Myocardial protective effect of dexmedetomidine on patients undergoing off-pump coronary artery bypass grafting

Objective To observe myocardial protective effect of dexmedetomidine (Dex) on patients undergoing off-pump coronary artery bypass grafting. Methods Fifty-seven patients scheduled for off-pump coronary artery bypass grafting surgery were selected, the gender was not restricted, aged 43-74 years and American Society of Anesthesiologists physical status Ⅱ or Ⅲ (New York Heart Association Ⅱ or Ⅲ). All patients had no history of acute myocardial infarction, heart failure, cardiac surgery, and obvious dysfunction of liver, kidney and lung. Enrolled patienrs were randomly divided into control group and Dex using computer random software. In Dex group, Dex was given as a bolus of 1 μg/kg over 10 min followed by an infusion of 0.5 μg/(kg·h) throughout the surgery before induction of anesthesia, and the equal volume of normal saline was given in control group. Artery systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were recorded after entering the operating room (T0), after loading dose injection (T1), before anesthesia induction (T2), immediately after endotracheal intubation (T3), after the vascular anastomosis (T4), and immediately at the end of surgery (T5). Blood samples were collected from the central vein for detection of high-sensiti cardiac troponin T (hs-cTnT) concentration after entering the operating room (T0), 3 h (T6) and 24 h (T7) after surgery. The operation time, intensive care unit (ICU) stay time, the incidence of arrhythmia and myocardial infarction, and mortality within 14 days postoperation were recorded. Results The levels of SBP in the Dex group [(127.70±10.40), (121.60±7.33) and (121.30±7.24) mmHg (1 mmHg=0.133 kPa)] were decreased significantly as compared with the control group [(139.00±13.09), (137.20±10.50) and (142.00±9.00) mmHg] at T3, T4 and T5 (P=0.000). The levels of DBP in the Dex group [(82.43±8.79) and (82.87±6.61) mmHg] were decreased significantly as compared with the control group [(96.93±10.17) and (101.3±9.89) mmHg] at T4 and T5 (P=0.000). The levels of HR in the Dex group [(67.97±5.08), (66.93±4.76), (68.43±4.47) and (66.53±4.59)/min] were lower than in the control group [(77.33±7.28), (77.87±8.25), (77.40±7.40) and (75.43±7.27)/min] from T2 to T5 (P=0.000). The levels of hs-cTnT concentration in the Dex group [(124.3±55.8) and (101.3±41.8) ng/L] were relatively decreased as compared with the control group [(152.2±52.5) and (122.5±47.6) ng/L], but no significant difference was found at T6 and T7 (P=0.057, 0.079). Conclusion The continuous infusion of Dex can maintain hemodynamic stability, mitigate myocardial ischemia-reperfusion injury and protect the myocardial cells in the patients undergoing off-pump coronary artery bypass grafting surgery. Key words: Dexmedetomidine; Coronary artery bypass grafting; Myocardial ischemia; Reperfusion injury; Myocardial preservation