Radiofrequency thermal ablation: a potential treatment for hydropic fetuses with a large chest mass.
OBJECTIVE
Physiological changes secondary to a rapidly enlarging fetal chest mass can lead to nonimmune hydrops, which is a predictor of impending fetal demise. Currently, open fetal surgery is offered for specific patients with hydrops before 32 weeks' gestation. The authors asked if a less-invasive technique, radiofrequency thermal ablation (RTA), could be applied safely to the destruction of fetal lung tissue.


METHODS
Time-dated pregnant ewes at 120 to 125 days' gestation (term, 140 to 145 days) underwent RTA through a hysterotomy (n = 3) or in a transuterine fashion under ultrasound guidance (n = 4). The probe is a 15-gauge needle with a maximal 2-cm deployment sphere at its tip. By varying the intensity and duration of treatment, the power settings were optimized to create a defined area of ablation with minimal surrounding tissue injury. Five of the 6 fetal lambs were killed acutely, and 1 was followed up for 1 week with frequent ultrasound examinations.


RESULTS
Gross examination of the animals killed acutely showed a consistent area of ablation using 10 watts of applied power for 3 minutes. Direct coagulation necrosis lesions ranged from 1x1 cm to 2x2 cm in size depending on the extent of the probe deployment. One animal was followed up for 1 week and showed no major adverse physiological effects.


CONCLUSIONS
Radiofrequency thermal ablation can be performed safely in this fetal sheep model to create a controlled area of lung tissue ablation.
Milner
R
R
The Center for Fetal Diagnosis and Treatment, The Children's Hospital of Philadelphia, PA 19104, USA.
Kitano
Y
Y
Olutoye
O
O
Flake
A W
AW
Adzick
N S
NS
D000818:Animals; D017115:Catheter Ablation; D004195:Disease Models, Animal; D005260:Female; D005333:Fetus / Q000601:surgery*; D015160:Hydrops Fetalis / Q000473:pathology / Q000601:surgery*; D008168:Lung / Q000601:surgery*; D011247:Pregnancy; D012756:Sheep