Left bundle branch block associated with propoxyphene hydrochloride poisoning

Described is the case of a patient who developed left bundle branch block following acute propoxyphene hydrochloride overdosage. The left bundle branch block was transient and associated with no permanent sequelae. Previously documented cardiac abnormalities, specific narcotic antagonist therapy, and animal studies correlating cardiac toxicity of propoxyphene hydrochloride with its potent local anesthetic action are discussed.