Can clonidine, enoximone, and enalaprilat help to protect the myocardium against ischaemia in cardiac surgery?
OBJECTIVE
To evaluate whether clonidine, enoximone, and enalaprilat reduce ischaemia-related myocardial cell damage in cardiac surgery.


METHODS
Prospective randomised controlled trial.


METHODS
Clinical investigation in a cardiac anaesthesia department of a university hospital.


METHODS
88 consecutive patients undergoing coronary artery bypass surgery.


METHODS
After induction of anaesthesia patients continuously received the alpha 2 agonist clonidine (group 1, n = 22), the phosphodiesterase (PDE) III inhibitor enoximone (group 2, n = 22), the angiotensin converting enzyme (ACE) inhibitor enalaprilat (group 3, n = 22), or saline solution as placebo (control group, n = 22). The infusion was stopped immediately before the start of cardiopulmonary bypass.


METHODS
The ST segment was analysed and the activity of creatine kinase isoenzyme MB (CKMB), cardiac troponin T (TnT), and the BB isoenzyme of glycogen phosphorylase (GPBB) were measured before the start of infusion (baseline), after weaning from cardiopulmonary bypass (CPB), at the end of surgery, 5 h after CPB, and on the morning of the first and third postoperative days.


RESULTS
Biometric data and time of cross-clamping were not significantly different in the four groups. Changes in the ST segment indicating ischaemia were least common in the enalaprilat group (P < 0.05). Postoperatively, CKMB activity was significantly higher in the clonidine and the control groups. Both new markers of myocardial cell damage increased more after CPB and postoperatively in the control patients (TnT peak: (mean (SD)) 3.99 (0.35) microgram/1; GPBB peak: 82 (15) ng/ml) and the clonidine-treated group (TnT peak: 3.80 (0.3) microgram/1; GPBB peak: 85 (14) ng/ml). Enalaprilat-treated patients showed the smallest overall changes in standard (CKMB) and new serological markers of myocardial ischaemia (TnT peak: 0.71 (0.1) microgram/1; GPBB peak: 44 (14) ng/ml).


CONCLUSIONS
In patients treated with enalaprilat before CPB, both new, more sensitive markers of ischaemic myocardial tissue damage increased significantly less than in an untreated control group. Those treated with enoximone also had lower plasma concentration of TnT and GPBB than the control group, whereas clonidine did not reduce the concentration of these markers of myocardial ischaemia. Pharmacological interventions, such as the continuous infusion of the ACE inhibitor enalaprilat, before start of CPB may help to protect the heart against ischaemia/reperfusion injury.
Boldt
J
J
Department of Anaesthesiology and Intensive Care Medicine, Justus-Liebig University Giessen, Germany.
Rothe
G
G
Schindler
E
E
Döll
C
C
Görlach
G
G
Hempelmann
G
G
D000316:Adrenergic alpha-Agonists / Q000627:therapeutic use; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use*; D015415:Biomarkers / Q000097:blood; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D003000:Clonidine / Q000627:therapeutic use; D015773:Enalaprilat / Q000627:therapeutic use*; D017335:Enoximone / Q000627:therapeutic use; D006801:Humans; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D017202:Myocardial Ischemia / Q000517:prevention & control*; D010726:Phosphodiesterase Inhibitors / Q000627:therapeutic use; D011446:Prospective Studies
D000316:Adrenergic alpha-Agonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D015415:Biomarkers; D010726:Phosphodiesterase Inhibitors; D017335:Enoximone; D015773:Enalaprilat; D003000:Clonidine