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

Abstract

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. Key Words: atrial septum ◼ cardiac catheterization ◼ fetal heart ◼ foramen ovale ◼ hypoplastic left heart syndrome ◼ stent

Induction of left ventricular hypoplasia by occluding the foramen ovale in the fetal lamb

“…In this study, fetuses with occluded FO were compared to aged-matched control fetuses which did not undergo the experimentation. In our published experimental data in the fetal sheep on the procedures of percutaneous transhepatic access both with and without positioning of a stent at the FO [16][17][18] , we did not observe any compromised haemodynamics on the post-procedural echocardiography, or any altered LV development on examination of the hearts at term birth. An additional sham group of fetuses was therefore not performed in the interest of limiting animal sacrifice.…”

“…Based on our previous experience of fetal cardiac interventions in a sheep model [16][17][18] , we present here a further novel interventional technique, which to our knowledge has not been performed before. We have previously described that stenting of a large FO in a sheep fetus seems to be possible only by a specially designed self-expandable stent which is deliverable through a 4 F sheath but expands to reach a stent lumen width of 8 mm 17 . The 8-mm stent lumen, together with its additional open-cell design, enables secure fixation in a widely opened FO with floppy atrial septum tissue around.…”

“…After stable positioning of the coronary guidewire, the ensemble of a 4 F delivery catheter system loaded with a self-expandable, open-cell-design, flexible stent (8 × 12 mm Superflex DS, OptiMed, Ettlingen, Germany) was advanced over the guidewire, to position and expand the stent across the FO (Fig. 1b) as previously described 17 . The delivery catheter was then carefully withdrawn, leaving the guidewire within the LA.…”

“…Here, we report the effects of in-utero occlusion of the FO in the fetal lamb in mid-gestation, using a novel fetal cardiac catheterisation method with trans-hepatic access that we have described previously 16,17 . Our technique of in-utero cardiac catheterisation allows occlusion of the FO without trauma or puncture into the fetal heart, and study of the effects of FO occlusion during fetal development.…”

A case report on stent placement in a fetus with hypoplastic left heart syndrome and intact interatrial setptum: first choice alternative standardized approach from left pulmonary vein

“…Finally, the usual occurrence of a small left atrium (LA) with a thick IS makes the approach from the right side challenging, or sometimes even impossible [6,7]. Recent preliminary experiences on a fetal lamb model have demonstrated the feasibility of foramen ovale stenting by trans-venous trans-hepatic approach [8].…”