November 04, 2010
In the neonatal intensive care unit at Children's, Dr. Kristine Guleserian peers into the incubator and reaches for the tiny hand of 12-day-old Audrey Nguyen. Not only does Audrey weigh just less than three pounds, but underneath the incision lining her chest, the smallest manufactured pacemaker in the world helps to regulate her heartbeat.
Karyn and Andy Nguyen couldn't wait to welcome a baby girl into the family. But at 17 weeks gestation, baby Audrey's heart rate had dipped to 50 — a normal rate for a baby at that stage is 150. Fluid also had accumulated around her heart. She was diagnosed with congenital complete heart block — she would need a pacemaker to survive.
"When we found out about Audrey, we were hurt and worried — we didn't know what to do," Karyn said. "We believed that Audrey needed the best place to increase her chances of living. Andy and I didn't know any doctors at Children's, but we heard it was one of the top hospitals in the nation and we quickly set up an appointment."
Children's was the only pediatric hospital in North Texas that could provide a team of specialists with the level of expertise Audrey needed. Neonatologists at Children's work closely with a team of multidisciplinary experts — cardiologists and fetal echocardiography specialists, cardiothoracic surgeons, anesthesiologists, nurses, critical care specialists and Neonatal ICU specialists to ensure the highest quality of care.
Karyn was treated in the Fetal Heart Program at Children's. Dr. Catherine Ikemba, a cardiologist at Children's who specializes in fetal echocardiography and assistant professor of Pediatrics at UT Southwestern, monitored Audrey to determine the most appropriate timing for delivery given her precarious heart rhythm. Managing Audrey's condition and knowing the exact time for delivery would be essential to saving her life.
Electrophysiology nurses at Children's educated the Nguyens about prenatal care and the pacemaker implantation. At 31 weeks gestation, the team determined it was time for Audrey to be delivered.
"What we needed was fetal growth so the baby would be big enough to put a pacemaker inside," said Ronda Hefton, RN, Fetal Heart Program Coordinator at Children's. "Our fear was that the pregnancy would have ended in fetal demise if Audrey had stayed inside another week."
Two hours after a successful delivery, an ambulance transported Audrey to Children's, where she was monitored in the Neonatal ICU.
A pacemaker consists of two parts — a generator that produces electrical impulses and wire leads that deliver the charges to the heart. Audrey's heart would be regulated by a pacemaker weighing 12.8 grams — approximately the size of two quarters stacked together.
"As small as the device seems, it is relatively large in relation to Audrey's body and heart size," said Dr. Guleserian, surgical director of Pediatric Cardiac Transplantation at Children's and assistant professor of Cardiothoracic Surgery at UT Southwestern. "In addition to the usual risks of bleeding and infection during pacemaker implantation, erosion into the abdominal cavity or through the skin is an added risk in a baby this size. The main challenge was to avoid injury to the heart muscle as it is very fragile in premature babies."
At 1 week old and just 2.6 pounds, Audrey would be the tiniest baby in Texas to receive the smallest manufactured pacemaker in the world.
After Dr. Guleserian implanted the pacemaker, several tests ensured the device was working properly, and the pacemaker was set to raise Audrey's heart rate from 58 to 135 beats per minute.
Audrey was taken to the Cardiovascular ICU for four days before she was transferred to the Neonatal ICU, where a team of specialists managed her care.
The electrophysiology team monitored the pacemaker's function with electrocardiograms and telemetry. Pacemaker evaluations were performed to measure the device's output and the team made appropriate adjustments.
"After Audrey's surgery, we had the option to be transported to another hospital, closer to our home," Andy said. "Even though we travel 30 minutes longer, we had no question that Audrey needed to stay at Children's.
"It's like the signs say — Children's is the one — and while we have been here everyone has treated us like Audrey is the one patient they have that day."
Through it all, Karyn and Andy gained another family member. In the midst of discussing their baby's future with Dr. Guleserian, the Nguyens asked her to be Audrey's godmother.
"Dr. G cared for our baby like she was her own child," Andy said. "What more can parents ask for in a godparent?"
Just before press time, Audrey died due to pulmonary hypertension. Babies like Audrey are at risk for a number of problems related to their prematurity, with lung disease being the most critical hurdle. Audrey continues to inspire the team at Children's to strive every day to make life better for children.