Mini pacemaker for fetus with heart block

Adriana Nicholson, Li Zhou

Complete heart block in the fetus can be a life-threatening emergency with no effective treatment options beyond watchful waiting. Fetal bradycardia due to heart block can progress in utero, and for more than a quarter of these fetuses may result in hydrops fetalis.3,4  Once hydrops fetalis develops, if the fetus cannot be delivered due to prematurity or other clinical concerns, fetal demise is nearly inevitable.

We have developed a novel micropacemaker to address the critical problem of complete heart block in the fetus.  This condition is a life-threatening emergency in a fetus, and is nearly always fatal if hydrops fetalis develops at a young gestational age. There are currently no effective treatment options in these cases, and attempts to implant an extra-uterine pacemaker with electrodes on the fetal heart have invariably failed due to lead dislodgement from fetal movement.

Original mechanical concept for the fetal pacemaker and its deployment

Our design (CHLA/USC patent pending) is a self-contained single-chamber micropacemaker that can be completely implanted in the fetus without exteriorized leads, allowing for subsequent fetal movement without risk of electrode dislodgement. Such a design and application is possible because of significant developments in microfabrication technology as well as advances in fetal intervention that allow percutaneous placement of the pacing system through the maternal abdomen under ultrasound and fetoscopic guidance.  With successful fetal pacing, a complete recovery from hydrops fetalis is expected with survival to term and a nearly normal life.

It is estimated that at least 500 pregnancies in the United States are affected by fetal heart block annually and may be candidates for this device.3 Beyond this immediate application, adaptation of this system could be extended to newborns, infants, and even adults with limited venous access.  Furthermore, with extended battery longevity, this system could replace standard single-chamber pacemaker techniques with implantation of the entire pacing system into the patient’s thorax via a minimally invasive technique.