Myocardial redox state during coronary artery bypass grafting assessed with microdialysis.
OBJECTIVE
Microdialysis allows the biochemical analysis of interstitial fluids of nearly every organ as a bedside procedure. This technique could be useful to reveal data about the myocardial metabolism during cardiopulmonary bypass in human coronary artery bypass graft (CABG) surgery.


METHODS
In 17 patients undergoing CABG a myocardial microdialysis catheter (CMA 70, CMA/Microdialysis AB, Sweden) was inserted in the apical region of the beating heart. Microdialysis measurements were performed at timed intervals before, during, and after cardiopulmonary bypass (CPB). The concentrations of lactate and pyruvate were analyzed semi-continuously.


RESULTS
During CPB the myocardial lactate-pyruvate-ratio (LPR) rose from an initial 11 (8-15) to 33 (29-41) ( P<0.01). After CPB the LPR decreased to 4 (3-7) at the end of observation ( P<0.05). The pyruvate concentration showed an immediate increase from 34 (30-42) microM at the end of CPB to 181 (147-234) microM after removal of the cross-clamp with subsequent increase during reperfusion ( P<0.01). Plasma lactate and pyruvate showed no essential changes during the study.


CONCLUSIONS
Using the microdialysis technique it was possible to analyze myocardial metabolic changes during CABG. The course of myocardial LPR as a sensitive indicator of the myocardial redox state showed profound changes during and after CPB. We propose the microdialysis technique as an additional monitoring tool in CABG.
Department of Anesthesiology, Medical University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany. Lbahlm@aol.com
Ludger
L
Bahlmann
Martin
M
Misfeld
Stephan
S
Klaus
Alexander
A
Leptien
Matthias
M
Heringlake
Peter
P
Schmucker
Hans-Hinrich
HH
Sievers
Urban
U
Ungerstedt
Ernst-Guenther
EG
Kraatz
D000368:Aged; D001026:Coronary Artery Bypass; D006801:Humans; D007773:Lactates / Q000097:blood*; D017551:Microdialysis; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009206:Myocardium / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D011184:Postoperative Period; D011773:Pyruvates / Q000097:blood*
D007773:Lactates; D011773:Pyruvates