Percutaneous Fetal Cardiac Catheterization Technique for Stenting the Foramen Ovale in a Midgestation Lamb Model

BACKGROUND: Intact or highly restricted intra-atrial septum can be reliably diagnosed in the human fetus as early as 22 to 24 weeks of gestation. Fetal interventions targeting the atrial septum have used a direct approach through the atrial wall. Here, we report stenting of the foramen ovale with a large, open-cell stent via percutaneous access through the fetal hepatic vein in a sheep model. METHODS AND RESULTS: In 5 fetal sheep of 109 to 111 days of gestation (term, 147 days), the fetal hepatic vein was punctured percutaneously under ultrasound guidance and a 13.3-cm 14-gauge intravenous catheter was inserted. After catheterization of the inferior vena cava, right atrium, foramen ovale, and left atrium with a guidewire and 1.8F to 2.6F tapered catheter, a self-expandable, 8×12-mm flexible open-cell stent was positioned in an unrestricted foramen ovale. Flow and fetal well-being were documented for 45 minutes after the procedure. Access to the left atrium was achieved in all 5 animals and all survived. In 4 animals, the stent was successfully positioned in the foramen ovale. One fetus was born at term and euthanized on day 3: postmortem examination confirmed the patency of the stent. The other 3 fetuses were well after being monitored by ultrasound for 45 minutes. In 1 animal, the stent dislodged immediately after release obstructing the mitral valve. This fetus developed ascites and was euthanized after 4 days. CONCLUSIONS: It is feasible to safely advance a large diameter, self-expandable, open-cell design stent into the fetal atrial septum via a percutaneous access route through the fetal hepatic vein.