Fetoscopic direct fetal cardiac access in sheep - An important experimental milestone along the route to human fetal cardiac intervention

Background-Fetal cardiac interventions by direct ultrasound-guided approach es or open fetal cardiac surgery have been fraught with technical difficult ies, as well as with significant maternal and fetal morbidity in humans. Th erefore, the purpose of our study in sheep was to assess the feasibility an d potential of fetoscopic direct fetal cardiac access. Methods and Results-In 15 anesthetized pregnant ewes (88 to 109 days of ges tation; term, 145 days), 3 to 4 trocars were percutaneously placed in the u terus. Using videofetoscopic equipment, we assessed the feasibility of achi eving direct fetal cardiac access. Minimally invasive direct fetal cardiac access by operative fetoscopy was achieved in 10 of the 15 fetal sheep. In 7 fetuses, the approach was successfully tested for fetal cardiac pacing (n =5) or antegrade fetal cardiac catheterization (n=2). Access was not achiev ed in 5 fetuses because of bleeding complications (n=2) or because the feto scopic setup could not be established (n=3). All but 2 fetal sheep were ali ve at the end of the procedure. Acute fetal demise resulted from maternal h ypotension or kinking of the fetal inferior caval vein by sternal suspensio n. Six ewes continued gestation; 3 of these went to term, with a normal fet al outcome. Two ewes died from septicemia 3 and 7 days after the procedure, and 1 ewe aborted 1 month after the procedure. Conclusions-Minimally invasive direct fetal cardiac access by operative fet oscopy is feasible in fetal sheep. The fetoscopic approach carries importan t potential for fetal cardiac pacing, antegrade fetal valvuloplasties, and resection of fetal intrapericardial teratomas in human fetuses.