Intravenous anesthesia with S-(+)-ketamine for 'on-pump' coronary artery bypass surgery: hemodynamic profile and effect on troponin T levels

Introduction

In patients with ischemic coronary artery disease the 'sympathomimetic' effects of ketamine can cause myocardial damage. However, the S-isomer of ketamine may have various advantages. We studied the cardiovascular stability and safety of intravenous anesthesia with S-(+)-ketamine for coronary artery bypass graft surgery (CABGS).

Methods

After approval of the local ethics committee and written informed consent, 315 patients scheduled for elective 'on-pump' CABGS were enrolled in the study. Patients were randomly allocated to three anesthetic protocols: sufentanil–sevofluorane–propofol (SSP), sufentanil–propofol (SP), and S-(+)-ketamine–midazolam–propofol (KMP). Standard invasive hemodynamic monitoring was performed using a pulmonary artery catheter and hemodynamic variables were reported. Measurements were taken after induction of anesthesia, after weaning from cardiopulmonary bypass, and 6 hours postoperatively. Serial plasma troponin T levels were taken: before induction of anesthesia, after surgery, and 6 and 24 hours postoperatively. All cardiovascular adverse events were recorded (such as electrocardiographic signs of ischemia, myocardial infarction, 28-day mortality).

Results

Groups (SSP: n = 106; SP: n = 108, KMP: n = 101) did not differ in preoperative data (for example, biometry, cardiac and coronary profile and risk). Intraoperative management was comparable among groups. Tropinin T levels were rather lower in the KMP group, but did not differ significantly between groups at 24 hours after aortic unclamping. Cardiovascular adverse events showed the same low incidence in all groups. Hemodynamic data were comparable; however, the heart rate (HR) and mean arterial pressure (MAP) after induction were significantly higher in the KMP group (HR: 59 ± 11 vs 63 ± 32 vs 66 ± 13 beats/min (P < 0.01); MAP: 74 ± 12 vs 81 ± 16 vs 83 ± 16 mmHg (P < 0.01)).

Conclusion

In our study, KMP anesthesia was safe to use for CABGS. In comparison with SSP and SP anesthesia, no significant rise in troponin T as a marker of myocardial damage was observed. All three regimens resulted in stable hemodynamics. However, the use of S-(+)-ketamine as an induction agent in patients with coronary artery disease may be limited due to its sympathomimetic effects leading to raised HR and MAP, even if supplemented by midazolam or propofol.