Comparison of the effectiveness of myocardial preservation in right atrium and left ventricle.

Ten patients underwent cardiac operations during which myocardial preservation was provided by systemic hypothermia, topical cardiac cooling, and cold blood cardioplegia. The duration of ischemia ranged from 45 to 142 minutes (mean, 84.2 +/- 36.2 minutes). Two serial specimens (preischemic and ischemic) were obtained from the right atrium and the left ventricle, respectively; thus, a total of 40 biopsy specimens was obtained from these 10 patients. A combination of grading of ischemic injury and stereological morphometric measurement of mitochondria was performed to assess the effectiveness of myocardial preservation. Our findings from the mitochondrial score studies (grading of ischemic injury) were as follows. In the right atrium, the average mitochondrial score rose from 0.337 +/- 0.235 in the preischemic stage to 1.969 +/- 0.492 in the ischemic stage. In contrast, the average mitochondrial score for the left ventricle was only elevated from 0.380 +/- 0.161 to 1.353 +/- 0.396. The difference between preischemia of the right atrium and left ventricle is not statistically significant, but the difference between ischemia of these chambers is significant (p less than 0.01). Our stereological morphometric studies revealed that in the left ventricle, the average mitochondrial surface area was 0.316 +/- 0.046 micron 2 in the preischemic stage and 0.347 +/- 0.073 micron 2 in the ischemic stage, a 9.8% increase in mitochondrial size (not significant). In contrast, the mitochondrial surface area of the right atrium showed a mean increase of 65.8%, from 0.231 +/- 0.038 micron 2 in the preischemic stage to 0.383 +/- 0.057 micron 2 in the ischemic stage (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)