"Prepare for extracorporeal circulation and cardiac arrest!"
Connect the extracorporeal circulation, inject the cardiac arrest fluid, and cause the heart to stop.
During the extracorporeal circulation process, gradually lower the infant's body temperature until the core temperature reaches 15°C, then turn off the extracorporeal circulation machine and stop all blood circulation. This is DHCA—deep hypothermic circulatory arrest technique.
Because infants cannot withstand long durations of extracorporeal circulation, this technique must be used.
Under deep hypothermic circulatory arrest, the heart is arrested, and blood flow is paused, so it resembles "death," albeit a controlled, reversible "death" that can be "revived" under certain conditions.
Those conditions stipulate that this state cannot last more than 45 minutes; revival is possible within 45 minutes, but past this duration, revival isn't possible, so the surgery must be completed within 45 minutes.