March 31, 2016
Generally, mild to moderate cases of congenital diaphragmatic hernia (CDH) — in which a hole in the diaphragm prompts abdominal organs to move into the chest, resulting in abnormal prenatal growth of the lungs and pulmonary hypertension — have been well managed with a mainstay postnatal approach: closure of the defect in the diaphragm at birth, which returns the organs to the abdominal cavity and allows the lungs to grow. Studies show survival of 67 to 90 percent of these patients, although not without the risk of neurodevelopmental, nutritional and pulmonary function morbidities, among others (J Pediatr Surg. 2006 May 41(5):888-92).
“These newborns need to be stabilized and managed very carefully by the neonatologist to avoid respiratory injury,” says Johns Hopkins Children’s Center pediatric surgeon Eric Jelin. “In less severe cases we can usually get by with gentle ventilation to avoid damaging the lung. Once the baby is stable, we can fix the defect, though the patient may have some developmental and feeding issues that can be troublesome.”
But what about the severe cases of CDH, those where the liver herniates well into the chest and poses an even greater risk of mortality and related complications? In the 1990s, open fetal CDH repair was attempted mid-gestation but found to be flawed, resulting in the death of the fetus (J Pediatr. Surg. 1993 Oct 28(10):1411-7).
“Open fetal surgery was found to be technically not feasible to fix these babies because of the vascular anatomy,” says Jelin. “Pushing the liver back into the abdomen during fetal repair leads to obstruction of the umbilical vein, a vital structure for the fetus.”
Now the Johns Hopkins’ Center for Fetal Therapy, under the direction of perinatologist Ahmet Baschat, offers a minimally invasive approach in utero that holds promise for reducing the mortality and morbidity of the more severe cases of CDH. In a recent case of right-sided CDH, which carries disproportionate high morbidity and mortality, Baschat and Jena Miller of the fetal surgery team accessed the trachea of the fetus at 26 weeks gestation, percutaneously and under ultrasound guidance, through a tiny, 3 millimeter fetoscope. They then deployed a tiny balloon in the trachea, plugging the lumen and allowing the lungs to grow and abdominal organs to drop. Using the same technique four weeks later, they pulled the balloon out so that the baby would be born without an airway obstruction.
“It’s very delicate and technically precise procedure,” says Jelin. “Everything is very small, which makes it challenging.”
The procedure does come with risks, mainly premature rupture of membranes and preterm labor. For the potential complication of preterm labor occurring prior to elective balloon removal, a multidisciplinary team is on standby around the clock. Because of these unique requirements, only a handful of centers in the country are approved for this procedure by the Food and Drug Administration.
“Although the risks are significant, without this minimally invasive fetal surgery approach, non-survival is the likely outcome,” says Jelin.
How did this patient do?
“The great news about this case is that we were able to get the balloon in and keep it in for the appropriate period of time, and the child went to term,” says Jelin. “Our patient did require an anti-reflux operation, which we do laparoscopically, and a feeding tube, which is very common for these patients. He still has a low oxygen requirement but he’s growing and getting better.”
Jelin attributes what can be considered a very favorable outcome for a patient with severe CDH to the Johns Hopkins Center for Fetal Therapy and the multidisciplinary Johns Hopkins Children’s Center Fetal Program, which meet regularly to review cases and collaboratively come up with the best treatment plan for each patient. In addition to Jelin, the program includes Baschat and pediatric surgeon-in-chief David Hackam. Other disciplines represented in the group include imaging, neonatology, and pediatric divisions of anesthesiology, cardiology, nephrology, neurosurgery, and urology. For more information, visit the center’s website.