[Effects of sevoflurane on regional myocardial oxygen balance in the canine heart with coronary artery stenosis].

ABSTRACT

The effects of increasing inspired sevoflurane (Sev) concentrations (0.5, 1.0, 1.5, 2.0 MAC) on regional myocardial oxygen balance and metabolism were studied in 10 open-chest dogs with coronary artery stenosis. Regional myocardial oxygen balance was assessed by continuous recording of subendocardial and subepicardial oxygen tensions. After the basal measurement, the left circumflex coronary artery blood flow (CBFLCX) was reduced by 20% with a screw flow regulator. The institution of stenosis caused a slight but significant decline in subendocardial oxygen tension. Otherwise, there were no significant differences between basal values and those after the stenosis. During the subsequent inhalation of Sev at 0.5, 1.0 and 1.5 MAC, endocardial oxygen tension was maintained at the level of control value. Sev 2.0 MAC caused a severe reduction in systemic arterial pressure and resulted in a marked and significant decline of endocardial oxygen tension compared with control value. On the other hand, subepicardial oxygen tension remained unchanged during each Sev inhalation. The ratio of epicardial/endocardial oxygen tension did not show a significant decline with increasing Sev concentration. It seems that Sev may not possess sufficient potency to cause myocardial ischemia by redistribution of coronary blood flow.