A Trial of Inhaled Nitric Oxide (NO) as an Anti-Inflammatory and Anti-Reperfusion Agent in the Treatment of Infants and Children Undergoing Cardiopulmonary Bypass for Repair of Congenital Heart Disease

Each year, there are over 400,000 cardiac surgical operations performed in the United States; of which 10,000 are performed on children. These operations are made possible by the use of the heart-lung bypass machine, also known as cardiopulmonary bypass. This machine allows for the body to be supported while the heart is repaired. While this machine has been life saving, it has risks and can lead to a variety of complications.

One such complication results from the fact that the patient's blood is exposed to the foreign material of the machine, such as plastic tubing. In nearly all cases of cardiac surgery, this leads to a whole body response in the patient following the operation. This response, inflammation, is characterized by alterations in the function of the heart and lungs, fever, fluid retention, and bleeding disorders in the postoperative period. While this is usually temporary and self limiting, significant morbidity occurs in approximately 1-2% of cases where this inflammatory response is present. Additionally, children appear to be more susceptible to this response. This can lead to significant postoperative complications that are not associated with the actually surgical procedure performed on the heart.

The exact cause of this response is not fully understood. However, it is important to understand the triggers, timing, and pattern of this complex inflammatory response in order to modify or arrest it. Unlike other situations associated with this type of whole-body inflammatory reaction such as trauma or overwhelming infection, cardiac surgical teams have the advantage of knowing when the trigger will occur (i.e. during the cardiac operation) and hence have the opportunity for preemptive intervention in an effort to minimize the response. One such effort is the focus of this proposal.

Nitric oxide (NO) is a gas that has been used for years in the treatment of lung disease in infants. It has been life saving and safe. Recently, it has been investigated for its anti-inflammatory effects outside the lungs. We propose delivering NO to the source of the greatest inflammation in cardiac surgery, the cardiopulmonary bypass machine. It is our intention to show that in doing so; we can minimize the inflammation found in the first 24 hours following cardiac surgery in children. If we are correct, the reduction of this inflammation will result in less damage to other organs of the child's body and improved outcome following surgery.