Technical note on FETTUS: a novel transcardiac ultrasound- and fluoroscopy-guided fetal embolization technique for vein of Galen malformation in fetal lambs

BACKGROUND: Fetal intervention addresses conditions in which postnatal therapy may be insufficient due to progressive end organ injury occurring in utero. Prenatal intervention has become standard of care for select fetal disorders, but vein of Galen malformation (VOGM) remains associated with high perinatal morbidity and mortality, and progressive cardiac and neurologic injury may limit the effectiveness of postnatal treatment. These considerations motivate exploration of innovative fetal endovascular strategies. METHODS: A novel endovascular technique was developed in fetal lambs called Fetal Embolization via Transcardiac, Transarterial, Ultrasound- and fluoroscopy-guided endovascular Surgery (FETTUS), designed to replicate the postnatal standard-of-care transarterial embolization technique. We evaluated procedural workflow, materials, technical challenges, and iterative refinements. RESULTS: FETTUS was performed on 17 lamb fetuses equivalent to human gestational ages of 26-34 weeks. Procedural efficiency improved across the fetus cohorts, with reduced time to successful left ventricular access reflecting technical optimization. Progressive refinements enabled reliable angiographic visualization and characterization of fetal vascular anatomy of the heart, head, and neck, facilitating endovascular navigation and allowing successful target embolization with fetal survival. Overall cumulative contrast and radiation doses remained below clinically acceptable thresholds. CONCLUSION: The FETTUS approach described here in fetal lambs represents the introduction of neuroendovascular surgery into the world of fetal surgery. In carefully selected high-risk cases, it opens the door for possible diagnostic, prognostic, and therapeutic strategies in severe prenatal VOGM as well as other life-threatening fetal vascular anomalies.