Sinus bradycardia due to lidocaine: clinical-electrophysiologic correlations

Summary Two patients in whom profound sinus bradycardia resulted from the use of lidocaine are described. In one patient, complete AV block also occurred in association with sinus bradycardia. While congestive failure and the associated hepatic insufficiency may have contributed to excessive blood levels of lidocaine in one patient, these factors were not evident in the other. The occurrence of sinoatrial block in isolated rabbit heart preparations during exposure to lidocaine suggests that a similar mechanism may be responsible for instances of “sinus bradycardia” and “sinus arrest” in patients with heart disease. The development of sinoatrial block in conjunction with suppression of latent pacemakers in the AV junction and the ventricles may result in particularly dangerous arrhythmias and should be borne in mind when using lidocaine in patients with heart disease.