Ultrastructural assessment of the infant myocardium receiving crystalloid cardioplegia
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Y Sawa1, H Matsuda, Y Shimazaki
1First Department of Surgery, Osaka University Medical School, Japan.
Insights
Cold crystalloid potassium cardioplegia did not fully prevent myocardial injury in infants undergoing heart repair. Infants with preoperative heart failure and those under 3 months old showed increased susceptibility to ischemic injury.
Area of Science:
- Cardiology
- Pediatric Cardiac Surgery
- Mitochondrial Biology
Background:
- Pediatric cardiac surgery often requires myocardial protection during procedures.
- Cold crystalloid potassium cardioplegia is a common method for myocardial protection.
- Infants represent a unique population with distinct physiological responses to cardiac surgery.
Purpose of the Study:
- To evaluate the effectiveness of cold crystalloid potassium cardioplegia in preventing myocardial injury in infants undergoing intracardiac repair.
- To assess factors influencing myocardial susceptibility to ischemic injury in this population.
Main Methods:
- Myocardial biopsy samples were collected from 26 infants before and after aortic cross-clamping (AXC).
- Semiquantitative assessment of mitochondrial structure was performed using a scoring system.
- Patient data including age and preoperative catecholamine support were analyzed.
Main Results:
- Post-AXC mitochondrial scores were significantly higher than pre-AXC scores, indicating myocardial injury.
- Patients on preoperative catecholamine support exhibited higher pre- and post-AXC scores.
- Infants under 3 months old showed significantly higher post-AXC scores compared to older infants.
Conclusions:
- Cold crystalloid potassium cardioplegia does not fully prevent myocardial injury in infants.
- Infants with preoperative heart failure and those younger than 3 months are more susceptible to ischemic injury during cardioplegia.
- Further research into optimized cardioplegia strategies for high-risk infant populations is warranted.
Abstract:
The effectiveness of cold crystalloid potassium cardioplegia was evaluated in 26 infants (age 27 days to 17 months, 7.5 +/- 5.2 months, mean +/- SD) who underwent intracardiac repair for various cardiac lesions. A myocardial biopsy sample was obtained before aortic cross-clamping (AXC) and 20 min after release of AXC (AXC time 22 to 161 min, mean 68 +/- 37 min), and semiquantitative assessment of the mitochondrial structure was made by scoring. The post-AXC score was significantly higher than the pre-AXC score (1.1 +/- 0.6 vs 0.4 +/- 0.4, p less than .001) for the whole group. Patients receiving preoperative catecholamine support had higher pre- and post-AXC scores than those who did not (pre-AXC score 0.7 +/- 0.4 vs 0.2 +/- 0.3, p less than .01; post-AXC score 1.4 +/- 0.5 vs 1.0 +/- 0.5, p less than .05). Infants less than 3 months old (n = 7) and those 3 to 12 months old (n = 11) had higher pre AXC scores than infants over 12 months old (n = 8). With respect to post-AXC score, only those less than 3 months old had significantly higher values than the other infants. These results indicate that the myocardial injury was not fully prevented by crystalloid potassium cardioplegia in infants, and that infants with preoperative heart failure and less than 3 months old appear to have increased myocardial susceptibility to ischemic injury under cardioplegia.