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* From the Laboratoire dAnesthésiologie, Université Claude Bernard et Départements dAnesthésie-Réanimation, Hôpital Edouard Herriot et Centre Hospitalier Lyon-Sud, Hospices Civils de Lyon, Lyon;
Laboratoire dAnesthésiologie, Université Pierre et Marie Curie et Département dAnesthésie-Réanimation, Service dAccueil des Urgences, CHU Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris;
Service dAnesthésie-Réanimation, Hôpital dInstruction des Armées Desgenettes, Lyon, France.
Address correspondence to: Dr. Jean-Stéphane David, Département dAnesthésie-Réanimation-SAMU, Hôpital Edouard Herriot, 3 place dArsonval, 69437 Lyon cedex 03, France. Phone: (33) 4 72 11 75 88; Fax: (33) 4 72 11 75 89; E-mail: js-david{at}univ-lyon1.fr
Purpose: Ropivacaine and levobupivacaine were developed to reduce the risk of occasional toxicity reported with bupivacaine. While the effects of long-acting local anesthetics (LAAs) on myocardial contractility (inotropy) are well described, their effects on relaxation (lusitropy) remain largely unknown. The present study aimed to compare the effects of LAAs on rat myocardium.
Methods: Left ventricular papillary muscles of male Wistar rats were used to compare the inotropic and lusitropic responses of increasing concentrations of LAAs (108 to 103 M) under isometric and isotonic conditions. Data are mean % (SD) of baseline value.
Results: Long-acting local anesthetics induced a significant impairment of relaxation in isotonic and isometric conditions. As compared to ropivacaine, bupivacaine and levobupivacaine induced greater negative lusitropic effects in isotony [at 103 M, maximum unloaded shortening velocity (maxVr) = 27 ± 11 vs 13 ± 6 and 8 ± 5%] and isometry (at 103 M, time-to-half-relaxation: 106 ± 10 vs 127 ± 17 and 133 ± 17%). When the comparison was made with equipotent concentrations, the negative lusitropic effects induced with levobupivacaine were significantly greater than those of bupivacaine and ropivacaine in isometric and isotonic conditions (at 103 M, maxVr = 7 ± 4 vs 13 ± 6 and 17 ± 4 %). As previously described, LAAs also induced concentration-dependent negative inotropic effects that were greater for levobupivacaine compared to equivalent or equipotent concentrations of bupivacaine and ropivacaine.
Conclusions: Long-acting local anesthetics induce marked negative inotropic and lusitropic effects. Among LAAs, levobupivacaine exerts the greater depressant effects. Impairment of calcium handling and sarcoplasmic reticulum could explain the differential responses to local anesthetics.
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