Left ventricular surface tissue oxygen pressures determined by oxygen sensitive multiwire electrodes in pigs.
OBJECTIVE
Polarographic oxygen sensitive electrodes can be used to measure tissue oxygen pressures on the surface of the beating heart. The purpose of the study was to clarify the significance of these PO2 determinations.


METHODS
Changes in left ventricular surface oxygen pressures, subendocardial or subepicardial wall functions (ultrasonic dimension technique), and blood flow (radioactive microsphere technique) were correlated during different degrees of acute coronary artery stenoses in pigs.


METHODS
19 anaesthetised open chest pigs, 28-40 kg body weight, were studied during different degrees of constriction of the left anterior descending artery which did not influence overall left ventricular function or irreversibly damage the myocardium.


RESULTS
Highly significant (p less than 0.001) correlations (each % delta) were obtained for surface tissue oxygen pressures (y) with subepicardial (y = 0.002 e 0.10x; r = 0.89) and subendocardial (y = 1.44 e 0.04x; r = 0.98) blood flow values, as well as with subendocardial function (y = 82.4 + 0.22x; r = 0.89); a significant correlation was also obtained for subendocardial function (y) with subendocardial blood flow (y = 66.0 + 0.28x; r = 0.69). However, no significant correlation was obtained for polarographic tissue PO2 with subepicardial segment function, indicating that regional function was maintained when tissue PO2 recordings were not much above 0 kPa and when blood flow was reduced by 25 to 30%.


CONCLUSIONS
Oxygen pressures of the superficial layers of the left ventricle are relatively high at normal values of oxygen consumption but decrease rapidly if blood supply is reduced. Regional wall function is preserved at low oxygen pressures. Polarographic surface PO2 electrodes hence can be used to study influences of experimental interventions on oxygenation of the normally perfused and of the moderately ischaemic myocardium.
Conzen
P F
PF
University of Munich, Germany.
Habazettl
H
H
Christ
M
M
Baier
H
H
Hobbhahn
J
J
Vollmar
B
B
Peter
K
K
D000818:Animals; D003250:Constriction; D003326:Coronary Circulation; D003327:Coronary Disease / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D004566:Electrodes; D005260:Female; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010100:Oxygen / Q000032:analysis*; D011048:Polarography; D013552:Swine; D016277:Ventricular Function, Left
D010100:Oxygen