Sinus node function and protamine sulfate.

Abstract

This report analyzes the effects of protamine sulfate (PS) on the heart rate and sinoatrial node function in dogs anesthetized with diazepam, fentanyl, and pancuronium bromide, and subjected to different modalities of extracorporeal circulation (ECC). All groups were given 3 mg/kg of heparin sodium and 5 mg/kg of PS. The sinus node function was evaluated by means of sinoatrial conduction time (SACT), absolute sinus node recovery time (SNRTa), and corrected sinus node recovery time (SNRTc). The spontaneous heart rate (HR) of the animals was also analyzed. Under the experimental conditions established in this study, the intravenous administration of a bolus of PS produced a decrease in the HR in all the groups, regardless of the type of ECC used. The modifications in the conduction and recovery times of the sinus node by PS did not correlate with those of the heart rate; the sinoatrial conduction time increased in groups subjected to ECC, while the absolute and corrected recovery times of the sinus node were prolonged only in the group that underwent rapid rewarming.