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Protean causes of myocardial stunning in infants and adults
1Department of Surgery, University of California, Los Angeles 90024-1741.
Abstract:
Myocardial stunning can follow regional or global ischemia in the adult or immature heart. This report reviews some of our studies of the protean causes of stunning including energy and substrate depletion, inefficient oxygen utilization, calcium loading, acidosis, oxyradical damage, and summarizes studies and strategies to limit its occurrence. Data showing that reintroduction of molecular oxygen during reoxygenation of immature cyanotic hearts can cause stunning via a newly described biochemical pathway involving superoxide anion and nitric oxide are also included.
Insights
Myocardial stunning, a heart muscle dysfunction, stems from various factors like energy depletion and oxygen issues. New research reveals oxygen
Area of Science:
- Cardiovascular Physiology
- Biochemistry
- Neonatal Cardiology
Background:
- Myocardial stunning, a post-ischemic dysfunction, affects both adult and immature hearts.
- Multiple factors contribute to myocardial stunning, including metabolic disturbances and oxidative stress.
Purpose of the Study:
- To review the diverse causes of myocardial stunning.
- To summarize strategies for limiting myocardial stunning.
- To present novel findings on oxygen-induced stunning in immature hearts.
Main Methods:
- Review of existing studies on myocardial stunning.
- Analysis of biochemical pathways involved in myocardial stunning.
- Experimental data on immature cyanotic hearts during reoxygenation.
Main Results:
- Identified key causes of stunning: energy depletion, inefficient oxygen use, calcium overload, acidosis, and oxyradical damage.
- Demonstrated that reintroducing oxygen during reoxygenation can induce stunning in immature hearts.
- Uncovered a new pathway involving superoxide anion and nitric oxide in oxygen-induced stunning.
Conclusions:
- Myocardial stunning is multifactorial, involving metabolic and oxidative insults.
- Strategies to limit stunning should address these identified causes.
- Oxygen reintroduction can paradoxically cause stunning in immature hearts via a specific biochemical mechanism.