[Conversion to 2nd degree from 1st degree atrioventricular (AV) block by the reversal of neuromuscular blockade].

A case of intraoperative conversion to 2nd degree from 1st degree AV block by the reversal of neuromuscular blockade was reported. A 78 year old male, who originally suffered from 1st degree AV block, underwent choledocholithotomy and T-tube drainage for choledocholithiasis. He was administered 4 mg of pancuronium at the time of intubation. The operation lasted for 160 minutes under epidural anesthesia, NLA and nitrous oxide-oxygen. The patient started spontaneous breathing and the recovery was confirmed after the operation which finished without any problem. Neuromuscular blockade was reversed with atropine 0.5 mg and neostigmine 1.0 mg that were administered simultaneously taking 3 minutes. Then he was extubated without any troublesome stimulation. Suddenly, however, he suffered from the worse condition of bradycardia with the 2nd degree AV block. It took about 45 minutes until he recovered to the original 1st degree AV block despite atropine treatment. We believe that this accident was induced by a vasovagal reflex which was triggered by extubation under the effect of neostigmine which acts longer than that of atropine. We should be careful in reversing the effect of the non-depolarizing neuromuscular blockade. A short acting neuromuscular blockade, i.e. vecuronium, is preferable so as to avoid neostigmine reversal, and extubation should be performed when the effect of neuromuscular blockade is confirmed to be exhausted.