Baby Girl Is Among The Youngest Recipients Of Life-Saving Pacemaker
Using a small, newly designed pacemaker, Inder Mehta, MD, assistant professor of surgery in the VCU School of Medicine and director of pediatric cardiac surgery at the Children's Heart Center of the VCU Health System's MCV Hospitals, corrected a congenital condition known as a heart block. In heart block, the upper and lower chambers fail to get an electrical signal in rhythmic fashion.
"She should have good cardiac function like a normal child," Mehta said about the baby girl, who remains on a respirator but is gaining weight. "She will always need a pacemaker. We will replace it as she grows, but we believe she will have a normal childhood and a normal life."
A team of VCU physicians, including pediatric cardiac surgeons, cardiologists, a obstetrician/gynecologist and a neonatologist, made the decision to deliver the baby 11 weeks early - at 29 weeks of gestational development -- and implant the pacemaker after a fetal echocardiogram revealed a fluid collection around the heart. Doctors already were concerned about the pregnancy going to full term of 40 weeks because the fetal heart rate had fallen to 43 beats a minute, one-third the rate of a normal fetal heart rate of 120 to 150 beats per minute.
At the time of surgery on January 12, 2002, the baby weighed only two pounds, 11 ounces.
"We originally had planned to try to wait until 32 weeks to deliver the child, " said Mary T Donofrio, MD, associate professor of pediatrics in the School of Medicine and medical director of the pediatric noninvasive cardiac lab and perinatal cardiology at the VCU Children's Heart Center.
"We attempted to improve fetal heart function by giving medicine to the
mother that crossed the placenta to the baby. Initially this worked, and
we were able to give additional medicine in the same way to help mature
fetal lungs," Donofrio said. "But when a follow up fetal echocardiogram
showed that the fluid buildup around the heart was worse, we couldn't
wait any longer and decided to go ahead with the delivery."
The pacemaker used was the Microny II SR+ AutoCapture Pacing System, the world's smallest pacemaker at 12.8 grams. Roughly the size of two quarters stacked together, the unit is 40 percent smaller than comparable single-chamber, rate-responsive pacemakers. It is manufactured by St. Jude Medical, Inc., of St. Paul, MN, the world's second-largest maker of pacemakers.
The pacemaker is comprised of two components, a generator that provides electrical impulses and wire leads that carry the charges to the heart. Mehta made one incision in the chest to connect the lead wires directly to muscle of the baby girl's heart and a second incision in the abdomen to place the miniature generator unit under the skin.
The generator works by sensing the patient's heart rhythm and heart rate and delivers an electrical stimulus to the heart to maintain rhythm when appropriate. The device also has an archival feature that retains data about the patient's heart rate and heart rhythm. It also tracks how the pacemaker has been pacing the patient for up to 10 years.
"If there were any irregularities, any episodes, where the heart rate went up, or if there were any arrhythmia, when the rhythm of the heart is not proper, it can all be stored in the pacemaker," Mehta said. "And that data can be reproduced after years and years of use."
Each year about 100 pediatric cardiac surgeries are performed at the
Children's Heart Center of the VCU Health System's MCV Hospitals. Of
those, about six involve pacemaker implants.