Fetal surgery for congenital heart disease.

Certain congenital heart defects, which present at birth as complex morphologic defects, are actually the result of a relatively simple primary lesion and the subsequent acquired development of a complex secondary lesion during gestation. Moreover, fetal heart approach during gestation can prevent simple cardiac lesions from such development. Specific structural lesions can be diagnosed before 12 weeks of gestation by transvaginal fetal echocardiography, and animal experiments have shown that direct or indirect fetal cardiac approach and fetal cardiac bypass are technically feasible. A number of fetal bypass models have resulted in long-term survivors, with for example, the delivery of normal lambs at full-term gestation. Also, successful full-term delivery has been obtained after fetal cardiac intervention. The success of fetal cardiac bypass was accomplished by the use of total spinal anesthesia and the administration of indomethacin. Moreover, a 42 % long-term survival after fetal cardiopulmonary bypass in a fetal lamb model has been reported. Maternal risk related to fetal bypass should be considered carefully alongside fetal risks and benefits. Most fetal malformations do not directly threaten maternal health, yet the procedures required to address fetal malformations can produce significant maternal risk and discomfort and subsequent pregnancies may be jeopardized. Further investigation of maternal outcome is required. Deep exploration of fetal and maternal pathophysiologic responses to intervention and comprehensive investigation is required to overcome current limitations, and should precede clinical trials as many problems remain to be solved before these techniques can be applied to human beings.