A multidisciplinary team within Norton Children’s Heart Institute, affiliated with the UofL School of Medicine, worked together to save the life of an infant born with structural heart defects and congenital complete atrioventricular block (CCAVB) that led to a slow heart rate. The patient was too small for the traditional path of care, driving the innovative team to perform the first known human implantation of a novelly-designed, tiny pacemaker in a premature infant.

“It is remarkable how our team of pediatric specialists came together with the device company to offer a resolution for such a small patient weighing less than three pounds at the time of implant,” said Soham Dasgupta, M.D., pediatric electrophysiologist with Norton Children’s Heart Institute and an assistant professor of pediatric cardiology at the University of Louisville School of Medicine. “This unique case is unlike any other, and we are so pleased to see this patient thriving as a result of the innovative approach.”

Approximately 1 in 22,000 infants are born with CCAVB. Untreated, the condition has a high incidence of prolonged illness or death. The usual treatment involves implantation of a pacemaker once the patient meets a minimum body size, typically 4 1/2 to 5 1/2 pounds, to accommodate the implantable device. Taking time for the baby to grow while being otherwise treated is strongly preferred for this situation. With this patient, however, the traditional plan was not working.

“In this instance, the patient was not of the optimal size and medical/conservative management was unsuccessful, so a specially modified, pediatric-sized pacemaker — also known as an implantable pulse generator (IPG) — created by Medtronic was used,” Dr. Dasgupta said.

Dr. Dasgupta and colleague Christopher L. Johnsrude, M.D., director of pediatric and adult congenital electrophysiology, reviewed the relevant preclinical data from a procedure where a similar tiny pediatric IPG had been implanted in an adult Yucatan miniature pig, an animal with a heart that resembles a child’s heart.

Sternotomy at the time of implantation of an epicardial single chamber pacemaker in a premature infant with congenital complete atrioventricular block (head at the top).

(A) Implantation of the cathode of the epicardial Medtronic 4968 pacing lead on the left ventricular apex, and (B) anode implanted on the right ventricular free wall. (C) Postoperative chest radiograph demonstrating a bipolar ventricular epicardial lead connected to the abdominal pediatric implantable pulse generator pacemaker

Once it was determined the pediatric IPG was potentially compatible with the patient at Norton Children’s, Dr. Dasgupta worked with Norton Children’s Research Institute, affiliated with the UofL School of Medicine, and the manufacturer, to obtain local Institutional Review Board approval and emergency authorization from the U.S. Food and Drug Administration.

Once the device was in hand, the procedure to place the implant was completed over the course of a two-hour open heart surgery. The tiny device measures 1.16 by 0.65 by 0.38 inches and weighs 0.18 ounce.

“While the operative steps might be comparable to the usual pacemaker implantation surgery, this surgery was especially delicate due to the very small size of the baby,” said Bahaaldin Alsoufi, M.D., chief of pediatric cardiothoracic surgery and co-director of Norton Children’s Heart Institute, as well as a professor of cardiothoracic surgery at the University of Louisville School of Medicine. “This tiny pacemaker generator was positioned in the abdominal wall on the right side and was connected to the usual leads that were attached to the heart. This novel device will provide the necessary support that the baby currently needs. At time of repair of the patient’s congenital heart defect in the future, we will be able to utilize these same leads and likely connect them then to a traditional larger pacemaker generator.”

To date, the patient is doing well and continues to be cared for by cardiac and neonatal specialists across Norton Children’s Heart Institute.