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A reference-free optical method for assessing cardiac ischemia via NADH autofluorescence dynamics
M M Slotvitsky1,2,3, M S Medvedev1,2, G S Pashintsev1,2
1Department of Research and Development, ITMO University, St. Petersburg 197101, Russia.
Chaos (Woodbury, N.Y.)
|December 29, 2025
Summary
Researchers developed a new optical method to assess cardiac tissue metabolism and ischemia. This technique analyzes the nicotinamide adenine dinucleature (NAD+) to its reduced form (NADH) balance, overcoming limitations of current imaging methods.
Area of Science:
- Biophysics
- Metabolic Imaging
- Biochemistry
Background:
- Nicotinamide adenine dinucleotide (NAD+) to NADH conversion is crucial for cellular energy.
- NADH autofluorescence imaging detects metabolic dysfunction but is limited by intensity variations.
- Identifying invariant quantities is key to accurately assessing tissue injury.
Purpose of the Study:
- To develop a novel optical method for assessing tissue metabolic activity and ischemia.
- To overcome limitations of intensity-based NADH autofluorescence imaging.
- To identify invariant quantities responsive to reversible ischemic tissue injury.
Main Methods:
- Experimental and in silico modeling of the NAD+/NADH balance.
- Utilizing glutamate dehydrogenase (GDH) to drive a competing semi-equilibrium (CSE) state.
- Employing UV-induced NADH photolysis to simulate NADH to NAD+ conversion in ex vivo heart tissue.
Main Results:
- A competing semi-equilibrium (CSE) state was identified, dependent on total NAD(H), GDH concentration, and external catalytic activity.
- GDH activity was successfully estimated in cardiac epicardium by analyzing the CSE.
- The method allows assessment of cardiac ischemia without needing to know the photolysis rate.
Conclusions:
- A new approach for optical assessment of tissue metabolic activity using NADH autofluorescence imaging was established.
- This method offers a robust way to evaluate cardiac tissue ischemia, overcoming previous optical detection limitations.
- The competing semi-equilibrium analysis provides an invariant quantity for metabolic assessment.
