Implantable Micropacemaker Treats Fetal Heart Block

The micropacemaker, which has already undergone pre-clinical testing, has been designated a humanitarian use device exemption by the US Food and Drug Administration (FDA). The investigators anticipate first human use of the device in the near future.

Although congenital heart block can be diagnosed in utero, all attempts to treat the condition with a standard pacemaker have so far failed, since the size of an adult pacemaker requires that only a small portion be implanted in the fetus, while the electronics remain externalized. This design has uniformly failed, likely due to fetal movement causing the electrodes to become dislodged from the heart. The study describing the fetal micropacemaker was published in the March 2015 issue of Heart Rhythm.

“Up until now, the pacemaker devices that have been used in an attempt to treat this condition in a fetus were designed for adults,” said lead author pediatric cardiologist Yaniv Bar-Cohen, MD, of CHLA. “We have lacked an effective treatment option for fetuses.”

“Building on our experience of using microfabrication techniques to create biomedical devices, we have developed a micropacemaker small enough to reside entirely within the fetus,” said study coauthor Gerald Loeb, MD, a professor of biomedical engineering at the Viterbi School of Engineering at USC. “This will allow the fetus to move freely without risk of dislodging the electrodes.”

Congenital heart block is a defect of the heart’s electrical system that originates in the developing fetus. Within the right atrium of a normal heart is a natural pacemaker that sends an electrical stimulus travels from the pacemaker (SA node) to the ventricles (AV node). If the transmission of the signal is impeded (heart block or an AV block), the transfer of the electrical nerve conduction that regulates the normal, rhythmic, pumping action of the heart muscle is interrupted or slowed. If the heart block occurs in the fetus or newborn, the condition is known as congenital heart block.

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Children’s Hospital Los Angeles
University of Southern California