Angiotensin II concentrations and gut mucosal perfusion in infants undergoing cardiopulmonary bypass.
OBJECTIVE
To determine whether hypothermic cardiopulmonary bypass (CPB) per se causes an increase in angiotensin II (A-II) concentration in infants and to investigate the relationship between A-II concentration and gut mucosal perfusion.


METHODS
Prospective, open, nonrandomized, observational study.


METHODS
Children's teaching hospital.


METHODS
Thirty acyanotic infants requiring CPB.


METHODS
A-II concentrations were measured on six occasions before, during, and after CPB. An orogastric tonometer allowed intermittent calculations of gastric intramucosal pH (pHi). Gastric mucosal blood flow (flux) was monitored using a laser Doppler flowmeter. Ten infants acted as controls (group 1); 10 infants received captopril, 0.9 mg/kg orally, 45 minutes before induction of anesthesia (group 2), and 10 infants received enalaprilat, 0.06 mg/kg intravenously, just before CPB (group 3).


RESULTS
A-II concentrations were abnormally high in 28 of 30 patients before CPB (median, 450 pg/mL (range, 83 to 5,787 pg/mL). A-II concentrations in groups 1 and 2 decreased during CPB, but values remained at twice normal levels throughout surgery (median, 171 to 198 pg/mL post-CPB). A-II concentrations remained normal (range, 52 to 120 pg/mL) during and after CPB in patients receiving enalaprilat (group 3). The authors found no significant correlation between A-II concentration and pHi or flux before, during, or after surgery.


CONCLUSIONS
Acyanotic infants requiring cardiac surgery may have high perioperative concentrations of A-II. Hypothermic CPB is associated with a decrease in A-II concentration. Reductions in gut mucosal perfusion seen in some infants during hypothermic CPB are not related to increases in A-II concentrations.
Booker
P D
PD
Royal Liverpool Children's Hospital, United Kingdom.
Davis
A J
AJ
Diver
M J
MJ
Whitehead
C F
CF
D000804:Angiotensin II / Q000097:blood*; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use; D001794:Blood Pressure; D002216:Captopril / Q000627:therapeutic use; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D015773:Enalaprilat / Q000627:therapeutic use; D005753:Gastric Mucosa / Q000098:blood supply* / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007223:Infant; D017078:Laser-Doppler Flowmetry; D011446:Prospective Studies; D012039:Regional Blood Flow
D000806:Angiotensin-Converting Enzyme Inhibitors; D000804:Angiotensin II; D002216:Captopril; D015773:Enalaprilat