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Upgrading acellular to sanguineous cardioplegic efficacy
R W Illes1, N A Silverman, I B Krukenkamp
1Department of Surgery, University of Illinois Medical Center, Chicago 60680.
The Journal of Surgical Research
|June 1, 1989
Summary
Red blood cells protect the heart after ischemia by providing buffering capacity, preventing increased oxygen use. Free radical scavengers also offer protection, suggesting dual mechanisms for myoprotection during cardioplegic arrest.
Area of Science:
- Cardiology
- Biochemistry
- Physiology
Background:
- Myocardial oxygen consumption (MVO2) can increase after ischemic injury.
- Red blood cells (RBCs) in cardioplegia may offer protection against this injury.
- The specific RBC component responsible for this protective effect requires identification.
Purpose of the Study:
- To identify the specific biochemical factor in red blood cells that prevents increased postischemic myocardial oxygen consumption.
- To compare the protective effects of histidine and superoxide dismutase/catalase in preventing ischemic injury.
Main Methods:
- 28 canine hearts underwent cardioplegic arrest (2 hours at 10°C).
- Hearts were studied using right heart bypass with incremental volume loading before and after arrest.
- Measurements included stroke work (SW) and myocardial oxygen consumption (MVO2).
- Interventions included unmodified oxygenated crystalloid cardioplegia (OC), OC with histidine (OC + H), and OC with superoxide dismutase and catalase (OC + SOD/C).
Main Results:
- All groups maintained unchanged SW vs. end-diastolic volume (Mw) and SW vs. MVO2 (Me) relationships post-arrest.
- The OC group showed an augmented SW vs. MVO2 intercept (Eo), indicating increased MVO2.
- Both OC + H and OC + SOD/C groups prevented the augmentation of Eo, preserving normal MVO2.
- This suggests both buffering capacity and free radical scavenging contribute to myoprotection.
Conclusions:
- Buffering capacity, provided by histidine, is likely the primary RBC characteristic responsible for myoprotection.
- Free radical scavengers (superoxide dismutase and catalase) also ameliorate ischemic damage.
- These findings highlight the importance of buffering and antioxidant properties in cardioplegic solutions for preventing postischemic myocardial dysfunction.