The effects of dopexamine in bupivacaine and ropivacaine induced cardiotoxicity in isolated rat heart

OBJECTIVE: To compare the inotropic and chronotropic effects of ropivacaine and bupivacaine in an isolated, spontaneously beating rat heart, and to determine the reversal effects of dopexamine on these effects.

METHODS: The study was conducted at the Department of Physiology, Medical Faculty, Osmangazi University, Eskisehir, Turkey in November 2001. Fifty animals were randomly assigned to 5 groups. Hearts were perfused with a modified Krebs Henseleit solution. In group I (n=10) hearts were exposed to bupivacaine 5 x 10-6 M and in group II (n=10) hearts were exposed to ropivacaine 5 x 10-6 M for 15 minutes. Group III (n=10) was the dopexamine control group and hearts were exposed to dopexamine 1 x 10-6 M for 5 minutes. In group IV (n=10) and in group V (n=10) hearts were exposed to dopexamine in 1 x 10-6 M doses immediately after the bupivacaine and ropivacaine infusions. Heart rates and contractile forces were recorded continuously during the study.

RESULTS: Both of the local anesthetics had cardiac depressant effect on isolated hearts. Bupivacaine created more significant effect on heart rate and contractility than ropivacaine. Hearts receiving dopexamine after the infusion of local anesthetic, recovered more quickly.

CONCLUSION: Bupivacaine had more depressant effects on cardiac contractility and chronotropy than ropivacaine. Dopexamine may provide an alternative to presently recommended pharmacological therapy in cases of bupivacaine and ropivacaine induced cardiotoxicity. But, the clinical impact of the use of dopexamine in this situation deserves further evaluation.