Differences in Cardiotoxicity of Bupivacaine and Ropivacaine Are the Result of Physicochemical and Stereoselective Properties

The results confirm that stereoselectivity can be demonstrated by a lengthening of atrioventricular conduction time for the more fat-soluble bupivacaine. However, for the less fat-soluble ropivacaine, the S(-)-isomer has no advantage over the R(+)-isomer for preventing slowing of atrioventricular conduction in clinical concentrations. Neither anesthetic showed stereoselective inotropic effects, but ropicavaine isomers had lesser cardiodepressant effects than bupivacaine isomers because of the replacement of the butyl- by a propyl-terminal group.