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

In the field of intermittent antegrade blood cardioplegia, 3 levels of temperature are commonly used: (1) cold (8 degrees C); (2) tepid (29 degrees C); and (3) warm (37 degrees C). Given the 21 degrees C spread and the metabolic changes that can occur between cold (8 degrees C) and tepid (29 degrees C) cardioplegia, we thought it worthwhile to test a temperature halfway between the cold and tepid levels. The aim of this study was to test the quality of myocardial protection provided by intermediate lukewarm (20 degrees C) cardioplegia by comparing it with cold and warm cardioplegia. Protection was assessed by measuring cardiac troponin I release.

One hundred thirty-five patients undergoing coronary artery bypass grafting were enrolled in a prospective randomized trial comparing cold (8 degrees C), intermediate lukewarm (20 degrees C), and warm (37 degrees C) antegrade intermittent blood cardioplegia. Cardiac troponin I concentrations were measured in serial venous blood samples.

The total amount of cardiac troponin I released was significantly higher in the cold group (4.7 +/- 2.3 microg) than in the intermediate lukewarm (3.4 +/- 2.0 microg) or the warm (3.1 +/- 2.7 microg) groups. The cardiac troponin I concentration was significantly higher at hour 6 in the intermediate lukewarm group (1. 23 +/- 0.55 microg/L) than in the warm group (0.89 +/- 0.50 microg/L).

Intermittent antegrade intermediate lukewarm blood cardioplegia is appropriate and clinically safe. Cardiac troponin I release suggests that intermediate lukewarm cardioplegia is better than cold cardioplegia but less effective than warm cardioplegia in low-risk patients. We therefore recommend the use of warm cardioplegia in low-risk patients.