487: New balloon for fetal endoscopic tracheal occlusion. In vitro tests and evaluation in the non-human primate model

One of the major concerns about Fetal Endoscopic Tracheal Occlusion (FETO) for prenatal management of congenital diaphragmatic hernia is the need for balloon removal. That’s why we developed a new patented balloon, which allows a non-invasive, easily triggered, and externally controlled reversal occlusion. Our objective was to evaluate the operation of this innovative balloon. The technology relies on a magnetic valve whose opening is actuated by the fringe field of an MRI scanner. The opening of the valve induces the deflation of the balloon, which is then washed out by the fluid coming out from the lungs. Outlines of the balloon are displayed in figure 1. We ran in vitro impermeability and occlusion tests in human amniotic fluid, which was kept at 37°C. Operation tests were conducted using the fringe field of a 1.5 Tesla MRI scanner. A total of 80 samples were tested. Then, we performed two animal tests in the monkey model. The Regional Ethics Committee on Animal Experimentation approved this study in 2017. Guidelines for the care and use of the monkeys were followed. Impermeability and occlusion tests showed that length, diameter, weight, and occlusive properties of the balloons were preserved across 12 weeks of time. Deflation of the balloon was achieved in 100% of the cases in the fringe field of the MRI, at 2 different heights and 4 different angles. Two pregnant rhesus monkeys underwent FETO procedure using the new balloon at 139 days of gestation. The non-invasive unplug procedures were performed 7 and 4 days after, i.e. at 146 and 143 days of gestation. The pregnant monkeys were both carried in front of an MRI scanner. In both cases the fringe field of the MRI scanner induced the deflation of the balloon, which was eventually washed out in the pulmonary secretions (figure 2). The impermeability, occlusion, and operation tests are promising, so as the animal experiments. Further tests are planned. The regulatory routes exploration is ongoing.