses come down with a treatable disease, the result can still be fatal. That’s because their tiny size and constant movement make it difficult for doctors to treat them in utero.
Just like adults, a fetus can develop a conduction block that causes the heart to beat too slowly to pump enough blood for their growing bodies. While adults who experience this can receive pacemakers, there is currently no way of treating heart blockages in early-stage fetuses.
This rare condition affects about 500 babies per year in the United States, according to the American Pregnancy Association.
To give these unborn children a chance at life, Gerald Loeb, medical doctor and professor in the Department of Biomedical Engineering at the USC Viterbi School of Engineering, and collaborating clinicians have invented the first micropacemaker to treat fetuses in utero.
“One of the things that attracts me to this problem is that it usually occurs in isolation,” Loeb said. “There are many syndromes that result in a very difficult existence once the child is born, but this isn’t one of them.”
Fit for the fetus
Previous attempts to address congenital heart blocks in fetuses had focused on placing a pacemaker in the mother and attaching its electrical lead to the unborn child. However, those failed when the fetus changed position. Loeb’s team figured out how to fabricate a pacemaker small enough to fit entirely in the fetus. The clinicians figured out how to implant it in the fetus through a 3.5 mm tube under ultrasound guidance.
“As it turned out, we were familiar with a medical power cell that was just the right size thanks to our previous work with neuromuscular stimulators,” said Loeb, adding that the project has received funding from the Coulter Foundation and National Institutes of Health, among other sources.
The pacemaker project, a joint collaboration between USC Viterbi engineers and clinicians from the Keck School of Medicine of USC, “has resulted in a constant process of design and redesign as we have developed a device that meets all of the tremendous challenges of fetal pacing,” said Keck School of Medicine Professor Yaniv Bar-Cohen.
The micropacemakers have already been successfully implanted in fetal sheep. The first human trials may occur within a year. After a positive human trial, the pacemakers would still need to go through a rigorous evaluation to receive U.S. Food and Drug Administration approval and insurance coverage. Only then would they become commercially available for clinical use.
“As I tell my students, no patient was ever made well by a journal article,” Loeb said. “In academia, we are often very happy when we get a publication or a grant, but if our goal is to make patients better, we have to commercialize our product so it’s actually available to them.”