Intermediate lukewarm (20 degrees C) antegrade intermittent blood cardioplegia compared with cold and warm blood cardioplegia

Background: In the field of intermittent antegrade blood cardioplegia, 3 le vels of temperature are commonly used: (1) cold (8 degrees C); (2) tepid (2 9 degrees C); and (3) warm (37 degrees C), Given the 21 degrees C spread an d the metabolic changes that can occur between cold (8 degrees C) and tepid (29 degrees C) cardioplegia, we thought it worthwhile to test a temperatur e halfway between the cold and tepid levels. The aim of this study was to t est the quality of myocardial protection provided by intermediate lukewarm (20 degrees C) cardioplegia by comparing it with told and warm cardioplegia . Protection was assessed by measuring cardiac troponin I release. Methods: One hundred thirty-five patients undergoing coronary artery bypass graftin g were enrolled in a prospective randomized trial comparing cold (8 degrees C), intermediate lukewarm (20 degrees C), and warm (37 degrees C) antegrad e intermittent blood cardioplegia. Cardiac troponin I concentrations were m easured in serial venous blood samples, Results: The total amount of cardia c troponin I released was significantly higher in the cold group (4.7 +/- 2 .3 mu g) than in the intermediate lukewarm (3.4 +/- 2.0 mu g) or the warm ( 3.1 +/- 2.7 mu g) groups, The cardiac troponin I concentration was signific antly higher at hour 6 in the intermediate lukewarm group (1.23 +/- 0.55 mu g/L) than in the warm group (0.89 +/- 0.50 mu g/L). Conclusions: Intermitt ent antegrade intermediate lukewarm blood cardioplegia is appropriate and c linically safe, Cardiac troponin I release suggests that intermediate lukew arm cardioplegia is better than cold cardioplegia but less effective than w arm cardioplegia in low-risk patients, We therefore recommend the use of wa rm cardioplegia in low-risk patients.