To the Editor:—
I read with interest the case report by Autore et al. 1that described anesthetic management of three parturients with hypertrophic cardiomyopathy receiving epidural anesthesia for cesarean delivery. After describing two cases wherein epidural anesthesia with lidocaine was provided and a third in which ropivacaine was used, the authors concluded that ropivacaine should be the “drug of choice” in this setting because of less cardiotoxicity versus bupivacaine and slower onset of block versus lidocaine.
This conclusion does not follow from the cases as presented nor from the available evidence currently published. Ropivacaine may be less cardiotoxic, but potency issues need to be settled before this can be concluded with certainty. 2It is not at all clear that patients with hypertrophic cardiomyopathy are more sensitive to local anesthetic–induced cardiotoxicity than patients with normal hearts. The toxicity of both ropivacaine and bupivacaine is not enhanced by pregnancy. 3Local anesthetic–induced toxicity would only occur with an unintentional large intravascular dose of drug, because proper epidural administration of either drug in doses used for cesarean delivery would not result in toxic blood levels. 4If one has a patient with hypertrophic cardiomyopathy, presumably one will be dosing the epidural slowly and carefully; therefore, large, rapid, intravascular drug administration should not occur. Most importantly, without regard to how the issue of bupivacaine versus ropivacaine toxicity is settled, certainly all would agree that lidocaine is less toxic than either, and thus this drug remains, in my opinion, the drug of choice for epidural use for any cesarean delivery unless highly unusual circumstances preclude its use.
The claim that ropivacaine has a slower onset than lidocaine is specious reasoning; it all depends on how you administer the drug. Previous data indicate that epidural ropivacaine, administered rapidly and in large doses, 4can produce very fast onset of surgical anesthesia. Likewise, lidocaine, administered slowly and carefully, as in the cases reported by Autore et al. , 1is perfectly compatible with stable intraoperative hemodynamics even in patients with severe cardiac disease.
The authors are to be congratulated for fine anesthetic management of three patients with complex cardiac disease for cesarean delivery. Certainly, ropivacaine would be an acceptable drug to use in these patients; however, to claim that it is the “drug of choice” in this setting is just not supported by the authors own cases nor by the current evidence available in the literature.