Complement activation during cardiac and thoracic vascular operations

Area of Science:

• Immunology
• Cardiovascular Surgery

Background:

• Complement activation is a critical immune response.
• Understanding complement activation during surgery is vital for patient outcomes.

Purpose of the Study:

• To investigate and compare complement activation levels in patients undergoing cardiac operations with and without cardiopulmonary bypass (CPB).
• To elucidate the pathways of complement activation induced by CPB and protamine administration.

Main Methods:

• Radioimmunoassay was used to measure C3a concentrations, a marker of complement activation.
• Patient groups included nine undergoing cardiac operations with CPB and nine undergoing thoracic vascular operations without CPB.

Main Results:

• CPB patients exhibited a tenfold increase in C3a post-bypass, with protamine causing a further twofold increase.
• Non-CPB patients showed a tenfold C3a increase solely after protamine administration.
• Peak post-protamine C3a levels were significantly higher in the CPB group (p < 0.01).

Conclusions:

• CPB triggers complement activation via the alternative pathway, with protamine subsequently activating the classical pathway.
• In non-CPB patients, complement activation occurs exclusively via the classical pathway in response to protamine.
• Surgical procedures involving CPB lead to a more pronounced complement activation response compared to non-CPB thoracic vascular operations.