OP02.06: The chick embryo as a model for intrauterine ultrasound‐guided heart interventions

Abstract

Some types of congenital heart disease (aortic or pulmonary stenosis, hypoplastic left heart syndrome) may cause irreversible secondary damage to ventricular morphology and require immediate surgical intervention after delivery. To reduce long-term complications of altered fetal heart development prenatal minimal-invasive cardiac intervention may represent a challenging option. In our study the potential of the chick embryo as a model for ultrasound guided fetal cardiac interventions is assessed. As not only the shell but also the shell membrane is impermeable to ultrasound, fenestrated eggs had to be used. Chick embryos were incubated for 18 days and their hearts were punctured in ovo with a 22-G needle under ultrasound control. Indian ink and nile-blue-sulfate were injected to mark the injection channel. After cardiac intervention, embryos were further incubated and subsequently sacrificed for macroscopic and histological evaluation of the heart. Stereomicroscopic analysis revealed that the needle had successfully penetrated the cardiac cavity in 26 out of 38 embryos. The myocardium had no macroscopic signs of injury and histological evaluation showed that the myocardium had almost re-occluded after the intervention with an injection channel clogged with fibrin. In one case, the embryo was not sacrificed, but was removed from the egg 24 hours after the intervention with no signs of cardiac dysfunction and was followed up for 6 months. Ultrasound-guided fetal heart interventions can be simulated in the chick embryo. In the pertinent stages the chick embryo heart measures approximately 1/50 the size of the corresponding human heart.