PANCURONIUM, VECURONIUM, AND HEART-RATE DURING ANESTHESIA FOR AORTOCORONARY BYPASS OPERATIONS

To determine the effects of pancuronium and vecuronium on heart rate, 90 patients scheduled for aortocoronary bypass were randomly assigned to one of three groups (30 patients each) which received vencuronium 1 00 mug[sdot ]kg-1, pancuronium 100 mug[sdot ]kg-1, or a mixture of vec uronium (50 mug[sdot ]kg-1) and pancuronium (50 mug[sdot ]kg-1) in a d ouble-blind fashion during induction of anesthesia. All patients were premedicated with lorazepam prior to surgery, hence avoiding the effec ts of scopolamine. Our results showed no significant increase in heart rate from the administration of pancuronium, following administration of this drug the heart rate increased by only four beats per minute. The heart rate was unchanged after the mixture, but decreased by twelv e beats per minute after vecuronium (P < 0.05). The heart rate respons e differed by 16 beats per minute between pancuronium and vecuronium. All patients who received either of the neuromuscular relaxants and wh o were on beta blockers showed a decrease in heart rate. In this study , the administration of pancuronium after an adequate induction dose o f fentanyl did not cause tachycardia. We therefore feel that pancuroni um still has a role in cardiac anesthesia, especially as the newer mus cle relaxants such as vecuronium, pipecuronium and doxacurium are sign ificantly more expensive.