A fetal goat model of cardiopulmonary bypass with cardioplegic arrest and hemodynamic assessment.

Objective: Increasing evidence shows that some cardiac defects may benefit from fetal interventions, including fetal cardiac surgery. We attempted to develop an in vivo animal model of fetal cardiopulmonary bypass with cardioplegic arrest.

Methods: Operations were performed on 14 pregnant goats. The extracorporeal circulation circuit consisted of a centrifugal pump, silicone tubings with an inner diameter of 6 mm, a roller pump, and a reservoir. The placenta was the sole oxygenator. Cardiopulmonary bypass was maintained at a mean flow rate of 344 ± 68 mL/kg/min, including 30 minutes of cardiac arrest and 15 minutes of reperfusion. Mean arterial blood pressure and heart rate were monitored. Arterial blood samples were analyzed. The pulse index and resistance index of the fetal umbilical artery were monitored.

Results: Experiments were completed in 11 cases (79%), with the fetuses weighing 0.65 to 1.8 kg. Fetal mean arterial blood pressure and heart rate remained stable throughout the experiments. A decrease in partial pressure of oxygen with concomitant increase in carbon dioxide partial pressure was noted, but trends were relatively stable. Metabolic acidosis was recognized during and after cardiac bypass. The pulse index and resistance index of the umbilical artery increased significantly after 2 hours off bypass.

Conclusions: We confirmed the technical feasibility of establishing an in vivo model of fetal cardiac bypass with cardioplegic arrest. This fetal goat model provides reproducible data and is suitable to study clinically relevant problems related to fetal cardiopulmonary bypass, myocardial protection, and hemodynamics.