Extent of myocardial tissue damage during transmyocardial laser revascularization with the CO2 heart Laser((R))

Objective and Background: Transmyocardial laser revascularization (TMR) is the only surgical treatment for patients with severe diffuse coronary arter y disease, who are not candidates for bypass grafting or percutaneous angio plasty. However, vaporization of tissue during the creation of channels lea ds to a certain loss of viable myocardium. during every TMR procedure. Meth ods: We analyzed serum levels of creatine kinase and creatine kinase MB sub type in 163 patients after sole TMR with a CO2 laser (wave length 10.6 mum, 800-watt power). The control group consisted of 35 consecutive CABG patien ts and 30 consecutive redo-CABG patients. Additionally, in the TMR group we measured echocardiographically the left ventricular ejection fraction befo re and after TMR. We recorded the total amount of laser energy applied, ave rage and maximum energy per channel, and the number of created channels, in order to calculate the correlation between these parameters and postoperat ive enzyme levels or changes in the LVEF. Results: After TMR, we measured h igher creatine kinase levels compared to those in CABG patients (607.8 +/- 558.4 UAL vs. 285.0 +/- 292.3 U/L,p < 0.01). The relative proportion of CK- MB of total CK, however, was significantly lower after TMR, compared to tha t of the control group (4.5 +/- 3.0% vs. 10.1 +/- 6.4%, p < 0.01). Patients with a pronounced postoperative increase in CK-MB levels or a higher perce ntage of CK-MB of total CK also after TMR operations show a decline in left ventricular contractility. In the laser group, the maximum enzyme levels w ere detected significantly later than in the control group (25.0 +/- 19.4 h postoperatively vs. 8.7 +/- 9.1 h, p < 0.01). There was no significant cor relation between the technical laser parameters or the number of created ch annels and the percentage of CK-MB of total CK or changes in left ventricul ar ejection fraction. Conclusions: CO2 laser TMR does not result in signifi cant injury to the myocardium. Cardiac enzymes play an important role in th e detection of perioperative myocardial infarction in TMR patients.