This research study is about the effect heart-lung bypass procedures have on the vital organs (brain, heart, lungs, and kidneys) during open-heart surgery in pediatric patients. There are two types of heart pumps used in surgery requiring heart-lung bypass; one pumps the blood continuously through the body and the other pumps the blood with repeated pulses. Both pumps are approved for clinical use by the FDA. Although 90% of institutions still use non-pulsatile flow, some studies show there may be benefits to using pulsatile flow during surgery.

The investigators want to learn whether the vital organs (brain, heart, lungs, and kidneys) respond differently to one method than they do to the other. Approximately 300 children will take part in this research at the Hershey Medical Center.

Inclusion Criteria:

• Patients recruited from Penn State Children's Hospital undergoing cardiac surgery with cardiopulmonary bypass.

Exclusion Criteria:

• Patients older than 17 years will be excluded.

300 children (150 per perfusion system) ages 1 year to < 18 years requiring CPB for cardiac surgery.