Background: Overexpression of heat shock proteins (Hsps) is associated to myocardial protection and it has been suggested that they could be a marker of cardiac preservation in conditions such as extracorporeal circulation. Aim of this study was to evaluate if cardioplegic arrest can modify the expression of Hsps in the heart and if this alteration is associated to cardiac preservation.
Method: The levels of Hsp 27, Hsp 60, and both the constitutive and the inducible form of Hsp 70 were measured in the cardiac tissue from right atrium of pediatric patients before and after aortic cross-clamping (ACC) during cardiopulmonary bypass surgery for correction of congenital heart disease (n=20). The quantitative evaluation of Hsps was made by Western blotting analysis after tissue extraction and protein separation. Hsp 72 mRNA expression was also evaluated in pre- and post-ACC samples of eight subjects by semiquantitative RT-PCR. Peripheral levels of Troponin I, Myoglobin, LDH, CK, CK-MB were measured in basal conditions and at 12 and 24h after cardiosurgery as markers of heart damage.
Results: The cardioplegic arrest did not significantly modify the mean levels of all the Hsps measured. Hsp 72 levels increased after cardioplegia in the 40% of the patients and all Hsps in the 28% of subjects. The patients whose levels of Hsps are increased after cardioplegia are associated with lower post-surgery concentrations of all the markers of cardiac injury.
Conclusions: This observation suggests a relationship between the increase of Hsps and the reduction of cardiac injury.