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Ultrastructural changes of the dog myocardium in extracorporeal circulation
Insights
Cardiopulmonary bypass circulation causes subendocardial hemorrhage and myofibril degradation in cardiac muscle cells. These damages, particularly to the right ventricle, occur rapidly during bypass.
Area of Science:
- Cardiovascular Science
- Cellular Biology
- Surgical Research
Background:
- Cardiopulmonary bypass (CPB) is essential for cardiac surgery but can induce myocardial injury.
- Understanding the cellular effects of CPB is crucial for mitigating ischemia-reperfusion damage.
Purpose of the Study:
- To investigate the electron microscopic effects of cardiopulmonary bypass circulation on cardiac muscle cells.
- To compare the severity and onset of CPB-induced myocardial damage between the right and left ventricles.
Main Methods:
- Electron microscopy was used to examine cardiac muscle cell ultrastructure.
- Samples were analyzed after varying periods of cardiopulmonary bypass circulation.
Main Results:
- Subendocardial hemorrhage was observed in both ventricles, appearing earlier and more severely in the right ventricle.
- Myofibril degradation, evidenced by flocculent areas, occurred within 1 hour of bypass.
- Myocardial cells exhibited degenerative changes including zonal lesions, contraction bands, and mitochondrial alterations, with greater damage in the right ventricle.
Conclusions:
- Cardiopulmonary bypass induces significant ultrastructural damage to myocardial cells, including hemorrhage and myofibril degradation.
- The right ventricle is more susceptible to CPB-induced injury than the left ventricle.
- Early and severe cellular damage highlights the need for strategies to protect the myocardium during CPB.
Abstract:
The effects of the cardiopulmonary bypass circulation on the cardiac muscle cells were studied electron microscopically. Subendocardial hemorrhage was commonly recognized in both ventricles. However, it appeared earlier and more severely in the right ventricle than in the left ventricle. Clear flocculent areas containing numerous filamentous structures were originated from degradation of myofibrils. Degradation of myofibrils occurred within 1 hour after bypass circulation. Degenerative changes of myocardial cells such as zonal lesions, contraction bands and swelling or condensation of mitochondria appeared in both ventricles. Damages of myocardial cells in right ventricular wall were more severer as compared with those in the left throughout the period of observation.