CHANGES IN MYOCARDIAL ENERGY-METABOLISM IN ELECTIVE CORONARY ANGIOPLASTY

Study objective - The aim was to investigate the effect of coronary angioplasty on myocardial energy metabolism, and to assure the safety of the procedure in patients with coronary heart disease. Design - Before angioplasty a catheter was introduced into the coronary sinus. Blood samples were taken simultaneously from femoral artery and coronary sinus before balloon inflation, upon balloon deflation, and two minutes later, and arteriovenous differences in myocardial substrates, pH, Pco2, oxygen saturation, and adenosine catabolites were determined. Patients - 14 patients with angiographically documented coronary artery disease with lesions in the left coronary artery suitable for elective coronary angioplasty were included in the study. Results - During balloon inflation the positive femoroarterial-coronary sinus difference of lactate turned negative, from 0.21(SEM 0.05) mM to -0.10(0.11) mM, p<0.02. At the same time pH and Pco2 differences increased: from 0.04(0.00) U to 0.07(0.01) U, p<0.01, and from - 1.15(0.10) kPa to -1.41(0.10)kPa, p<0.01, respectively. The changes were, however, transient and the arteriovenous differences in these metabolic variables rapidly returned towards preinflation levels after balloon deflation. The femorarterial-coronary sinus concentration differences in glucose and free fatty acids became positive in coronary angioplasty. The energy state remained good during the procedure as assessed from the negligible net efflux of adenosine and its degradation products. Conclusions - Elective coronary angioplasty can be performed without any persistent derangements in myocardial metabolism, and may in fact lead to improvement of utilisation of some myocardial substrates. Lactate appears to be a more sensitive indicator of short term ischaemia than adenosine degradation products.