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In-vivo myocardial substrate alteration during perfused ventricular fibrillation
M G Angelos1, C A Torres, D P Rath
1Department of Emergency Medicine, The Ohio State University, Columbus 43210-1270, USA. angelos.1@osu.edu
Summary
Myocardial substrate utilization during ventricular fibrillation (VF) with perfusion mirrors that of a normally beating heart under increased workload, indicating similar metabolic adaptations despite the absence of contractions.
Area of Science:
- Cardiovascular Physiology
- Metabolic Research
- Cardiac Electrophysiology
Background:
- The heart's substrate utilization adapts to workload.
- Ventricular fibrillation (VF) presents high oxygen demands.
- Previous research suggests altered myocardial metabolism during cardiac stress.
Purpose of the Study:
- To investigate myocardial substrate utilization during VF with perfusion.
- To compare metabolic changes during VF with increased cardiac workload.
- To test the hypothesis that substrate utilization is similar in both conditions.
Main Methods:
- In-vivo porcine model using 13C-NMR spectroscopy.
- Studied substrate selection under increased workload (dobutamine) and perfused VF.
- Monitored glutamate pool labeling after infusing [2-13C] acetate.
Main Results:
- No significant baseline differences in blood markers between groups.
- Both dobutamine and VF groups showed decreased C4 glutamate labeling.
- This indicates a shift away from acetate oxidation in favor of endogenous substrates.
Conclusions:
- Myocardial substrate utilization during perfused VF resembles that of increased workload in a beating heart.
- Metabolic adaptations occur even without functional cardiac contractions.
- The heart prioritizes specific substrates under conditions of high demand, irrespective of contractile state.