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Updated: Jun 19, 2026
A Model of Long-Term Ventricular Fibrillation in Isolated Rat Hearts
Published on: February 17, 2023
Effect of global ischemia and reperfusion during ventricular fibrillation in myopathic human hearts
Stéphane Massé1, Talha Farid, Paul Dorian
1Division of Cardiology, Toronto General Hospital, GW 3-522, 150 Gerrard St. West, Toronto, ON, Canada M5G 2C4.
Insights
Global myocardial ischemia slows heart activation rate and organization during ventricular fibrillation (VF) in myopathic hearts. Short reperfusion periods quickly restore these vital functions, highlighting the importance of blood flow.
Area of Science:
- Cardiovascular Physiology
- Cardiac Electrophysiology
- Myocardial Ischemia Research
Background:
- Ventricular fibrillation (VF) is a life-threatening arrhythmia.
- The impact of global coronary hypoperfusion on VF dynamics in human hearts is poorly understood.
- Myopathic hearts may exhibit altered responses to ischemia during VF.
Purpose of the Study:
- To investigate the effects of global myocardial ischemia on activation rate and wavebreak during VF in human hearts.
- To determine if short reperfusion can reverse ischemia-induced changes in VF spatiotemporal dynamics.
- To test the hypothesis that ischemia decreases activation rate and organization while increasing wavebreak.
Main Methods:
- Utilized a human Langendorff model with myopathic hearts.
- Acquired electrograms during VF using simultaneous epicardial and endocardial mapping with 112-electrode arrays.
- Analyzed myocardial activation rate, gradient, and wavebreak index during ischemia and reperfusion.
Main Results:
- Global ischemia significantly slowed the global activation rate from 4.89 Hz to 3.60 Hz.
- An activation rate gradient and significant differences in wavebreak were observed between endocardium and epicardium during ischemia.
- Two minutes of reperfusion reversed these ischemia-induced changes, restoring activation rate near baseline levels.
Conclusions:
- Global myocardial ischemia profoundly alters VF spatiotemporal dynamics in myopathic human hearts.
- These alterations include reduced activation rate and increased wavebreak.
- Short-term reperfusion effectively reverses these detrimental effects, emphasizing the critical role of coronary perfusion.
Abstract:
The effect of lack of global coronary perfusion on myocardial activation rate, wavebreak, and its temporal progression during human ventricular fibrillation (VF) is not known. We tested the hypothesis that global myocardial ischemia decreases activation rate and spatiotemporal organization during VF in myopathic human hearts, while increasing wavebreak, and that a short duration of reperfusion can restore these spatiotemporal changes to baseline levels. The electrograms were acquired during VF in a human Langendorff model using global mapping consisting of two 112-electrode arrays placed on the epicardium and endocardium simultaneously. We found that global myocardial ischemia results in slowing of the global activation rate (combined endo and epi), from 4.89+/-0.04 Hz. to 3.60+/-0.04 Hz. during the 200 s of global ischemia (no coronary flow) (P<0.01) in eight myopathic hearts. Two minutes of reperfusion contributed to reversal of the slowing with activation rate value increasing close to VF onset (4.72+/-0.04 Hz). In addition, during the period of ischemia, an activation rate gradient between the endocardium (3.76+/-0.06 Hz) and epicardium (3.45+/-0.06 Hz) was observed (P<0.01). There was a concomitant difference in wavebreak index (that provides a normalized parameterization of phase singularities) between the epicardium (11.29+/-2.7) and endocardium (3.25+/-2.7) during the 200 s of ischemia (P=0.02). The activation rate, gradient, and wavebreak changes were reversed by short duration (2 min) of reperfusion. Global myocardial ischemia of 3 min leads to complex spatiotemporal changes during VF in myopathic human hearts; these changes can be reversed by a short duration of reperfusion.
