The Role of Echocardiography in Intraoperative Management of Fetal MMC Repair

Maternal and fetal risks are present during fetal surgery for myelomeningocele (MMC). Myocardial depressant effects of anesthesia, fetal stress, and the potential for placental insufficiency or mechanical cord compression can lead to significant alteration in the intraoperative cardiovascular state that may impact the conduct of the surgery and affect long-term outcomes.

At CHOP, we have initiated a standard practice of continuous intraoperative echocardiographic monitoring for all fetuses undergoing surgery. We incorporate ongoing fetal echocardiographic data into our intraoperative decisions such as reducing the concentration of inhalational agents, altering the degree of intra-amniotic fluid infusion, changing the holding position of the fetus, or simply temporarily halting the operation to better assess the situation.

From January 2011 to February 2014, we studied fetuses with intent to repair MMC to document our experience with intraoperative fetal echocardiography during repair of MMC and report management of serious intraoperative cardiovascular events. Fetal echocardiography protocol involves continuous assessment of the following, in a looping, sequential manner, from uterine incision until closure:

• 2-D qualitative ventricular systolic function
• Heart rate (HR) via pulse-wave Doppler sampling above the aortic valve
• Color Doppler of tricuspid (TR) and mitral valve regurgitation (MR)

Careful attention to monitoring of the cardiovascular system through continuous echocardiography during fetal surgery has led to potentially important intraoperative observations. Of 101 cases of intended fetal MMC repair, 100 completed surgery. At preoperative screening, no cardiovascular abnormalities were noted. Intraoperative ventricular dysfunction was present in 60 percent (20 mild, 25 moderate, 15 severe). Heart rate of < 100 was noted in 11 cases. Tricuspid regurgitation was present in 35 percent (26 mild, 7 moderate, 2 severe). And mitral regurgitation was present in 19 percent (15 mild, 4 moderate).

Seven cases experienced serious cardiovascular events, which affected conduct of surgery and/or outcome. In four of these, medications were given via umbilical vein and external cardiac compressions performed. Fetal echocardiography was used to gauge efficacy of compressions and guide resuscitation, and also allowed for visualization of the ultrasound contrast created by medication infusion via the umbilical vein as the drugs appeared in the right atrium, confirming entry into the circulation.

This study highlights the importance of careful fetal echocardiographic monitoring during fetal surgery. This practice should be routinely added to the overall care package offered to the maternal-fetal unit during fetal surgery in order to achieve the best outcomes.

Reference

Rychik J, Cohen D, Tran KM, Szwast A, Natarajan SS, Johnson MP, Moldenhauer JS, Khalek N, Martinez-Poyer J, Flake AW, Hedrick HL, Adzick NS. The Role of Echocardiography in the Intraoperative Management of the Fetus Undergoing Myelomeningocele Repair. Fetal Diagn Ther. 2014 Jul 18. [Epub ahead of print]