“…In contrast to previous studies which, in general, reported a decrease in heart rate (con comitant with a decrease in arterial blood pressure) during propofol anesthesia [1], the basic SCL decreased (i.e., an increase in heart rate) transiently from 565 ± 36 ms at baseline to 527 ± 26 ms after high-dose propofol (p < 0.05). The reported effects of propofol on the heart rate have not been uniform: some investigators have described an increase [17,18], whereas others have observed a decrease [19] or minimal or no change [20,21] in heart rate. The reason for these different results is not clear, but may, in part, reflect differences in autonomic tone and the concomitant use of other anesthetic agents [4][5][6][7][8][9]22] Clinically, propofol has been reported to occasionally cause profound sinus bradycardia [4][5][6][7][8], often persisting into the postoperative period [4], and asystolic cardiac arrest [5][6][7][8], especially when used in combination with potent opioid agents [4][5][6][7][8][9]22], Although less frequently, propofol has also been reported to cause significant AV block, resulting in cardiac arrest [9], However, with the exception of published case reports [4][5][6][7][8][9], significant bradyarrhythmias, in general, have not been seen in large number of patients exposed to propofol for a variety of procedures [22,…”