# Multiplexed Fiber-Optic Fluorescence for Functional Monitoring of Perfused Hearts

## TL;DR

A new fiber-optic system allows real-time monitoring of heart function and biochemistry using fluorescence, offering insights into cardiac health and disease.

## Contribution

A novel multiexcitation fiber-optic platform enables simultaneous fluorescence and pressure measurements in perfused hearts.

## Key findings

- The system uses a fiber-optic balloon probe for concurrent optical and pressure measurements.
- A ratiometric approach improves accuracy by using paired fluorescence agents.
- TMRE is used as a noninvasive biomarker for mitochondrial membrane potential.

## Abstract

Monitoring molecular dynamics in the heart is essential
for advancing
our understanding of cardiac physiology and biochemistry in both healthy
and diseased states, as well as for guiding the development and evaluation
of novel cardiac therapies. We present a multiexcitation, ratiometric
fiber-optic spectroscopic platform for noninvasive, real-time monitoring
of biochemical and physiological processes in isolated Langendorff-perfused
rat hearts. The system employs a fiber-optic balloon probe capable
of concurrent optical measurements and intraventricular pressure sensing,
thereby providing complementary physiological data. A multiedge bandpass
filter enables parallel fluorescence spectroscopy, allowing simultaneous
detection and analysis of both exogenous and endogenous fluorophores.
Coupled with multivariate regression analysis, we demonstrate the
accurate quantification of fluorophore concentrations, facilitating
comprehensive assessment of cardiac biochemical and functional dynamics.
To mitigate geometric variability and motion artifacts, we developed
a robust ratiometric approach using paired fluorescence agents. We
demonstrate the system’s capability by employing the fluorescent
lipophilic cation tetramethylrhodamine ethyl ester (TMRE) as a noninvasive
biomarker for mitochondrial membrane potential, extracting physiologically
relevant metrics. This platform enables sensitive assessment of cardiac
function with established fluorescent probes and holds promising potential
as a versatile tool for investigating the dynamics of novel fluorophores.