Objective To investigate the protective effect of target heart rate-guided individualized infusion of dexmedetomidine on perioperative stress response, hemodynamics, and myocardial protection in elderly high-risk patients undergoing laparoscopic colorectal cancer surgery. Methods Sixty elderly high-risk patients scheduled for elective laparoscopic colorectal cancer surgery were enrolled and randomly divided into an observation group and a control group, with 30 cases in each group, using the random number table method. Based on the conventional hemodynamic management, the observation group received individualized dexmedetomidine infusion guided by target heart rate: five minutes after the induction of anesthesia, dexmedetomidine was intravenously infused at an initial dose of 0.5 μg·kg−1·h−1. The infusion rate was dynamically adjusted according to the intraoperative target heart rate (50-70 beats/min) until the end of the surgery. The control group received only conventional hemodynamic management. Heart rate and mean arterial pressure were recorded in both groups at the following time points: before anesthesia induction (T0), immediately after tracheal intubation (T1), 5 minutes after pneumoperitoneum (T2), 30 minutes after pneumoperitoneum (T3), 60 minutes after pneumoperitoneum (T4), 5 minutes after pneumoperitoneum deflation (T5), and at the end of surgery (T6). And the rate-pressure product was calculated accordingly. Serum levels of norepinephrine (NE) and cortisol were measured in both groups at time points T0, T4, and T6. Serum levels of high-sensitivity cardiac troponin T (hs-cTnT) were measured in both groups preoperatively and on postoperative day 1 and postoperative day 2. The operation duration, pneumoperitoneum time, and intraoperative blood loss were recorded in both groups, as well as the occurrence of intraoperative adverse events (hypotension or hypertension, bradycardia or tachycardia, premature ventricular beats, and myocardial ischemia); the intraoperative use of vasoactive drugs and the occurrence of cardiovascular events (hypotension or hypertension, bradycardia or tachycardia, and myocardial ischemia symptoms) during postoperative hospitalization were recorded in both groups; a 30-day postoperative follow-up was performed to record the occurrence of major adverse cardiovascular events (cerebral infarction, myocardial infarction, and sudden cardiac death) in both groups. Results At T0 and T1, there were no statistically significant differences in heart rate, mean arterial pressure, or rate-pressure product between the two groups (P>0.05). At T2, T3, T5 and T6, heart rate, mean arterial pressure, and rate-pressure product in the observation group were lower than those in the control group (P<0.05). At T2, T3, T4, T5 and T6, heart rate in the observation group was lower than that at T0 (P<0.05). At T4 and T6, serum levels of NE and cortisol in the observation group were lower than those in the control group (P<0.05); at T4 and T6, serum levels of NE and cortisol in the control group were higher than those at T0 (P<0.05). On postoperative day 1 and postoperative day 2, serum levels of hs-cTnT in the observation group were lower than those in the control group (P<0.05). Compared with the control group, the observation group had a lower incidence of intraoperative hypertention, tachycardia and myocardial ischemia (P<0.05). The intraoperative utilization rates of esmolol and urapidil were lower in the observation group than in the control group (P<0.05). During postoperative hospitalization, there were no statistically significant differences in the incidence of hypotension, hypertension, bradycardia, tachycardia, and myocardial ischemia symptoms between the two groups (P>0.05). At the 30-day postoperative follow-up, no adverse cardiovascular events occurred in either group. Conclusion Compared with conventional hemodynamic management, target heart rate-guided individualized infusion of dexmedetomidine can effectively alleviate the stress response, maintain hemodynamic stability, and provide superior myocardial protection in elderly high-risk patients undergoing laparoscopic colorectal cancer surgery.

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