RISK-FACTORS OF INCOMPLETE DISTRIBUTION OF CARDIOPLEGIC SOLUTION DURING CORONARY-ARTERY GRAFTING

Myocardial distribution of cardioplegic solution infused by combined a ntegrade/ retrograde routes was assessed with myocardial contrast echo cardiography in 18 patients with chronic stable angina and three-vesse l disease undergoing elective coronary artery bypass grafting. Overall myocardial opacification was significantly greater in retrograde than in antegrade cardioplegia (77.7% +/- 13.4% versus 59.1% +/- 15.7%; p = 0.0009). The difference was affected by collateral circulation, as p ointed out by the significant interaction between coronary collateral circulation and percent of myocardial opacification after antegrade an d retrograde cardioplegia (p = 0.002). When we performed multiple comp arisons, in patients with good collaterals the opacification differenc e between antegrade and retrograde cardioplegia was not statistically significant (66.4% +/- 10.2% versus 76.0% +/- 15.2%; p = not significa nt), whereas in patients with poor collaterals myocardial opacificatio n during retrograde cardioplegia was significantly greater (44.3% +/- 15.0% versus 81.2% +/- 9.0%; p < 0.02). During antegrade cardioplegia, patients with poor collaterals showed a lower degree of myocardial op acification than patients with good collaterals (44.3% +/- 15.0% versu s 66.4% +/- 10.2%; p < 0.01). Our results show that retrograde cardiop legia in patients undergoing elective coronary artery bypass grafting offers no advantage over antegrade cardioplegia when collateral circul ation is well developed. On the other hand, conventional aortic root i nfusion may not provide adequate myocardial protection in the subset o f patients with significantly narrowed or occluded coronary arteries a nd poor collaterals.