Irreversible myocardial cell injury and early postoperative function of the heart after coronary artery bypass grafting (CABG)

Myocardial injury can be assessed by release of Troponin I (TnI) and creatinine kinase MB isoenzyme (CK MB). Concentrations of TnI have prognostic value for morbidity and mortality after cardiac surgery. The aim of the study was to evaluate whether the extent of myocardial necrosis is predictive for contractile dysfunction of the heart after CABG.

Methods

Twenty patients underwent CABG with cardiopulmonary bypass (CPB). The cardioplegia (CP) time was 84 (50–126) min. Blood for TnI and CK MB mass was simultaneously sampled from radial artery and coronary sinus (CS) cannulas before CPB and at 1, 5, 10, 20 min of reperfusion and arterio-CS differences were calculated. The cardiac index (CI), right ventricular stroke work index (RVSWI), and left ventricular stroke work index (LVSWI) were measured before sternotomy, 15 min and 1, 2, 4, 6, 9, 12 hours after CPB.

Results

Before CP myocardial necrosis was not detectable. Release of TnI and CK MB to the CS appeared from the first minute of reperfusion, and was increased in time (Fig. 1). The early postoperative performance of the heart was not inferior to pre-CPB values (Table 1).

Figure 1

Table 1

Conclusion

CP is associated with irreversible myocardial injury. The contractile function of the heart evaluated by pulmonary artery catheter provides little information of the exent of myocardial damage.