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.