After initial cooling the perfusion of low concentration cryoprotectants begins through aortic cannulation. Perfusion and continued cool down is done with a heart lung machine. As the patient continues to cool, stronger concentrations of cryoprotectant solutions are perfused until the concentration is high enough for
vitrification. The final temperature reached during cryoprotection is -76°C (dry ice temperature). At this point the perfusion is stopped and the focus becomes temperature maintenance.