Background: There is a need for sensitive markers of ischemia and myocardial viability to guide transplantation and experimental heart perfusion strategies. In this study, we induced controlled ischemia in whole hearts to identify quantifiable electrical and optical indicators of perfusion mismatch and recovery potential.
Methods:
We used whole human and porcine hearts (n=6) that were reperfused in a Langendorff system and suspended in a hexagonal torso tank filled with a conductive solution. Ischemia was induced through a stepwise reduction of coronary flow, hypoxia, and temperature modulation (ranging from 37°C to 32°C). We recorded electrical signals using surface electrodes placed on the heart and 192 electrodes within the tank. Optical signals were captured through voltage-sensitive dye imaging. The metrics we analyzed included unipolar voltage, potential slope, conduction velocity, action potential duration (APD), and triangulation.Results: Ischemia caused significant reductions in unipolar voltage and optical action potential duration (APD), along with increased spatial dispersion and slowed conduction. Low-voltage areas and flattened optical upstrokes were observed in regions associated with impaired contractile recovery. We noted ST segment deviations and QRS prolongation in the torso signals. After reperfusion and rewarming, the electrophysiological markers partially normalized, indicating functional injury in reversible areas while persistent impairment remained in non-viable regions.
Conclusion: Controlled perfusion stress in ex vivo hearts demonstrates specific electrical and optical changes that predict myocardial viability. These findings support the development of marker-based tools for assessing viability in donation after circulation death (DCD) hearts and lay the groundwork for integrating real-time electrical mapping into transplant evaluation protocols.