Metabolic and haemodynamic changes in the heart during the early phase of cardiopulmonary bypass: II. Animal experiments.
A significant release of lactate instead of uptake was observed during the first 10 min of cardiopulmonary bypass preceding aorto-coronary bypass surgery in human patients. To clarify these findings in more detail, myocardial lactate and oxygen metabolism was studied in healthy dog hearts subjected to a protocol similar to the clinical situation. In one group (n = 11) normothermia at 34 degrees C was used with an empty beating heart, and in the other group (n = 11) hypothermia with ventricular fibrillation was applied. Within the first 10 min of bypass no significant changes in high energy phosphates were observed in myocardial biopsies. However, a marked decrease in mean aortic blood pressure and a simultaneous lowering in oxygen consumption was observed in both groups after instalment of bypass. An initial shift from lactate uptake to lactate release occurred while on bypass in the normothermia group. After 10 min of bypass, lactate uptake was restored in hearts of both groups. Therefore, the lactate release during the initial phase of bypass in patients originates both from the instalment of the bypass and from (local) inadequate perfusion, which is most likely to be due to stenosed coronary arteries.
van der Veen
F H
FH
Department of Physiology, University of Limburg, Maastricht, The Netherlands.
van der Vusse
G J
GJ
Kruger
R T
RT
van der Nagel
T
T
Willemsen
P
P
Reneman
R S
RS
D000818:Animals; D001011:Aorta / Q000502:physiology*; D001794:Blood Pressure; D001831:Body Temperature; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D004285:Dogs; D006439:Hemodynamics; D007773:Lactates / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption
D007773:Lactates