Metabolic correlates of myocardial stunning and the effect of cardiopulmonary bypass.
In order to study the metabolic consequences of myocardial stunning, repeated coronary occlusions were performed in dogs. The production of CO2, adenosine triphosphate (ATP), phosphocreatine (PCr), and inorganic phosphate (Pi) by myocardial cells was assessed, along with extracellular and intracellular pH. Our results indicate that regional coronary artery occlusion reduces the ability of the myocardium to produce H+ and CO2 and to replenish ATP post ischemia. These alterations, then, represent the hallmark of metabolic viability during periods of ischemic insult. Decreases in PCr and Pi were completely eliminated during reperfusion and, therefore, are ot reflective of myocardial stunning. When normothermic cardiopulmonary bypass (CPB) is instituted and the coronary artery is occluded three times with reperfusion between each occlusion, alterations in myocardial H+ and high energy phosphates are identical to those observed using only repetitive coronary occlusion. Systemic hypothermia during CPB does not protect against myocardial stunning; however, it is anticipated that interventions that prevent the reduction in H+ and ATP levels may overcome the effects of myocardial stunning that occur during cardiac surgery.
Khuri
S F
SF
Department of Surgery, Brockton/West Roxbury VA Medical Center, West Roxbury 02132.
Axford
T C
TC
Garcia
J P
JP
Khabbaz
K R
KR
Dearani
J A
JA
Khait
I
I
Zolkewitz
M
M
Healey
N A
NA
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D009202:Cardiomyopathies / Q000209:etiology* / Q000378:metabolism* / Q000503:physiopathology; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D004285:Dogs; D007036:Hypothermia, Induced / Q000009:adverse effects; D009200:Myocardial Contraction / Q000502:physiology*; D015425:Myocardial Reperfusion / Q000009:adverse effects; D009206:Myocardium / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism
D010710:Phosphates; D010725:Phosphocreatine; D002245:Carbon Dioxide; D000255:Adenosine Triphosphate