Effect of enflurane on myocardial metabolism in dog hearts with a narrowed coronary artery
Sakata, S.; Toriumi, S.; Arase, T.; Saito, T.
Masui. Japanese Journal of Anesthesiology 37(1): 65-74
1988
ISSN/ISBN: 0021-4892 PMID: 3367503 Document Number: 312032
To assess the effect of enflurane upon left ventricular myocardium in relation to the graded severities of induced coronary stenosis, tissue oxygen tensions, lactate metabolism and global hemodynamics before and after stepwise increases in inspired enflurane concentrations (0.85, 1.7, 2.5 and 3.5 per cent) were observed in two groups of open-chest dogs. In the moderate and severe stenosis groups, 26.4% and 68.5% reductions in left circumflex coronary flow at buprenorphine-anesthetized basal condition were deliberately induced. Moderate stenosis group: Subendocardial oxygen tension which had decreased after constriction, increased by enflurane inhalation. The restoration reached the peak at the end of 1.7% or 2.5% enflurane inhalation and tended to disappear after inhalation of 3.5% enflurane. Subepicardial oxygen tension was not significantly changed and myocardial lactate extraction ratio fluctuated in parallel with the ups and downs of the subendocardial oxygen tension throughout the experiment. Severe stenosis group: Subendo- and subepi- cardial oxygen tensions as well as myocardial lactate extraction ratio were markedly depressed after constriction, and no longer improved at the end of inhalation of 0.85, 1.7, 2.5 and 3.5% enflurane. It seems that as the severity of coronary stenosis increases, the imbalance of oxygen demand/supply relationship and ischemic metabolism were induced by enflurane of lower concentration and extended from the subendocardium to the subepicardium.