Submitted on January 29, 2009
Revised on October 5, 2009
Accepted on October 5, 2009
The Effect of Global Ischemia and Reperfusion during Ventricular Fibrillation in Myopathic Human Hearts.
Stephane Masse1, Talha Farid, Paul Dorian2, Karthikeyan Umapathy, Krishnakumar Nair, John Asta, Heather Ross3, Vivek Rao4, Elias Sevaptsidis3, and Kumaraswamy Nanthakumar3*
1 University Health Network
2 St. Michael's Hospital
3 University of Toronto
4 University Health Network- Toronto General Hospital
* To whom correspondence should be addressed. E-mail: k.nanthakumar{at}uhn.on.ca.
The effect of lack of global coronary perfusion on myocardial activation rate, wavebreak and its temporal progression during human VF is not known. We tested the hypothesis that global myocardial ischemia decreases activation rate and spatio-temporal organization during VF in myopathic human hearts, while increasing wavebreak, and that a short duration of reperfusion can restore these spatio-temporal 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 activation rate, from 4.89 ± 0.04 Hz. to 3.60 ± 0.04 Hz. during the 200 seconds 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 normalised parameterisation of phase singularities) between the epicardium (11.29 ± 2.7) and endocardium (3.25 ± 2.7) during the 200s of ischemia (p = 0.02). The activation rate, gradient and wavebreak changes were reversed by short duration of reperfusion. Global myocardial ischemia of 3 minutes leads to complex spatio-temporal changes during VF in myopathic human hearts; these changes can be reversed by a short duration of reperfusion.
