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Neutrophil degranulation and complement activation during fetal cardiac bypass
A J Parry1, E Petrossian, D B McElhinney
1Department of Pediatric Cardiac Surgery, University of California, San Francisco, USA. ajparry@yahoo.co.uk
The Annals of Thoracic Surgery
|September 2, 2000
Summary
Fetal cardiac bypass activates neutrophils, contributing to fetoplacental unit dysfunction. A Hemopump circuit may reduce this inflammatory response, improving fetal outcomes during bypass.
Area of Science:
- Cardiovascular Surgery
- Neonatal Physiology
- Immunology
Background:
- Fetal cardiac bypass can lead to fetoplacental unit (FPU) dysfunction, characterized by increased placental vascular resistance and acidosis.
- The precise mechanisms underlying this FPU dysfunction remain incompletely understood.
- This study investigates the roles of complement activation and neutrophil degranulation in placental dysfunction during fetal bypass.
Purpose of the Study:
- To test the hypothesis that complement activation and neutrophil degranulation contribute to placental dysfunction during fetal bypass.
- To compare placental hemodynamics, complement activation, and neutrophil degranulation in fetuses undergoing bypass with a Hemopump circuit versus a conventional roller pump circuit, and controls.
- To elucidate the mechanisms of FPU dysfunction associated with fetal cardiac bypass.
Main Methods:
- Twenty-six Western Cross sheep fetuses underwent 30 minutes of cardiac bypass using either a Hemopump (n=8) or conventional roller pump (n=10) circuit, or served as controls (n=8).
- Blood samples were collected pre-bypass, post-bypass, and 1-2 hours after bypass to measure white cell counts, C3a, and lactoferrin levels.
- Placental hemodynamics and blood gases were monitored throughout the study.
Main Results:
- Neutrophil and lymphocyte counts decreased over time in all groups.
- C3a levels significantly increased post-bypass only in the roller pump group.
- Lactoferrin levels significantly increased in both Hemopump and roller pump groups, coinciding with worsened placental gas exchange and cardiac function.
Conclusions:
- Complement and neutrophil activation occur during fetal cardiac bypass.
- Neutrophil activation, indicated by lactoferrin levels, correlated with FPU and cardiac dysfunction.
- Minimizing extracorporeal surface and priming volume in bypass circuits may reduce inflammatory responses and improve FPU function.