Multimodal fetal transesophageal echocardiography for fetal cardiac intervention in sheep

Background-The overall performance of available mechanical intravascular ul trasound catheters for fetal transesophageal echocardiography during fetosc opic fetal cardiac interventions in sheep has been limited by radioelectron ic interference, low system frame rates, and low acoustic outputs. Therefor e, a more reliable device is desired for human fetoscopic surgical procedur es. Methods and Results-We assessed the potential of a newly available 10-Frenc h phased-array intravascular ultrasound catheter for multimodal fetal trans esophageal echocardiography in 5 fetal sheep between 78 and 98 days of gest ation (term, 145 to 150 d). The intravascular ultrasound catheter was easil y inserted through the mouth into the esophagus in all 5 sheep fetuses (mea n weight, 600 g), and it permitted high-quality 2D imaging of the fetal hea rt in vertical imaging planes that were validated by MRI. Color Doppler and pulsed Doppler imaging permitted clear assessment of fetal cardiovascular flows and recording of velocity-time integral tracings of the fetal heart a nd great vessels. The vertical imaging planes were particularly useful to d emonstrate interventional material inside the fetal heart and great vessels . Conclusions-Our early experience with the phased-array intravascular ultras ound catheter indicates that multimodal fetal transesophageal echocardiogra phy has now become possible in these smallest of patients.